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  • Concurrency with listeners and upload: is this solution sound?

    - by cbrulak
    I'm working on an Android app. We have listeners for position data and camera capture which is timed on a background thread (not a service). The timer thread dictates when the image is captured and also when the data is cached in a local sqlite db. So, my question is how to properly store the location data as it comes in based on the listeners and pull that data so that the database can be updated as the camera capture is executed. I can't put the location data into the database as it arrives because it is processed more frequently than the camera images and the camera images are what dominates the architecture at the moment. (Location data is supplement). However I need the location data to get a rough location of the where the image is captured. My first thought was to have singleton store the location data. And have a semaphore on the getInstance method so if the database update is happening (after an image is captured) we don't have an error. The location data can wait for the database update or it can be lost for that particular event it doesn't really matter. What are you thoughts? Am I on the right track? (And is this the right sub-site or would this be better on stackoverflow?)

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  • Is Moving Entity Framework objects over a webservice really the best way?

    - by aceinthehole
    I've inherited a .NET project that has close to 2 thousand clients out in the field that need to push data periodically up to a central repository. The clients wake up and attempt to push the data up via a series of WCF webservices where they are passing each entity framework entity as parameter. Once the service receives this object, it preforms some business logic on the data, and then turns around and sticks it in it's own database that mirrors the database on the client machines. The trick is, is that this data is being transmitted over a metered connection, which is very expensive. So optimizing the data is a serious priority. Now, we are using a custom encoder that compresses the data (and decompresses it on the other end) while it is being transmitted, and this is reducing the data footprint. However, the amount of data that the clients are using, seem ridiculously large, given the amount of information that is actually being transmitted. It seems me that entity framework itself may be to blame. I'm suspecting that the objects are very large when serialized to be sent over wire, with a lot context information and who knows what else, when what we really need is just the 'new' inserts. Is using the entity framework and WCF services as we have done so far the correct way, architecturally, of approaching this n-tiered, asynchronous, push only problem? Or is there a different approach, that could optimize the data use?

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  • How to capture a Header or Trailer Count Value in a Flat File and Assign to a Variable

    - by Compudicted
    Recently I had several questions concerning how to process files that carry a header and trailer in them. Typically those files are a product of data extract from non Microsoft products e.g. Oracle database encompassing various tables data where every row starts with an identifier. For example such a file data record could look like: HDR,INTF_01,OUT,TEST,3/9/2011 11:23 B1,121156789,DATA TEST DATA,2011-03-09 10:00:00,Y,TEST 18 10:00:44,2011-07-18 10:00:44,Y B2,TEST DATA,2011-03-18 10:00:44,Y B3,LEG 1 TEST DATA,TRAN TEST,N B4,LEG 2 TEST DATA,TRAN TEST,Y FTR,4,TEST END,3/9/2011 11:27 A developer is normally able to break the records using a Conditional Split Transformation component by employing an expression similar to Output1 -- SUBSTRING(Output1,1,2) == "B1" and so on, but often a verification is required after this step to check if the number of data records read corresponds to the number specified in the trailer record of the file. This portion sometimes stumbles some people so I decided to share what I came up with. As an aside, I want to mention that the approach I use is slightly more portable than some others I saw because I use a separate DFT that can be copied and pasted into a new SSIS package designer surface or re-used within the same package again and it can survive several trailer/footer records (!). See how a ready DFT can look: The first step is to create a Flat File Connection Manager and make sure you get the row split into columns like this: After you are done with the Flat File connection, move onto adding an aggregate which is in use to simply assign a value to a variable (here the aggregate is used to handle the possibility of multiple footers/headers): The next step is adding a Script Transformation as destination that requires very little coding. First, some variable setup: and finally the code: As you can see it is important to place your code into the appropriate routine in the script, otherwise the end result may not be as expected. As the last step you would use the regular Script Component to compare the variable value obtained from the DFT above to a package variable value obtained say via a Row Count component to determine if the file being processed has the right number of rows.

