shared object - Page 417

How do I restrict concurrent statistics gathering to a small set of tables from a single schema?

- by Maria Colgan

I got an interesting question from one of my colleagues in the performance team last week about how to restrict a concurrent statistics gather to a small subset of tables from one schema, rather than the entire schema. I thought I would share the solution we came up with because it was rather elegant, and took advantage of concurrent statistics gathering, incremental statistics, and the not so well known “obj_filter_list” parameter in DBMS_STATS.GATHER_SCHEMA_STATS procedure. You should note that the solution outline below with “obj_filter_list” still applies, even when concurrent statistics gathering and/or incremental statistics gathering is disabled. The reason my colleague had asked the question in the first place was because he wanted to enable incremental statistics for 5 large partitioned tables in one schema. The first time you gather statistics after you enable incremental statistics on a table, you have to gather statistics for all of the existing partitions so that a synopsis may be created for them. If the partitioned table in question is large and contains a lot of partition, this could take a considerable amount of time. Since my colleague only had the Exadata environment at his disposal overnight, he wanted to re-gather statistics on 5 partition tables as quickly as possible to ensure that it all finished before morning. Prior to Oracle Database 11g Release 2, the only way to do this would have been to write a script with an individual DBMS_STATS.GATHER_TABLE_STATS command for each partition, in each of the 5 tables, as well as another one to gather global statistics on the table. Then, run each script in a separate session and manually manage how many of this session could run concurrently. Since each table has over one thousand partitions that would definitely be a daunting task and would most likely keep my colleague up all night! In Oracle Database 11g Release 2 we can take advantage of concurrent statistics gathering, which enables us to gather statistics on multiple tables in a schema (or database), and multiple (sub)partitions within a table concurrently. By using concurrent statistics gathering we no longer have to run individual statistics gathering commands for each partition. Oracle will automatically create a statistics gathering job for each partition, and one for the global statistics on each partitioned table. With the use of concurrent statistics, our script can now be simplified to just five DBMS_STATS.GATHER_TABLE_STATS commands, one for each table. This approach would work just fine but we really wanted to get this down to just one command. So how can we do that? You may be wondering why we didn’t just use the DBMS_STATS.GATHER_SCHEMA_STATS procedure with the OPTION parameter set to ‘GATHER STALE’. Unfortunately the statistics on the 5 partitioned tables were not stale and enabling incremental statistics does not mark the existing statistics stale. Plus how would we limit the schema statistics gather to just the 5 partitioned tables? So we went to ask one of the statistics developers if there was an alternative way. The developer told us the advantage of the “obj_filter_list” parameter in DBMS_STATS.GATHER_SCHEMA_STATS procedure. The “obj_filter_list” parameter allows you to specify a list of objects that you want to gather statistics on within a schema or database. The parameter takes a collection of type DBMS_STATS.OBJECTTAB. Each entry in the collection has 5 feilds; the schema name or the object owner, the object type (i.e., ‘TABLE’ or ‘INDEX’), object name, partition name, and subpartition name. You don't have to specify all five fields for each entry. Empty fields in an entry are treated as if it is a wildcard field (similar to ‘*’ character in LIKE predicates). Each entry corresponds to one set of filter conditions on the objects. If you have more than one entry, an object is qualified for statistics gathering as long as it satisfies the filter conditions in one entry. You first must create the collection of objects, and then gather statistics for the specified collection. It’s probably easier to explain this with an example. I’m using the SH sample schema but needed a couple of additional partitioned table tables to get recreate my colleagues scenario of 5 partitioned tables. So I created SALES2, SALES3, and COSTS2 as copies of the SALES and COSTS table respectively (setup.sql). I also deleted statistics on all of the tables in the SH schema beforehand to more easily demonstrate our approach. Step 0. Delete the statistics on the tables in the SH schema. Step 1. Enable concurrent statistics gathering. Remember, this has to be done at the global level. Step 2. Enable incremental statistics for the 5 partitioned tables. Step 3. Create the DBMS_STATS.OBJECTTAB and pass it to the DBMS_STATS.GATHER_SCHEMA_STATS command. Here, you will notice that we defined two variables of DBMS_STATS.OBJECTTAB type. The first, filter_lst, will be used to pass the list of tables we want to gather statistics on, and will be the value passed to the obj_filter_list parameter. The second, obj_lst, will be used to capture the list of tables that have had statistics gathered on them by this command, and will be the value passed to the objlist parameter. In Oracle Database 11g Release 2, you need to specify the objlist parameter in order to get the obj_filter_list parameter to work correctly due to bug 14539274. Will also needed to define the number of objects we would supply in the obj_filter_list. In our case we ere specifying 5 tables (filter_lst.extend(5)). Finally, we need to specify the owner name and object name for each of the objects in the list. Once the list definition is complete we can issue the DBMS_STATS.GATHER_SCHEMA_STATS command. Step 4. Confirm statistics were gathered on the 5 partitioned tables. Here are a couple of other things to keep in mind when specifying the entries for the obj_filter_list parameter. If a field in the entry is empty, i.e., null, it means there is no condition on this field. In the above example , suppose you remove the statement Obj_filter_lst(1).ownname := ‘SH’; You will get the same result since when you have specified gather_schema_stats so there is no need to further specify ownname in the obj_filter_lst. All of the names in the entry are normalized, i.e., uppercased if they are not double quoted. So in the above example, it is OK to use Obj_filter_lst(1).objname := ‘sales’;. However if you have a table called ‘MyTab’ instead of ‘MYTAB’, then you need to specify Obj_filter_lst(1).objname := ‘”MyTab”’; As I said before, although we have illustrated the usage of the obj_filter_list parameter for partitioned tables, with concurrent and incremental statistics gathering turned on, the obj_filter_list parameter is generally applicable to any gather_database_stats, gather_dictionary_stats and gather_schema_stats command. You can get a copy of the script I used to generate this post here. +Maria Colgan

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MapReduce in DryadLINQ and PLINQ

- by JoshReuben

MapReduce See http://en.wikipedia.org/wiki/Mapreduce The MapReduce pattern aims to handle large-scale computations across a cluster of servers, often involving massive amounts of data. "The computation takes a set of input key/value pairs, and produces a set of output key/value pairs. The developer expresses the computation as two Func delegates: Map and Reduce. Map - takes a single input pair and produces a set of intermediate key/value pairs. The MapReduce function groups results by key and passes them to the Reduce function. Reduce - accepts an intermediate key I and a set of values for that key. It merges together these values to form a possibly smaller set of values. Typically just zero or one output value is produced per Reduce invocation. The intermediate values are supplied to the user's Reduce function via an iterator." the canonical MapReduce example: counting word frequency in a text file. MapReduce using DryadLINQ see http://research.microsoft.com/en-us/projects/dryadlinq/ and http://connect.microsoft.com/Dryad DryadLINQ provides a simple and straightforward way to implement MapReduce operations. This The implementation has two primary components: A Pair structure, which serves as a data container. A MapReduce method, which counts word frequency and returns the top five words. The Pair Structure - Pair has two properties: Word is a string that holds a word or key. Count is an int that holds the word count. The structure also overrides ToString to simplify printing the results. The following example shows the Pair implementation. public struct Pair { private string word; private int count; public Pair(string w, int c) { word = w; count = c; } public int Count { get { return count; } } public string Word { get { return word; } } public override string ToString() { return word + ":" + count.ToString(); } } The MapReduce function that gets the results. the input data could be partitioned and distributed across the cluster. 1. Creates a DryadTable<LineRecord> object, inputTable, to represent the lines of input text. For partitioned data, use GetPartitionedTable<T> instead of GetTable<T> and pass the method a metadata file. 2. Applies the SelectMany operator to inputTable to transform the collection of lines into collection of words. The String.Split method converts the line into a collection of words. SelectMany concatenates the collections created by Split into a single IQueryable<string> collection named words, which represents all the words in the file. 3. Performs the Map part of the operation by applying GroupBy to the words object. The GroupBy operation groups elements with the same key, which is defined by the selector delegate. This creates a higher order collection, whose elements are groups. In this case, the delegate is an identity function, so the key is the word itself and the operation creates a groups collection that consists of groups of identical words. 4. Performs the Reduce part of the operation by applying Select to groups. This operation reduces the groups of words from Step 3 to an IQueryable<Pair> collection named counts that represents the unique words in the file and how many instances there are of each word. Each key value in groups represents a unique word, so Select creates one Pair object for each unique word. IGrouping.Count returns the number of items in the group, so each Pair object's Count member is set to the number of instances of the word. 5. Applies OrderByDescending to counts. This operation sorts the input collection in descending order of frequency and creates an ordered collection named ordered. 6. Applies Take to ordered to create an IQueryable<Pair> collection named top, which contains the 100 most common words in the input file, and their frequency. Test then uses the Pair object's ToString implementation to print the top one hundred words, and their frequency. public static IQueryable<Pair> MapReduce( string directory, string fileName, int k) { DryadDataContext ddc = new DryadDataContext("file://" + directory); DryadTable<LineRecord> inputTable = ddc.GetTable<LineRecord>(fileName); IQueryable<string> words = inputTable.SelectMany(x => x.line.Split(' ')); IQueryable<IGrouping<string, string>> groups = words.GroupBy(x => x); IQueryable<Pair> counts = groups.Select(x => new Pair(x.Key, x.Count())); IQueryable<Pair> ordered = counts.OrderByDescending(x => x.Count); IQueryable<Pair> top = ordered.Take(k); return top; } To Test: IQueryable<Pair> results = MapReduce(@"c:\DryadData\input", "TestFile.txt", 100); foreach (Pair words in results) Debug.Print(words.ToString()); Note: DryadLINQ applications can use a more compact way to represent the query: return inputTable .SelectMany(x => x.line.Split(' ')) .GroupBy(x => x) .Select(x => new Pair(x.Key, x.Count())) .OrderByDescending(x => x.Count) .Take(k); MapReduce using PLINQ The pattern is relevant even for a single multi-core machine, however. We can write our own PLINQ MapReduce in a few lines. the Map function takes a single input value and returns a set of mapped values àLINQ's SelectMany operator. These are then grouped according to an intermediate key à LINQ GroupBy operator. The Reduce function takes each intermediate key and a set of values for that key, and produces any number of outputs per key à LINQ SelectMany again. We can put all of this together to implement MapReduce in PLINQ that returns a ParallelQuery<T> public static ParallelQuery<TResult> MapReduce<TSource, TMapped, TKey, TResult>( this ParallelQuery<TSource> source, Func<TSource, IEnumerable<TMapped>> map, Func<TMapped, TKey> keySelector, Func<IGrouping<TKey, TMapped>, IEnumerable<TResult>> reduce) { return source .SelectMany(map) .GroupBy(keySelector) .SelectMany(reduce); } the map function takes in an input document and outputs all of the words in that document. The grouping phase groups all of the identical words together, such that the reduce phase can then count the words in each group and output a word/count pair for each grouping: var files = Directory.EnumerateFiles(dirPath, "*.txt").AsParallel(); var counts = files.MapReduce( path => File.ReadLines(path).SelectMany(line => line.Split(delimiters)), word => word, group => new[] { new KeyValuePair<string, int>(group.Key, group.Count()) });

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Restructuring a large Chrome Extension/WebApp

- by A.M.K

I have a very complex Chrome Extension that has gotten too large to maintain in its current format. I'd like to restructure it, but I'm 15 and this is the first webapp or extension of it's type I've built so I have no idea how to do it. TL;DR: I have a large/complex webapp I'd like to restructure and I don't know how to do it. Should I follow my current restructure plan (below)? Does that sound like a good starting point, or is there a different approach that I'm missing? Should I not do any of the things I listed? While it isn't relevant to the question, the actual code is on Github and the extension is on the webstore. The basic structure is as follows: index.html <html> <head> <link href="css/style.css" rel="stylesheet" />  <link href="css/widgets.css" rel="stylesheet" />  </head> <body class="unloaded">  <div class="tab-container" tabindex="-1">  </div>  <template id="template.toolbar">  </template>   <script type="text/javascript" src="js/plugins.js"></script>  <script type="text/javascript" src="js/widgets.js"></script>  <script type="text/javascript" src="js/script.js"></script> </body> </html> widgets.js (initLog || (window.initLog = [])).push([new Date().getTime(), "A log is kept during page load so performance can be analyzed and errors pinpointed"]); // Widgets are stored in an object and extended (with jQuery, but I'll probably switch to underscore if using Backbone) as necessary var Widgets = { 1: { // Widget ID, this is set here so widgets can be retreived by ID id: 1, // Widget ID again, this is used after the widget object is duplicated and detached size: 3, // Default size, medium in this case order: 1, // Order shown in "store" name: "Weather", // Widget name interval: 300000, // Refresh interval nicename: "weather", // HTML and JS safe widget name sizes: ["tiny", "small", "medium"], // Available widget sizes desc: "Short widget description", settings: [ { // Widget setting specifications stored as an array of objects. These are used to dynamically generate widget setting popups. type: "list", nicename: "location", label: "Location(s)", placeholder: "Enter a location and press Enter" } ], config: { // Widget settings as stored in the tabs object (see script.js for storage information) size: "medium", location: ["San Francisco, CA"] }, data: {}, // Cached widget data stored locally, this lets it work offline customFunc: function(cb) {}, // Widgets can optionally define custom functions in any part of their object refresh: function() {}, // This fetches data from the web and caches it locally in data, then calls render. It gets called after the page is loaded for faster loads render: function() {} // This renders the widget only using information from data, it's called on page load. } }; script.js (initLog || (window.initLog = [])).push([new Date().getTime(), "These are also at the end of every file"]); // Plugins, extends and globals go here. i.e. Number.prototype.pad = .... var iChrome = function(refresh) { // The main iChrome init, called with refresh when refreshing to not re-run libs iChrome.Status.log("Starting page generation"); // From now on iChrome.Status.log is defined, it's used in place of the initLog iChrome.CSS(); // Dynamically generate CSS based on settings iChrome.Tabs(); // This takes the tabs stored in the storage (see fetching below) and renders all columns and widgets as necessary iChrome.Status.log("Tabs rendered"); // These will be omitted further along in this excerpt, but they're used everywhere // Checks for justInstalled => show getting started are run here /* The main init runs the bare minimum required to display the page, this sets all non-visible or instantly need things (such as widget dragging) on a timeout */ iChrome.deferredTimeout = setTimeout(function() { iChrome.deferred(refresh); // Pass refresh along, see above }, 200); }; iChrome.deferred = function(refresh) {}; // This calls modules one after the next in the appropriate order to finish rendering the page iChrome.Search = function() {}; // Modules have a base init function and are camel-cased and capitalized iChrome.Search.submit = function(val) {}; // Methods within modules are camel-cased and not capitalized /* Extension storage is async and fetched at the beginning of plugins.js, it's then stored in a variable that iChrome.Storage processes. The fetcher checks to see if processStorage is defined, if it is it gets called, otherwise settings are left in iChromeConfig */ var processStorage = function() { iChrome.Storage(function() { iChrome.Templates(); // Templates are read from their elements and held in a cache iChrome(); // Init is called }); }; if (typeof iChromeConfig == "object") { processStorage(); } Objectives of the restructure Memory usage: Chrome apparently has a memory leak in extensions, they're trying to fix it but memory still keeps on getting increased every time the page is loaded. The app also uses a lot on its own. Code readability: At this point I can't follow what's being called in the code. While rewriting the code I plan on properly commenting everything. Module interdependence: Right now modules call each other a lot, AFAIK that's not good at all since any change you make to one module could affect countless others. Fault tolerance: There's very little fault tolerance or error handling right now. If a widget is causing the rest of the page to stop rendering the user should at least be able to remove it. Speed is currently not an issue and I'd like to keep it that way. How I think I should do it The restructure should be done using Backbone.js and events that call modules (i.e. on storage.loaded = init). Modules should each go in their own file, I'm thinking there should be a set of core files that all modules can rely on and call directly and everything else should be event based. Widget structure should be kept largely the same, but maybe they should also be split into their own files. AFAIK you can't load all templates in a folder, therefore they need to stay inline. Grunt should be used to merge all modules, plugins and widgets into one file. Templates should also all be precompiled. Question: Should I follow my current restructure plan? Does that sound like a good starting point, or is there a different approach that I'm missing? Should I not do any of the things I listed? Do applications written with Backbone tend to be more intensive (memory and speed) than ones written in Vanilla JS? Also, can I expect to improve this with a proper restructure or is my current code about as good as can be expected?

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Part 3 of 4 : Tips/Tricks for Silverlight Developers.

- by mbcrump

Part 1 | Part 2 | Part 3 | Part 4 I wanted to create a series of blog post that gets right to the point and is aimed specifically at Silverlight Developers. The most important things I want this series to answer is : What is it? Why do I care? How do I do it? I hope that you enjoy this series. Let’s get started: Tip/Trick #11) What is it? Underline Text in a TextBlock. Why do I care? I’ve seen people do some crazy things to get underlined text in a Silverlight Application. In case you didn’t know there is a property for that. How do I do it: On a TextBlock you have a property called TextDecorations. You can easily set this property in XAML or CodeBehind with the following snippet: <UserControl x:Class="SilverlightApplication19.MainPage" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400"> <Grid x:Name="LayoutRoot" Background="White"> <TextBlock Name="txtTB" Text="MichaelCrump.NET" TextDecorations="Underline" /> </Grid> </UserControl> or you can do it in CodeBehind… txtTB.TextDecorations = TextDecorations.Underline; Tip/Trick #12) What is it? Get the browser information from a Silverlight Application. Why do I care? This will allow you to program around certain browser conditions that otherwise may not be aware of. How do I do it: It is very easy to extract Browser Information out a Silverlight Application by using the BrowserInformation class. You can copy/paste this code snippet to have access to all of them. string strBrowserName = HtmlPage.BrowserInformation.Name; string strBrowserMinorVersion = HtmlPage.BrowserInformation.BrowserVersion.Minor.ToString(); string strIsCookiesEnabled = HtmlPage.BrowserInformation.CookiesEnabled.ToString(); string strPlatform = HtmlPage.BrowserInformation.Platform; string strProductName = HtmlPage.BrowserInformation.ProductName; string strProductVersion = HtmlPage.BrowserInformation.ProductVersion; string strUserAgent = HtmlPage.BrowserInformation.UserAgent; string strBrowserVersion = HtmlPage.BrowserInformation.BrowserVersion.ToString(); string strBrowserMajorVersion = HtmlPage.BrowserInformation.BrowserVersion.Major.ToString(); Tip/Trick #13) What is it? Always check the minRuntimeVersion after creating a new Silverlight Application. Why do I care? Whenever you create a new Silverlight Application and host it inside of an ASP.net website you will notice Visual Studio generates some code for you as shown below. The minRuntimeVersion value is set by the SDK installed on your system. Be careful, if you are playing with beta’s like “Lightswitch” because you will have a higher version of the SDK installed. So when you create a new Silverlight 4 project and deploy it your customers they will get a prompt telling them they need to upgrade Silverlight. They also will not be able to upgrade to your version because its not released to the public yet. How do I do it: Open up the .aspx or .html file Visual Studio generated and look for the line below. Make sure it matches whatever version you are actually targeting. Tip/Trick #14) What is it? The VisualTreeHelper class provides useful methods for involving nodes in a visual tree. Why do I care? It’s nice to have the ability to “walk” a visual tree or to get the rendered elements of a ListBox. I have it very useful for debugging my Silverlight application. How do I do it: Many examples exist on the web, but say that you have a huge Silverlight application and want to find the parent object of a control. In the code snippet below, we would get 3 MessageBoxes with (StackPanel first, Grid second and UserControl Third). This is a tiny application, but imagine how helpful this would be on a large project. <UserControl x:Class="SilverlightApplication18.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400"> <Grid x:Name="LayoutRoot" Background="White"> <StackPanel> <Button Content="Button" Height="23" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" /> </StackPanel> </Grid> </UserControl> private void button1_Click(object sender, RoutedEventArgs e) { DependencyObject obj = button1; while ((obj = VisualTreeHelper.GetParent(obj)) != null) { MessageBox.Show(obj.GetType().ToString()); } } Tip/Trick #15) What is it? Add ChildWindows to your Silverlight Application. Why do I care? ChildWindows are a great way to direct a user attention to a particular part of your application. This could be used when saving or entering data. How do I do it: Right click your Silverlight Application and click Add then New Item. Select Silverlight Child Window as shown below. Add an event and call the ChildWindow with the following snippet below: private void button1_Click(object sender, RoutedEventArgs e) { ChildWindow1 cw = new ChildWindow1(); cw.Show(); } Your main application can still process information but this screen forces the user to select an action before proceeding. The code behind of the ChildWindow will look like the following: namespace SilverlightApplication18 { public partial class ChildWindow1 : ChildWindow { public ChildWindow1() { InitializeComponent(); } private void OKButton_Click(object sender, RoutedEventArgs e) { this.DialogResult = true; //TODO: Add logic to save what the user entered. } private void CancelButton_Click(object sender, RoutedEventArgs e) { this.DialogResult = false; } } } Thanks for reading and please come back for Part 4. Subscribe to my feed CodeProject

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Silverlight 4 + WCF RIA - Data Service Design Best Practices

- by Chadd Nervig

Hey all. I realize this is a rather long question, but I'd really appreciate any help from anyone experienced with RIA services. Thanks! I'm working on a Silverlight 4 app that views data from the server. I'm relatively inexperienced with RIA Services, so have been working through the tasks of getting the data I need down to the client, but every new piece I add to the puzzle seems to be more and more problematic. I feel like I'm missing some basic concepts here, and it seems like I'm just 'hacking' pieces on, in time-consuming ways, each one breaking the previous ones as I try to add them. I'd love to get the feedback of developers experienced with RIA services, to figure out the intended way to do what I'm trying to do. Let me lay out what I'm trying to do: First, the data. The source of this data is a variety of sources, primarily created by a shared library which reads data from our database, and exposes it as POCOs (Plain Old CLR Objects). I'm creating my own POCOs to represent the different types of data I need to pass between server and client. DataA - This app is for viewing a certain type of data, lets call DataA, in near-realtime. Every 3 minutes, the client should pull data down from the server, of all the new DataA since the last time it requested data. DataB - Users can view the DataA objects in the app, and may select one of them from the list, which displays additional details about that DataA. I'm bringing these extra details down from the server as DataB. DataC - One of the things that DataB contains is a history of a couple important values over time. I'm calling each data point of this history a DataC object, and each DataB object contains many DataCs. The Data Model - On the server side, I have a single DomainService: [EnableClientAccess] public class MyDomainService : DomainService { public IEnumerable<DataA> GetDataA(DateTime? startDate) { /*Pieces together the DataAs that have been created since startDate, and returns them*/ } public DataB GetDataB(int dataAID) { /*Looks up the extended info for that dataAID, constructs a new DataB with that DataA's data, plus the extended info (with multiple DataCs in a List<DataC> property on the DataB), and returns it*/ } //Not exactly sure why these are here, but I think it //wouldn't compile without them for some reason? The data //is entirely read-only, so I don't need to update. public void UpdateDataA(DataA dataA) { throw new NotSupportedException(); } public void UpdateDataB(DataB dataB) { throw new NotSupportedException(); } } The classes for DataA/B/C look like this: [KnownType(typeof(DataB))] public partial class DataA { [Key] [DataMember] public int DataAID { get; set; } [DataMember] public decimal MyDecimalA { get; set; } [DataMember] public string MyStringA { get; set; } [DataMember] public DataTime MyDateTimeA { get; set; } } public partial class DataB : DataA { [Key] [DataMember] public int DataAID { get; set; } [DataMember] public decimal MyDecimalB { get; set; } [DataMember] public string MyStringB { get; set; } [Include] //I don't know which of these, if any, I need? [Composition] [Association("DataAToC","DataAID","DataAID")] public List<DataC> DataCs { get; set; } } public partial class DataC { [Key] [DataMember] public int DataAID { get; set; } [Key] [DataMember] public DateTime Timestamp { get; set; } [DataMember] public decimal MyHistoricDecimal { get; set; } } I guess a big question I have here is... Should I be using Entities instead of POCOs? Are my classes constructed correctly to be able to pass the data down correctly? Should I be using Invoke methods instead of Query (Get) methods on the DomainService? On the client side, I'm having a number of issues. Surprisingly, one of my biggest ones has been threading. I didn't expect there to be so many threading issues with MyDomainContext. What I've learned is that you only seem to be able to create MyDomainContextObjects on the UI thread, all of the queries you can make are done asynchronously only, and that if you try to fake doing it synchronously by blocking the calling thread until the LoadOperation finishes, you have to do so on a background thread, since it uses the UI thread to make the query. So here's what I've got so far. The app should display a stream of the DataA objects, spreading each 3min chunk of them over the next 3min (so they end up displayed 3min after the occurred, looking like a continuous stream, but only have to be downloaded in 3min bursts). To do this, the main form initializes, creates a private MyDomainContext, and starts up a background worker, which continuously loops in a while(true). On each loop, it checks if it has any DataAs left over to display. If so, it displays that Data, and Thread.Sleep()s until the next DataA is scheduled to be displayed. If it's out of data, it queries for more, using the following methods: public DataA[] GetDataAs(DateTime? startDate) { _loadOperationGetDataACompletion = new AutoResetEvent(false); LoadOperation<DataA> loadOperationGetDataA = null; loadOperationGetDataA = _context.Load(_context.GetDataAQuery(startDate), System.ServiceModel.DomainServices.Client.LoadBehavior.RefreshCurrent, false); loadOperationGetDataA.Completed += new EventHandler(loadOperationGetDataA_Completed); _loadOperationGetDataACompletion.WaitOne(); List<DataA> dataAs = new List<DataA>(); foreach (var dataA in loadOperationGetDataA.Entities) dataAs.Add(dataA); return dataAs.ToArray(); } private static AutoResetEvent _loadOperationGetDataACompletion; private static void loadOperationGetDataA_Completed(object sender, EventArgs e) { _loadOperationGetDataACompletion.Set(); } Seems kind of clunky trying to force it into being synchronous, but since this already is on a background thread, I think this is OK? So far, everything actually works, as much of a hack as it seems like it may be. It's important to note that if I try to run that code on the UI thread, it locks, because it waits on the WaitOne() forever, locking the thread, so it can't make the Load request to the server. So once the data is displayed, users can click on one as it goes by to fill a details pane with the full DataB data about that object. To do that, I have the the details pane user control subscribing to a selection event I have setup, which gets fired when the selection changes (on the UI thread). I use a similar technique there, to get the DataB object: void SelectionService_SelectedDataAChanged(object sender, EventArgs e) { DataA dataA = /*Get the selected DataA*/; MyDomainContext context = new MyDomainContext(); var loadOperationGetDataB = context.Load(context.GetDataBQuery(dataA.DataAID), System.ServiceModel.DomainServices.Client.LoadBehavior.RefreshCurrent, false); loadOperationGetDataB.Completed += new EventHandler(loadOperationGetDataB_Completed); } private void loadOperationGetDataB_Completed(object sender, EventArgs e) { this.DataContext = ((LoadOperation<DataB>)sender).Entities.SingleOrDefault(); } Again, it seems kinda hacky, but it works... except on the DataB that it loads, the DataCs list is empty. I've tried all kinds of things there, and I don't see what I'm doing wrong to allow the DataCs to come down with the DataB. I'm about ready to make a 3rd query for the DataCs, but that's screaming even more hackiness to me. It really feels like I'm fighting against the grain here, like I'm doing this in an entirely unintended way. If anyone could offer any assistance, and point out what I'm doing wrong here, I'd very much appreciate it! Thanks!