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  • Reporting Solution in PHP / CodeIgniter - Server side logic vs client side

    - by dot
    I'm building a report for an end user. They would like to see a list of all widgets... but then also like to see widgets with missing attributes, like missing names, or missing size. So i was thinking of creating one method that returns json data containing all widgets... and then using javascript to let them filter the data for missing data, instead of requerying the database. Ultimately, they need to be able to save all "reports" (filtered versions of data) inside a csv file. These are the two options I'm mulling over: Design 1 Create 3 separate methods in my controller/model like: get_all_data() get_records_with_missing_names() get_records_with_missing_size() And then when these methods are called, I would display the data on screen and give them a button to save to csv file. Design 2 Create one method called get_all_data() and then somehow, give them tools in the view to filter the json data using tables etc... and then letting them save subsets of the data. The reality is, in order to display all data, I still need to massage the data, and therefore, I know which records are missing attributes. So i'd rather not create separate methods by each filter. I'm not sure how I would do that just yet but at this point, i would like to know some pros/cons of each method. Thanks.

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  • Connection String Incorrectly Formatted [migrated]

    - by Randy E
    I'm running into some issues. Every time I launch into debug mode and hit the "Create User" button, I'm getting an exception being thrown that is due to the Connection String either being in the wrong syntax or just wrong. Using Visual Studio 2010, project is .NET 3.5 with SQL 2008 Express. This is just a personal project that I'm testing some other things with, I know this generally isn't the recommended format but for a personal small project, I don't see the point in doing it any other way. The things I'm testing actually work :) Data Source=.\SQLEXPRESS;AttachDbFilename=|Data Directory|ASPAppDatabase.mdf;Integrated Security=True;User Instance=True That doesn't work. Data Source=.\SQLEXPRESS;AttachDbFilename="|Data Directory|ASPAppDatabase.mdf";Integrated Security=True;User Instance=True Neither does that. Data Source=.\SQLEXPRESS;AttachDbFilename='|Data Directory|ASPAppDatabase.mdf';Integrated Security=True;User Instance=True And again, neither does that :/ However, rather than using "|Data directory| if I use the full path to the local DB file it works just fine and no exception is thrown, and I can read and write as I need. And just to cover all my bases, here is the button click event that creates the User. protected void btnAddUser_Click(object sender, EventArgs e) { Membership.CreateUser(txtUserName.Text, txtPassword.Text); btnLogin_Click(sender, e); } So, what am I missing in regards to the |Data Directory|? Here is an example of the above not working correctly..taken directly from web.config. <add name="ASPAppDatabaseConnection" connectionString='Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|ASPAppDatabase.mdf;Integrated Security=True;User Instance=True'/>

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  • Use a SQL Database for a Desktop Game

    - by sharethis
    Developing a Game Engine I am planning a computer game and its engine. There will be a 3 dimensional world with first person view and it will be single player for now. The programming language is C++ and it uses OpenGL. Data Centered Design Decision My design decision is to use a data centered architecture where there is a global event manager and a global data manager. There are many components like physics, input, sound, renderer, ai, ... Each component can trigger and listen to events. Moreover, each component can read, edit, create and remove data. The question is about the data manager. Whether to Use a Relational Database Should I use a SQL Database, e.g. SQLite or MySQL, to store the game data? This contains virtually all game content like items, characters, inventories, ... Except of meshes and textures which are even more performance related, so I will keep them in memory. Is a SQL database fast enough to use it for realtime reading and writing game informations, like the position of a moving character? I also need to care about cross-platform compatibility. Aside from keeping everything in memory, what alternatives do I have? Advantages Would Be The advantages of using a relational database like MySQL would be the data orientated structure which allows fast computation. I would not need objects for representing entities. I could easily query data of objects near the player needed for rendering. And I don't have to take care about data of objects far away. Moreover there would be no need for savegames since the hole game state is saved in the database. Last but not least, expanding the game to an online game would be relative easy because there already is a place where the hole game state is stored.