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Ninject.ActivationException: Error activating IMainLicense

- by Stefan Karlsson

Im don't know fully how Ninject works thats wye i ask this question here to figure out whats wrong. If i create a empty constructor in ClaimsSecurityService it gets hit. This is my error: Error activating IMainLicense No matching bindings are available, and the type is not self-bindable. Activation path: 3) Injection of dependency IMainLicense into parameter mainLicenses of constructor of type ClaimsSecurityService 2) Injection of dependency ISecurityService into parameter securityService of constructor of type AccountController 1) Request for AccountController Stack: Ninject.KernelBase.Resolve(IRequest request) +474 Ninject.Planning.Targets.Target`1.GetValue(Type service, IContext parent) +153 Ninject.Planning.Targets.Target`1.ResolveWithin(IContext parent) +747 Ninject.Activation.Providers.StandardProvider.GetValue(IContext context, ITarget target) +269 Ninject.Activation.Providers.<>c__DisplayClass4.<Create>b__2(ITarget target) +69 System.Linq.WhereSelectArrayIterator`2.MoveNext() +66 System.Linq.Buffer`1..ctor(IEnumerable`1 source) +216 System.Linq.Enumerable.ToArray(IEnumerable`1 source) +77 Ninject.Activation.Providers.StandardProvider.Create(IContext context) +847 Ninject.Activation.Context.ResolveInternal(Object scope) +218 Ninject.Activation.Context.Resolve() +277 Ninject.<>c__DisplayClass15.<Resolve>b__f(IBinding binding) +86 System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +145 System.Linq.Enumerable.SingleOrDefault(IEnumerable`1 source) +4059897 Ninject.Planning.Targets.Target`1.GetValue(Type service, IContext parent) +169 Ninject.Planning.Targets.Target`1.ResolveWithin(IContext parent) +747 Ninject.Activation.Providers.StandardProvider.GetValue(IContext context, ITarget target) +269 Ninject.Activation.Providers.<>c__DisplayClass4.<Create>b__2(ITarget target) +69 System.Linq.WhereSelectArrayIterator`2.MoveNext() +66 System.Linq.Buffer`1..ctor(IEnumerable`1 source) +216 System.Linq.Enumerable.ToArray(IEnumerable`1 source) +77 Ninject.Activation.Providers.StandardProvider.Create(IContext context) +847 Ninject.Activation.Context.ResolveInternal(Object scope) +218 Ninject.Activation.Context.Resolve() +277 Ninject.<>c__DisplayClass15.<Resolve>b__f(IBinding binding) +86 System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +145 System.Linq.Enumerable.SingleOrDefault(IEnumerable`1 source) +4059897 Ninject.Web.Mvc.NinjectDependencyResolver.GetService(Type serviceType) +145 System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +87 [InvalidOperationException: An error occurred when trying to create a controller of type 'Successful.Struct.Web.Controllers.AccountController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +247 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +438 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +257 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +326 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +157 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +88 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +50 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +301 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Account controller: public class AccountController : Controller { private readonly ISecurityService _securityService; public AccountController(ISecurityService securityService) { _securityService = securityService; } // // GET: /Account/Login [AllowAnonymous] public ActionResult Login(string returnUrl) { ViewBag.ReturnUrl = returnUrl; return View(); } } NinjectWebCommon: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Http; using System.Web.Http.Dependencies; using Microsoft.Web.Infrastructure.DynamicModuleHelper; using Ninject; using Ninject.Extensions.Conventions; using Ninject.Parameters; using Ninject.Syntax; using Ninject.Web.Common; using Successful.Struct.Web; [assembly: WebActivator.PreApplicationStartMethod(typeof(NinjectWebCommon), "Start")] [assembly: WebActivator.ApplicationShutdownMethodAttribute(typeof(NinjectWebCommon), "Stop")] namespace Successful.Struct.Web { public static class NinjectWebCommon { private static readonly Bootstrapper Bootstrapper = new Bootstrapper(); /// <summary> /// Starts the application /// </summary> public static void Start() { DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule)); DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule)); Bootstrapper.Initialize(CreateKernel); } /// <summary> /// Stops the application. /// </summary> public static void Stop() { Bootstrapper.ShutDown(); } /// <summary> /// Creates the kernel that will manage your application. /// </summary> /// <returns>The created kernel.</returns> private static IKernel CreateKernel() { var kernel = new StandardKernel(); kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel); kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>(); kernel.Load("Successful*.dll"); kernel.Bind(x => x.FromAssembliesMatching("Successful*.dll") .SelectAllClasses() .BindAllInterfaces() ); GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel); RegisterServices(kernel); return kernel; } /// <summary> /// Load your modules or register your services here! /// </summary> /// <param name="kernel">The kernel.</param> private static void RegisterServices(IKernel kernel) { } } public class NinjectResolver : NinjectScope, IDependencyResolver { private readonly IKernel _kernel; public NinjectResolver(IKernel kernel) : base(kernel) { _kernel = kernel; } public IDependencyScope BeginScope() { return new NinjectScope(_kernel.BeginBlock()); } } public class NinjectScope : IDependencyScope { protected IResolutionRoot ResolutionRoot; public NinjectScope(IResolutionRoot kernel) { ResolutionRoot = kernel; } public object GetService(Type serviceType) { var request = ResolutionRoot.CreateRequest(serviceType, null, new Parameter[0], true, true); return ResolutionRoot.Resolve(request).SingleOrDefault(); } public IEnumerable<object> GetServices(Type serviceType) { var request = ResolutionRoot.CreateRequest(serviceType, null, new Parameter[0], true, true); return ResolutionRoot.Resolve(request).ToList(); } public void Dispose() { var disposable = (IDisposable)ResolutionRoot; if (disposable != null) disposable.Dispose(); ResolutionRoot = null; } } } ClaimsSecurityService: public class ClaimsSecurityService : ISecurityService { private const string AscClaimsIdType = "http://schemas.microsoft.com/accesscontrolservice/2010/07/claims/identityprovider"; private const string SuccessfulStructWebNamespace = "Successful.Struct.Web"; private readonly IMainLicense _mainLicenses; private readonly ICompany _companys; private readonly IAuthTokenService _authService; [Inject] public IApplicationContext ApplicationContext { get; set; } [Inject] public ILogger<LocationService> Logger { get; set; } public ClaimsSecurityService(IMainLicense mainLicenses, ICompany companys, IAuthTokenService authService) { _mainLicenses = mainLicenses; _companys = companys; _authService = authService; } }

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How to use Ninject with XNA?

- by Rosarch

I'm having difficulty integrating Ninject with XNA. static class Program { /** * The main entry point for the application. */ static void Main(string[] args) { IKernel kernel = new StandardKernel(NinjectModuleManager.GetModules()); CachedContentLoader content = kernel.Get<CachedContentLoader>(); // stack overflow here MasterEngine game = kernel.Get<MasterEngine>(); game.Run(); } } // constructor for the game public MasterEngine(IKernel kernel) : base(kernel) { this.inputReader = kernel.Get<IInputReader>(); graphicsDeviceManager = kernel.Get<GraphicsDeviceManager>(); Components.Add(kernel.Get<GamerServicesComponent>()); // Tell the loader to look for all files relative to the "Content" directory. Assets = kernel.Get<CachedContentLoader>(); //Sets dimensions of the game window graphicsDeviceManager.PreferredBackBufferWidth = 800; graphicsDeviceManager.PreferredBackBufferHeight = 600; graphicsDeviceManager.ApplyChanges(); IsMouseVisible = false; } Ninject.cs: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Ninject.Modules; using HWAlphaRelease.Controller; using Microsoft.Xna.Framework; using Nuclex.DependencyInjection.Demo.Scaffolding; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.Graphics; namespace HWAlphaRelease { public static class NinjectModuleManager { public static NinjectModule[] GetModules() { return new NinjectModule[1] { new GameModule() }; } /// <summary>Dependency injection rules for the main game instance</summary> public class GameModule : NinjectModule { #region class ServiceProviderAdapter /// <summary>Delegates to the game's built-in service provider</summary> /// <remarks> /// <para> /// When a class' constructor requires an IServiceProvider, the dependency /// injector cannot just construct a new one and wouldn't know that it has /// to create an instance of the Game class (or take it from the existing /// Game instance). /// </para> /// <para> /// The solution, then, is this small adapter that takes a Game instance /// and acts as if it was a freely constructable IServiceProvider implementation /// while in reality, it delegates all lookups to the Game's service container. /// </para> /// </remarks> private class ServiceProviderAdapter : IServiceProvider { /// <summary>Initializes a new service provider adapter for the game</summary> /// <param name="game">Game the service provider will be taken from</param> public ServiceProviderAdapter(Game game) { this.gameServices = game.Services; } /// <summary>Retrieves a service from the game service container</summary> /// <param name="serviceType">Type of the service that will be retrieved</param> /// <returns>The service that has been requested</returns> public object GetService(Type serviceType) { return this.gameServices; } /// <summary>Game services container of the Game instance</summary> private GameServiceContainer gameServices; } #endregion // class ServiceProviderAdapter #region class ContentManagerAdapter /// <summary>Delegates to the game's built-in ContentManager</summary> /// <remarks> /// This provides shared access to the game's ContentManager. A dependency /// injected class only needs to require the ISharedContentService in its /// constructor and the dependency injector will automatically resolve it /// to this adapter, which delegates to the Game's built-in content manager. /// </remarks> private class ContentManagerAdapter : ISharedContentService { /// <summary>Initializes a new shared content manager adapter</summary> /// <param name="game">Game the content manager will be taken from</param> public ContentManagerAdapter(Game game) { this.contentManager = game.Content; } /// <summary>Loads or accesses shared game content</summary> /// <typeparam name="AssetType">Type of the asset to be loaded or accessed</typeparam> /// <param name="assetName">Path and name of the requested asset</param> /// <returns>The requested asset from the the shared game content store</returns> public AssetType Load<AssetType>(string assetName) { return this.contentManager.Load<AssetType>(assetName); } /// <summary>The content manager this instance delegates to</summary> private ContentManager contentManager; } #endregion // class ContentManagerAdapter /// <summary>Initializes the dependency configuration</summary> public override void Load() { // Allows access to the game class for any components with a dependency // on the 'Game' or 'DependencyInjectionGame' classes. Bind<MasterEngine>().ToSelf().InSingletonScope(); Bind<NinjectGame>().To<MasterEngine>().InSingletonScope(); Bind<Game>().To<MasterEngine>().InSingletonScope(); // Let the dependency injector construct a graphics device manager for // all components depending on the IGraphicsDeviceService and // IGraphicsDeviceManager interfaces Bind<GraphicsDeviceManager>().ToSelf().InSingletonScope(); Bind<IGraphicsDeviceService>().To<GraphicsDeviceManager>().InSingletonScope(); Bind<IGraphicsDeviceManager>().To<GraphicsDeviceManager>().InSingletonScope(); // Some clever adapters that hand out the Game's IServiceProvider and allow // access to its built-in ContentManager Bind<IServiceProvider>().To<ServiceProviderAdapter>().InSingletonScope(); Bind<ISharedContentService>().To<ContentManagerAdapter>().InSingletonScope(); Bind<IInputReader>().To<UserInputReader>().InSingletonScope().WithConstructorArgument("keyMapping", Constants.DEFAULT_KEY_MAPPING); Bind<CachedContentLoader>().ToSelf().InSingletonScope().WithConstructorArgument("rootDir", "Content"); } } } } NinjectGame.cs /// <summary>Base class for Games making use of Ninject</summary> public class NinjectGame : Game { /// <summary>Initializes a new Ninject game instance</summary> /// <param name="kernel">Kernel the game has been created by</param> public NinjectGame(IKernel kernel) { Type ownType = this.GetType(); if(ownType != typeof(Game)) { kernel.Bind<NinjectGame>().To<MasterEngine>().InSingletonScope(); } kernel.Bind<Game>().To<NinjectGame>().InSingletonScope(); } } } // namespace Nuclex.DependencyInjection.Demo.Scaffolding When I try to get the CachedContentLoader, I get a stack overflow exception. I'm basing this off of this tutorial, but I really have no idea what I'm doing. Help?

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Where is this System.MissingMethodException occurring? How can I tell?

- by Jeremy Holovacs

I am a newbie to ASP.NET MVC (v2), and I am trying to use a strongly-typed view tied to a model object that contains two optional multi-select listbox objects. Upon clicking the submit button, these objects may have 0 or more values selected for them. My model class looks like this: using System; using System.Web.Mvc; using System.Collections.Generic; namespace ModelClasses.Messages { public class ComposeMessage { public bool is_html { get; set; } public bool is_urgent { get; set; } public string message_subject { get; set; } public string message_text { get; set; } public string action { get; set; } public MultiSelectList recipients { get; set; } public MultiSelectList recipient_roles { get; set; } public ComposeMessage() { this.is_html = false; this.is_urgent = false; this.recipients = new MultiSelectList(new Dictionary<int, string>(), "Key", "Value"); this.recipient_roles = new MultiSelectList(new Dictionary<int, string>(), "Key", "Value"); } } } My view looks like this: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<ModelClasses.Messages.ComposeMessage>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">Compose A Message </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2> Compose A New Message:</h2> <br /> <span id="navigation_top"> <%= Html.ActionLink("\\Home", "Index", "Home") %><%= Html.ActionLink("\\Messages", "Home") %></span> <% using (Html.BeginForm()) { %> <fieldset> <legend>Message Headers</legend> <label for="message_subject"> Subject:</label> <%= Html.TextBox("message_subject")%> <%= Html.ValidationMessage("message_subject")%> <label for="selected_recipients"> Recipient Users:</label> <%= Html.ListBox("recipients") %> <%= Html.ValidationMessage("selected_recipients")%> <label for="selected_recipient_roles"> Recipient Roles:</label> <%= Html.ListBox("recipient_roles") %> <%= Html.ValidationMessage("selected_recipient_roles")%> <label for="is_urgent"> Urgent?</label> <%= Html.CheckBox("is_urgent") %> <%= Html.ValidationMessage("is_urgent")%> </fieldset> <fieldset> <legend>Message Text</legend> <%= Html.TextArea("message_text") %> <%= Html.ValidationMessage("message_text")%> </fieldset> <input type="reset" name="reset" id="reset" value="Reset" /> <input type="submit" name="action" id="send_message" value="Send" /> <% } %> <span id="navigation_bottom"> <%= Html.ActionLink("\\Home", "Index", "Home") %><%= Html.ActionLink("\\Messages", "Home") %></span> </asp:Content> <asp:Content ID="Content3" ContentPlaceHolderID="Scripts" runat="server"> </asp:Content> I have a parameterless ActionResult in my MessagesController like this: [Authorize] public ActionResult ComposeMessage() { ModelClasses.Messages.ComposeMessage FormData = new ModelClasses.Messages.ComposeMessage(); Common C = (Common)Session["Common"]; FormData.recipients = new MultiSelectList(C.AvailableUsers, "Key", "Value"); FormData.recipient_roles = new MultiSelectList(C.AvailableRoles, "Key", "Value"); return View(FormData); } ...and my model-based controller looks like this: [Authorize, AcceptVerbs(HttpVerbs.Post)] public ActionResult ComposeMessage(DCASS3.Classes.Messages.ComposeMessage FormData) { DCASSUser CurrentUser = (DCASSUser)Session["CurrentUser"]; Common C = (Common)Session["Common"]; //... (business logic) return View(FormData); } Problem is, I can access the page fine before a submit. When I actually make selections and press the submit button, however, I get: Server Error in '/' Application. No parameterless constructor defined for this object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.MissingMethodException: No parameterless constructor defined for this object. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [MissingMethodException: No parameterless constructor defined for this object.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 System.Activator.CreateInstance(Type type) +6 System.Web.Mvc.DefaultModelBinder.CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType) +307 System.Web.Mvc.DefaultModelBinder.BindSimpleModel(ControllerContext controllerContext, ModelBindingContext bindingContext, ValueProviderResult valueProviderResult) +495 System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +473 System.Web.Mvc.DefaultModelBinder.GetPropertyValue(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder) +45 System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor) +642 System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext controllerContext, ModelBindingContext bindingContext) +144 System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Object model) +95 System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +2386 System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +539 System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +447 System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +173 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +801 System.Web.Mvc.Controller.ExecuteCore() +151 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +105 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +36 System.Web.Mvc.<c_DisplayClass8.b_4() +65 System.Web.Mvc.Async.<c_DisplayClass1.b_0() +44 System.Web.Mvc.Async.<c__DisplayClass81.<BeginSynchronous>b__7(IAsyncResult _) +42 System.Web.Mvc.Async.WrappedAsyncResult1.End() +140 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +52 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +36 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8677678 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Version Information: Microsoft .NET Framework Version:2.0.50727.3603; ASP.NET Version:2.0.50727.3082 This error shows up before I can trap it. I have no idea where it's choking, or what it's choking on. I don't see any point of this model that cannot be created with a parameterless constructor, and I can't find out where it's dying... Help is appreciated, thanks. -Jeremy

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Getting ClassCastException with JSF 1.2 Custom Component and BEA 10.3

- by Tobi

Im getting a ClassCastException if i use Attributes in my Custom Headline Tag. Without Attributes rendering works fine. Calling <t:headline value="test" /> gives a ClassCastException even before a Method in my HeadlineComponent or HeadlineTag-Class is called. <t:headline /> works fine. I'm using MyFaces-1.2, on BEA 10.3 default.jsp <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <%@ taglib prefix="f" uri="http://java.sun.com/jsf/core"%> <%@ taglib prefix="h" uri="http://java.sun.com/jsf/html"%> <%@ taglib prefix="t" uri="http://www.tobi.de/taglibrary" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Tobi Test</title> </head> <body> <f:view> <t:headline value="test" /> </f:view> </body> </html> HeadlineComponent.java package tobi.web.component.headline; import java.io.IOException; import javax.el.ValueExpression; import javax.faces.component.UIOutput; import javax.faces.context.FacesContext; import javax.faces.context.ResponseWriter; public class HeadlineComponent extends UIOutput { private String value; private Integer size; @Override public Object saveState(FacesContext context) { Object values[] = new Object[3]; values[0] = super.saveState(context); values[1] = value; values[2] = size; return ((Object)(values)); } @Override public void restoreState(FacesContext context, Object state) { Object values[] = (Object[])state; super.restoreState(context, values[0]); value = (String)values[1]; size = (Integer)values[2]; } @Override public void encodeBegin(FacesContext context) throws IOException { // Wenn keine Groesse angegeben wurde default 3 String htmlTag = (size == null) ? "h3" : "h"+getSize().toString(); ResponseWriter writer = context.getResponseWriter(); writer.startElement(htmlTag, this); if(value == null) { writer.write(""); } else { writer.write(value); } writer.endElement(htmlTag); writer.flush(); } public String getValue() { if(value != null) { return value; } ValueExpression ve = getValueExpression("value"); if(ve != null) { return (String)ve.getValue(getFacesContext().getELContext()); } return null; } public void setValue(String value) { this.value = value; } public Integer getSize() { if(size != null) { return size; } ValueExpression ve = getValueExpression("size"); if(ve != null) { return (Integer)ve.getValue(getFacesContext().getELContext()); } return null; } public void setSize(Integer size) { if(size>6) size = 6; if(size<1) size = 1; this.size = size; } } HeadlineTag.java package tobi.web.component.headline; import javax.el.ValueExpression; import javax.faces.component.UIComponent; import javax.faces.webapp.UIComponentELTag; public class HeadlineTag extends UIComponentELTag { private ValueExpression value; private ValueExpression size; @Override public String getComponentType() { return "tobi.headline"; } @Override public String getRendererType() { // null, da wir hier keinen eigenen Render benutzen return null; } protected void setProperties(UIComponent component) { super.setProperties(component); HeadlineComponent headline = (HeadlineComponent)component; if(value != null) { if(value.isLiteralText()) { headline.getAttributes().put("value", value.getExpressionString()); } else { headline.setValueExpression("value", value); } } if(size != null) { if(size.isLiteralText()) { headline.getAttributes().put("size", size.getExpressionString()); } else { headline.setValueExpression("size", size); } } } @Override public void release() { super.release(); this.value = null; this.size = null; } public ValueExpression getValue() { return value; } public void setValue(ValueExpression value) { this.value = value; } public ValueExpression getSize() { return size; } public void setSize(ValueExpression size) { this.size = size; } } taglibrary.tld <?xml version="1.0" encoding="UTF-8" ?> <taglib xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd" version="2.1"> <description>Tobi Webclient Taglibrary</description> <tlib-version>1.0</tlib-version> <short-name>tobi-taglibrary</short-name> <uri>http://www.tobi.de/taglibrary</uri> <tag> <description>Eine Überschrift im HTML-Stil</description> <name>headline</name> <tag-class>tobi.web.component.headline.HeadlineTag</tag-class> <body-content>empty</body-content> <attribute> <description>Der Text der Überschrift</description> <name>value</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <description>Die Größe der Überschrift nach HTML (h1 - h6)</description> <name>size</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib> faces-config.xml <?xml version="1.0" encoding="UTF-8"?> <faces-config xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_1_2.xsd" version="1.2"> <component> <description>Erzeugt eine Überschrift nach HTML-Stil</description> <display-name>headline</display-name> <component-type>tobi.headline</component-type> <component-class>tobi.web.component.headline.HeadlineComponent</component-class> <attribute> <attribute-name>value</attribute-name> <attribute-class>java.lang.String</attribute-class> </attribute> <attribute> <attribute-name>size</attribute-name> <attribute-class>java.lang.Integer</attribute-class> <default-value>3</default-value> </attribute> </component> </faces-config>

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Array help Index out of range exeption was unhandled

- by Michael Quiles

I am trying to populate combo boxes from a text file using comma as a delimiter everything was working fine, but now when I debug I get the "Index out of range exeption was unhandled" warning. I guess I need a fresh pair of eyes to see where I went wrong, I commented on the line that gets the error //Fname = fields[1]; using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Drawing.Printing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO; namespace Sullivan_Payroll { public partial class xEmpForm : Form { bool complete = false; public xEmpForm() { InitializeComponent(); } private void xEmpForm_Resize(object sender, EventArgs e) { this.xCenterPanel.Left = Convert.ToInt16((this.Width - this.xCenterPanel.Width) / 2); this.xCenterPanel.Top = Convert.ToInt16((this.Height - this.xCenterPanel.Height) / 2); Refresh(); } private void exitToolStripMenuItem_Click(object sender, EventArgs e) { //Exits the application this.Close(); } private void xEmpForm_FormClosing(object sender, FormClosingEventArgs e) //use this on xtrip calculator { DialogResult Response; if (complete == true) { Application.Exit(); } else { Response = MessageBox.Show("Are you sure you want to Exit?", "Exit", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2); if (Response == DialogResult.No) { complete = false; e.Cancel = true; } else { complete = true; Application.Exit(); } } } private void xEmpForm_Load(object sender, EventArgs e) { //file sources string fileDept = "source\\Department.txt"; string fileSex = "source\\Sex.txt"; string fileStatus = "source\\Status.txt"; if (File.Exists(fileDept)) { using (System.IO.StreamReader sr = System.IO.File.OpenText(fileDept)) { string dept = ""; while ((dept = sr.ReadLine()) != null) { this.xDeptComboBox.Items.Add(dept); } } } else { MessageBox.Show("The Department file can not be found.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } if (File.Exists(fileSex)) { using (System.IO.StreamReader sr = System.IO.File.OpenText(fileSex)) { string sex = ""; while ((sex = sr.ReadLine()) != null) { this.xSexComboBox.Items.Add(sex); } } } else { MessageBox.Show("The Sex file can not be found.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } if (File.Exists(fileStatus)) { using (System.IO.StreamReader sr = System.IO.File.OpenText(fileStatus)) { string status = ""; while ((status = sr.ReadLine()) != null) { this.xStatusComboBox.Items.Add(status); } } } else { MessageBox.Show("The Status file can not be found.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } } private void xFileSaveMenuItem_Click(object sender, EventArgs e) { { const string fileNew = "source\\New Staff.txt"; string recordIn; FileStream outFile = new FileStream(fileNew, FileMode.Create, FileAccess.Write); StreamWriter writer = new StreamWriter(outFile); for (int count = 0; count <= this.xEmployeeListBox.Items.Count - 1; count++) { this.xEmployeeListBox.SelectedIndex = count; recordIn = this.xEmployeeListBox.SelectedItem.ToString(); writer.WriteLine(recordIn); } writer.Close(); outFile.Close(); this.xDeptComboBox.SelectedIndex = -1; this.xStatusComboBox.SelectedIndex = -1; this.xSexComboBox.SelectedIndex = -1; MessageBox.Show("your file is saved"); } } private void xViewFacultyMenuItem_Click(object sender, EventArgs e) { const string fileStaff = "source\\Staff.txt"; const char DELIM = ','; string Lname, Fname, Depart, Stat, Sex, Salary, cDept, cStat, cSex; double Gtotal; string recordIn; string[] fields; cDept = this.xDeptComboBox.SelectedItem.ToString(); cStat = this.xStatusComboBox.SelectedItem.ToString(); cSex = this.xSexComboBox.SelectedItem.ToString(); FileStream inFile = new FileStream(fileStaff, FileMode.Open, FileAccess.Read); StreamReader reader = new StreamReader(inFile); recordIn = reader.ReadLine(); while (recordIn != null) { fields = recordIn.Split(DELIM); Lname = fields[0]; Fname = fields[1]; // this is where the error appears Depart = fields[2]; Stat = fields[3]; Sex = fields[4]; Salary = fields[5]; Fname = fields[1].TrimStart(null); Depart = fields[2].TrimStart(null); Stat = fields[3].TrimStart(null); Sex = fields[4].TrimStart(null); Salary = fields[5].TrimStart(null); Gtotal = double.Parse(Salary); if (Depart == cDept && cStat == Stat && cSex == Sex) { this.xEmployeeListBox.Items.Add(recordIn); } recordIn = reader.ReadLine(); } reader.Close(); inFile.Close(); if (this.xEmployeeListBox.Items.Count >= 1) { this.xFileSaveMenuItem.Enabled = true; this.xFilePrintMenuItem.Enabled = true; this.xEditClearMenuItem.Enabled = true; } else { this.xFileSaveMenuItem.Enabled = false; this.xFilePrintMenuItem.Enabled = false; this.xEditClearMenuItem.Enabled = false; MessageBox.Show("Records not found"); } } private void xEditClearMenuItem_Click(object sender, EventArgs e) { this.xEmployeeListBox.Items.Clear(); this.xDeptComboBox.SelectedIndex = -1; this.xStatusComboBox.SelectedIndex = -1; this.xSexComboBox.SelectedIndex = -1; this.xFileSaveMenuItem.Enabled = false; this.xFilePrintMenuItem.Enabled = false; this.xEditClearMenuItem.Enabled = false; } } } Source file -- Anderson, Kristen, Accounting, Assistant, Female, 43155 Ball, Robin, Accounting, Instructor, Female, 42723 Chin, Roger, Accounting, Full, Male,59281 Coats, William, Accounting, Assistant, Male, 45371 Doepke, Cheryl, Accounting, Full, Female, 52105 Downs, Clifton, Accounting, Associate, Male, 46887 Garafano, Karen, Finance, Associate, Female, 49000 Hill, Trevor, Management, Instructor, Male, 38590 Jackson, Carole, Accounting, Instructor, Female, 38781 Jacobson, Andrew, Management, Full, Male, 56281 Lewis, Karl, Management, Associate, Male, 48387 Mack, Kevin, Management, Assistant, Male, 45000 McKaye, Susan, Management, Instructor, Female, 43979 Nelsen, Beth, Finance, Full, Female, 52339 Nelson, Dale, Accounting, Full, Male, 54578 Palermo, Sheryl, Accounting, Associate, Female, 45617 Rais, Mary, Finance, Instructor, Female, 27000 Scheib, Earl, Management, Instructor, Male, 37389 Smith, Tom, Finance, Full, Male, 57167 Smythe, Janice, Management, Associate, Female, 46887 True, David, Accounting, Full, Male, 53181 Young, Jeff, Management, Assistant, Male, 43513

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Ideas for multiplatform encrypted java mobile storage system

- by Fernando Miguélez

Objective I am currently designing the API for a multiplatform storage system that would offer same interface and capabilities accross following supported mobile Java Platforms: J2ME. Minimum configuration/profile CLDC 1.1/MIDP 2.0 with support for some necessary JSRs (JSR-75 for file storage). Android. No minimum platform version decided yet, but rather likely could be API level 7. Blackberry. It would use the same base source of J2ME but taking advantage of some advaced capabilities of the platform. No minimum configuration decided yet (maybe 4.6 because of 64 KB limitation for RMS on 4.5). Basically the API would sport three kind of stores: Files. These would allow standard directory/file manipulation (read/write through streams, create, mkdir, etc.). Preferences. It is a special store that handles properties accessed through keys (Similar to plain old java properties file but supporting some improvements such as different value data types such as SharedPreferences on Android platform) Local Message Queues. This store would offer basic message queue functionality. Considerations Inspired on JSR-75, all types of stores would be accessed in an uniform way by means of an URL following RFC 1738 conventions, but with custom defined prefixes (i.e. "file://" for files, "prefs://" for preferences or "queue://" for message queues). The address would refer to a virtual location that would be mapped to a physical storage object by each mobile platform implementation. Only files would allow hierarchical storage (folders) and access to external extorage memory cards (by means of a unit name, the same way as in JSR-75, but that would not change regardless of underlying platform). The other types would only support flat storage. The system should also support a secure version of all basic types. The user would indicate it by prefixing "s" to the URL (i.e. "sfile://" instead of "file://"). The API would only require one PIN (introduced only once) to access any kind of secure object types. Implementation issues For the implementation of both plaintext and encrypted stores, I would use the functionality available on the underlying platforms: Files. These are available on all platforms (J2ME only with JSR-75, but it is mandatory for our needs). The abstract File to actual File mapping is straight except for addressing issues. RMS. This type of store available on J2ME (and Blackberry) platforms is convenient for Preferences and maybe Message Queues (though depending on performance or size requirements these could be implemented by means of normal files). SharedPreferences. This type of storage, only available on Android, would match Preferences needs. SQLite databases. This could be used for message queues on Android (and maybe Blackberry). When it comes to encryption some requirements should be met: To ease the implementation it will be carried out on read/write operations basis on streams (for files), RMS Records, SharedPreferences key-value pairs, SQLite database columns. Every underlying storage object should use the same encryption key. Handling of encrypted stores should be the same as the unencrypted counterpart. The only difference (from the user point of view) accessing an encrypted store would be the addressing. The user PIN provides access to any secure storage object, but the change of it would not require to decrypt/re-encrypt all the encrypted data. Cryptographic capabilities of underlying platform should be used whenever it is possible, so we would use: J2ME: SATSA-CRYPTO if it is available (not mandatory) or lightweight BoncyCastle cryptographic framework for J2ME. Blackberry: RIM Cryptographic API or BouncyCastle Android: JCE with integraced cryptographic provider (BouncyCastle?) Doubts Having reached this point I was struck by some doubts about what solution would be more convenient, taking into account the limitation of the plataforms. These are some of my doubts: Encryption Algorithm for data. Would AES-128 be strong and fast enough? What alternatives for such scenario would you suggest? Encryption Mode. I have read about the weakness of ECB encryption versus CBC, but in this case the first would have the advantage of random access to blocks, which is interesting for seek functionality on files. What type of encryption mode would you choose instead? Is stream encryption suitable for this case? Key generation. There could be one key generated for each storage object (file, RMS RecordStore, etc.) or just use one for all the objects of the same type. The first seems "safer", though it would require some extra space on device. In your opinion what would the trade-offs of each? Key storage. For this case using a standard JKS (or PKCS#12) KeyStore file could be suited to store encryption keys, but I could also define a smaller structure (encryption-transformation / key data / checksum) that could be attached to each storage store (i.e. using addition files with the same name and special extension for plain files or embedded inside other types of objects such as RMS Record Stores). What approach would you prefer? And when it comes to using a standard KeyStore with multiple-key generation (given this is your preference), would it be better to use a record-store per storage object or just a global KeyStore keeping all keys (i.e. using the URL identifier of abstract storage object as alias)? Master key. The use of a master key seems obvious. This key should be protected by user PIN (introduced only once) and would allow access to the rest of encryption keys (they would be encrypted by means of this master key). Changing the PIN would only require to reencrypt this key and not all the encrypted data. Where would you keep it taking into account that if this got lost all data would be no further accesible? What further considerations should I take into account? Platform cryptography support. Do SATSA-CRYPTO-enabled J2ME phones really take advantage of some dedicated hardware acceleration (or other advantage I have not foreseen) and would this approach be prefered (whenever possible) over just BouncyCastle implementation? For the same reason is RIM Cryptographic API worth the license cost over BouncyCastle? Any comments, critics, further considerations or different approaches are welcome.

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Setting an XAML Window always on top (but no TopMost property)

- by Brian Scherady

I am developing an application based on OptiTrack SDK (from NaturalPoint). I need to run the application window as "Always on Top". The window is designed in XAML and is controled in the class "CameraView" but it does not seem to include a "TopMost" property or equivalent. Attached are the code of "CameraView.xaml.cs" and the code of "CameraView.xaml" that are part of OptiTrack SDK (NaturalPoint) called "Single_Camera_CSharp_.NET_3.0". One could expect the class CameraView to contain properties or members to set the position of the window on the screen or to set it to TopMost but as far as searched I found nothing. I wonder what I should do. Thank you, Brian ================ "CameraView.xaml.cs" using System; using System.IO; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Navigation; using System.Drawing.Imaging; using System.Drawing.Drawing2D; using System.Windows.Threading; namespace TestProject { public partial class CameraView { private const int NP_OPTION_OBJECT_COLOR_OPTION = 3; private const int NP_OPTION_VIDEO_TYPE = 48; private const int NP_OPTION_NUMERIC_DISPLAY_ON = 71; private const int NP_OPTION_NUMERIC_DISPLAY_OFF = 72; private const int NP_OPTION_FETCH_RLE = 73; private const int NP_OPTION_FETCH_GRAYSCALE = 74; private const int NP_OPTION_FRAME_DECIMATION = 52; private const int NP_OPTION_INTENSITY = 50; private const int NP_OPTION_SEND_EMPTY_FRAMES = 41; private const int NP_OPTION_THRESHOLD = 5; private const int NP_OPTION_EXPOSURE = 46; private const int NP_OPTION_SEND_FRAME_MASK = 73; private const int NP_OPTION_TEXT_OVERLAY_OPTION = 74; // public delegate void OnCameraViewCreate(CameraView camera); // public static OnCameraViewCreate onCameraViewCreate; private System.Drawing.Bitmap raw = new System.Drawing.Bitmap(353, 288, System.Drawing.Imaging.PixelFormat.Format32bppArgb); private int mFrameCounter; private int mDisplayCounter; private DispatcherTimer timer1 = new DispatcherTimer(); private bool mVideoFrameAvailable = false; private int mNumeric = -1; private bool mGreyscale = false; private bool mOverlay = true; public CameraView() { this.InitializeComponent(); timer1.Interval = new TimeSpan(0, 0, 0, 0, 10); timer1.Tick += new EventHandler(timer1_Tick); } public int Numeric { get { return mNumeric; } set { mNumeric = value % 100; if (mNumeric = 0) { if (Camera != null) Camera.SetOption(NP_OPTION_NUMERIC_DISPLAY_ON, value % 100); } } } private bool CameraRunning = false; private OptiTrack.NPCamera mCamera; public OptiTrack.NPCamera Camera { get { return mCamera; } set { if (mCamera == value) return; //== Don't do anything if you're assigning the same camera == if (mCamera != null) { //== Shut the selected camera down ==<< if (CameraRunning) { CameraRunning = false; mCamera.Stop(); mCamera.FrameAvailable -= FrameAvailable; } } mCamera = value; if (mCamera == null) { mNumeric = -1; } else { serialLabel.Content = "Camera "+mCamera.SerialNumber.ToString(); //mNumeric.ToString(); } } } private void FrameAvailable(OptiTrack.NPCamera Camera) { mFrameCounter++; try { OptiTrack.NPCameraFrame frame = Camera.GetFrame(0); int id = frame.Id; if (CameraRunning) { GetFrameData(Camera, frame); } frame.Free(); } catch (Exception) { int r = 0; r++; } } private void GetFrameData(OptiTrack.NPCamera camera, OptiTrack.NPCameraFrame frame) { BitmapData bmData = raw.LockBits(new System.Drawing.Rectangle(0, 0, raw.Width, raw.Height), ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb); int stride = bmData.Stride; System.IntPtr bufferPtr = bmData.Scan0; unsafe { byte* buffer = (byte*)(void*)bufferPtr; camera.GetFrameImage(frame, bmData.Width, bmData.Height, bmData.Stride, 32, ref buffer[0]); } raw.UnlockBits(bmData); mVideoFrameAvailable = true; } private void timer1_Tick(object sender, EventArgs e) { if (CameraRunning && mVideoFrameAvailable) { mVideoFrameAvailable = false; cameraImage.Source = Img(raw); mDisplayCounter++; } } private System.Windows.Media.ImageSource Img(System.Drawing.Bitmap img) { System.Drawing.Imaging.BitmapData bmData = img.LockBits(new System.Drawing.Rectangle(0, 0, img.Width, img.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppPArgb); System.Windows.Media.Imaging.BitmapSource bitmap = System.Windows.Media.Imaging.BitmapSource.Create( img.Width, img.Height, 96, 96, PixelFormats.Bgra32, System.Windows.Media.Imaging.BitmapPalettes.WebPalette, bmData.Scan0, bmData.Stride * bmData.Height, bmData.Stride); img.UnlockBits(bmData); return bitmap; } private void startStopButton_Click(object sender, RoutedEventArgs e) { if (CameraRunning) StopCamera(); else StartCamera(); } public void StartCamera() { if (Camera != null) { mFrameCounter = 0; mDisplayCounter = 0; Camera.FrameAvailable += FrameAvailable; Camera.SetOption(NP_OPTION_VIDEO_TYPE, 0); Camera.SetOption(NP_OPTION_FRAME_DECIMATION, 1); Camera.SetOption(NP_OPTION_INTENSITY, 0); Camera.SetOption(NP_OPTION_EXPOSURE, 10); Camera.SetOption(NP_OPTION_THRESHOLD, 50); Camera.SetOption(NP_OPTION_OBJECT_COLOR_OPTION, 0); SetOverlayOption(); SetGreyscaleOption(); timer1.Start(); Camera.Start(); CameraRunning = true; this.Numeric = mNumeric; startStopButton.Content = "Stop Camera"; } } private void SetGreyscaleOption() { if(mGreyscale) Camera.SetOption(NP_OPTION_VIDEO_TYPE, 1); else Camera.SetOption(NP_OPTION_VIDEO_TYPE, 0); } private void SetOverlayOption() { if(mOverlay) Camera.SetOption(NP_OPTION_TEXT_OVERLAY_OPTION, 255); else Camera.SetOption(NP_OPTION_TEXT_OVERLAY_OPTION, 0); } public void StopCamera() { if (Camera != null) { Camera.Stop(); timer1.Stop(); CameraRunning = false; Camera.FrameAvailable -= FrameAvailable; Camera.SetOption(NP_OPTION_NUMERIC_DISPLAY_OFF, 0); startStopButton.Content = "Start Camera"; } } private void greyscaleButton_Click(object sender, RoutedEventArgs e) { if(mGreyscale) mGreyscale = false; else mGreyscale = true; SetGreyscaleOption(); } private void OverlayButton_Click(object sender, RoutedEventArgs e) { if(mOverlay) mOverlay = false; else mOverlay = true; SetOverlayOption(); } private void exposureSlider_ValueChanged(object sender, RoutedEventArgs e) { if (mCamera!=null) { mCamera.SetOption(NP_OPTION_EXPOSURE, (int) this.exposureSlider.Value); } } private void thresholdSlider_ValueChanged(object sender, RoutedEventArgs e) { if (mCamera != null) { mCamera.SetOption(NP_OPTION_THRESHOLD, (int)this.thresholdSlider.Value); } } private void optionsButton_Click(object sender, RoutedEventArgs e) { if (!propertyPanel.IsVisible) propertyPanel.Visibility = Visibility.Visible; else propertyPanel.Visibility = Visibility.Collapsed; } } } ================ "CameraView.xaml"

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How would I define "GetDataFromNumber" so that my class contains a definition?

- by JB

My code gets an error saying: 'Eagle_Eye_Class_Finder.GetSchedule' does not contain a definition for 'GetDataFromNumber' and no extension method 'GetDataFromNumber'. using System; using System.IO; using System.Data; using System.Text; using System.Drawing; using System.Data.OleDb; using System.Collections; using System.Windows.Forms; using System.ComponentModel; using System.Drawing.Printing; using System.Collections.Generic; namespace Eagle_Eye_Class_Finder { /// This form is the entry form, it is the first form the user will see when the app is run. /// public class Form1 : System.Windows.Forms.Form { private System.Windows.Forms.TextBox textBox1; private System.Windows.Forms.ProgressBar progressBar1; private System.Windows.Forms.PictureBox pictureBox1; private System.Windows.Forms.Button button2; private System.Windows.Forms.DateTimePicker dateTimePicker1; private IContainer components; private Timer timer1; private BindingSource form1BindingSource; public static Form Mainform = null; // creates new instance of second form YOURCLASSSCHEDULE SecondForm = new YOURCLASSSCHEDULE(); public Form1() { InitializeComponent(); // TODO: Add any constructor code after InitializeComponent call } /// Clean up any resources being used. protected override void Dispose(bool disposing) { if (disposing) { if (components != null) { components.Dispose(); } } base.Dispose(disposing); } #region Windows Form Designer generated code /// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { this.components = new System.ComponentModel.Container(); System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(Form1)); this.textBox1 = new System.Windows.Forms.TextBox(); this.progressBar1 = new System.Windows.Forms.ProgressBar(); this.pictureBox1 = new System.Windows.Forms.PictureBox(); this.button2 = new System.Windows.Forms.Button(); this.dateTimePicker1 = new System.Windows.Forms.DateTimePicker(); this.timer1 = new System.Windows.Forms.Timer(this.components); this.form1BindingSource = new System.Windows.Forms.BindingSource(this.components); ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit(); ((System.ComponentModel.ISupportInitialize)(this.form1BindingSource)).BeginInit(); this.SuspendLayout(); // // textBox1 // this.textBox1.BackColor = System.Drawing.SystemColors.ActiveCaption; this.textBox1.DataBindings.Add(new System.Windows.Forms.Binding("Text", this.form1BindingSource, "Text", true, System.Windows.Forms.DataSourceUpdateMode.OnValidation, null, "900456317")); this.textBox1.Location = new System.Drawing.Point(328, 280); this.textBox1.Name = "textBox1"; this.textBox1.Size = new System.Drawing.Size(208, 20); this.textBox1.TabIndex = 2; this.textBox1.TextChanged += new System.EventHandler(this.textBox1_TextChanged); // // progressBar1 // this.progressBar1.Location = new System.Drawing.Point(258, 410); this.progressBar1.MarqueeAnimationSpeed = 10; this.progressBar1.Name = "progressBar1"; this.progressBar1.Size = new System.Drawing.Size(344, 8); this.progressBar1.TabIndex = 3; this.progressBar1.Click += new System.EventHandler(this.progressBar1_Click); // // pictureBox1 // this.pictureBox1.BackColor = System.Drawing.SystemColors.ControlLightLight; this.pictureBox1.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D; this.pictureBox1.Image = ((System.Drawing.Image)(resources.GetObject("pictureBox1.Image"))); this.pictureBox1.Location = new System.Drawing.Point(680, 400); this.pictureBox1.Name = "pictureBox1"; this.pictureBox1.Size = new System.Drawing.Size(120, 112); this.pictureBox1.TabIndex = 4; this.pictureBox1.TabStop = false; this.pictureBox1.Click += new System.EventHandler(this.pictureBox1_Click); // // button2 // this.button2.Font = new System.Drawing.Font("Mistral", 15.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0))); this.button2.Image = ((System.Drawing.Image)(resources.GetObject("button2.Image"))); this.button2.Location = new System.Drawing.Point(699, 442); this.button2.Name = "button2"; this.button2.Size = new System.Drawing.Size(78, 28); this.button2.TabIndex = 5; this.button2.Text = "OK"; this.button2.Click += new System.EventHandler(this.button2_Click); // // dateTimePicker1 // this.dateTimePicker1.Location = new System.Drawing.Point(336, 104); this.dateTimePicker1.Name = "dateTimePicker1"; this.dateTimePicker1.Size = new System.Drawing.Size(200, 20); this.dateTimePicker1.TabIndex = 6; this.dateTimePicker1.ValueChanged += new System.EventHandler(this.dateTimePicker1_ValueChanged); // // timer1 // this.timer1.Tick += new System.EventHandler(this.timer1_Tick); // // form1BindingSource // this.form1BindingSource.DataSource = typeof(Eagle_Eye_Class_Finder.Form1); // // Form1 // this.AcceptButton = this.button2; this.AutoScaleBaseSize = new System.Drawing.Size(5, 13); this.BackgroundImage = ((System.Drawing.Image)(resources.GetObject("$this.BackgroundImage"))); this.BackgroundImageLayout = System.Windows.Forms.ImageLayout.Stretch; this.ClientSize = new System.Drawing.Size(856, 556); this.Controls.Add(this.dateTimePicker1); this.Controls.Add(this.button2); this.Controls.Add(this.pictureBox1); this.Controls.Add(this.progressBar1); this.Controls.Add(this.textBox1); this.Name = "Form1"; this.Text = "Eagle Eye Class Finder"; this.Load += new System.EventHandler(this.Form1_Load); ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit(); ((System.ComponentModel.ISupportInitialize)(this.form1BindingSource)).EndInit(); this.ResumeLayout(false); this.PerformLayout(); } #endregion /// The main entry point for the application. [STAThread] static void Main() { Application.Run(new Form1()); } public void Form1_Load(object sender, System.EventArgs e) { } public void textBox1_TextChanged(object sender, System.EventArgs e) { //allows only numbers to be entered in textbox string Str = textBox1.Text.Trim(); double Num; bool isNum = double.TryParse(Str, out Num); if (isNum) Console.ReadLine(); else MessageBox.Show("Enter A Valid ID Number!"); } public void button2_Click(object sender, System.EventArgs e) { string text = textBox1.Text; Mainform = this; this.Hide(); GetSchedule myScheduleFinder = new GetSchedule(); string result = myScheduleFinder.GetDataFromNumber(text);<<<-----MY PROBLEM if (!string.IsNullOrEmpty(result)) { MessageBox.Show(result); } else { MessageBox.Show("Enter A Valid ID Number!"); } } public void dateTimePicker1_ValueChanged(object sender, System.EventArgs e) { } public void pictureBox1_Click(object sender, System.EventArgs e) { } public void progressBar1_Click(object sender, EventArgs e) { //this.progressBar1 = new System.progressBar1(); //progressBar1.Maximum = 200; //progressBar1.Minimum = 0; //progressBar1.Step = 20; } private void timer1_Tick(object sender, EventArgs e) { //if (progressBar1.Value >= 200 ) //{ //progressBar1.Value = 0; //} //return; //} //progressBar1.Value != 20; } } }

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Differences Between NHibernate and Entity Framework

- by Ricardo Peres

Introduction NHibernate and Entity Framework are two of the most popular O/RM frameworks on the .NET world. Although they share some functionality, there are some aspects on which they are quite different. This post will describe this differences and will hopefully help you get started with the one you know less. Mind you, this is a personal selection of features to compare, it is by no way an exhaustive list. History First, a bit of history. NHibernate is an open-source project that was first ported from Java’s venerable Hibernate framework, one of the first O/RM frameworks, but nowadays it is not tied to it, for example, it has .NET specific features, and has evolved in different ways from those of its Java counterpart. Current version is 3.3, with 3.4 on the horizon. It currently targets .NET 3.5, but can be used as well in .NET 4, it only makes no use of any of its specific functionality. You can find its home page at NHForge. Entity Framework 1 came out with .NET 3.5 and is now on its second major version, despite being version 4. Code First sits on top of it and but came separately and will also continue to be released out of line with major .NET distributions. It is currently on version 4.3.1 and version 5 will be released together with .NET Framework 4.5. All versions will target the current version of .NET, at the time of their release. Its home location is located at MSDN. Architecture In NHibernate, there is a separation between the Unit of Work and the configuration and model instances. You start off by creating a Configuration object, where you specify all global NHibernate settings such as the database and dialect to use, the batch sizes, the mappings, etc, then you build an ISessionFactory from it. The ISessionFactory holds model and metadata that is tied to a particular database and to the settings that came from the Configuration object, and, there will typically be only one instance of each in a process. Finally, you create instances of ISession from the ISessionFactory, which is the NHibernate representation of the Unit of Work and Identity Map. This is a lightweight object, it basically opens and closes a database connection as required and keeps track of the entities associated with it. ISession objects are cheap to create and dispose, because all of the model complexity is stored in the ISessionFactory and Configuration objects. As for Entity Framework, the ObjectContext/DbContext holds the configuration, model and acts as the Unit of Work, holding references to all of the known entity instances. This class is therefore not lightweight as its NHibernate counterpart and it is not uncommon to see examples where an instance is cached on a field. Mappings Both NHibernate and Entity Framework (Code First) support the use of POCOs to represent entities, no base classes are required (or even possible, in the case of NHibernate). As for mapping to and from the database, NHibernate supports three types of mappings: XML-based, which have the advantage of not tying the entity classes to a particular O/RM; the XML files can be deployed as files on the file system or as embedded resources in an assembly; Attribute-based, for keeping both the entities and database details on the same place at the expense of polluting the entity classes with NHibernate-specific attributes; Strongly-typed code-based, which allows dynamic creation of the model and strongly typing it, so that if, for example, a property name changes, the mapping will also be updated. Entity Framework can use: Attribute-based (although attributes cannot express all of the available possibilities – for example, cascading); Strongly-typed code mappings. Database Support With NHibernate you can use mostly any database you want, including: SQL Server; SQL Server Compact; SQL Server Azure; Oracle; DB2; PostgreSQL; MySQL; Sybase Adaptive Server/SQL Anywhere; Firebird; SQLLite; Informix; Any through OLE DB; Any through ODBC. Out of the box, Entity Framework only supports SQL Server, but a number of providers exist, both free and commercial, for some of the most used databases, such as Oracle and MySQL. See a list here. Inheritance Strategies Both NHibernate and Entity Framework support the three canonical inheritance strategies: Table Per Type Hierarchy (Single Table Inheritance), Table Per Type (Class Table Inheritance) and Table Per Concrete Type (Concrete Table Inheritance). Associations Regarding associations, both support one to one, one to many and many to many. However, NHibernate offers far more collection types: Bags of entities or values: unordered, possibly with duplicates; Lists of entities or values: ordered, indexed by a number column; Maps of entities or values: indexed by either an entity or any value; Sets of entities or values: unordered, no duplicates; Arrays of entities or values: indexed, immutable. Querying NHibernate exposes several querying APIs: LINQ is probably the most used nowadays, and really does not need to be introduced; Hibernate Query Language (HQL) is a database-agnostic, object-oriented SQL-alike language that exists since NHibernate’s creation and still offers the most advanced querying possibilities; well suited for dynamic queries, even if using string concatenation; Criteria API is an implementation of the Query Object pattern where you create a semi-abstract conceptual representation of the query you wish to execute by means of a class model; also a good choice for dynamic querying; Query Over offers a similar API to Criteria, but using strongly-typed LINQ expressions instead of strings; for this, although more refactor-friendlier that Criteria, it is also less suited for dynamic queries; SQL, including stored procedures, can also be used; Integration with Lucene.NET indexer is available. As for Entity Framework: LINQ to Entities is fully supported, and its implementation is considered very complete; it is the API of choice for most developers; Entity-SQL, HQL’s counterpart, is also an object-oriented, database-independent querying language that can be used for dynamic queries; SQL, of course, is also supported. Caching Both NHibernate and Entity Framework, of course, feature first-level cache. NHibernate also supports a second-level cache, that can be used among multiple ISessionFactorys, even in different processes/machines: Hashtable (in-memory); SysCache (uses ASP.NET as the cache provider); SysCache2 (same as above but with support for SQL Server SQL Dependencies); Prevalence; SharedCache; Memcached; Redis; NCache; Appfabric Caching. Out of the box, Entity Framework does not have any second-level cache mechanism, however, there are some public samples that show how we can add this. ID Generators NHibernate supports different ID generation strategies, coming from the database and otherwise: Identity (for SQL Server, MySQL, and databases who support identity columns); Sequence (for Oracle, PostgreSQL, and others who support sequences); Trigger-based; HiLo; Sequence HiLo (for databases that support sequences); Several GUID flavors, both in GUID as well as in string format; Increment (for single-user uses); Assigned (must know what you’re doing); Sequence-style (either uses an actual sequence or a single-column table); Table of ids; Pooled (similar to HiLo but stores high values in a table); Native (uses whatever mechanism the current database supports, identity or sequence). Entity Framework only supports: Identity generation; GUIDs; Assigned values. Properties NHibernate supports properties of entity types (one to one or many to one), collections (one to many or many to many) as well as scalars and enumerations. It offers a mechanism for having complex property types generated from the database, which even include support for querying. It also supports properties originated from SQL formulas. Entity Framework only supports scalars, entity types and collections. Enumerations support will come in the next version. Events and Interception NHibernate has a very rich event model, that exposes more than 20 events, either for synchronous pre-execution or asynchronous post-execution, including: Pre/Post-Load; Pre/Post-Delete; Pre/Post-Insert; Pre/Post-Update; Pre/Post-Flush. It also features interception of class instancing and SQL generation. As for Entity Framework, only two events exist: ObjectMaterialized (after loading an entity from the database); SavingChanges (before saving changes, which include deleting, inserting and updating). Tracking Changes For NHibernate as well as Entity Framework, all changes are tracked by their respective Unit of Work implementation. Entities can be attached and detached to it, Entity Framework does, however, also support self-tracking entities. Optimistic Concurrency Control NHibernate supports all of the imaginable scenarios: SQL Server’s ROWVERSION; Oracle’s ORA_ROWSCN; A column containing date and time; A column containing a version number; All/dirty columns comparison. Entity Framework is more focused on Entity Framework, so it only supports: SQL Server’s ROWVERSION; Comparing all/some columns. Batching NHibernate has full support for insertion batching, but only if the ID generator in use is not database-based (for example, it cannot be used with Identity), whereas Entity Framework has no batching at all. Cascading Both support cascading for collections and associations: when an entity is deleted, their conceptual children are also deleted. NHibernate also offers the possibility to set the foreign key column on children to NULL instead of removing them. Flushing Changes NHibernate’s ISession has a FlushMode property that can have the following values: Auto: changes are sent to the database when necessary, for example, if there are dirty instances of an entity type, and a query is performed against this entity type, or if the ISession is being disposed; Commit: changes are sent when committing the current transaction; Never: changes are only sent when explicitly calling Flush(). As for Entity Framework, changes have to be explicitly sent through a call to AcceptAllChanges()/SaveChanges(). Lazy Loading NHibernate supports lazy loading for Associated entities (one to one, many to one); Collections (one to many, many to many); Scalar properties (thing of BLOBs or CLOBs). Entity Framework only supports lazy loading for: Associated entities; Collections. Generating and Updating the Database Both NHibernate and Entity Framework Code First (with the Migrations API) allow creating the database model from the mapping and updating it if the mapping changes. Extensibility As you can guess, NHibernate is far more extensible than Entity Framework. Basically, everything can be extended, from ID generation, to LINQ to SQL transformation, HQL native SQL support, custom column types, custom association collections, SQL generation, supported databases, etc. With Entity Framework your options are more limited, at least, because practically no information exists as to what can be extended/changed. It features a provider model that can be extended to support any database. Integration With Other Microsoft APIs and Tools When it comes to integration with Microsoft technologies, it will come as no surprise that Entity Framework offers the best support. For example, the following technologies are fully supported: ASP.NET (through the EntityDataSource); ASP.NET Dynamic Data; WCF Data Services; WCF RIA Services; Visual Studio (through the integrated designer). Documentation This is another point where Entity Framework is superior: NHibernate lacks, for starters, an up to date API reference synchronized with its current version. It does have a community mailing list, blogs and wikis, although not much used. Entity Framework has a number of resources on MSDN and, of course, several forums and discussion groups exist. Conclusion Like I said, this is a personal list. I may come as a surprise to some that Entity Framework is so behind NHibernate in so many aspects, but it is true that NHibernate is much older and, due to its open-source nature, is not tied to product-specific timeframes and can thus evolve much more rapidly. I do like both, and I chose whichever is best for the job I have at hands. I am looking forward to the changes in EF5 which will add significant value to an already interesting product. So, what do you think? Did I forget anything important or is there anything else worth talking about? Looking forward for your comments!