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  • Business Forces: SOA Adoption

    The only constant in today’s business environment is change. Businesses that continuously foresee change and adapt quickly will gain market share and increased growth. In our ever growing global business environment change is driven by data in regards to collecting, maintaining, verifying and distributing data.  Companies today are made and broken over data. Would anyone still use Google if they did not have one of the most accurate search indexes on the internet? No, because their value is in their data and the quality of their data. Due to the increasing focus on data, companies have been adopting new methodologies for gaining more control over their data while attempting to reduce the costs of maintaining it. In addition, companies are also trying to reduce the time it takes to analyze data in regards to various market forces to foresee changes prior to them actually occurring.   Benefits of Adopting SOA Services can be maintained separately from other services and applications so that a change in one service will only affect itself and client services or applications. The advent of services allows for system functionality to be distributed across a network or multiple networks. The costs associated with maintain business functionality is much higher in standard application development over SOA due to the fact that one Services can be maintained and shared to other applications instead of multiple instances of business functionality being duplicated via hard coding in to several applications. When multiple applications use a single service for a specific business function then the all of the data being processed will be consistent in terms of quality and accuracy through the applications. Disadvantages of Adopting SOA Increased initial costs and timelines are associated with SOA due to the fact that services need to be created as well as applications need to be modified to call the services In order for an SOA project to be successful the project must obtain company and management support in order to gain the proper exposure, funding, and attention. If SOA is new to a company they must also support the proper training in order for the project to be designed, and implemented correctly. References: Tews, R. (2007). Beyond IT: Exploring the Business Value of SOA. SOA Magazine Issue XI.

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  • Designing communications for extensibility

    - by Thomas S.
    I am working on the design stages of an application that will a) collect data from various sources (in my case that's scientific data from serial ports), keeping track of the age of the data, b) generate real-time statistics (e.g. running averages) c) display, record, and otherwise handle the data (and statistics). I anticipate that I will be adding both data producers and consumers over time, and would like to design this application abstractly so that I will be able to trivially add functionality with a small amount of interface code. What I'm stumbling on is deciding what communication infrastructure I should use to handle the interfaces. In particular, how should I make the processed data and statistics available to multiple consumers? Some things I've considered: Writing to several named pipes (variable number). Each consumer reads from one of them. Using FUSE to make a userspace filesystem where a read() returns the latest line of data even if another process has already read it. Making a TCP server, and having consumers connect and request data individually. Simply writing the consumers as part of the same program that aggregates the data. So I would like to hear your all's advice on deciding how to interface these functions in the best way to keep them separate and allow room for extenstions.

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  • What does the ".align" x86 Assembler directive do exactly? [migrated]

    - by Sinister Clock
    I will list exactly what I do not understand, and show you the parts I can not understand as well. First off, The .Align Directive .align integer, pad. The .align directive causes the next data generated to be aligned modulo integer bytes 1.~ ? : What is implied with "causes the next data generated to be aligned modulo integer bytes?" I can surmise that the next data generated is a memory-to-register transfer, no? Modulo would imply the remainder of a division. I do not understand "to be aligned modulo integer bytes"....... What would be a remainder of a simple data declaration, and how would the next data generated being aligned by a remainder be useful? If the next data is aligned modulo, that is saying the next generated data, whatever that means exactly, is the remainder of an integer? That makes absolutely no sense. What specifically would the .align, say, .align 8 directive issued in x86 for a data byte compiled from a C char, i.e., char CHARACTER = 0; be for? Or specifically coded directly with that directive, not preliminary Assembly code after compiling C? I have debugged in Assembly and noticed that any C/C++ data declarations, like chars, ints, floats, etc. will insert the directive .align 8 to each of them, and add other directives like .bss, .zero, .globl, .text, .Letext0, .Ltext0. What are all of these directives for, or at least my main asking? I have learned a lot of the main x86 Assembly instructions, but never was introduced or pointed at all of these strange directives. How do they affect the opcodes, and are all of them necessary?