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Creating a dynamic proxy generator – Part 1 – Creating the Assembly builder, Module builder and cach

- by SeanMcAlinden

I’ve recently started a project with a few mates to learn the ins and outs of Dependency Injection, AOP and a number of other pretty crucial patterns of development as we’ve all been using these patterns for a while but have relied totally on third part solutions to do the magic. We thought it would be interesting to really get into the details by rolling our own IoC container and hopefully learn a lot on the way, and you never know, we might even create an excellent framework. The open source project is called Rapid IoC and is hosted at http://rapidioc.codeplex.com/ One of the most interesting tasks for me is creating the dynamic proxy generator for enabling Aspect Orientated Programming (AOP). In this series of articles, I’m going to track each step I take for creating the dynamic proxy generator and I’ll try my best to explain what everything means - mainly as I’ll be using Reflection.Emit to emit a fair amount of intermediate language code (IL) to create the proxy types at runtime which can be a little taxing to read. It’s worth noting that building the proxy is without a doubt going to be slightly painful so I imagine there will be plenty of areas I’ll need to change along the way. Anyway lets get started… Part 1 - Creating the Assembly builder, Module builder and caching mechanism Part 1 is going to be a really nice simple start, I’m just going to start by creating the assembly, module and type caches. The reason we need to create caches for the assembly, module and types is simply to save the overhead of recreating proxy types that have already been generated, this will be one of the important steps to ensure that the framework is fast… kind of important as we’re calling the IoC container ‘Rapid’ – will be a little bit embarrassing if we manage to create the slowest framework. The Assembly builder The assembly builder is what is used to create an assembly at runtime, we’re going to have two overloads, one will be for the actual use of the proxy generator, the other will be mainly for testing purposes as it will also save the assembly so we can use Reflector to examine the code that has been created. Here’s the code: DynamicAssemblyBuilder using System; using System.Reflection; using System.Reflection.Emit; namespace Rapid.DynamicProxy.Assembly { /// <summary> /// Class for creating an assembly builder. /// </summary> internal static class DynamicAssemblyBuilder { #region Create /// <summary> /// Creates an assembly builder. /// </summary> /// <param name="assemblyName">Name of the assembly.</param> public static AssemblyBuilder Create(string assemblyName) { AssemblyName name = new AssemblyName(assemblyName); AssemblyBuilder assembly = AppDomain.CurrentDomain.DefineDynamicAssembly( name, AssemblyBuilderAccess.Run); DynamicAssemblyCache.Add(assembly); return assembly; } /// <summary> /// Creates an assembly builder and saves the assembly to the passed in location. /// </summary> /// <param name="assemblyName">Name of the assembly.</param> /// <param name="filePath">The file path.</param> public static AssemblyBuilder Create(string assemblyName, string filePath) { AssemblyName name = new AssemblyName(assemblyName); AssemblyBuilder assembly = AppDomain.CurrentDomain.DefineDynamicAssembly( name, AssemblyBuilderAccess.RunAndSave, filePath); DynamicAssemblyCache.Add(assembly); return assembly; } #endregion } } So hopefully the above class is fairly explanatory, an AssemblyName is created using the passed in string for the actual name of the assembly. An AssemblyBuilder is then constructed with the current AppDomain and depending on the overload used, it is either just run in the current context or it is set up ready for saving. It is then added to the cache. DynamicAssemblyCache using System.Reflection.Emit; using Rapid.DynamicProxy.Exceptions; using Rapid.DynamicProxy.Resources.Exceptions; namespace Rapid.DynamicProxy.Assembly { /// <summary> /// Cache for storing the dynamic assembly builder. /// </summary> internal static class DynamicAssemblyCache { #region Declarations private static object syncRoot = new object(); internal static AssemblyBuilder Cache = null; #endregion #region Adds a dynamic assembly to the cache. /// <summary> /// Adds a dynamic assembly builder to the cache. /// </summary> /// <param name="assemblyBuilder">The assembly builder.</param> public static void Add(AssemblyBuilder assemblyBuilder) { lock (syncRoot) { Cache = assemblyBuilder; } } #endregion #region Gets the cached assembly /// <summary> /// Gets the cached assembly builder. /// </summary> /// <returns></returns> public static AssemblyBuilder Get { get { lock (syncRoot) { if (Cache != null) { return Cache; } } throw new RapidDynamicProxyAssertionException(AssertionResources.NoAssemblyInCache); } } #endregion } } The cache is simply a static property that will store the AssemblyBuilder (I know it’s a little weird that I’ve made it public, this is for testing purposes, I know that’s a bad excuse but hey…) There are two methods for using the cache – Add and Get, these just provide thread safe access to the cache. The Module Builder The module builder is required as the create proxy classes will need to live inside a module within the assembly. Here’s the code: DynamicModuleBuilder using System.Reflection.Emit; using Rapid.DynamicProxy.Assembly; namespace Rapid.DynamicProxy.Module { /// <summary> /// Class for creating a module builder. /// </summary> internal static class DynamicModuleBuilder { /// <summary> /// Creates a module builder using the cached assembly. /// </summary> public static ModuleBuilder Create() { string assemblyName = DynamicAssemblyCache.Get.GetName().Name; ModuleBuilder moduleBuilder = DynamicAssemblyCache.Get.DefineDynamicModule (assemblyName, string.Format("{0}.dll", assemblyName)); DynamicModuleCache.Add(moduleBuilder); return moduleBuilder; } } } As you can see, the module builder is created on the assembly that lives in the DynamicAssemblyCache, the module is given the assembly name and also a string representing the filename if the assembly is to be saved. It is then added to the DynamicModuleCache. DynamicModuleCache using System.Reflection.Emit; using Rapid.DynamicProxy.Exceptions; using Rapid.DynamicProxy.Resources.Exceptions; namespace Rapid.DynamicProxy.Module { /// <summary> /// Class for storing the module builder. /// </summary> internal static class DynamicModuleCache { #region Declarations private static object syncRoot = new object(); internal static ModuleBuilder Cache = null; #endregion #region Add /// <summary> /// Adds a dynamic module builder to the cache. /// </summary> /// <param name="moduleBuilder">The module builder.</param> public static void Add(ModuleBuilder moduleBuilder) { lock (syncRoot) { Cache = moduleBuilder; } } #endregion #region Get /// <summary> /// Gets the cached module builder. /// </summary> /// <returns></returns> public static ModuleBuilder Get { get { lock (syncRoot) { if (Cache != null) { return Cache; } } throw new RapidDynamicProxyAssertionException(AssertionResources.NoModuleInCache); } } #endregion } } The DynamicModuleCache is very similar to the assembly cache, it is simply a statically stored module with thread safe Add and Get methods. The DynamicTypeCache To end off this post, I’m going to create the cache for storing the generated proxy classes. I’ve spent a fair amount of time thinking about the type of collection I should use to store the types and have finally decided that for the time being I’m going to use a generic dictionary. This may change when I can actually performance test the proxy generator but the time being I think it makes good sense in theory, mainly as it pretty much maintains it’s performance with varying numbers of items – almost constant (0)1. Plus I won’t ever need to loop through the items which is not the dictionaries strong point. Here’s the code as it currently stands: DynamicTypeCache using System; using System.Collections.Generic; using System.Security.Cryptography; using System.Text; namespace Rapid.DynamicProxy.Types { /// <summary> /// Cache for storing proxy types. /// </summary> internal static class DynamicTypeCache { #region Declarations static object syncRoot = new object(); public static Dictionary<string, Type> Cache = new Dictionary<string, Type>(); #endregion /// <summary> /// Adds a proxy to the type cache. /// </summary> /// <param name="type">The type.</param> /// <param name="proxy">The proxy.</param> public static void AddProxyForType(Type type, Type proxy) { lock (syncRoot) { Cache.Add(GetHashCode(type.AssemblyQualifiedName), proxy); } } /// <summary> /// Tries the type of the get proxy for. /// </summary> /// <param name="type">The type.</param> /// <returns></returns> public static Type TryGetProxyForType(Type type) { lock (syncRoot) { Type proxyType; Cache.TryGetValue(GetHashCode(type.AssemblyQualifiedName), out proxyType); return proxyType; } } #region Private Methods private static string GetHashCode(string fullName) { SHA1CryptoServiceProvider provider = new SHA1CryptoServiceProvider(); Byte[] buffer = Encoding.UTF8.GetBytes(fullName); Byte[] hash = provider.ComputeHash(buffer, 0, buffer.Length); return Convert.ToBase64String(hash); } #endregion } } As you can see, there are two public methods, one for adding to the cache and one for getting from the cache. Hopefully they should be clear enough, the Get is a TryGet as I do not want the dictionary to throw an exception if a proxy doesn’t exist within the cache. Other than that I’ve decided to create a key using the SHA1CryptoServiceProvider, this may change but my initial though is the SHA1 algorithm is pretty fast to put together using the provider and it is also very unlikely to have any hashing collisions. (there are some maths behind how unlikely this is – here’s the wiki if you’re interested http://en.wikipedia.org/wiki/SHA_hash_functions) Anyway, that’s the end of part 1 – although I haven’t started any of the fun stuff (by fun I mean hairpulling, teeth grating Relfection.Emit style fun), I’ve got the basis of the DynamicProxy in place so all we have to worry about now is creating the types, interceptor classes, method invocation information classes and finally a really nice fluent interface that will abstract all of the hard-core craziness away and leave us with a lightning fast, easy to use AOP framework. Hope you find the series interesting. All of the source code can be viewed and/or downloaded at our codeplex site - http://rapidioc.codeplex.com/ Kind Regards, Sean.

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Red Gate Coder interviews: Alex Davies