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  • PHP Code (modules) included via MySQL database, good idea?

    - by ionFish
    The main script includes "modules" which add functionality to it. Each module is set up like this: <?php //data collection stuff //(...) approx 80 lines of code //end data collection $var1 = 'some data'; $var2 = 'more data'; $var3 = 'other data'; ?> Each module has the same exact variables, just the data collection is different. I was wondering if it's a reasonable idea to store the module data in MySQL like this: [database] |_modules |_name |_function (the raw PHP data from above) |_description |_author |_update-url |_version |_enabled ...and then include the PHP-data from the database and execute it? Something like, a tab-navigation system at the top of the page for each module name, then inside each of those tabs the page content would function by parsing the database-stored code of the module from the function section. The purpose would be to save code space (fewer lines), allow for easy updates, and include/exclude modules based on the enabled option. This is how many other web-apps work, some of my own too. But never had I thought about this so deeply. Are there any drawbacks or security risks to this?

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  • ASP.NET Creating a Rich Repeater, DataBind wiping out custom added controls...

    - by tonyellard
    So...I had this clever idea that I'd create my own Repeater control that implements paging and sorting by inheriting from Repeater and extending it's capabilities. I found some information and bits and pieces on how to go about this and everything seemed ok... I created a WebControlLibrary to house my custom controls. Along with the enriched repeater, I created a composite control that would act as the "pager bar", having forward, back and page selection. My pager bar works 100% on it's own, properly firing a paged changed event when the user interacts with it. The rich repeater databinds without issue, but when the databind fires (when I call base.databind()), the control collection is cleared out and my pager bars are removed. This screws up the viewstate for the pager bars making them unable to fire their events properly or maintain their state. I've tried adding the controls back to the collection after base.databind() fires, but that doesn't solve the issue. I start to get very strange results including problems with altering the hierarchy of the control tree (resolved by adding [ViewStateModeById]). Before I go back to the drawing board and create a second composite control which contains a repeater and the pager bars (so that the repeater isn't responsible for the pager bars viewstate) are there any thoughts about how to resolve the issue? In the interest of share and share alike, the code for the repeater itself is below, the pagerbars aren't as significant as the issue is really the maintaining of state for any additional child controls. (forgive the roughness of some of the code...it's still a work in progress) using System; using System.Collections.Generic; using System.ComponentModel; using System.Text; using System.Data; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; [ViewStateModeById] public class SortablePagedRepeater : Repeater, INamingContainer { private SuperRepeaterPagerBar topBar = new SuperRepeaterPagerBar(); private SuperRepeaterPagerBar btmBar = new SuperRepeaterPagerBar(); protected override void OnInit(EventArgs e) { Page.RegisterRequiresControlState(this); InitializeControls(); base.OnInit(e); EnsureChildControls(); } protected void InitializeControls() { topBar.ID = this.ID + "__topPagerBar"; topBar.NumberOfPages = this._currentProperties.numOfPages; topBar.CurrentPage = this.CurrentPageNumber; topBar.PageChanged += new SuperRepeaterPagerBar.PageChangedEventHandler(PageChanged); btmBar.ID = this.ID + "__btmPagerBar"; btmBar.NumberOfPages = this._currentProperties.numOfPages; btmBar.CurrentPage = this.CurrentPageNumber; btmBar.PageChanged += new SuperRepeaterPagerBar.PageChangedEventHandler(PageChanged); } protected override void CreateChildControls() { EnsureDataBound(); this.Controls.Add(topBar); this.Controls.Add(btmBar); //base.CreateChildControls(); } private void PageChanged(object sender, int