- by Michael Williamson

Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

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SQL Server 2012 - AlwaysOn

- by Claus Jandausch

Ich war nicht nur irritiert, ich war sogar regelrecht schockiert - und für einen kurzen Moment sprachlos (was nur selten der Fall ist). Gerade eben hatte mich jemand gefragt "Wann Oracle denn etwas Vergleichbares wie AlwaysOn bieten würde - und ob überhaupt?" War ich hier im falschen Film gelandet? Ich konnte nicht anders, als meinen Unmut kundzutun und zu erklären, dass die Fragestellung normalerweise anders herum läuft. Zugegeben - es mag vielleicht strittige Punkte geben im Vergleich zwischen Oracle und SQL Server - bei denen nicht unbedingt immer Oracle die Nase vorn haben muss - aber das Thema Clustering für Hochverfügbarkeit (HA), Disaster Recovery (DR) und Skalierbarkeit gehört mit Sicherheit nicht dazu. Dieses Erlebnis hakte ich am Nachgang als Einzelfall ab, der so nie wieder vorkommen würde. Bis ich kurz darauf eines Besseren belehrt wurde und genau die selbe Frage erneut zu hören bekam. Diesmal sogar im Exadata-Umfeld und einem Oracle Stretch Cluster. Einmal ist keinmal, doch zweimal ist einmal zu viel... Getreu diesem alten Motto war mir klar, dass man das so nicht länger stehen lassen konnte. Ich habe keine Ahnung, wie die Microsoft Marketing Abteilung es geschafft hat, unter dem AlwaysOn Brading eine innovative Technologie vermuten zu lassen - aber sie hat ihren Job scheinbar gut gemacht. Doch abgesehen von einem guten Marketing, stellt sich natürlich die Frage, was wirklich dahinter steckt und wie sich das Ganze mit Oracle vergleichen lässt - und ob überhaupt? Damit wären wir wieder bei der ursprünglichen Frage angelangt. So viel zum Hintergrund dieses Blogbeitrags - von meiner Antwort handelt der restliche Blog. "Windows was the God ..." Um den wahren Unterschied zwischen Oracle und Microsoft verstehen zu können, muss man zunächst das bedeutendste Microsoft Dogma kennen. Es lässt sich schlicht und einfach auf den Punkt bringen: "Alles muss auf Windows basieren." Die Überschrift dieses Absatzes ist kein von mir erfundener Ausspruch, sondern ein Zitat. Konkret stammt es aus einem längeren Artikel von Kurt Eichenwald in der Vanity Fair aus dem August 2012. Er lautet Microsoft's Lost Decade und sei jedem ans Herz gelegt, der die "Microsoft-Maschinerie" unter Steve Ballmer und einige ihrer Kuriositäten besser verstehen möchte. "YOU TALKING TO ME?" Microsoft C.E.O. Steve Ballmer bei seiner Keynote auf der 2012 International Consumer Electronics Show in Las Vegas am 9. Januar Manche Dinge in diesem Artikel mögen überspitzt dargestellt erscheinen - sind sie aber nicht. Vieles davon kannte ich bereits aus eigener Erfahrung und kann es nur bestätigen. Anderes hat sich mir erst so richtig erschlossen. Insbesondere die folgenden Passagen führten zum Aha-Erlebnis: “Windows was the god—everything had to work with Windows,” said Stone... “Every little thing you want to write has to build off of Windows (or other existing roducts),” one software engineer said. “It can be very confusing, …” Ich habe immer schon darauf hingewiesen, dass in einem SQL Server Failover Cluster die Microsoft Datenbank eigentlich nichts Nenneswertes zum Geschehen beiträgt, sondern sich voll und ganz auf das Windows Betriebssystem verlässt. Deshalb muss man auch die Windows Server Enterprise Edition installieren, soll ein Failover Cluster für den SQL Server eingerichtet werden. Denn hier werden die Cluster Services geliefert - nicht mit dem SQL Server. Er ist nur lediglich ein weiteres Server Produkt, für das Windows in Ausfallszenarien genutzt werden kann - so wie Microsoft Exchange beispielsweise, oder Microsoft SharePoint, oder irgendein anderes Server Produkt das auf Windows gehostet wird. Auch Oracle kann damit genutzt werden. Das Stichwort lautet hier: Oracle Failsafe. Nur - warum sollte man das tun, wenn gleichzeitig eine überlegene Technologie wie die Oracle Real Application Clusters (RAC) zur Verfügung steht, die dann auch keine Windows Enterprise Edition voraussetzen, da Oracle die eigene Clusterware liefert. Welche darüber hinaus für kürzere Failover-Zeiten sorgt, da diese Cluster-Technologie Datenbank-integriert ist und sich nicht auf "Dritte" verlässt. Wenn man sich also schon keine technischen Vorteile mit einem SQL Server Failover Cluster erkauft, sondern zusätzlich noch versteckte Lizenzkosten durch die Lizenzierung der Windows Server Enterprise Edition einhandelt, warum hat Microsoft dann in den vergangenen Jahren seit SQL Server 2000 nicht ebenfalls an einer neuen und innovativen Lösung gearbeitet, die mit Oracle RAC mithalten kann? Entwickler hat Microsoft genügend? Am Geld kann es auch nicht liegen? Lesen Sie einfach noch einmal die beiden obenstehenden Zitate und sie werden den Grund verstehen. Anders lässt es sich ja auch gar nicht mehr erklären, dass AlwaysOn aus zwei unterschiedlichen Technologien besteht, die beide jedoch wiederum auf dem Windows Server Failover Clustering (WSFC) basieren. Denn daraus ergeben sich klare Nachteile - aber dazu später mehr. Um AlwaysOn zu verstehen, sollte man sich zunächst kurz in Erinnerung rufen, was Microsoft bisher an HA/DR (High Availability/Desaster Recovery) Lösungen für SQL Server zur Verfügung gestellt hat. Replikation Basiert auf logischer Replikation und Pubisher/Subscriber Architektur Transactional Replication Merge Replication Snapshot Replication Microsoft's Replikation ist vergleichbar mit Oracle GoldenGate. Oracle GoldenGate stellt jedoch die umfassendere Technologie dar und bietet High Performance. Log Shipping Microsoft's Log Shipping stellt eine einfache Technologie dar, die vergleichbar ist mit Oracle Managed Recovery in Oracle Version 7. Das Log Shipping besitzt folgende Merkmale: Transaction Log Backups werden von Primary nach Secondary/ies geschickt Einarbeitung (z.B. Restore) auf jedem Secondary individuell Optionale dritte Server Instanz (Monitor Server) für Überwachung und Alarm Log Restore Unterbrechung möglich für Read-Only Modus (Secondary) Keine Unterstützung von Automatic Failover Database Mirroring Microsoft's Database Mirroring wurde verfügbar mit SQL Server 2005, sah aus wie Oracle Data Guard in Oracle 9i, war funktional jedoch nicht so umfassend. Für ein HA/DR Paar besteht eine 1:1 Beziehung, um die produktive Datenbank (Principle DB) abzusichern. Auf der Standby Datenbank (Mirrored DB) werden alle Insert-, Update- und Delete-Operationen nachgezogen. Modi Synchron (High-Safety Modus) Asynchron (High-Performance Modus) Automatic Failover Unterstützt im High-Safety Modus (synchron) Witness Server vorausgesetzt Zur Frage der Kontinuität Es stellt sich die Frage, wie es um diesen Technologien nun im Zusammenhang mit SQL Server 2012 bestellt ist. Unter Fanfaren seinerzeit eingeführt, war Database Mirroring das erklärte Mittel der Wahl. Ich bin kein Produkt Manager bei Microsoft und kann hierzu nur meine Meinung äußern, aber zieht man den SQL AlwaysOn Team Blog heran, so sieht es nicht gut aus für das Database Mirroring - zumindest nicht langfristig. "Does AlwaysOn Availability Group replace Database Mirroring going forward?” “The short answer is we recommend that you migrate from the mirroring configuration or even mirroring and log shipping configuration to using Availability Group. Database Mirroring will still be available in the Denali release but will be phased out over subsequent releases. Log Shipping will continue to be available in future releases.” Damit wären wir endlich beim eigentlichen Thema angelangt. Was ist eine sogenannte Availability Group und was genau hat es mit der vielversprechend klingenden Bezeichnung AlwaysOn auf sich? SQL Server 2012 - AlwaysOn Zwei HA-Features verstekcne sich hinter dem “AlwaysOn”-Branding. Einmal das AlwaysOn Failover Clustering aka SQL Server Failover Cluster Instances (FCI) - zum Anderen die AlwaysOn Availability Groups. Failover Cluster Instances (FCI) Entspricht ungefähr dem Stretch Cluster Konzept von Oracle Setzt auf Windows Server Failover Clustering (WSFC) auf Bietet HA auf Instanz-Ebene AlwaysOn Availability Groups (Verfügbarkeitsgruppen) Ähnlich der Idee von Consistency Groups, wie in Storage-Level Replikations-Software von z.B. EMC SRDF Abhängigkeiten zu Windows Server Failover Clustering (WSFC) Bietet HA auf Datenbank-Ebene Hinweis: Verwechseln Sie nicht eine SQL Server Datenbank mit einer Oracle Datenbank. Und auch nicht eine Oracle Instanz mit einer SQL Server Instanz. Die gleichen Begriffe haben hier eine andere Bedeutung - nicht selten ein Grund, weshalb Oracle- und Microsoft DBAs schnell aneinander vorbei reden. Denken Sie bei einer SQL Server Datenbank eher an ein Oracle Schema, das kommt der Sache näher. So etwas wie die SQL Server Northwind Datenbank ist vergleichbar mit dem Oracle Scott Schema. Wenn Sie die genauen Unterschiede kennen möchten, finden Sie eine detaillierte Beschreibung in meinem Buch "Oracle10g Release 2 für Windows und .NET", erhältich bei Lehmanns, Amazon, etc. Windows Server Failover Clustering (WSFC) Wie man sieht, basieren beide AlwaysOn Technologien wiederum auf dem Windows Server Failover Clustering (WSFC), um einerseits Hochverfügbarkeit auf Ebene der Instanz zu gewährleisten und andererseits auf der Datenbank-Ebene. Deshalb nun eine kurze Beschreibung der WSFC. Die WSFC sind ein mit dem Windows Betriebssystem geliefertes Infrastruktur-Feature, um HA für Server Anwendungen, wie Microsoft Exchange, SharePoint, SQL Server, etc. zu bieten. So wie jeder andere Cluster, besteht ein WSFC Cluster aus einer Gruppe unabhängiger Server, die zusammenarbeiten, um die Verfügbarkeit einer Applikation oder eines Service zu erhöhen. Falls ein Cluster-Knoten oder -Service ausfällt, kann der auf diesem Knoten bisher gehostete Service automatisch oder manuell auf einen anderen im Cluster verfügbaren Knoten transferriert werden - was allgemein als Failover bekannt ist. Unter SQL Server 2012 verwenden sowohl die AlwaysOn Avalability Groups, als auch die AlwaysOn Failover Cluster Instances die WSFC als Plattformtechnologie, um Komponenten als WSFC Cluster-Ressourcen zu registrieren. Verwandte Ressourcen werden in eine Ressource Group zusammengefasst, die in Abhängigkeit zu anderen WSFC Cluster-Ressourcen gebracht werden kann. Der WSFC Cluster Service kann jetzt die Notwendigkeit zum Neustart der SQL Server Instanz erfassen oder einen automatischen Failover zu einem anderen Server-Knoten im WSFC Cluster auslösen. Failover Cluster Instances (FCI) Eine SQL Server Failover Cluster Instanz (FCI) ist eine einzelne SQL Server Instanz, die in einem Failover Cluster betrieben wird, der aus mehreren Windows Server Failover Clustering (WSFC) Knoten besteht und so HA (High Availability) auf Ebene der Instanz bietet. Unter Verwendung von Multi-Subnet FCI kann auch Remote DR (Disaster Recovery) unterstützt werden. Eine weitere Option für Remote DR besteht darin, eine unter FCI gehostete Datenbank in einer Availability Group zu betreiben. Hierzu später mehr. FCI und WSFC Basis FCI, das für lokale Hochverfügbarkeit der Instanzen genutzt wird, ähnelt der veralteten Architektur eines kalten Cluster (Aktiv-Passiv). Unter SQL Server 2008 wurde diese Technologie SQL Server 2008 Failover Clustering genannt. Sie nutzte den Windows Server Failover Cluster. In SQL Server 2012 hat Microsoft diese Basistechnologie unter der Bezeichnung AlwaysOn zusammengefasst. Es handelt sich aber nach wie vor um die klassische Aktiv-Passiv-Konfiguration. Der Ablauf im Failover-Fall ist wie folgt: Solange kein Hardware-oder System-Fehler auftritt, werden alle Dirty Pages im Buffer Cache auf Platte geschrieben Alle entsprechenden SQL Server Services (Dienste) in der Ressource Gruppe werden auf dem aktiven Knoten gestoppt Die Ownership der Ressource Gruppe wird auf einen anderen Knoten der FCI transferriert Der neue Owner (Besitzer) der Ressource Gruppe startet seine SQL Server Services (Dienste) Die Connection-Anforderungen einer Client-Applikation werden automatisch auf den neuen aktiven Knoten mit dem selben Virtuellen Network Namen (VNN) umgeleitet Abhängig vom Zeitpunkt des letzten Checkpoints, kann die Anzahl der Dirty Pages im Buffer Cache, die noch auf Platte geschrieben werden müssen, zu unvorhersehbar langen Failover-Zeiten führen. Um diese Anzahl zu drosseln, besitzt der SQL Server 2012 eine neue Fähigkeit, die Indirect Checkpoints genannt wird. Indirect Checkpoints ähnelt dem Fast-Start MTTR Target Feature der Oracle Datenbank, das bereits mit Oracle9i verfügbar war. SQL Server Multi-Subnet Clustering Ein SQL Server Multi-Subnet Failover Cluster entspricht vom Konzept her einem Oracle RAC Stretch Cluster. Doch dies ist nur auf den ersten Blick der Fall. Im Gegensatz zu RAC ist in einem lokalen SQL Server Failover Cluster jeweils nur ein Knoten aktiv für eine Datenbank. Für die Datenreplikation zwischen geografisch entfernten Sites verlässt sich Microsoft auf 3rd Party Lösungen für das Storage Mirroring. Die Verbesserung dieses Szenario mit einer SQL Server 2012 Implementierung besteht schlicht darin, dass eine VLAN-Konfiguration (Virtual Local Area Network) nun nicht mehr benötigt wird, so wie dies bisher der Fall war. Das folgende Diagramm stellt dar, wie der Ablauf mit SQL Server 2012 gehandhabt wird. In Site A und Site B wird HA jeweils durch einen lokalen Aktiv-Passiv-Cluster sichergestellt. Besondere Aufmerksamkeit muss hier der Konfiguration und dem Tuning geschenkt werden, da ansonsten völlig inakzeptable Failover-Zeiten resultieren. Dies liegt darin begründet, weil die Downtime auf Client-Seite nun nicht mehr nur von der reinen Failover-Zeit abhängt, sondern zusätzlich von der Dauer der DNS Replikation zwischen den DNS Servern. (Rufen Sie sich in Erinnerung, dass wir gerade von Multi-Subnet Clustering sprechen). Außerdem ist zu berücksichtigen, wie schnell die Clients die aktualisierten DNS Informationen abfragen. Spezielle Konfigurationen für Node Heartbeat, HostRecordTTL (Host Record Time-to-Live) und Intersite Replication Frequeny für Active Directory Sites und Services werden notwendig. Default TTL für Windows Server 2008 R2: 20 Minuten Empfohlene Einstellung: 1 Minute DNS Update Replication Frequency in Windows Umgebung: 180 Minuten Empfohlene Einstellung: 15 Minuten (minimaler Wert) Betrachtet man diese Werte, muss man feststellen, dass selbst eine optimale Konfiguration die rigiden SLAs (Service Level Agreements) heutiger geschäftskritischer Anwendungen für HA und DR nicht erfüllen kann. Denn dies impliziert eine auf der Client-Seite erlebte Failover-Zeit von insgesamt 16 Minuten. Hierzu ein Auszug aus der SQL Server 2012 Online Dokumentation: Cons: If a cross-subnet failover occurs, the client recovery time could be 15 minutes or longer, depending on your HostRecordTTL setting and the setting of your cross-site DNS/AD replication schedule. Wir sind hier an einem Punkt unserer Überlegungen angelangt, an dem sich erklärt, weshalb ich zuvor das "Windows was the God ..." Zitat verwendet habe. Die unbedingte Abhängigkeit zu Windows wird zunehmend zum Problem, da sie die Komplexität einer Microsoft-basierenden Lösung erhöht, anstelle sie zu reduzieren. Und Komplexität ist das Letzte, was sich CIOs heutzutage wünschen. Zur Ehrenrettung des SQL Server 2012 und AlwaysOn muss man sagen, dass derart lange Failover-Zeiten kein unbedingtes "Muss" darstellen, sondern ein "Kann". Doch auch ein "Kann" kann im unpassenden Moment unvorhersehbare und kostspielige Folgen haben. Die Unabsehbarkeit ist wiederum Ursache vieler an der Implementierung beteiligten Komponenten und deren Abhängigkeiten, wie beispielsweise drei Cluster-Lösungen (zwei von Microsoft, eine 3rd Party Lösung). Wie man die Sache auch dreht und wendet, kommt man an diesem Fakt also nicht vorbei - ganz unabhängig von der Dauer einer Downtime oder Failover-Zeiten. Im Gegensatz zu AlwaysOn und der hier vorgestellten Version eines Stretch-Clusters, vermeidet eine entsprechende Oracle Implementierung eine derartige Komplexität, hervorgerufen duch multiple Abhängigkeiten. Den Unterschied machen Datenbank-integrierte Mechanismen, wie Fast Application Notification (FAN) und Fast Connection Failover (FCF). Für Oracle MAA Konfigurationen (Maximum Availability Architecture) sind Inter-Site Failover-Zeiten im Bereich von Sekunden keine Seltenheit. Wenn Sie dem Link zur Oracle MAA folgen, finden Sie außerdem eine Reihe an Customer Case Studies. Auch dies ist ein wichtiges Unterscheidungsmerkmal zu AlwaysOn, denn die Oracle Technologie hat sich bereits zigfach in höchst kritischen Umgebungen bewährt. Availability Groups (Verfügbarkeitsgruppen) Die sogenannten Availability Groups (Verfügbarkeitsgruppen) sind - neben FCI - der weitere Baustein von AlwaysOn. Hinweis: Bevor wir uns näher damit beschäftigen, sollten Sie sich noch einmal ins Gedächtnis rufen, dass eine SQL Server Datenbank nicht die gleiche Bedeutung besitzt, wie eine Oracle Datenbank, sondern eher einem Oracle Schema entspricht. So etwas wie die SQL Server Northwind Datenbank ist vergleichbar mit dem Oracle Scott Schema. Eine Verfügbarkeitsgruppe setzt sich zusammen aus einem Set mehrerer Benutzer-Datenbanken, die im Falle eines Failover gemeinsam als Gruppe behandelt werden. Eine Verfügbarkeitsgruppe unterstützt ein Set an primären Datenbanken (primäres Replikat) und einem bis vier Sets von entsprechenden sekundären Datenbanken (sekundäre Replikate). Es können jedoch nicht alle SQL Server Datenbanken einer AlwaysOn Verfügbarkeitsgruppe zugeordnet werden. Der SQL Server Spezialist Michael Otey zählt in seinem SQL Server Pro Artikel folgende Anforderungen auf: Verfügbarkeitsgruppen müssen mit Benutzer-Datenbanken erstellt werden. System-Datenbanken können nicht verwendet werden Die Datenbanken müssen sich im Read-Write Modus befinden. Read-Only Datenbanken werden nicht unterstützt Die Datenbanken in einer Verfügbarkeitsgruppe müssen Multiuser Datenbanken sein Sie dürfen nicht das AUTO_CLOSE Feature verwenden Sie müssen das Full Recovery Modell nutzen und es muss ein vollständiges Backup vorhanden sein Eine gegebene Datenbank kann sich nur in einer einzigen Verfügbarkeitsgruppe befinden und diese Datenbank düerfen nicht für Database Mirroring konfiguriert sein Microsoft empfiehl außerdem, dass der Verzeichnispfad einer Datenbank auf dem primären und sekundären Server identisch sein sollte Wie man sieht, eignen sich Verfügbarkeitsgruppen nicht, um HA und DR vollständig abzubilden. Die Unterscheidung zwischen der Instanzen-Ebene (FCI) und Datenbank-Ebene (Availability Groups) ist von hoher Bedeutung. Vor kurzem wurde mir gesagt, dass man mit den Verfügbarkeitsgruppen auf Shared Storage verzichten könne und dadurch Kosten spart. So weit so gut ... Man kann natürlich eine Installation rein mit Verfügbarkeitsgruppen und ohne FCI durchführen - aber man sollte sich dann darüber bewusst sein, was man dadurch alles nicht abgesichert hat - und dies wiederum für Desaster Recovery (DR) und SLAs (Service Level Agreements) bedeutet. Kurzum, um die Kombination aus beiden AlwaysOn Produkten und der damit verbundene Komplexität kommt man wohl in der Praxis nicht herum. Availability Groups und WSFC AlwaysOn hängt von Windows Server Failover Clustering (WSFC) ab, um die aktuellen Rollen der Verfügbarkeitsreplikate einer Verfügbarkeitsgruppe zu überwachen und zu verwalten, und darüber zu entscheiden, wie ein Failover-Ereignis die Verfügbarkeitsreplikate betrifft. Das folgende Diagramm zeigt de Beziehung zwischen Verfügbarkeitsgruppen und WSFC: Der Verfügbarkeitsmodus ist eine Eigenschaft jedes Verfügbarkeitsreplikats. Synychron und Asynchron können also gemischt werden: Availability Modus (Verfügbarkeitsmodus) Asynchroner Commit-Modus Primäres replikat schließt Transaktionen ohne Warten auf Sekundäres Synchroner Commit-Modus Primäres Replikat wartet auf Commit von sekundärem Replikat Failover Typen Automatic Manual Forced (mit möglichem Datenverlust) Synchroner Commit-Modus Geplanter, manueller Failover ohne Datenverlust Automatischer Failover ohne Datenverlust Asynchroner Commit-Modus Nur Forced, manueller Failover mit möglichem Datenverlust Der SQL Server kennt keinen separaten Switchover Begriff wie in Oracle Data Guard. Für SQL Server werden alle Role Transitions als Failover bezeichnet. Tatsächlich unterstützt der SQL Server keinen Switchover für asynchrone Verbindungen. Es gibt nur die Form des Forced Failover mit möglichem Datenverlust. Eine ähnliche Fähigkeit wie der Switchover unter Oracle Data Guard ist so nicht gegeben. SQL Sever FCI mit Availability Groups (Verfügbarkeitsgruppen) Neben den Verfügbarkeitsgruppen kann eine zweite Failover-Ebene eingerichtet werden, indem SQL Server FCI (auf Shared Storage) mit WSFC implementiert wird. Ein Verfügbarkeitesreplikat kann dann auf einer Standalone Instanz gehostet werden, oder einer FCI Instanz. Zum Verständnis: Die Verfügbarkeitsgruppen selbst benötigen kein Shared Storage. Diese Kombination kann verwendet werden für lokale HA auf Ebene der Instanz und DR auf Datenbank-Ebene durch Verfügbarkeitsgruppen. Das folgende Diagramm zeigt dieses Szenario: Achtung! Hier handelt es sich nicht um ein Pendant zu Oracle RAC plus Data Guard, auch wenn das Bild diesen Eindruck vielleicht vermitteln mag - denn alle sekundären Knoten im FCI sind rein passiv. Es existiert außerdem eine weitere und ernsthafte Einschränkung: SQL Server Failover Cluster Instanzen (FCI) unterstützen nicht das automatische AlwaysOn Failover für Verfügbarkeitsgruppen. Jedes unter FCI gehostete Verfügbarkeitsreplikat kann nur für manuelles Failover konfiguriert werden. Lesbare Sekundäre Replikate Ein oder mehrere Verfügbarkeitsreplikate in einer Verfügbarkeitsgruppe können für den lesenden Zugriff konfiguriert werden, wenn sie als sekundäres Replikat laufen. Dies ähnelt Oracle Active Data Guard, jedoch gibt es Einschränkungen. Alle Abfragen gegen die sekundäre Datenbank werden automatisch auf das Snapshot Isolation Level abgebildet. Es handelt sich dabei um eine Versionierung der Rows. Microsoft versuchte hiermit die Oracle MVRC (Multi Version Read Consistency) nachzustellen. Tatsächlich muss man die SQL Server Snapshot Isolation eher mit Oracle Flashback vergleichen. Bei der Implementierung des Snapshot Isolation Levels handelt sich um ein nachträglich aufgesetztes Feature und nicht um einen inhärenten Teil des Datenbank-Kernels, wie im Falle Oracle. (Ich werde hierzu in Kürze einen weiteren Blogbeitrag verfassen, wenn ich mich mit der neuen SQL Server 2012 Core Lizenzierung beschäftige.) Für die Praxis entstehen aus der Abbildung auf das Snapshot Isolation Level ernsthafte Restriktionen, derer man sich für den Betrieb in der Praxis bereits vorab bewusst sein sollte: Sollte auf der primären Datenbank eine aktive Transaktion zu dem Zeitpunkt existieren, wenn ein lesbares sekundäres Replikat in die Verfügbarkeitsgruppe aufgenommen wird, werden die Row-Versionen auf der korrespondierenden sekundären Datenbank nicht sofort vollständig verfügbar sein. Eine aktive Transaktion auf dem primären Replikat muss zuerst abgeschlossen (Commit oder Rollback) und dieser Transaktions-Record auf dem sekundären Replikat verarbeitet werden. Bis dahin ist das Isolation Level Mapping auf der sekundären Datenbank unvollständig und Abfragen sind temporär geblockt. Microsoft sagt dazu: "This is needed to guarantee that row versions are available on the secondary replica before executing the query under snapshot isolation as all isolation levels are implicitly mapped to snapshot isolation." (SQL Storage Engine Blog: AlwaysOn: I just enabled Readable Secondary but my query is blocked?) Grundlegend bedeutet dies, dass ein aktives lesbares Replikat nicht in die Verfügbarkeitsgruppe aufgenommen werden kann, ohne das primäre Replikat vorübergehend stillzulegen. Da Leseoperationen auf das Snapshot Isolation Transaction Level abgebildet werden, kann die Bereinigung von Ghost Records auf dem primären Replikat durch Transaktionen auf einem oder mehreren sekundären Replikaten geblockt werden - z.B. durch eine lang laufende Abfrage auf dem sekundären Replikat. Diese Bereinigung wird auch blockiert, wenn die Verbindung zum sekundären Replikat abbricht oder der Datenaustausch unterbrochen wird. Auch die Log Truncation wird in diesem Zustant verhindert. Wenn dieser Zustand längere Zeit anhält, empfiehlt Microsoft das sekundäre Replikat aus der Verfügbarkeitsgruppe herauszunehmen - was ein ernsthaftes Downtime-Problem darstellt. Die Read-Only Workload auf den sekundären Replikaten kann eingehende DDL Änderungen blockieren. Obwohl die Leseoperationen aufgrund der Row-Versionierung keine Shared Locks halten, führen diese Operatioen zu Sch-S Locks (Schemastabilitätssperren). DDL-Änderungen durch Redo-Operationen können dadurch blockiert werden. Falls DDL aufgrund konkurrierender Lese-Workload blockiert wird und der Schwellenwert für 'Recovery Interval' (eine SQL Server Konfigurationsoption) überschritten wird, generiert der SQL Server das Ereignis sqlserver.lock_redo_blocked, welches Microsoft zum Kill der blockierenden Leser empfiehlt. Auf die Verfügbarkeit der Anwendung wird hierbei keinerlei Rücksicht genommen. Keine dieser Einschränkungen existiert mit Oracle Active Data Guard. Backups auf sekundären Replikaten Über die sekundären Replikate können Backups (BACKUP DATABASE via Transact-SQL) nur als copy-only Backups einer vollständigen Datenbank, Dateien und Dateigruppen erstellt werden. Das Erstellen inkrementeller Backups ist nicht unterstützt, was ein ernsthafter Rückstand ist gegenüber der Backup-Unterstützung physikalischer Standbys unter Oracle Data Guard. Hinweis: Ein möglicher Workaround via Snapshots, bleibt ein Workaround. Eine weitere Einschränkung dieses Features gegenüber Oracle Data Guard besteht darin, dass das Backup eines sekundären Replikats nicht ausgeführt werden kann, wenn es nicht mit dem primären Replikat kommunizieren kann. Darüber hinaus muss das sekundäre Replikat synchronisiert sein oder sich in der Synchronisation befinden, um das Beackup auf dem sekundären Replikat erstellen zu können. Vergleich von Microsoft AlwaysOn mit der Oracle MAA Ich komme wieder zurück auf die Eingangs erwähnte, mehrfach an mich gestellte Frage "Wann denn - und ob überhaupt - Oracle etwas Vergleichbares wie AlwaysOn bieten würde?" und meine damit verbundene (kurze) Irritation. Wenn Sie diesen Blogbeitrag bis hierher gelesen haben, dann kennen Sie jetzt meine darauf gegebene Antwort. Der eine oder andere Punkt traf dabei nicht immer auf Jeden zu, was auch nicht der tiefere Sinn und Zweck meiner Antwort war. Wenn beispielsweise kein Multi-Subnet mit im Spiel ist, sind alle diesbezüglichen Kritikpunkte zunächst obsolet. Was aber nicht bedeutet, dass sie nicht bereits morgen schon wieder zum Thema werden könnten (Sag niemals "Nie"). In manch anderes Fettnäpfchen tritt man wiederum nicht unbedingt in einer Testumgebung, sondern erst im laufenden Betrieb. Erst recht nicht dann, wenn man sich potenzieller Probleme nicht bewusst ist und keine dedizierten Tests startet. Und wer AlwaysOn erfolgreich positionieren möchte, wird auch gar kein Interesse daran haben, auf mögliche Schwachstellen und den besagten Teufel im Detail aufmerksam zu machen. Das ist keine Unterstellung - es ist nur menschlich. Außerdem ist es verständlich, dass man sich in erster Linie darauf konzentriert "was geht" und "was gut läuft", anstelle auf das "was zu Problemen führen kann" oder "nicht funktioniert". Wer will schon der Miesepeter sein? Für mich selbst gesprochen, kann ich nur sagen, dass ich lieber vorab von allen möglichen Einschränkungen wissen möchte, anstelle sie dann nach einer kurzen Zeit der heilen Welt schmerzhaft am eigenen Leib erfahren zu müssen. Ich bin davon überzeugt, dass es Ihnen nicht anders geht. Nachfolgend deshalb eine Zusammenfassung all jener Punkte, die ich im Vergleich zur Oracle MAA (Maximum Availability Architecture) als unbedingt Erwähnenswert betrachte, falls man eine Evaluierung von Microsoft AlwaysOn in Betracht zieht. 1. AlwaysOn ist eine komplexe Technologie Der SQL Server AlwaysOn Stack ist zusammengesetzt aus drei verschiedenen Technlogien: Windows Server Failover Clustering (WSFC) SQL Server Failover Cluster Instances (FCI) SQL Server Availability Groups (Verfügbarkeitsgruppen) Man kann eine derartige Lösung nicht als nahtlos bezeichnen, wofür auch die vielen von Microsoft dargestellten Einschränkungen sprechen. Während sich frühere SQL Server Versionen in Richtung eigener HA/DR Technologien entwickelten (wie Database Mirroring), empfiehlt Microsoft nun die Migration. Doch weshalb dieser Schwenk? Er führt nicht zu einem konsisten und robusten Angebot an HA/DR Technologie für geschäftskritische Umgebungen. Liegt die Antwort in meiner These begründet, nach der "Windows was the God ..." noch immer gilt und man die Nachteile der allzu engen Kopplung mit Windows nicht sehen möchte? Entscheiden Sie selbst ... 2. Failover Cluster Instanzen - Kein RAC-Pendant Die SQL Server und Windows Server Clustering Technologie basiert noch immer auf dem veralteten Aktiv-Passiv Modell und führt zu einer Verschwendung von Systemressourcen. In einer Betrachtung von lediglich zwei Knoten erschließt sich auf Anhieb noch nicht der volle Mehrwert eines Aktiv-Aktiv Clusters (wie den Real Application Clusters), wie er von Oracle bereits vor zehn Jahren entwickelt wurde. Doch kennt man die Vorzüge der Skalierbarkeit durch einfaches Hinzufügen weiterer Cluster-Knoten, die dann alle gemeinsam als ein einziges logisches System zusammenarbeiten, versteht man was hinter dem Motto "Pay-as-you-Grow" steckt. In einem Aktiv-Aktiv Cluster geht es zwar auch um Hochverfügbarkeit - und ein Failover erfolgt zudem schneller, als in einem Aktiv-Passiv Modell - aber es geht eben nicht nur darum. An dieser Stelle sei darauf hingewiesen, dass die Oracle 11g Standard Edition bereits die Nutzung von Oracle RAC bis zu vier Sockets kostenfrei beinhaltet. Möchten Sie dazu Windows nutzen, benötigen Sie keine Windows Server Enterprise Edition, da Oracle 11g die eigene Clusterware liefert. Sie kommen in den Genuss von Hochverfügbarkeit und Skalierbarkeit und können dazu die günstigere Windows Server Standard Edition nutzen. 3. SQL Server Multi-Subnet Clustering - Abhängigkeit zu 3rd Party Storage Mirroring Die SQL Server Multi-Subnet Clustering Architektur unterstützt den Aufbau eines Stretch Clusters, basiert dabei aber auf dem Aktiv-Passiv Modell. Das eigentlich Problematische ist jedoch, dass man sich zur Absicherung der Datenbank auf 3rd Party Storage Mirroring Technologie verlässt, ohne Integration zwischen dem Windows Server Failover Clustering (WSFC) und der darunterliegenden Mirroring Technologie. Wenn nun im Cluster ein Failover auf Instanzen-Ebene erfolgt, existiert keine Koordination mit einem möglichen Failover auf Ebene des Storage-Array. 4. Availability Groups (Verfügbarkeitsgruppen) - Vier, oder doch nur Zwei? Ein primäres Replikat erlaubt bis zu vier sekundäre Replikate innerhalb einer Verfügbarkeitsgruppe, jedoch nur zwei im Synchronen Commit Modus. Während dies zwar einen Vorteil gegenüber dem stringenten 1:1 Modell unter Database Mirroring darstellt, fällt der SQL Server 2012 damit immer noch weiter zurück hinter Oracle Data Guard mit bis zu 30 direkten Stanbdy Zielen - und vielen weiteren durch kaskadierende Ziele möglichen. Damit eignet sich Oracle Active Data Guard auch für die Bereitstellung einer Reader-Farm Skalierbarkeit für Internet-basierende Unternehmen. Mit AwaysOn Verfügbarkeitsgruppen ist dies nicht möglich. 5. Availability Groups (Verfügbarkeitsgruppen) - kein asynchrones Switchover Die Technologie der Verfügbarkeitsgruppen wird auch als geeignetes Mittel für administrative Aufgaben positioniert - wie Upgrades oder Wartungsarbeiten. Man muss sich jedoch einem gravierendem Defizit bewusst sein: Im asynchronen Verfügbarkeitsmodus besteht die einzige Möglichkeit für Role Transition im Forced Failover mit Datenverlust! Um den Verlust von Daten durch geplante Wartungsarbeiten zu vermeiden, muss man den synchronen Verfügbarkeitsmodus konfigurieren, was jedoch ernstzunehmende Auswirkungen auf WAN Deployments nach sich zieht. Spinnt man diesen Gedanken zu Ende, kommt man zu dem Schluss, dass die Technologie der Verfügbarkeitsgruppen für geplante Wartungsarbeiten in einem derartigen Umfeld nicht effektiv genutzt werden kann. 6. Automatisches Failover - Nicht immer möglich Sowohl die SQL Server FCI, als auch Verfügbarkeitsgruppen unterstützen automatisches Failover. Möchte man diese jedoch kombinieren, wird das Ergebnis kein automatisches Failover sein. Denn ihr Zusammentreffen im Failover-Fall führt zu Race Conditions (Wettlaufsituationen), weshalb diese Konfiguration nicht länger das automatische Failover zu einem Replikat in einer Verfügbarkeitsgruppe erlaubt. Auch hier bestätigt sich wieder die tiefere Problematik von AlwaysOn, mit einer Zusammensetzung aus unterschiedlichen Technologien und der Abhängigkeit zu Windows. 7. Problematische RTO (Recovery Time Objective) Microsoft postioniert die SQL Server Multi-Subnet Clustering Architektur als brauchbare HA/DR Architektur. Bedenkt man jedoch die Problematik im Zusammenhang mit DNS Replikation und den möglichen langen Wartezeiten auf Client-Seite von bis zu 16 Minuten, sind strenge RTO Anforderungen (Recovery Time Objectives) nicht erfüllbar. Im Gegensatz zu Oracle besitzt der SQL Server keine Datenbank-integrierten Technologien, wie Oracle Fast Application Notification (FAN) oder Oracle Fast Connection Failover (FCF). 8. Problematische RPO (Recovery Point Objective) SQL Server ermöglicht Forced Failover (erzwungenes Failover), bietet jedoch keine Möglichkeit zur automatischen Übertragung der letzten Datenbits von einem alten zu einem neuen primären Replikat, wenn der Verfügbarkeitsmodus asynchron war. Oracle Data Guard hingegen bietet diese Unterstützung durch das Flush Redo Feature. Dies sichert "Zero Data Loss" und beste RPO auch in erzwungenen Failover-Situationen. 9. Lesbare Sekundäre Replikate mit Einschränkungen Aufgrund des Snapshot Isolation Transaction Level für lesbare sekundäre Replikate, besitzen diese Einschränkungen mit Auswirkung auf die primäre Datenbank. Die Bereinigung von Ghost Records auf der primären Datenbank, wird beeinflusst von lang laufenden Abfragen auf der lesabaren sekundären Datenbank. Die lesbare sekundäre Datenbank kann nicht in die Verfügbarkeitsgruppe aufgenommen werden, wenn es aktive Transaktionen auf der primären Datenbank gibt. Zusätzlich können DLL Änderungen auf der primären Datenbank durch Abfragen auf der sekundären blockiert werden. Und imkrementelle Backups werden hier nicht unterstützt. Keine dieser Restriktionen existiert unter Oracle Data Guard.

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Import Data from Excel sheet to DB Table through OAF page

- by PRajkumar

1. Create a New Workspace and Project File > New > General > Workspace Configured for Oracle Applications File Name – PrajkumarImportxlsDemo Automatically a new OA Project will also be created Project Name -- ImportxlsDemo Default Package -- prajkumar.oracle.apps.fnd.importxlsdemo 2. Add JAR file jxl-2.6.3.jar to Apache Library Download jxl-2.6.3.jar from following link – http://www.findjar.com/jar/net.sourceforge.jexcelapi/jars/jxl-2.6.jar.html Steps to add jxl.jar file in Local Machine Right Click on ImportxlsDemo > Project Properties > Libraries > Add jar/Directory and browse to directory where jxl-2.6.3.jar has been downloaded and select the JAR file Steps to add jxl.jar file at EBS middle tier On your EBS middile tier copy jxl.jar at $FND_TOP/java/3rdparty/standalone Add $FND_TOP/java/3rdparty/standalone\jxl.jar to custom classpath in Jser.properties file which is at $IAS_ORACLE_HOME/Apache/Jserv/etc wrapper.classpath=/U01/oracle/dev/devappl/fnd/11.5.0/java/3rdparty/stdalone/jxl.jar Bounce Apache Server 3. Create a New Application Module (AM) Right Click on ImportxlsDemo > New > ADF Business Components > Application Module Name -- ImportxlsAM Package -- prajkumar.oracle.apps.fnd.importxlsdemo.server Check Application Module Class: ImportxlsAMImpl Generate JavaFile(s) 4. Create Test Table in which we will insert data from excel CREATE TABLE xx_import_excel_data_demo ( -- -------------------- -- Data Columns -- -------------------- column1 VARCHAR2(100), column2 VARCHAR2(100), column3 VARCHAR2(100), column4 VARCHAR2(100), column5 VARCHAR2(100), -- -------------------- -- Who Columns -- -------------------- last_update_date DATE NOT NULL, last_updated_by NUMBER NOT NULL, creation_date DATE NOT NULL, created_by NUMBER NOT NULL, last_update_login NUMBER ); 5. Create a New Entity Object (EO) Right click on ImportxlsDemo > New > ADF Business Components > Entity Object Name – ImportxlsEO Package -- prajkumar.oracle.apps.fnd.importxlsdemo.schema.server Database Objects -- XX_IMPORT_EXCEL_DATA_DEMO Note – By default ROWID will be the primary key if we will not make any column to be primary key Check the Accessors, Create Method, Validation Method and Remove Method 6. Create a New View Object (VO) Right click on ImportxlsDemo > New > ADF Business Components > View Object Name -- ImportxlsVO Package -- prajkumar.oracle.apps.fnd.importxlsdemo.server In Step2 in Entity Page select ImportxlsEO and shuttle it to selected list In Step3 in Attributes Window select all columns and shuttle them to selected list In Java page Uncheck Generate Java file for View Object Class: ImportxlsVOImpl Select Generate Java File for View Row Class: ImportxlsVORowImpl -> Generate Java File -> Accessors 7. Add Your View Object to Root UI Application Module Right click on ImportxlsAM > Edit ImportxlsAM > Data Model > Select ImportxlsVO and shuttle to Data Model list 8. Create a New Page Right click on ImportxlsDemo > New > Web Tier > OA Components > Page Name -- ImportxlsPG Package -- prajkumar.oracle.apps.fnd.importxlsdemo.webui 9. Select the ImportxlsPG and go to the strcuture pane where a default region has been created 10. Select region1 and set the following properties: Attribute Property ID PageLayoutRN AM Definition prajkumar.oracle.apps.fnd.importxlsdemo.server.ImportxlsAM Window Title Import Data From Excel through OAF Page Demo Window Title Import Data From Excel through OAF Page Demo 11. Create messageComponentLayout Region Under Page Layout Region Right click PageLayoutRN > New > Region Attribute Property ID MainRN Item Style messageComponentLayout 12. Create a New Item messageFileUpload Bean under MainRN Right click on MainRN > New > messageFileUpload Set Following Properties for New Item -- Attribute Property ID MessageFileUpload Item Style messageFileUpload 13. Create a New Item Submit Button Bean under MainRN Right click on MainRN > New > messageLayout Set Following Properties for messageLayout -- Attribute Property ID ButtonLayout Right Click on ButtonLayout > New > Item Attribute Property ID Go Item Style submitButton Attribute Set /oracle/apps/fnd/attributesets/Buttons/Go 14. Create Controller for page ImportxlsPG Right Click on PageLayoutRN > Set New Controller Package Name: prajkumar.oracle.apps.fnd.importxlsdemo.webui Class Name: ImportxlsCO Write Following Code in ImportxlsCO in processFormRequest import oracle.apps.fnd.framework.OAApplicationModule; import oracle.apps.fnd.framework.OAException; import java.io.Serializable; import oracle.apps.fnd.framework.webui.OAControllerImpl; import oracle.apps.fnd.framework.webui.OAPageContext; import oracle.apps.fnd.framework.webui.beans.OAWebBean; import oracle.cabo.ui.data.DataObject; import oracle.jbo.domain.BlobDomain; public void processFormRequest(OAPageContext pageContext, OAWebBean webBean) { super.processFormRequest(pageContext, webBean); if (pageContext.getParameter("Go") != null) { DataObject fileUploadData = (DataObject)pageContext.getNamedDataObject("MessageFileUpload"); String fileName = null; try { fileName = (String)fileUploadData.selectValue(null, "UPLOAD_FILE_NAME"); } catch(NullPointerException ex) { throw new OAException("Please Select a File to Upload", OAException.ERROR); } BlobDomain uploadedByteStream = (BlobDomain)fileUploadData.selectValue(null, fileName); try { OAApplicationModule oaapplicationmodule = pageContext.getRootApplicationModule(); Serializable aserializable2[] = {uploadedByteStream}; Class aclass2[] = {BlobDomain.class }; oaapplicationmodule.invokeMethod("ReadExcel", aserializable2,aclass2); } catch (Exception ex) { throw new OAException(ex.toString(), OAException.ERROR); } } } Write Following Code in ImportxlsAMImpl.java import java.io.IOException; import java.io.InputStream; import jxl.Cell; import jxl.CellType; import jxl.Sheet; import jxl.Workbook; import jxl.read.biff.BiffException; import oracle.apps.fnd.framework.server.OAApplicationModuleImpl; import oracle.jbo.Row; import oracle.apps.fnd.framework.OAViewObject; import oracle.apps.fnd.framework.server.OAViewObjectImpl; import oracle.jbo.domain.BlobDomain; public void createRecord(String[] excel_data) { OAViewObject vo = (OAViewObject)getImportxlsVO1(); if (!vo.isPreparedForExecution()) { vo.executeQuery(); } Row row = vo.createRow(); try { for (int i=0; i < excel_data.length; i++) { row.setAttribute("Column" +(i+1) ,excel_data[i]); } } catch(Exception e) { System.out.println(e.getMessage()); } vo.insertRow(row); getTransaction().commit(); } public void ReadExcel(BlobDomain fileData) throws IOException { String[] excel_data = new String[5]; InputStream inputWorkbook = fileData.getInputStream(); Workbook w; try { w = Workbook.getWorkbook(inputWorkbook); // Get the first sheet Sheet sheet = w.getSheet(0); for (int i = 0; i < sheet.getRows(); i++) { for (int j = 0; j < sheet.getColumns(); j++) { Cell cell = sheet.getCell(j, i); CellType type = cell.getType(); if (cell.getType() == CellType.LABEL) { System.out.println("I got a label " + cell.getContents()); excel_data[j] = cell.getContents(); } if (cell.getType() == CellType.NUMBER) { System.out.println("I got a number " + cell.getContents()); excel_data[j] = cell.getContents(); } } createRecord(excel_data); } } catch (BiffException e) { e.printStackTrace(); } } 15. Congratulation you have successfully finished. Run Your page and Test Your Work Consider Excel PRAJ_TEST.xls with following data -- Lets Try to import this data into DB Table --

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Insert Record by Drag & Drop from ADF Tree to ADF Tree Table

- by arul.wilson(at)oracle.com

If you want to create record based on the values Dragged from ADF Tree and Dropped on a ADF Tree Table, then here you go.UseCase DescriptionUser Drags a tree node from ADF Tree and Drops it on a ADF Tree Table node. A new row gets added in the Tree Table based on the source tree node, subsequently a record gets added to the database table on which Tree table in based on.Following description helps to achieve this using ADF BC.Run the DragDropSchema.sql to create required tables.Create Business Components from tables (PRODUCTS, COMPONENTS, SUB_COMPONENTS, USERS, USER_COMPONENTS) created above.Add custom method to App Module Impl, this method will be used to insert record from view layer. public String createUserComponents(String p_bugdbId, String p_productId, String p_componentId, String p_subComponentId){ Row newUserComponentsRow = this.getUserComponentsView1().createRow(); try { newUserComponentsRow.setAttribute("Bugdbid", p_bugdbId); newUserComponentsRow.setAttribute("ProductId", new oracle.jbo.domain.Number(p_productId)); newUserComponentsRow.setAttribute("Component1", p_componentId); newUserComponentsRow.setAttribute("SubComponent", p_subComponentId); } catch (Exception e) { e.printStackTrace(); return "Failure"; } return "Success"; }Expose this method to client interface.To display the root node we need a custom VO which can be achieved using below query. SELECT Users.ACTIVE, Users.BUGDB_ID, Users.EMAIL, Users.FIRSTNAME, Users.GLOBAL_ID, Users.LASTNAME, Users.MANAGER_ID, Users.MANAGER_PRIVILEGEFROM USERS UsersWHERE Users.MANAGER_ID is NULLCreate VL between UsersView and UsersRootNodeView VOs.Drop ProductsView from DC as ADF Tree to jspx page.Add Tree Level Rule based on ComponentsView and SubComponentsView.Drop UsersRootNodeView as ADF Tree TableAdd Tree Level Rules based on UserComponentsView and UsersView.Add DragSource to ADF Tree and CollectionDropTarget to ADF Tree Table respectively.Bind CollectionDropTarget's DropTarget to backing bean and implement method of signature DnDAction (DropEvent), this method gets invoked when Tree Table encounters a drop action, here details required for creating new record are captured from the drag source and passed to 'createUserComponents' method. public DnDAction onTreeDrop(DropEvent dropEvent) { String newBugdbId = ""; String msgtxt=""; try { // Getting the target node bugdb id Object serverRowKey = dropEvent.getDropSite(); if (serverRowKey != null) { //Code for Tree Table as target String dropcomponent = dropEvent.getDropComponent().toString(); dropcomponent = (String)dropcomponent.subSequence(0, dropcomponent.indexOf("[")); if (dropcomponent.equals("RichTreeTable")){ RichTreeTable richTreeTable = (RichTreeTable)dropEvent.getDropComponent(); richTreeTable.setRowKey(serverRowKey); int rowIndexTreeTable = richTreeTable.getRowIndex(); //Drop Target Logic if (((JUCtrlHierNodeBinding)richTreeTable.getRowData(rowIndexTreeTable)).getAttributeValue()==null) { //Get Parent newBugdbId = (String)((JUCtrlHierNodeBinding)richTreeTable.getRowData(rowIndexTreeTable)).getParent().getAttributeValue(); } else { if (isNum(((JUCtrlHierNodeBinding)richTreeTable.getRowData(rowIndexTreeTable)).getAttributeValue().toString())) { //Get Parent's parent newBugdbId = (String)((JUCtrlHierNodeBinding)richTreeTable.getRowData(rowIndexTreeTable)).getParent().getParent().getAttributeValue(); } else{ //Dropped on USER newBugdbId = (String)((JUCtrlHierNodeBinding)richTreeTable.getRowData(rowIndexTreeTable)).getAttributeValue(); } } } } DataFlavor<RowKeySet> df = DataFlavor.getDataFlavor(RowKeySet.class); RowKeySet droppedValue = dropEvent.getTransferable().getData(df); Object[] keys = droppedValue.toArray(); Key componentKey = null; Key subComponentKey = null; // binding for createUserComponents method defined in AppModuleImpl class to insert record in database. operationBinding = bindings.getOperationBinding("createUserComponents"); // get the Product, Component, Subcomponent details and insert to UserComponents table. // loop through the keys if more than one comp/subcomponent is select. for (int i = 0; i < keys.length; i++) { System.out.println("in for :"+i); List list = (List)keys[i]; System.out.println("list "+i+" : "+list); System.out.println("list size "+list.size()); if (list.size() == 1) { // we cannot drag and drop the highest node ! msgtxt="You cannot drop Products, please drop Component or SubComponent from the Tree."; System.out.println(msgtxt); this.showInfoMessage(msgtxt); } else { if (list.size() == 2) { // were doing the first branch, in this case all components. componentKey = (Key)list.get(1); Object[] droppedProdCompValues = componentKey.getAttributeValues(); operationBinding.getParamsMap().put("p_bugdbId",newBugdbId); operationBinding.getParamsMap().put("p_productId",droppedProdCompValues[0]); operationBinding.getParamsMap().put("p_componentId",droppedProdCompValues[1]); operationBinding.getParamsMap().put("p_subComponentId","ALL"); Object result = operationBinding.execute(); } else { subComponentKey = (Key)list.get(2); Object[] droppedProdCompSubCompValues = subComponentKey.getAttributeValues(); operationBinding.getParamsMap().put("p_bugdbId",newBugdbId); operationBinding.getParamsMap().put("p_productId",droppedProdCompSubCompValues[0]); operationBinding.getParamsMap().put("p_componentId",droppedProdCompSubCompValues[1]); operationBinding.getParamsMap().put("p_subComponentId",droppedProdCompSubCompValues[2]); Object result = operationBinding.execute(); } } } /* this.getCil1().setDisabled(false); this.getCil1().setPartialSubmit(true); */ return DnDAction.MOVE; } catch (Exception ex) { System.out.println("drop failed with : " + ex.getMessage()); ex.printStackTrace(); /* this.getCil1().setDisabled(true); */ return DnDAction.NONE; } } Run jspx page and drop a Component or Subcomponent from Products Tree to UserComponents Tree Table.

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ASP.NET MVC 3 Hosting :: How to Deploy Web Apps Using ASP.NET MVC 3, Razor and EF Code First - Part I

- by mbridge

First, you can download the source code from http://efmvc.codeplex.com. The following frameworks will be used for this step by step tutorial. public class Category { public int CategoryId { get; set; } [Required(ErrorMessage = "Name Required")] [StringLength(25, ErrorMessage = "Must be less than 25 characters")] public string Name { get; set;} public string Description { get; set; } public virtual ICollection<Expense> Expenses { get; set; } } Expense Class public class Expense { public int ExpenseId { get; set; } public string Transaction { get; set; } public DateTime Date { get; set; } public double Amount { get; set; } public int CategoryId { get; set; } public virtual Category Category { get; set; } } Define Domain Model Let’s create domain model for our simple web application Category Class We have two domain entities - Category and Expense. A single category contains a list of expense transactions and every expense transaction should have a Category. In this post, we will be focusing on CRUD operations for the entity Category and will be working on the Expense entity with a View Model object in the later post. And the source code for this application will be refactored over time. The above entities are very simple POCO (Plain Old CLR Object) classes and the entity Category is decorated with validation attributes in the System.ComponentModel.DataAnnotations namespace. Now we want to use these entities for defining model objects for the Entity Framework 4. Using the Code First approach of Entity Framework, we can first define the entities by simply writing POCO classes without any coupling with any API or database library. This approach lets you focus on domain model which will enable Domain-Driven Development for applications. EF code first support is currently enabled with a separate API that is runs on top of the Entity Framework 4. EF Code First is reached CTP 5 when I am writing this article. Creating Context Class for Entity Framework We have created our domain model and let’s create a class in order to working with Entity Framework Code First. For this, you have to download EF Code First CTP 5 and add reference to the assembly EntitFramework.dll. You can also use NuGet to download add reference to EEF Code First. public class MyFinanceContext : DbContext { public MyFinanceContext() : base("MyFinance") { } public DbSet<Category> Categories { get; set; } public DbSet<Expense> Expenses { get; set; } } The above class MyFinanceContext is derived from DbContext that can connect your model classes to a database. The MyFinanceContext class is mapping our Category and Expense class into database tables Categories and Expenses using DbSet<TEntity> where TEntity is any POCO class. When we are running the application at first time, it will automatically create the database. EF code-first look for a connection string in web.config or app.config that has the same name as the dbcontext class. If it is not find any connection string with the convention, it will automatically create database in local SQL Express database by default and the name of the database will be same name as the dbcontext class. You can also define the name of database in constructor of the the dbcontext class. Unlike NHibernate, we don’t have to use any XML based mapping files or Fluent interface for mapping between our model and database. The model classes of Code First are working on the basis of conventions and we can also use a fluent API to refine our model. The convention for primary key is ‘Id’ or ‘<class name>Id’. If primary key properties are detected with type ‘int’, ‘long’ or ‘short’, they will automatically registered as identity columns in the database by default. Primary key detection is not case sensitive. We can define our model classes with validation attributes in the System.ComponentModel.DataAnnotations namespace and it automatically enforces validation rules when a model object is updated or saved. Generic Repository for EF Code First We have created model classes and dbcontext class. Now we have to create generic repository pattern for data persistence with EF code first. If you don’t know about the repository pattern, checkout Martin Fowler’s article on Repository Let’s create a generic repository to working with DbContext and DbSet generics. public interface IRepository<T> where T : class { void Add(T entity); void Delete(T entity); T GetById(long Id); IEnumerable<T> All(); } RepositoryBasse – Generic Repository class protected MyFinanceContext Database { get { return database ?? (database = DatabaseFactory.Get()); } } public virtual void Add(T entity) { dbset.Add(entity); } public virtual void Delete(T entity) { dbset.Remove(entity); } public virtual T GetById(long id) { return dbset.Find(id); } public virtual IEnumerable<T> All() { return dbset.ToList(); } } DatabaseFactory class public class DatabaseFactory : Disposable, IDatabaseFactory { private MyFinanceContext database; public MyFinanceContext Get() { return database ?? (database = new MyFinanceContext()); } protected override void DisposeCore() { if (database != null) database.Dispose(); } } Unit of Work If you are new to Unit of Work pattern, checkout Fowler’s article on Unit of Work . According to Martin Fowler, the Unit of Work pattern "maintains a list of objects affected by a business transaction and coordinates the writing out of changes and the resolution of concurrency problems." Let’s create a class for handling Unit of Work public interface IUnitOfWork { void Commit(); } UniOfWork class public class UnitOfWork : IUnitOfWork { private readonly IDatabaseFactory databaseFactory; private MyFinanceContext dataContext; public UnitOfWork(IDatabaseFactory databaseFactory) { this.databaseFactory = databaseFactory; } protected MyFinanceContext DataContext { get { return dataContext ?? (dataContext = databaseFactory.Get()); } } public void Commit() { DataContext.Commit(); } } The Commit method of the UnitOfWork will call the commit method of MyFinanceContext class and it will execute the SaveChanges method of DbContext class. Repository class for Category In this post, we will be focusing on the persistence against Category entity and will working on other entities in later post. Let’s create a repository for handling CRUD operations for Category using derive from a generic Repository RepositoryBase<T>. public class CategoryRepository: RepositoryBase<Category>, ICategoryRepository { public CategoryRepository(IDatabaseFactory databaseFactory) : base(databaseFactory) { } } public interface ICategoryRepository : IRepository<Category> { } If we need additional methods than generic repository for the Category, we can define in the CategoryRepository. Dependency Injection using Unity 2.0 If you are new to Inversion of Control/ Dependency Injection or Unity, please have a look on my articles at http://weblogs.asp.net/shijuvarghese/archive/tags/IoC/default.aspx. I want to create a custom lifetime manager for Unity to store container in the current HttpContext. public class HttpContextLifetimeManager<T> : LifetimeManager, IDisposable { public override object GetValue() { return HttpContext.Current.Items[typeof(T).AssemblyQualifiedName]; } public override void RemoveValue() { HttpContext.Current.Items.Remove(typeof(T).AssemblyQualifiedName); } public override void SetValue(object newValue) { HttpContext.Current.Items[typeof(T).AssemblyQualifiedName] = newValue; } public void Dispose() { RemoveValue(); } } Let’s create controller factory for Unity in the ASP.NET MVC 3 application. 404, String.Format( "The controller for path '{0}' could not be found" + "or it does not implement IController.", reqContext.HttpContext.Request.Path)); if (!typeof(IController).IsAssignableFrom(controllerType)) throw new ArgumentException( string.Format( "Type requested is not a controller: {0}", controllerType.Name), "controllerType"); try { controller= container.Resolve(controllerType) as IController; } catch (Exception ex) { throw new InvalidOperationException(String.Format( "Error resolving controller {0}", controllerType.Name), ex); } return controller; } } Configure contract and concrete types in Unity Let’s configure our contract and concrete types in Unity for resolving our dependencies. private void ConfigureUnity() { //Create UnityContainer IUnityContainer container = new UnityContainer() .RegisterType<IDatabaseFactory, DatabaseFactory>(new HttpContextLifetimeManager<IDatabaseFactory>()) .RegisterType<IUnitOfWork, UnitOfWork>(new HttpContextLifetimeManager<IUnitOfWork>()) .RegisterType<ICategoryRepository, CategoryRepository>(new HttpContextLifetimeManager<ICategoryRepository>()); //Set container for Controller Factory ControllerBuilder.Current.SetControllerFactory( new UnityControllerFactory(container)); } In the above ConfigureUnity method, we are registering our types onto Unity container with custom lifetime manager HttpContextLifetimeManager. Let’s call ConfigureUnity method in the Global.asax.cs for set controller factory for Unity and configuring the types with Unity. protected void Application_Start() { AreaRegistration.RegisterAllAreas(); RegisterGlobalFilters(GlobalFilters.Filters); RegisterRoutes(RouteTable.Routes); ConfigureUnity(); } Developing web application using ASP.NET MVC 3 We have created our domain model for our web application and also have created repositories and configured dependencies with Unity container. Now we have to create controller classes and views for doing CRUD operations against the Category entity. Let’s create controller class for Category Category Controller public class CategoryController : Controller { private readonly ICategoryRepository categoryRepository; private readonly IUnitOfWork unitOfWork; public CategoryController(ICategoryRepository categoryRepository, IUnitOfWork unitOfWork) { this.categoryRepository = categoryRepository; this.unitOfWork = unitOfWork; } public ActionResult Index() { var categories = categoryRepository.All(); return View(categories); } [HttpGet] public ActionResult Edit(int id) { var category = categoryRepository.GetById(id); return View(category); } [HttpPost] public ActionResult Edit(int id, FormCollection collection) { var category = categoryRepository.GetById(id); if (TryUpdateModel(category)) { unitOfWork.Commit(); return RedirectToAction("Index"); } else return View(category); } [HttpGet] public ActionResult Create() { var category = new Category(); return View(category); } [HttpPost] public ActionResult Create(Category category) { if (!ModelState.IsValid) { return View("Create", category); } categoryRepository.Add(category); unitOfWork.Commit(); return RedirectToAction("Index"); } [HttpPost] public ActionResult Delete(int id) { var category = categoryRepository.GetById(id); categoryRepository.Delete(category); unitOfWork.Commit(); var categories = categoryRepository.All(); return PartialView("CategoryList", categories); } } Creating Views in Razor Now we are going to create views in Razor for our ASP.NET MVC 3 application. Let’s create a partial view CategoryList.cshtml for listing category information and providing link for Edit and Delete operations. CategoryList.cshtml @using MyFinance.Helpers; @using MyFinance.Domain; @model IEnumerable<Category> <table> <tr> <th>Actions</th> <th>Name</th> <th>Description</th> </tr> @foreach (var item in Model) { <tr> <td> @Html.ActionLink("Edit", "Edit",new { id = item.CategoryId }) @Ajax.ActionLink("Delete", "Delete", new { id = item.CategoryId }, new AjaxOptions { Confirm = "Delete Expense?", HttpMethod = "Post", UpdateTargetId = "divCategoryList" }) </td> <td> @item.Name </td> <td> @item.Description </td> </tr> } </table> <p> @Html.ActionLink("Create New", "Create") </p> The delete link is providing Ajax functionality using the Ajax.ActionLink. This will call an Ajax request for Delete action method in the CategoryCotroller class. In the Delete action method, it will return Partial View CategoryList after deleting the record. We are using CategoryList view for the Ajax functionality and also for Index view using for displaying list of category information. Let’s create Index view using partial view CategoryList Index.chtml @model IEnumerable<MyFinance.Domain.Category> @{ ViewBag.Title = "Index"; } <h2>Category List</h2> <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script> <div id="divCategoryList"> @Html.Partial("CategoryList", Model) </div> We can call the partial views using Html.Partial helper method. Now we are going to create View pages for insert and update functionality for the Category. Both view pages are sharing common user interface for entering the category information. So I want to create an EditorTemplate for the Category information. We have to create the EditorTemplate with the same name of entity object so that we can refer it on view pages using @Html.EditorFor(model => model) . So let’s create template with name Category. Category.cshtml @model MyFinance.Domain.Category <div class="editor-label"> @Html.LabelFor(model => model.Name) </div> <div class="editor-field"> @Html.EditorFor(model => model.Name) @Html.ValidationMessageFor(model => model.Name) </div> <div class="editor-label"> @Html.LabelFor(model => model.Description) </div> <div class="editor-field"> @Html.EditorFor(model => model.Description) @Html.ValidationMessageFor(model => model.Description) </div> Let’s create view page for insert Category information @model MyFinance.Domain.Category @{ ViewBag.Title = "Save"; } <h2>Create</h2> <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script> @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>Category</legend> @Html.EditorFor(model => model) <p> <input type="submit" value="Create" /> </p> </fieldset> } <div> @Html.ActionLink("Back to List", "Index") </div> ViewStart file In Razor views, we can add a file named _viewstart.cshtml in the views directory and this will be shared among the all views with in the Views directory. The below code in the _viewstart.cshtml, sets the Layout page for every Views in the Views folder. @{ Layout = "~/Views/Shared/_Layout.cshtml"; } Tomorrow, we will cotinue the second part of this article. :)

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CodePlex Daily Summary for Tuesday, April 20, 2010