newPage) { this.CurrentPageNumber = newPage; } public override void DataBind() { //pageDataSource(); //DataBind removes all controls from control collection... base.DataBind(); Controls.Add(topBar); Controls.Add(btmBar); } private void pageDataSource() { //Create paged data source PagedDataSource pds = new PagedDataSource(); pds.PageSize = this.ItemsPerPage; pds.AllowPaging = true; // first get a PagedDataSource going and perform sort if possible... if (base.DataSource is System.Collections.IEnumerable) { pds.DataSource = (System.Collections.IEnumerable)base.DataSource; } else if (base.DataSource is System.Data.DataView) { DataView data = (DataView)DataSource; if (this.SortBy != null && data.Table.Columns.Contains(this.SortBy)) { data.Sort = this.SortBy; } pds.DataSource = data.Table.Rows; } else if (base.DataSource is System.Data.DataTable) { DataTable data = (DataTable)DataSource; if (this.SortBy != null && data.Columns.Contains(this.SortBy)) { data.DefaultView.Sort = this.SortBy; } pds.DataSource = data.DefaultView; } else if (base.DataSource is System.Data.DataSet) { DataSet data = (DataSet)DataSource; if (base.DataMember != null && data.Tables.Contains(base.DataMember)) { if (this.SortBy != null && data.Tables[base.DataMember].Columns.Contains(this.SortBy)) { data.Tables[base.DataMember].DefaultView.Sort = this.SortBy; } pds.DataSource = data.Tables[base.DataMember].DefaultView; } else if (data.Tables.Count > 0) { if (this.SortBy != null && data.Tables[0].Columns.Contains(this.SortBy)) { data.Tables[0].DefaultView.Sort = this.SortBy; } pds.DataSource = data.Tables[0].DefaultView; } else { throw new Exception("DataSet doesn't have any tables."); } } else if (base.DataSource == null) { // don't do anything? } else { throw new Exception("DataSource must be of type System.Collections.IEnumerable. The DataSource you provided is of type " + base.DataSource.GetType().ToString()); } if (pds != null && base.DataSource != null) { //Make sure that the page doesn't exceed the maximum number of pages //available if (this.CurrentPageNumber >= pds.PageCount) { this.CurrentPageNumber = pds.PageCount - 1; } //Set up paging values... btmBar.CurrentPage = topBar.CurrentPage = pds.CurrentPageIndex = this.CurrentPageNumber; this._currentProperties.numOfPages = btmBar.NumberOfPages = topBar.NumberOfPages = pds.PageCount; base.DataSource = pds; } } public override object DataSource { get { return base.DataSource; } set { //init(); //reset paging/sorting values since we've potentially changed data sources. base.DataSource = value; pageDataSource(); } } protected override void Render(HtmlTextWriter writer) { topBar.RenderControl(writer); base.Render(writer); btmBar.RenderControl(writer); } [Serializable] protected struct CurrentProperties { public int pageNum; public int itemsPerPage; public int numOfPages; public string sortBy; public bool sortDir; } protected CurrentProperties _currentProperties = new CurrentProperties(); protected override object SaveControlState() { return this._currentProperties; } protected override void LoadControlState(object savedState) { this._currentProperties = (CurrentProperties)savedState; } [Category("Status")] [Browsable(true)] [NotifyParentProperty(true)] [DefaultValue("")] [Localizable(false)] public string SortBy { get { return this._currentProperties.sortBy; } set { //If sorting by the same column, swap the sort direction. if (this._currentProperties.sortBy == value) { this.SortAscending = !this.SortAscending; } else { this.SortAscending = true; } this._currentProperties.sortBy = value; } } [Category("Status")] [Browsable(true)] [NotifyParentProperty(true)] [DefaultValue(true)] [Localizable(false)] public bool SortAscending { get { return this._currentProperties.sortDir; } set { this._currentProperties.sortDir = value; } } [Category("Status")] [Browsable(true)] [NotifyParentProperty(true)] [DefaultValue(25)] [Localizable(false)] public int ItemsPerPage { get { return this._currentProperties.itemsPerPage; } set { this._currentProperties.itemsPerPage = value; } } [Category("Status")] [Browsable(true)] [NotifyParentProperty(true)] [DefaultValue(1)] [Localizable(false)] public int CurrentPageNumber { get { return this._currentProperties.pageNum; } set { this._currentProperties.pageNum = value; pageDataSource(); } } }

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  • How to simulate browser form POST method using PHP/cURL

    - by user283266
    I'm trying to simulate browser with POST method using PHP/cURL. When I looked at that live Http header it shows Content-Type: multipart/form-data. I checked on the internet where it was suggested that cURL will send multipart/form-data when a custom headers is specified to Content-Type: multipart/form-data. $headers = array( 'Content-Type' => 'multipart/form-data; boundary='.$boundary ); This didn't work for me either when I print_r(curl_getinfo()) it showed [content_type] => text/html; charset=UTF-8 Which means cURL sent a default headers I also read that sending/uploading a file with cURL will cause data to be send as multipart/form-data. I created a file which curl uploaded but again when I ran curl_getinfo I got [content_type] => text/html; charset=UTF-8 $data_array = array("field" => "@c:\file_location.txt"); I also tried to read a file content so that the only thing sent would be content NOT ATTACHED FILE but this didn't work for me curl_getinfo shows [content_type] => text/html; charset=UTF-8. $data_array = array("field" => "<c:\file_location.txt"); // note @ replaced with < Do I miss somthing here? This is the referer url POST somepath HTTP/1.1 Host: www(dot)domain(dot)com User-Agent: Mozilla/5.0 (Windows) Gecko/13081217 Firefox/3 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Referer: url/some-file.php Content-Type: multipart/form-data; boundary=--------------------------$boundary Content-Length: $some_number ----------------------------$boundary Content-Disposition: form-data; name="$some_Value1" $some_text1 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value2" $some_text2 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value3" $some_text3 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value4" $some_text4 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value5" $some_text5 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value6" $some_text6 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value7" $some_text7 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value8" $some_text8 ----------------------------$boundary Content-Disposition: form-data; name="$some_Value9" ----------------------------$boundary Content-Disposition: form-data; name="$some_Value10" ----------------------------$boundary-- Here is a piece of code. <? //Include files set_time_limit(0); include'body.php'; include'keyword.php'; include'bio.php'; include'summary.php'; include'headline.php'; include'category.php'; include'spin.php'; include'random-text.php'; $category = category(); $headline = headline() ; $summary = summary(); $keyword = keyword(); $body = body(); $bio = bio(); $target="url"; $ref ="url_ref"; $c = "Content-Disposition: form-data; name="; $boundary = "---------------------------".random_text(); $category = category(); $headline = headline() ; $summary = summary(); $keyword = keyword(); $body = body(); $bio = bio(); // emulating content form as it appears on livehttp header $data = "\r\n".$boundary."\r\n".$c."\"pen_id\"\r\n\r\n".$Auth_id."\r\n".$boundary."\r\n".$c."\"cat_id\"\r\n\r\n".category()."\r\n".$boundary."\r\n".$c."\"title\"\r\n\r\n".headline()."\r\n".$boundary."\r\n".$c."\"meta_desc\"\r\n\r\n".summary()."\r\n".$boundary."\r\n".$c."\"meta_keys\"\r\n\r\n".keyword()."\r\n".$boundary."\r\n".$c."\"content\"\r\n\r\n".body()."\r\n".$boundary."\r\n".$c."\"author_bio\"\r\n\r\n".bio()."\r\n".$boundary."\r\n".$c."\"allow_comments\"\r\n\r\ny\r\n".$boundary."\r\n".$c."\"id\"\r\n\r\n\r\n".$boundary."\r\n".$c."\"action\"\r\n\r\n\r\n".$boundary."--\r\n"; // inserting content into a file $file = "C:\file_path.txt"; $fh = fopen($file, 'w+') or die("Can't open file"); fwrite($fh,$data); fclose($fh); // pulling out content from a file as multipart/form-data $data_array = array ("field" => "<C:\file_path.txt"); $headers = array ( 'POST /myhome/article/new HTTP/1.1', 'Host: url', 'User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.20) Gecko/20081217 Firefox/2.0.0.20 (.NET CLR 3.5.30729)', 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9;q=0.8', 'Accept-Language: en-us,en;q=0.5', 'Accept-Encoding: gzip,deflate', 'Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7', 'Keep-Alive: 300', 'Connection: keep-alive', 'Content-Type: multipart/form-data; boundary='.$boundary, 'Content-Length: '.strlen($data), ); # Create the cURL session $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $target); // Define target site curl_setopt($ch, CURLOPT_POST,1); curl_setopt($ch, CURLOPT_HEADER, $headers); // No http head //curl_setopt($ch, CURLOPT_REFERER, $ref); curl_setopt($ch, CURLOPT_NOBODY, FALSE); curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); // Return page in string curl_setopt($ch, CURLOPT_COOKIEJAR, "c:\cookie\cookies.txt"); // Tell cURL where to write curl_setopt($ch, CURLOPT_COOKIEFILE, "c:\cookie\cookies.txt"); // Tell cURL which cookies //curl_setopt($ch, CURLOPT_USERAGENT, $agent); curl_setopt($ch, CURLOPT_POST, TRUE); curl_setopt($ch, CURLOPT_POSTFIELDS, "$data_array"); curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE); // Follow redirects curl_setopt($ch, CURLOPT_MAXREDIRS, 4); # Execute the PHP/CURL session and echo the downloaded page $page = curl_exec($ch); $err = curl_error($ch); $info =curl_getinfo($ch); # Close the cURL session curl_close($ch); print_r($err); print_r($info); ?>