CodePlex Daily Summary for Tuesday, April 20, 2010New ProjectsASP.NET MVC Extensibility: ASP.NET MVC Extensibility.ASP.NET MVC Starter: Tekpub's ASP.NET MVC 2.0 Starter Site, as put together by Rob Conery in Episode 15 of Mastering ASP.NET MVC (http://tekpub.com/production/starter)AzureDemo: An internal Azure demo and test bed for some projects. After demo is complete this project will be closed.Basic Sprite Sheet Creator: A basic c# program to create sprite sheets. CodeDefender: Protect your .Net codes easily with this smart obfuscator!Crawlr: Tema 2 projectDocument Session Manager - Visual Studio addin: Document Session Manager is a Visual Studio 2008 addin for saving and restoring the list of opened documents (xml files, source files, winforms, et...Esferatec.Text.RegularExpressions: assembly to build regular expression patternsFIFA World Cup 2010 Mobile Sticker Checklist: FIFA World Cup 2010 Mobile Sticker Checklist is a small application for Windows Mobile developed in CF 3.5 to keep tracking of your sticker album. ...Finia.net: 追忆游乐网·幻之大地FusspawnsAI: Fusspawns UT AI is a small test engine for a classic ut remote bot api. intending to improve ut's ai to a god like level without cheating bots(bots...G.A.E.T.: This is a Graphical Asymmetric Encryption Tool based on R.S.A. algorithm with the help of Java Language.Even though, this may be a small applicatio...ItzyBitzySpider: Webcrawler project from computer science at UCN.JingQiao.Ads: My DDD NTier Architecture example project.Managed Meizu SDK Demo: In this project we are sharing the source code to demonstrate the usage of managed SDK for Meizu cell phones, currently for M8. With the help of th...MaxxUtils.MaxxTagger: MaxxTagger: An Mp3 Tag Editor.. Add /Edit/Remove MP3 ID3 V1 and 2.3 Tags like Title, Artist, Album, Album Art, Genre. Besides tag editing, it also ...Maya Project Management: The Maya Project Management is a clone of RedMine with all its functions and plug-in support, using the following technologies: Microsoft .net Fra...MessageBoxLib: A simple, robust library for Xbox 360 and Windows development using the XNA Game Studio that makes using the Guide class's message box functionalit...MyWSAT - ASP.NET Membership Administration Tool: MyWSAT aka ASP.NET WSAT is a WebForms based website Starter Kit for the ASP.NET Membership Provider. It is a feature rich application that takes ca...OntologyCreator: this is my thesis and it is not finished yetPOS for .Net Handheld Products Service Object: POS for .Net Service Object Handheld Products Bar Code ScannerPostBinder: PostBinder is a small helper library that deserializes ASP.NET requests into C# classes. This eliminates having to write repeated hand wiring co...PostSharp for ASP.NET Web Sites: Adds support for PostSharp 2.0 on ASP.NET Web Sites.Rapid Dictionary: * Rapid Dictionary is a Translation Dictionary initialized by language learning network http://wordsteps.com. * Dictionary developed in C# and Co...ROrganizer: If you feel your movie files are kept in messy way, try out the ROrganizer which helps you rearrange them.RoRoWoBlog: 萝萝窝个人博客开源项目SPGroupDeflector - Explicitly deny groups to webs within your Site Collection: Secure webs within your MOSS or WSS Portal by explicitly denying access to specific users in SharePoint groups.SSIS ShapeFileSource: SSIS ShapeFileSource imports ESRI Shapefiles, and the associated attribute file (.dbf). The component based on the free Shapefile C Library.StoreManagement: University assignment. The task is to build an application that can perform basic CRUD operations on a property and use an arbitrary database. ...Surfium: TODO ;-)TaskCleaner: This is a Windows Forms project created to kill some running process in order to enhace the performance of Windows execution. Sometimes it is desi...The Expert Calendar: The Expert Calendar is a MOSS 2007 webpart which allows to connect to a Event Item List and display event items in a small design customizable cale...Visual Studio Find Results Window Tweak: This is a Visual Studio 2010 add-in which enables you to adjust the format of the Find Results Window. It is written in C#, .NET 4.0 and requires ...Weightlifting Sinclair coeficient calculator: Weightlifting Sinclair coeficient calculator for competitors (for Windows Mobile platform)Windows Azure Web Storage Explorer: Windows Azure Web Storage Explorer makes it easier for developers to browse and manage Blobs, Queues and Tables from Windows Azure Storage account....New Releases#SNMP - C# Based Open Source SNMP for .NET and Mono: CatPaw (5.0) Beta 1: SNMP v3 support in snmpd is complete.ASP.Net MVC Crud with JqGrid: Mvc Crud with JqGrid 0.3.0: Fairly major reworking of the GenericDataGrid (with alot of work from James). Most noticeable is the replacing of Edit and Delete with action butt...Basic Sprite Sheet Creator: Sprite Tool v1.1: Fixed the progress bar, it now correctly displays text and progress. Also download will now come with an installer and an executable so you don't h...Basic Sprite Sheet Creator: Sprite Tool Version 1.0: Program used to make basic sprite sheets. please visit http://coderplex.blogspot.com for more infoBraintree Client Library: Braintree-1.2.1: Escape all XMLCodeDefender: CodeDefender v0.1: Protect your .Net exe and dll files with this smart tool.ColinTesting: test: testColinTesting: test2: test2ColinTesting: test3: test3ColinTesting: test4: test4ColinTesting: test6: test6CycleMania Starter Kit EAP - ASP.NET 4 Problem - Design - Solution: Cyclemania 0.08.63: See Source Code tab for recent change history.Document Session Manager - Visual Studio addin: Release v0.45948: Release v0.45948DotNetNuke® Community Edition: 05.04.00: Major Highlights Fixed issue where portal settings were not saved per portal. Fixed issue with importing page templates. Fixed issue with...DotNetNuke® Postgres Data Provider: DNN PG Provider 01.00.00 Beta2: Fixes problems with deprecated datatype money in Postgres. Upgrades DotnetNuke code base to 04.09.05 It comes with a patch for the DotNetNuke insta...FIFA World Cup 2010 Mobile Sticker Checklist: FIFA World Cup 2010 Mobile Sticker Checklist v0.1b: FIFA World Cup 2010 Mobile Sticker Checklist v0.1b First beta release. Requires Microsoft Compact Framework 3.5. It was tested on an HTC Touch Viva...FIFA World Cup 2010 Mobile Sticker Checklist: FIFA World Cup 2010 Mobile Sticker Checklist v0.2b: FIFA World Cup 2010 Mobile Sticker Checklist v0.2b Second beta release. Requires Microsoft Compact Framework 3.5. It was tested on an HTC Touch Viv...Fluent Ribbon Control Suite: Fluent Ribbon Control Suite 1.2: Fluent Ribbon Control Suite 1.2(supports .NET 3.5 and .NET 4 RTM) Includes: Fluent.dll (with .pdb and .xml) Showcase Application Samples Found...G.A.E.T.: Graphical Asymmetric Encryption Tool: User Interface The GAET User Interface is a window with five buttons. Each button is explained the following sections. Each button has a functional...HTML Ruby: 6.21.7: As long as I don't find anything else that I can improve, this will be submitted to Mozilla for review tomorrow. Added back process inserted conten...IBCSharp: IBCSharp 1.03: What IBCSharp 1.03.zip unzips to: http://i43.tinypic.com/24ffbqr.png Note: The above solution has MSTest, Typemock Isolator, and Microsoft CHESS c...LogikBug's IoC Container: Second Release: This project is dependent upon Microsoft.Practices.ServiceLocation and must be referenced when referencing LogikBug.Injection. Click here to view d...Managed Meizu SDK Demo: Library and Demo: Library and DemoMaxxUtils.MaxxTagger: MaxxUtils.MaxxTagger: Version: 1.0.0 (Beta) Instructions: Unzip the files to a folder and then dbl click on the exe. Known Issues: 1. When u copy or move a folde...OrthoLab: Cellule: Compile with Autodesk Maya 2008 32bit and 2010 64bit.OWASP Code Crawler: OWASP Code Crawler 2.7: Code Crawler 2.7 DescriptionIn terms of functionality there is not much new stuff in this release. We transplanted the new engine. Code Crawler is ...PerceptiveMCAPI - A .NET wrapper for the MailChimp Api: V1.2.3 PerceptiveMCAPI .Net Wrapper [Beta 2]: PerceptiveMCAPI – v 1.2.3 Change logFunctionality through MailChimp API announce v1.2.5 on 15-Feb-2010 .NET Wrapper New wrapper directives; api_Me...POS for .Net Handheld Products Service Object: POS for .Net Handhelp Products Service Object: The Service Object contained herein is a work in progress. This Service Object's is written as VS 2008 C# Project. The Target Platform is x86. ...PostSharp for ASP.NET Web Sites: R1: First release.Rich Ajax empowered Web/Cloud Applications: 6.4 beta 2c: A revisiov to the first fully featured version of Visual webGui offering web/cloud development tool that puts all ASP.NET Ajax limits behind with e...Should: Beta - 1.0: This is the initial release of the Should assertions extensions.Shrinkr: v1.0: First public release.Site Directory for SharePoint 2010 (from Microsoft Consulting Services, UK): v1.2: Address a bug found in v1.1 relating to the Delete Site Listings job not incrementing the 'Site Missing Count' for some SharePoint sites.Software Localization Tool: SharpSLT 1.0: New functions Backup before saving Delete entries Undo deletion Added more comments in the codeSPGroupDeflector - Explicitly deny groups to webs within your Site Collection: SPGroupDeflector: Download the source code, the wsp solution package, and Setup.docSSIS ShapeFileSource: Version 0.1: Short Preview of SSIS ShapeFileSource ComponentStarter Kit Mytrip.Mvc.Entity: Mytrip.Mvc.Entity 1.0: Warning Install MySql Connector/Net 6.3 MySQL Membership MSSQL Membership XML Membership UserManager FileManager Localization Captcha ...Surfium: Linux Expo Prebuild: First public releaseTaskCleaner: Initial Working Version: In this version we have all the features listed in the project description working fine. Built under Framework 3.5.Text to HTML: 0.4.5.0: CambiosSustitución de los siguientes caracteres: Anteriores: " < > ¡ © º ¿ Á Ä É Í Ñ Ó Ö Ú Ü ß á ä é í ñ ó ö ú ü € Nuevos: & ´ ≈ ¦ • ¸ ˆ ↓ ð … ∫ ...TS3QueryLib.Net: TS3QueryLib.Net Version 0.21.16.0: This release contains a bugfix for a bug that caused connection problems when connecting using an IP for some cases. So it's strongly recommended t...Tweety - Twitter Client: Tweety - 0.96: Form activation from system tray improved. General fixes. General code refactor.Web/Cloud Applications Development Framework | Visual WebGui: 6.4 Beta 2c: A revision to the first fully featured version of Visual webGui offering unique developer/designer interface and enhanced extensibility and customi...Windows Azure - PHP contributions: PhpAzureExtensions (Azure Drives) - 0.2.0: Extension for use with Windows Azure SDK 1.1! Breaking changes! Documentation can be found at http://phpazurecontrib.codeplex.com/wikipage?title=A...WoW Character Viewer: Viewer (40545): New setup build for 40545.Xrns2XMod: Xrns2XMod 0.0.5.3: Major Source code optimization: >> Separated logical code of xm/mod conversion from renoiseSong xml. Now all necessary renoise song data code is st...XsltDb - DotNetNuke XSLT module: 01.00.99: callable tag is introduced - create javascript ajax functions more easy import/export bug is fixed mdo:ajax checkbox processing is now the same...Most Popular ProjectsRawrWBFS ManagerSilverlight ToolkitAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseWindows Presentation Foundation (WPF)ASP.NETpatterns & practices – Enterprise LibraryPHPExcelMicrosoft SQL Server Community & SamplesMost Active ProjectsRawrpatterns & practices – Enterprise LibraryIndustrial DashboardIonics Isapi Rewrite FilterFarseer Physics EngineBlogEngine.NETPHPExcelCaliburn: An Application Framework for WPF and SilverlightNB_Store - Free DotNetNuke Ecommerce Catalog ModuleTweetSharp

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C#/.NET Fundamentals: Choosing the Right Collection Class

- by James Michael Hare

The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be, choosing the right collection can be absolutely key to the performance and maintainability of your application! This post will look at breaking down any confusion between each collection and the situations in which they excel. We will be spending most of our time looking at the System.Collections.Generic namespace, which is the recommended set of collections. The Generic Collections: System.Collections.Generic namespace The generic collections were introduced in .NET 2.0 in the System.Collections.Generic namespace. This is the main body of collections you should tend to focus on first, as they will tend to suit 99% of your needs right up front. It is important to note that the generic collections are unsynchronized. This decision was made for performance reasons because depending on how you are using the collections its completely possible that synchronization may not be required or may be needed on a higher level than simple method-level synchronization. Furthermore, concurrent read access (all writes done at beginning and never again) is always safe, but for concurrent mixed access you should either synchronize the collection or use one of the concurrent collections. So let's look at each of the collections in turn and its various pros and cons, at the end we'll summarize with a table to help make it easier to compare and contrast the different collections. The Associative Collection Classes Associative collections store a value in the collection by providing a key that is used to add/remove/lookup the item. Hence, the container associates the value with the key. These collections are most useful when you need to lookup/manipulate a collection using a key value. For example, if you wanted to look up an order in a collection of orders by an order id, you might have an associative collection where they key is the order id and the value is the order. The Dictionary<TKey,TVale> is probably the most used associative container class. The Dictionary<TKey,TValue> is the fastest class for associative lookups/inserts/deletes because it uses a hash table under the covers. Because the keys are hashed, the key type should correctly implement GetHashCode() and Equals() appropriately or you should provide an external IEqualityComparer to the dictionary on construction. The insert/delete/lookup time of items in the dictionary is amortized constant time - O(1) - which means no matter how big the dictionary gets, the time it takes to find something remains relatively constant. This is highly desirable for high-speed lookups. The only downside is that the dictionary, by nature of using a hash table, is unordered, so you cannot easily traverse the items in a Dictionary in order. The SortedDictionary<TKey,TValue> is similar to the Dictionary<TKey,TValue> in usage but very different in implementation. The SortedDictionary<TKey,TValye> uses a binary tree under the covers to maintain the items in order by the key. As a consequence of sorting, the type used for the key must correctly implement IComparable<TKey> so that the keys can be correctly sorted. The sorted dictionary trades a little bit of lookup time for the ability to maintain the items in order, thus insert/delete/lookup times in a sorted dictionary are logarithmic - O(log n). Generally speaking, with logarithmic time, you can double the size of the collection and it only has to perform one extra comparison to find the item. Use the SortedDictionary<TKey,TValue> when you want fast lookups but also want to be able to maintain the collection in order by the key. The SortedList<TKey,TValue> is the other ordered associative container class in the generic containers. Once again SortedList<TKey,TValue>, like SortedDictionary<TKey,TValue>, uses a key to sort key-value pairs. Unlike SortedDictionary, however, items in a SortedList are stored as an ordered array of items. This means that insertions and deletions are linear - O(n) - because deleting or adding an item may involve shifting all items up or down in the list. Lookup time, however is O(log n) because the SortedList can use a binary search to find any item in the list by its key. So why would you ever want to do this? Well, the answer is that if you are going to load the SortedList up-front, the insertions will be slower, but because array indexing is faster than following object links, lookups are marginally faster than a SortedDictionary. Once again I'd use this in situations where you want fast lookups and want to maintain the collection in order by the key, and where insertions and deletions are rare. The Non-Associative Containers The other container classes are non-associative. They don't use keys to manipulate the collection but rely on the object itself being stored or some other means (such as index) to manipulate the collection. The List<T> is a basic contiguous storage container. Some people may call this a vector or dynamic array. Essentially it is an array of items that grow once its current capacity is exceeded. Because the items are stored contiguously as an array, you can access items in the List<T> by index very quickly. However inserting and removing in the beginning or middle of the List<T> are very costly because you must shift all the items up or down as you delete or insert respectively. However, adding and removing at the end of a List<T> is an amortized constant operation - O(1). Typically List<T> is the standard go-to collection when you don't have any other constraints, and typically we favor a List<T> even over arrays unless we are sure the size will remain absolutely fixed. The LinkedList<T> is a basic implementation of a doubly-linked list. This means that you can add or remove items in the middle of a linked list very quickly (because there's no items to move up or down in contiguous memory), but you also lose the ability to index items by position quickly. Most of the time we tend to favor List<T> over LinkedList<T> unless you are doing a lot of adding and removing from the collection, in which case a LinkedList<T> may make more sense. The HashSet<T> is an unordered collection of unique items. This means that the collection cannot have duplicates and no order is maintained. Logically, this is very similar to having a Dictionary<TKey,TValue> where the TKey and TValue both refer to the same object. This collection is very useful for maintaining a collection of items you wish to check membership against. For example, if you receive an order for a given vendor code, you may want to check to make sure the vendor code belongs to the set of vendor codes you handle. In these cases a HashSet<T> is useful for super-quick lookups where order is not important. Once again, like in Dictionary, the type T should have a valid implementation of GetHashCode() and Equals(), or you should provide an appropriate IEqualityComparer<T> to the HashSet<T> on construction. The SortedSet<T> is to HashSet<T> what the SortedDictionary<TKey,TValue> is to Dictionary<TKey,TValue>. That is, the SortedSet<T> is a binary tree where the key and value are the same object. This once again means that adding/removing/lookups are logarithmic - O(log n) - but you gain the ability to iterate over the items in order. For this collection to be effective, type T must implement IComparable<T> or you need to supply an external IComparer<T>. Finally, the Stack<T> and Queue<T> are two very specific collections that allow you to handle a sequential collection of objects in very specific ways. The Stack<T> is a last-in-first-out (LIFO) container where items are added and removed from the top of the stack. Typically this is useful in situations where you want to stack actions and then be able to undo those actions in reverse order as needed. The Queue<T> on the other hand is a first-in-first-out container which adds items at the end of the queue and removes items from the front. This is useful for situations where you need to process items in the order in which they came, such as a print spooler or waiting lines. So that's the basic collections. Let's summarize what we've learned in a quick reference table. Collection Ordered? Contiguous Storage? Direct Access? Lookup Efficiency Manipulate Efficiency Notes Dictionary No Yes Via Key Key: O(1) O(1) Best for high performance lookups. SortedDictionary Yes No Via Key Key: O(log n) O(log n) Compromise of Dictionary speed and ordering, uses binary search tree. SortedList Yes Yes Via Key Key: O(log n) O(n) Very similar to SortedDictionary, except tree is implemented in an array, so has faster lookup on preloaded data, but slower loads. List No Yes Via Index Index: O(1) Value: O(n) O(n) Best for smaller lists where direct access required and no ordering. LinkedList No No No Value: O(n) O(1) Best for lists where inserting/deleting in middle is common and no direct access required. HashSet No Yes Via Key Key: O(1) O(1) Unique unordered collection, like a Dictionary except key and value are same object. SortedSet Yes No Via Key Key: O(log n) O(log n) Unique ordered collection, like SortedDictionary except key and value are same object. Stack No Yes Only Top Top: O(1) O(1)* Essentially same as List<T> except only process as LIFO Queue No Yes Only Front Front: O(1) O(1) Essentially same as List<T> except only process as FIFO The Original Collections: System.Collections namespace The original collection classes are largely considered deprecated by developers and by Microsoft itself. In fact they indicate that for the most part you should always favor the generic or concurrent collections, and only use the original collections when you are dealing with legacy .NET code. Because these collections are out of vogue, let's just briefly mention the original collection and their generic equivalents: ArrayList A dynamic, contiguous collection of objects. Favor the generic collection List<T> instead. Hashtable Associative, unordered collection of key-value pairs of objects. Favor the generic collection Dictionary<TKey,TValue> instead. Queue First-in-first-out (FIFO) collection of objects. Favor the generic collection Queue<T> instead. SortedList Associative, ordered collection of key-value pairs of objects. Favor the generic collection SortedList<T> instead. Stack Last-in-first-out (LIFO) collection of objects. Favor the generic collection Stack<T> instead. In general, the older collections are non-type-safe and in some cases less performant than their generic counterparts. Once again, the only reason you should fall back on these older collections is for backward compatibility with legacy code and libraries only. The Concurrent Collections: System.Collections.Concurrent namespace The concurrent collections are new as of .NET 4.0 and are included in the System.Collections.Concurrent namespace. These collections are optimized for use in situations where multi-threaded read and write access of a collection is desired. The concurrent queue, stack, and dictionary work much as you'd expect. The bag and blocking collection are more unique. Below is the summary of each with a link to a blog post I did on each of them. ConcurrentQueue Thread-safe version of a queue (FIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentStack Thread-safe version of a stack (LIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentBag Thread-safe unordered collection of objects. Optimized for situations where a thread may be bother reader and writer. For more information see: C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection ConcurrentDictionary Thread-safe version of a dictionary. Optimized for multiple readers (allows multiple readers under same lock). For more information see C#/.NET Little Wonders: The ConcurrentDictionary BlockingCollection Wrapper collection that implement producers & consumers paradigm. Readers can block until items are available to read. Writers can block until space is available to write (if bounded). For more information see C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection Summary The .NET BCL has lots of collections built in to help you store and manipulate collections of data. Understanding how these collections work and knowing in which situations each container is best is one of the key skills necessary to build more performant code. Choosing the wrong collection for the job can make your code much slower or even harder to maintain if you choose one that doesn’t perform as well or otherwise doesn’t exactly fit the situation. Remember to avoid the original collections and stick with the generic collections. If you need concurrent access, you can use the generic collections if the data is read-only, or consider the concurrent collections for mixed-access if you are running on .NET 4.0 or higher. 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Synchronize Data between a Silverlight ListBox and a User Control

- by psheriff

One of the great things about XAML is the powerful data-binding capabilities. If you load up a list box with a collection of objects, you can display detail data about each object without writing any C# or VB.NET code. Take a look at Figure 1 that shows a collection of Product objects in a list box. When you click on a list box you bind the current Product object selected in the list box to a set of controls in a user control with just a very simple Binding statement in XAML. Figure 1: Synchronizing a ListBox to a User Control is easy with Data Binding Product and Products Classes To illustrate this data binding feature I am going to just create some local data instead of using a WCF service. The code below shows a Product class that has three properties, namely, ProductId, ProductName and Price. This class also has a constructor that takes 3 parameters and allows us to set the 3 properties in an instance of our Product class. C#public class Product{ public Product(int productId, string productName, decimal price) { ProductId = productId; ProductName = productName; Price = price; } public int ProductId { get; set; } public string ProductName { get; set; } public decimal Price { get; set; }} VBPublic Class Product Public Sub New(ByVal _productId As Integer, _ ByVal _productName As String, _ ByVal _price As Decimal) ProductId = _productId ProductName = _productName Price = _price End Sub Private mProductId As Integer Private mProductName As String Private mPrice As Decimal Public Property ProductId() As Integer Get Return mProductId End Get Set(ByVal value As Integer) mProductId = value End Set End Property Public Property ProductName() As String Get Return mProductName End Get Set(ByVal value As String) mProductName = value End Set End Property Public Property Price() As Decimal Get Return mPrice End Get Set(ByVal value As Decimal) mPrice = value End Set End PropertyEnd Class To fill up a list box you need a collection class of Product objects. The code below creates a generic collection class of Product objects. In the constructor of the Products class I have hard-coded five product objects and added them to the collection. In a real-world application you would get your data through a call to service to fill the list box, but for simplicity and just to illustrate the data binding, I am going to just hard code the data. C#public class Products : List<Product>{ public Products() { this.Add(new Product(1, "Microsoft VS.NET 2008", 1000)); this.Add(new Product(2, "Microsoft VS.NET 2010", 1000)); this.Add(new Product(3, "Microsoft Silverlight 4", 1000)); this.Add(new Product(4, "Fundamentals of N-Tier eBook", 20)); this.Add(new Product(5, "ASP.NET Security eBook", 20)); }} VBPublic Class Products Inherits List(Of Product) Public Sub New() Me.Add(New Product(1, "Microsoft VS.NET 2008", 1000)) Me.Add(New Product(2, "Microsoft VS.NET 2010", 1000)) Me.Add(New Product(3, "Microsoft Silverlight 4", 1000)) Me.Add(New Product(4, "Fundamentals of N-Tier eBook", 20)) Me.Add(New Product(5, "ASP.NET Security eBook", 20)) End SubEnd Class The Product Detail User Control Below is a user control (named ucProduct) that is used to display the product detail information seen in the bottom portion of Figure 1. This is very basic XAML that just creates a text block and a text box control for each of the three properties in the Product class. Notice the {Binding Path=[PropertyName]} on each of the text box controls. This means that if the DataContext property of this user control is set to an instance of a Product class, then the data in the properties of that Product object will be displayed in each of the text boxes. <UserControl x:Class="SL_SyncListBoxAndUserControl_CS.ucProduct" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" HorizontalAlignment="Left" VerticalAlignment="Top"> <Grid Margin="4"> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition MinWidth="120" /> <ColumnDefinition /> </Grid.ColumnDefinitions> <TextBlock Grid.Row="0" Grid.Column="0" Text="Product Id" /> <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=ProductId}" /> <TextBlock Grid.Row="1" Grid.Column="0" Text="Product Name" /> <TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Path=ProductName}" /> <TextBlock Grid.Row="2" Grid.Column="0" Text="Price" /> <TextBox Grid.Row="2" Grid.Column="1" Text="{Binding Path=Price}" /> </Grid></UserControl> Synchronize ListBox with User Control You are now ready to fill the list box with the collection class of Product objects and then bind the SelectedItem of the list box to the Product detail user control. The XAML below is the complete code for Figure 1. <UserControl x:Class="SL_SyncListBoxAndUserControl_CS.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:src="clr-namespace:SL_SyncListBoxAndUserControl_CS" VerticalAlignment="Top" HorizontalAlignment="Left"> <UserControl.Resources> <src:Products x:Key="productCollection" /> </UserControl.Resources> <Grid x:Name="LayoutRoot" Margin="4" Background="White"> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="*" /> </Grid.RowDefinitions> <ListBox x:Name="lstData" Grid.Row="0" BorderBrush="Black" BorderThickness="1" ItemsSource="{Binding Source={StaticResource productCollection}}" DisplayMemberPath="ProductName" /> <src:ucProduct x:Name="prodDetail" Grid.Row="1" DataContext="{Binding ElementName=lstData, Path=SelectedItem}" /> </Grid></UserControl> The first step to making this happen is to reference the Silverlight project (SL_SyncListBoxAndUserControl_CS) where the Product and Products classes are located. I added this namespace and assigned it a namespace prefix of “src” as shown in the line below: xmlns:src="clr-namespace:SL_SyncListBoxAndUserControl_CS" Next, to use the data from an instance of the Products collection, you create a UserControl.Resources section in the XAML and add a tag that creates an instance of the Products class and assigns it a key of “productCollection”. <UserControl.Resources> <src:Products x:Key="productCollection" /> </UserControl.Resources> Next, you bind the list box to this productCollection object using the ItemsSource property. You bind the ItemsSource of the list box to the static resource named productCollection. You can then set the DisplayMemberPath attribute of the list box to any property of the Product class that you want. In the XAML below I used the ProductName property. <ListBox x:Name="lstData" ItemsSource="{Binding Source={StaticResource productCollection}}" DisplayMemberPath="ProductName" /> You now need to create an instance of the ucProduct user contol below the list box. You do this by once again referencing the “src” namespace and typing in the name of the user control. You then set the DataContext property on this user control to a binding. The binding uses the ElementName attribute to bind to the list box name, in this case “lstData”. The Path of the data is SelectedItem. These two attributes together tell Silverlight to bind the DataContext to the selected item of the list box. That selected item is a Product object. So, once this is bound, the bindings on each text box in the user control are updated and display the current product information. <src:ucProduct x:Name="prodDetail" DataContext="{Binding ElementName=lstData, Path=SelectedItem}" /> Summary Once you understand the basics of data binding in XAML, you eliminate a lot code that is otherwise needed to move data into controls and out of controls back into an object. Connecting two controls together is easy by just binding using the ElementName and Path properties of the Binding markup extension. Another good tip out of this blog is use user controls and set the DataContext of the user control to have all of the data on the user control update through the bindings. NOTE: You can download the complete sample code (in both VB and C#) at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "SL – Synchronize List Box Data with User Control" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free eBook on "Fundamentals of N-Tier".

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SQL Server – Undelete a Table and Restore a Single Table from Backup

- by Mladen Prajdic

This post is part of the monthly community event called T-SQL Tuesday started by Adam Machanic (blog|twitter) and hosted by someone else each month. This month the host is Sankar Reddy (blog|twitter) and the topic is Misconceptions in SQL Server. You can follow posts for this theme on Twitter by looking at #TSQL2sDay hashtag. Let me start by saying: This code is a crazy hack that is to never be used unless you really, really have to. Really! And I don’t think there’s a time when you would really have to use it for real. Because it’s a hack there are number of things that can go wrong so play with it knowing that. I’ve managed to totally corrupt one database. :) Oh… and for those saying: yeah yeah.. you have a single table in a file group and you’re restoring that, I say “nay nay” to you. As we all know SQL Server can’t do single table restores from backup. This is kind of a obvious thing due to different relational integrity (RI) concerns. Since we have to maintain that we have to restore all tables represented in a RI graph. For this exercise i say BAH! to those concerns. Note that this method “works” only for simple tables that don’t have LOB and off rows data. The code can be expanded to include those but I’ve tried to leave things “simple”. Note that for this to work our table needs to be relatively static data-wise. This doesn’t work for OLTP table. Products are a perfect example of static data. They don’t change much between backups, pretty much everything depends on them and their table is one of those tables that are relatively easy to accidentally delete everything from. This only works if the database is in Full or Bulk-Logged recovery mode for tables where the contents have been deleted or truncated but NOT when a table was dropped. Everything we’ll talk about has to be done before the data pages are reused for other purposes. After deletion or truncation the pages are marked as reusable so you have to act fast. The best thing probably is to put the database into single user mode ASAP while you’re performing this procedure and return it to multi user after you’re done. How do we do it? We will be using an undocumented but known DBCC commands: DBCC PAGE, an undocumented function sys.fn_dblog and a little known DATABASE RESTORE PAGE option. All tests will be on a copy of Production.Product table in AdventureWorks database called Production.Product1 because the original table has FK constraints that prevent us from truncating it for testing. -- create a duplicate table. This doesn't preserve indexes!SELECT *INTO AdventureWorks.Production.Product1FROM AdventureWorks.Production.Product After we run this code take a full back to perform further testing. First let’s see what the difference between DELETE and TRUNCATE is when it comes to logging. With DELETE every row deletion is logged in the transaction log. With TRUNCATE only whole data page deallocations are logged in the transaction log. Getting deleted data pages is simple. All we have to look for is row delete entry in the sys.fn_dblog output. But getting data pages that were truncated from the transaction log presents a bit of an interesting problem. I will not go into depths of IAM(Index Allocation Map) and PFS (Page Free Space) pages but suffice to say that every IAM page has intervals that tell us which data pages are allocated for a table and which aren’t. If we deep dive into the sys.fn_dblog output we can see that once you truncate a table all the pages in all the intervals are deallocated and this is shown in the PFS page transaction log entry as deallocation of pages. For every 8 pages in the same extent there is one PFS page row in the transaction log. This row holds information about all 8 pages in CSV format which means we can get to this data with some parsing. A great help for parsing this stuff is Peter Debetta’s handy function dbo.HexStrToVarBin that converts hexadecimal string into a varbinary value that can be easily converted to integer tus giving us a readable page number. The shortened (columns removed) sys.fn_dblog output for a PFS page with CSV data for 1 extent (8 data pages) looks like this: -- [Page ID] is displayed in hex format. -- To convert it to readable int we'll use dbo.HexStrToVarBin function found at -- http://sqlblog.com/blogs/peter_debetta/archive/2007/03/09/t-sql-convert-hex-string-to-varbinary.aspx -- This function must be installed in the master databaseSELECT Context, AllocUnitName, [Page ID], DescriptionFROM sys.fn_dblog(NULL, NULL)WHERE [Current LSN] = '00000031:00000a46:007d' The pages at the end marked with 0x00—> are pages that are allocated in the extent but are not part of a table. We can inspect the raw content of each data page with a DBCC PAGE command: -- we need this trace flag to redirect output to the query window.DBCC TRACEON (3604); -- WITH TABLERESULTS gives us data in table format instead of message format-- we use format option 3 because it's the easiest to read and manipulate further onDBCC PAGE (AdventureWorks, 1, 613, 3) WITH TABLERESULTS Since the DBACC PAGE output can be quite extensive I won’t put it here. You can see an example of it in the link at the beginning of this section. Getting deleted data back When we run a delete statement every row to be deleted is marked as a ghost record. A background process periodically cleans up those rows. A huge misconception is that the data is actually removed. It’s not. Only the pointers to the rows are removed while the data itself is still on the data page. We just can’t access it with normal means. To get those pointers back we need to restore every deleted page using the RESTORE PAGE option mentioned above. This restore must be done from a full backup, followed by any differential and log backups that you may have. This is necessary to bring the pages up to the same point in time as the rest of the data. However the restore doesn’t magically connect the restored page back to the original table. It simply replaces the current page with the one from the backup. After the restore we use the DBCC PAGE to read data directly from all data pages and insert that data into a temporary table. To finish the RESTORE PAGE procedure we finally have to take a tail log backup (simple backup of the transaction log) and restore it back. We can now insert data from the temporary table to our original table by hand. Getting truncated data back When we run a truncate the truncated data pages aren’t touched at all. Even the pointers to rows stay unchanged. Because of this getting data back from truncated table is simple. we just have to find out which pages belonged to our table and use DBCC PAGE to read data off of them. No restore is necessary. Turns out that the problems we had with finding the data pages is alleviated by not having to do a RESTORE PAGE procedure. Stop stalling… show me The Code! This is the code for getting back deleted and truncated data back. It’s commented in all the right places so don’t be afraid to take a closer look. Make sure you have a full backup before trying this out. Also I suggest that the last step of backing and restoring the tail log is performed by hand. USE masterGOIF OBJECT_ID('dbo.HexStrToVarBin') IS NULL RAISERROR ('No dbo.HexStrToVarBin installed. Go to http://sqlblog.com/blogs/peter_debetta/archive/2007/03/09/t-sql-convert-hex-string-to-varbinary.aspx and install it in master database' , 18, 1) SET NOCOUNT ONBEGIN TRY DECLARE @dbName VARCHAR(1000), @schemaName VARCHAR(1000), @tableName VARCHAR(1000), @fullBackupName VARCHAR(1000), @undeletedTableName VARCHAR(1000), @sql VARCHAR(MAX), @tableWasTruncated bit; /* THE FIRST LINE ARE OUR INPUT PARAMETERS In this case we're trying to recover Production.Product1 table in AdventureWorks database. My full backup of AdventureWorks database is at e:\AW.bak */ SELECT @dbName = 'AdventureWorks', @schemaName = 'Production', @tableName = 'Product1', @fullBackupName = 'e:\AW.bak', @undeletedTableName = '##' + @tableName + '_Undeleted', @tableWasTruncated = 0, -- copy the structure from original table to a temp table that we'll fill with restored data @sql = 'IF OBJECT_ID(''tempdb..' + @undeletedTableName + ''') IS NOT NULL DROP TABLE ' + @undeletedTableName + ' SELECT *' + ' INTO ' + @undeletedTableName + ' FROM [' + @dbName + '].[' + @schemaName + '].[' + @tableName + ']' + ' WHERE 1 = 0' EXEC (@sql) IF OBJECT_ID('tempdb..#PagesToRestore') IS NOT NULL DROP TABLE #PagesToRestore /* FIND DATA PAGES WE NEED TO RESTORE*/ CREATE TABLE #PagesToRestore ([ID] INT IDENTITY(1,1), [FileID] INT, [PageID] INT, [SQLtoExec] VARCHAR(1000)) -- DBCC PACE statement to run later RAISERROR ('Looking for deleted pages...', 10, 1) -- use T-LOG direct read to get deleted data pages INSERT INTO #PagesToRestore([FileID], [PageID], [SQLtoExec]) EXEC('USE [' + @dbName + '];SELECT FileID, PageID, ''DBCC TRACEON (3604); DBCC PAGE ([' + @dbName + '], '' + FileID + '', '' + PageID + '', 3) WITH TABLERESULTS'' as SQLToExecFROM (SELECT DISTINCT LEFT([Page ID], 4) AS FileID, CONVERT(VARCHAR(100), ' + 'CONVERT(INT, master.dbo.HexStrToVarBin(SUBSTRING([Page ID], 6, 20)))) AS PageIDFROM sys.fn_dblog(NULL, NULL)WHERE AllocUnitName LIKE ''%' + @schemaName + '.' + @tableName + '%'' ' + 'AND Context IN (''LCX_MARK_AS_GHOST'', ''LCX_HEAP'') AND Operation in (''LOP_DELETE_ROWS''))t');SELECT *FROM #PagesToRestore -- if upper EXEC returns 0 rows it means the table was truncated so find truncated pages IF (SELECT COUNT(*) FROM #PagesToRestore) = 0 BEGIN RAISERROR ('No deleted pages found. Looking for truncated pages...', 10, 1) -- use T-LOG read to get truncated data pages INSERT INTO #PagesToRestore([FileID], [PageID], [SQLtoExec]) -- dark magic happens here -- because truncation simply deallocates pages we have to find out which pages were deallocated. -- we can find this out by looking at the PFS page row's Description column. -- for every deallocated extent the Description has a CSV of 8 pages in that extent. -- then it's just a matter of parsing it. -- we also remove the pages in the extent that weren't allocated to the table itself -- marked with '0x00-->00' EXEC ('USE [' + @dbName + '];DECLARE @truncatedPages TABLE(DeallocatedPages VARCHAR(8000), IsMultipleDeallocs BIT);INSERT INTO @truncatedPagesSELECT REPLACE(REPLACE(Description, ''Deallocated '', ''Y''), ''0x00-->00 '', ''N'') + '';'' AS DeallocatedPages, CHARINDEX('';'', Description) AS IsMultipleDeallocsFROM (SELECT DISTINCT LEFT([Page ID], 4) AS FileID, CONVERT(VARCHAR(100), CONVERT(INT, master.dbo.HexStrToVarBin(SUBSTRING([Page ID], 6, 20)))) AS PageID, DescriptionFROM sys.fn_dblog(NULL, NULL)WHERE Context IN (''LCX_PFS'') AND Description LIKE ''Deallocated%'' AND AllocUnitName LIKE ''%' + @schemaName + '.' + @tableName + '%'') t;SELECT FileID, PageID , ''DBCC TRACEON (3604); DBCC PAGE ([' + @dbName + '], '' + FileID + '', '' + PageID + '', 3) WITH TABLERESULTS'' as SQLToExecFROM (SELECT LEFT(PageAndFile, 1) as WasPageAllocatedToTable , SUBSTRING(PageAndFile, 2, CHARINDEX('':'', PageAndFile) - 2 ) as FileID , CONVERT(VARCHAR(100), CONVERT(INT, master.dbo.HexStrToVarBin(SUBSTRING(PageAndFile, CHARINDEX('':'', PageAndFile) + 1, LEN(PageAndFile))))) as PageIDFROM ( SELECT SUBSTRING(DeallocatedPages, delimPosStart, delimPosEnd - delimPosStart) as PageAndFile, IsMultipleDeallocs FROM ( SELECT *, CHARINDEX('';'', DeallocatedPages)*(N-1) + 1 AS delimPosStart, CHARINDEX('';'', DeallocatedPages)*N AS delimPosEnd FROM @truncatedPages t1 CROSS APPLY (SELECT TOP (case when t1.IsMultipleDeallocs = 1 then 8 else 1 end) ROW_NUMBER() OVER(ORDER BY number) as N FROM master..spt_values) t2 )t)t)tWHERE WasPageAllocatedToTable = ''Y''') SELECT @tableWasTruncated = 1 END DECLARE @lastID INT, @pagesCount INT SELECT @lastID = 1, @pagesCount = COUNT(*) FROM #PagesToRestore SELECT @sql = 'Number of pages to restore: ' + CONVERT(VARCHAR(10), @pagesCount) IF @pagesCount = 0 RAISERROR ('No data pages to restore.', 18, 1) ELSE RAISERROR (@sql, 10, 1) -- If the table was truncated we'll read the data directly from data pages without restoring from backup IF @tableWasTruncated = 0 BEGIN -- RESTORE DATA PAGES FROM FULL BACKUP IN BATCHES OF 200 WHILE @lastID <= @pagesCount BEGIN -- create CSV string of pages to restore SELECT @sql = STUFF((SELECT ',' + CONVERT(VARCHAR(100), FileID) + ':' + CONVERT(VARCHAR(100), PageID) FROM #PagesToRestore WHERE ID BETWEEN @lastID AND @lastID + 200 ORDER BY ID FOR XML PATH('')), 1, 1, '') SELECT @sql = 'RESTORE DATABASE [' + @dbName + '] PAGE = ''' + @sql + ''' FROM DISK = ''' + @fullBackupName + '''' RAISERROR ('Starting RESTORE command:' , 10, 1) WITH NOWAIT; RAISERROR (@sql , 10, 1) WITH NOWAIT; EXEC(@sql); RAISERROR ('Restore DONE' , 10, 1) WITH NOWAIT; SELECT @lastID = @lastID + 200 END /* If you have any differential or transaction log backups you should restore them here to bring the previously restored data pages up to date */ END DECLARE @dbccSinglePage TABLE ( [ParentObject] NVARCHAR(500), [Object] NVARCHAR(500), [Field] NVARCHAR(500), [VALUE] NVARCHAR(MAX) ) DECLARE @cols NVARCHAR(MAX), @paramDefinition NVARCHAR(500), @SQLtoExec VARCHAR(1000), @FileID VARCHAR(100), @PageID VARCHAR(100), @i INT = 1 -- Get deleted table columns from information_schema view -- Need sp_executeSQL because database name can't be passed in as variable SELECT @cols = 'select @cols = STUFF((SELECT '', ['' + COLUMN_NAME + '']''FROM ' + @dbName + '.INFORMATION_SCHEMA.COLUMNSWHERE TABLE_NAME = ''' + @tableName + ''' AND TABLE_SCHEMA = ''' + @schemaName + '''ORDER BY ORDINAL_POSITIONFOR XML PATH('''')), 1, 2, '''')', @paramDefinition = N'@cols nvarchar(max) OUTPUT' EXECUTE sp_executesql @cols, @paramDefinition, @cols = @cols OUTPUT -- Loop through all the restored data pages, -- read data from them and insert them into temp table -- which you can then insert into the orignial deleted table DECLARE dbccPageCursor CURSOR GLOBAL FORWARD_ONLY FOR SELECT [FileID], [PageID], [SQLtoExec] FROM #PagesToRestore ORDER BY [FileID], [PageID] OPEN dbccPageCursor; FETCH NEXT FROM dbccPageCursor INTO @FileID, @PageID, @SQLtoExec; WHILE @@FETCH_STATUS = 0 BEGIN RAISERROR ('---------------------------------------------', 10, 1) WITH NOWAIT; SELECT @sql = 'Loop iteration: ' + CONVERT(VARCHAR(10), @i); RAISERROR (@sql, 10, 1) WITH NOWAIT; SELECT @sql = 'Running: ' + @SQLtoExec RAISERROR (@sql, 10, 1) WITH NOWAIT; -- if something goes wrong with DBCC execution or data gathering, skip it but print error BEGIN TRY INSERT INTO @dbccSinglePage EXEC (@SQLtoExec) -- make the data insert magic happen here IF (SELECT CONVERT(BIGINT, [VALUE]) FROM @dbccSinglePage WHERE [Field] LIKE '%Metadata: ObjectId%') = OBJECT_ID('['+@dbName+'].['+@schemaName +'].['+@tableName+']') BEGIN DELETE @dbccSinglePage WHERE NOT ([ParentObject] LIKE 'Slot % Offset %' AND [Object] LIKE 'Slot % Column %') SELECT @sql = 'USE tempdb; ' + 'IF (OBJECTPROPERTY(object_id(''' + @undeletedTableName + '''), ''TableHasIdentity'') = 1) ' + 'SET IDENTITY_INSERT ' + @undeletedTableName + ' ON; ' + 'INSERT INTO ' + @undeletedTableName + '(' + @cols + ') ' + STUFF((SELECT ' UNION ALL SELECT ' + STUFF((SELECT ', ' + CASE WHEN VALUE = '[NULL]' THEN 'NULL' ELSE '''' + [VALUE] + '''' END FROM ( -- the unicorn help here to correctly set ordinal numbers of columns in a data page -- it's turning STRING order into INT order (1,10,11,2,21 into 1,2,..10,11...21) SELECT [ParentObject], [Object], Field, VALUE, RIGHT('00000' + O1, 6) AS ParentObjectOrder, RIGHT('00000' + REVERSE(LEFT(O2, CHARINDEX(' ', O2)-1)), 6) AS ObjectOrder FROM ( SELECT [ParentObject], [Object], Field, VALUE, REPLACE(LEFT([ParentObject], CHARINDEX('Offset', [ParentObject])-1), 'Slot ', '') AS O1, REVERSE(LEFT([Object], CHARINDEX('Offset ', [Object])-2)) AS O2 FROM @dbccSinglePage WHERE t.ParentObject = ParentObject )t)t ORDER BY ParentObjectOrder, ObjectOrder FOR XML PATH('')), 1, 2, '') FROM @dbccSinglePage t GROUP BY ParentObject FOR XML PATH('') ), 1, 11, '') + ';' RAISERROR (@sql, 10, 1) WITH NOWAIT; EXEC (@sql) END END TRY BEGIN CATCH SELECT @sql = 'ERROR!!!' + CHAR(10) + CHAR(13) + 'ErrorNumber: ' + ERROR_NUMBER() + '; ErrorMessage' + ERROR_MESSAGE() + CHAR(10) + CHAR(13) + 'FileID: ' + @FileID + '; PageID: ' + @PageID RAISERROR (@sql, 10, 1) WITH NOWAIT; END CATCH DELETE @dbccSinglePage SELECT @sql = 'Pages left to process: ' + CONVERT(VARCHAR(10), @pagesCount - @i) + CHAR(10) + CHAR(13) + CHAR(10) + CHAR(13) + CHAR(10) + CHAR(13), @i = @i+1 RAISERROR (@sql, 10, 1) WITH NOWAIT; FETCH NEXT FROM dbccPageCursor INTO @FileID, @PageID, @SQLtoExec; END CLOSE dbccPageCursor; DEALLOCATE dbccPageCursor; EXEC ('SELECT ''' + @undeletedTableName + ''' as TableName; SELECT * FROM ' + @undeletedTableName)END TRYBEGIN CATCH SELECT ERROR_NUMBER() AS ErrorNumber, ERROR_MESSAGE() AS ErrorMessage IF CURSOR_STATUS ('global', 'dbccPageCursor') >= 0 BEGIN CLOSE dbccPageCursor; DEALLOCATE dbccPageCursor; ENDEND CATCH-- if the table was deleted we need to finish the restore page sequenceIF @tableWasTruncated = 0BEGIN -- take a log tail backup and then restore it to complete page restore process DECLARE @currentDate VARCHAR(30) SELECT @currentDate = CONVERT(VARCHAR(30), GETDATE(), 112) RAISERROR ('Starting Log Tail backup to c:\Temp ...', 10, 1) WITH NOWAIT; PRINT ('BACKUP LOG [' + @dbName + '] TO DISK = ''c:\Temp\' + @dbName + '_TailLogBackup_' + @currentDate + '.trn''') EXEC ('BACKUP LOG [' + @dbName + '] TO DISK = ''c:\Temp\' + @dbName + '_TailLogBackup_' + @currentDate + '.trn''') RAISERROR ('Log Tail backup done.', 10, 1) WITH NOWAIT; RAISERROR ('Starting Log Tail restore from c:\Temp ...', 10, 1) WITH NOWAIT; PRINT ('RESTORE LOG [' + @dbName + '] FROM DISK = ''c:\Temp\' + @dbName + '_TailLogBackup_' + @currentDate + '.trn''') EXEC ('RESTORE LOG [' + @dbName + '] FROM DISK = ''c:\Temp\' + @dbName + '_TailLogBackup_' + @currentDate + '.trn''') RAISERROR ('Log Tail restore done.', 10, 1) WITH NOWAIT;END-- The last step is manual. Insert data from our temporary table to the original deleted table The misconception here is that you can do a single table restore properly in SQL Server. You can't. But with little experimentation you can get pretty close to it. One way to possible remove a dependency on a backup to retrieve deleted pages is to quickly run a similar script to the upper one that gets data directly from data pages while the rows are still marked as ghost records. It could be done if we could beat the ghost record cleanup task.

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A jQuery Plug-in to monitor Html Element CSS Changes

- by Rick Strahl

Here's a scenario I've run into on a few occasions: I need to be able to monitor certain CSS properties on an HTML element and know when that CSS element changes. The need for this arose out of wanting to build generic components that could 'attach' themselves to other objects and monitor changes on the ‘parent’ object so the dependent object can adjust itself accordingly. What I wanted to create is a jQuery plug-in that allows me to specify a list of CSS properties to monitor and have a function fire in response to any change to any of those CSS properties. The result are the .watch() and .unwatch() jQuery plug-ins. Here’s a simple example page of this plug-in that demonstrates tracking changes to an element being moved with draggable and closable behavior: http://www.west-wind.com/WestWindWebToolkit/samples/Ajax/jQueryPluginSamples/WatcherPlugin.htm Try it with different browsers – IE and FireFox use the DOM event handlers and Chrome, Safari and Opera use setInterval handlers to manage this behavior. It should work in all of them but all but IE and FireFox will show a bit of lag between the changes in the main element and the shadow. The relevant HTML for this example is this fragment of a main <div> (#notebox) and an element that is to mimic a shadow (#shadow). <div class="containercontent"> <div id="notebox" style="width: 200px; height: 150px;position: absolute; z-index: 20; padding: 20px; background-color: lightsteelblue;"> Go ahead drag me around and close me! </div> <div id="shadow" style="background-color: Gray; z-index: 19;position:absolute;display: none;"> </div> </div> The watcher plug in is then applied to the main <div> and shadow in sync with the following plug-in code: <script type="text/javascript"> $(document).ready(function () { var counter = 0; $("#notebox").watch("top,left,height,width,display,opacity", function (data, i) { var el = $(this); var sh = $("#shadow"); var propChanged = data.props[i]; var valChanged = data.vals[i]; counter++; showStatus("Prop: " + propChanged + " value: " + valChanged + " " + counter); var pos = el.position(); var w = el.outerWidth(); var h = el.outerHeight(); sh.css({ width: w, height: h, left: pos.left + 5, top: pos.top + 5, display: el.css("display"), opacity: el.css("opacity") }); }) .draggable() .closable() .css("left", 10); }); </script> When you run this page as you drag the #notebox element the #shadow element will maintain and stay pinned underneath the #notebox element effectively keeping the shadow attached to the main element. Likewise, if you hide or fadeOut() the #notebox element the shadow will also go away – show the #notebox element and the shadow also re-appears because we are assigning the display property from the parent on the shadow. Note we’re attaching the .watch() plug-in to the #notebox element and have it fire whenever top,left,height,width,opacity or display CSS properties are changed. The passed data element contains a props[] and vals[] array that holds the properties monitored and their current values. An index passed as the second parm tells you which property has changed and what its current value is (propChanged/valChanged in the code above). The rest of the watcher handler code then deals with figuring out the main element’s position and recalculating and setting the shadow’s position using the jQuery .css() function. Note that this is just an example to demonstrate the watch() behavior here – this is not the best way to create a shadow. If you’re interested in a more efficient and cleaner way to handle shadows with a plug-in check out the .shadow() plug-in in ww.jquery.js (code search for fn.shadow) which uses native CSS features when available but falls back to a tracked shadow element on browsers that don’t support it, which is how this watch() plug-in came about in the first place :-) How does it work? The plug-in works by letting the user specify a list of properties to monitor as a comma delimited string and a handler function: el.watch("top,left,height,width,display,opacity", function (data, i) {}, 100, id) You can also specify an interval (if no DOM event monitoring isn’t available in the browser) and an ID that identifies the event handler uniquely. The watch plug-in works by hooking up to DOMAttrModified in FireFox, to onPropertyChanged in Internet Explorer, or by using a timer with setInterval to handle the detection of changes for other browsers. Unfortunately WebKit doesn’t support DOMAttrModified consistently at the moment so Safari and Chrome currently have to use the slower setInterval mechanism. In response to a changed property (or a setInterval timer hit) a JavaScript handler is fired which then runs through all the properties monitored and determines if and which one has changed. The DOM events fire on all property/style changes so the intermediate plug-in handler filters only those hits we’re interested in. If one of our monitored properties has changed the specified event handler function is called along with a data object and an index that identifies the property that’s changed in the data.props/data.vals arrays. The jQuery plugin to implement this functionality looks like this: (function($){ $.fn.watch = function (props, func, interval, id) { /// <summary> /// Allows you to monitor changes in a specific /// CSS property of an element by polling the value. /// when the value changes a function is called. /// The function called is called in the context /// of the selected element (ie. this) /// </summary> /// <param name="prop" type="String">CSS Properties to watch sep. by commas</param> /// <param name="func" type="Function"> /// Function called when the value has changed. /// </param> /// <param name="interval" type="Number"> /// Optional interval for browsers that don't support DOMAttrModified or propertychange events. /// Determines the interval used for setInterval calls. /// </param> /// <param name="id" type="String">A unique ID that identifies this watch instance on this element</param> /// <returns type="jQuery" /> if (!interval) interval = 100; if (!id) id = "_watcher"; return this.each(function () { var _t = this; var el$ = $(this); var fnc = function () { __watcher.call(_t, id) }; var data = { id: id, props: props.split(","), vals: [props.split(",").length], func: func, fnc: fnc, origProps: props, interval: interval, intervalId: null }; // store initial props and values $.each(data.props, function (i) { data.vals[i] = el$.css(data.props[i]); }); el$.data(id, data); hookChange(el$, id, data); }); function hookChange(el$, id, data) { el$.each(function () { var el = $(this); if (typeof (el.get(0).onpropertychange) == "object") el.bind("propertychange." + id, data.fnc); else if ($.browser.mozilla) el.bind("DOMAttrModified." + id, data.fnc); else data.intervalId = setInterval(data.fnc, interval); }); } function __watcher(id) { var el$ = $(this); var w = el$.data(id); if (!w) return; var _t = this; if (!w.func) return; // must unbind or else unwanted recursion may occur el$.unwatch(id); var changed = false; var i = 0; for (i; i < w.props.length; i++) { var newVal = el$.css(w.props[i]); if (w.vals[i] != newVal) { w.vals[i] = newVal; changed = true; break; } } if (changed) w.func.call(_t, w, i); // rebind event hookChange(el$, id, w); } } $.fn.unwatch = function (id) { this.each(function () { var el = $(this); var data = el.data(id); try { if (typeof (this.onpropertychange) == "object") el.unbind("propertychange." + id, data.fnc); else if ($.browser.mozilla) el.unbind("DOMAttrModified." + id, data.fnc); else clearInterval(data.intervalId); } // ignore if element was already unbound catch (e) { } }); return this; } })(jQuery); Note that there’s a corresponding .unwatch() plug-in that can be used to stop monitoring properties. The ID parameter is optional both on watch() and unwatch() – a standard name is used if you don’t specify one, but it’s a good idea to use unique names for each element watched to avoid overlap in event ids especially if you’re monitoring many elements. The syntax is: $.fn.watch = function(props, func, interval, id) props A comma delimited list of CSS style properties that are to be watched for changes. If any of the specified properties changes the function specified in the second parameter is fired. func The function fired in response to a changed styles. Receives this as the element changed and an object parameter that represents the watched properties and their respective values. The first parameter is passed in this structure: { id: watcherId, props: [], vals: [], func: thisFunc, fnc: internalHandler, origProps: strPropertyListOnWatcher }; A second parameter is the index of the changed property so data.props[i] or data.vals[i] gets the property and changed value. interval The interval for setInterval() for those browsers that don't support property watching in the DOM. In milliseconds. id An optional id that identifies this watcher. Required only if multiple watchers might be hooked up to the same element. The default is _watcher if not specified. It’s been a Journey I started building this plug-in about two years ago and had to make many modifications to it in response to changes in jQuery and also in browser behaviors. I think the latest round of changes made should make this plug-in fairly future proof going forward (although I hope there will be better cross-browser change event notifications in the future). One of the big problems I ran into had to do with recursive change notifications – it looks like starting with jQuery 1.44 and later, jQuery internally modifies element properties on some calls to some .css() property retrievals and things like outerHeight/Width(). In IE this would cause nasty lock up issues at times. In response to this I changed the code to unbind the events when the handler function is called and then rebind when it exits. This also makes user code less prone to stack overflow recursion as you can actually change properties on the base element. It also means though that if you change one of the monitors properties in the handler the watch() handler won’t fire in response – you need to resort to a setTimeout() call instead to force the code to run outside of the handler: $("#notebox") el.watch("top,left,height,width,display,opacity", function (data, i) { var el = $(this); … // this makes el changes work setTimeout(function () { el.css("top", 10) },10); }) Since I’ve built this component I’ve had a lot of good uses for it. The .shadow() fallback functionality is one of them. Resources The watch() plug-in is part of ww.jquery.js and the West Wind West Wind Web Toolkit. You’re free to use this code here or the code from the toolkit. West Wind Web Toolkit Latest version of ww.jquery.js (search for fn.watch) watch plug-in documentation © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET JavaScript jQuery

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