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  • using Generics in C# [closed]

    - by Uphaar Goyal
    I have started looking into using generics in C#. As an example what i have done is that I have an abstract class which implements generic methods. these generic methods take a sql query, a connection string and the Type T as parameters and then construct the data set, populate the object and return it back. This way each business object does not need to have a method to populate it with data or construct its data set. All we need to do is pass the type, the sql query and the connection string and these methods do the rest.I am providing the code sample here. I am just looking to discuss with people who might have a better solution to what i have done. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; using System.Data.SqlClient; using MWTWorkUnitMgmtLib.Business; using System.Collections.ObjectModel; using System.Reflection; namespace MWTWorkUnitMgmtLib.TableGateway { public abstract class TableGateway { public TableGateway() { } protected abstract string GetConnection(); protected abstract string GetTableName(); public DataSet GetDataSetFromSql(string connectionString, string sql) { DataSet ds = null; using (SqlConnection connection = new SqlConnection(connectionString)) using (SqlCommand command = connection.CreateCommand()) { command.CommandText = sql; connection.Open(); using (ds = new DataSet()) using (SqlDataAdapter adapter = new SqlDataAdapter(command)) { adapter.Fill(ds); } } return ds; } public static bool ContainsColumnName(DataRow dr, string columnName) { return dr.Table.Columns.Contains(columnName); } public DataTable GetDataTable(string connString, string sql) { DataSet ds = GetDataSetFromSql(connString, sql); DataTable dt = null; if (ds != null) { if (ds.Tables.Count 0) { dt = ds.Tables[0]; } } return dt; } public T Construct(DataRow dr, T t) where T : class, new() { Type t1 = t.GetType(); PropertyInfo[] properties = t1.GetProperties(); foreach (PropertyInfo property in properties) { if (ContainsColumnName(dr, property.Name) && (dr[property.Name] != null)) property.SetValue(t, dr[property.Name], null); } return t; } public T GetByID(string connString, string sql, T t) where T : class, new() { DataTable dt = GetDataTable(connString, sql); DataRow dr = dt.Rows[0]; return Construct(dr, t); } public List GetAll(string connString, string sql, T t) where T : class, new() { List collection = new List(); DataTable dt = GetDataTable(connString, sql); foreach (DataRow dr in dt.Rows) collection.Add(Construct(dr, t)); return collection; } } }

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  • Skype crash immediatly after launch

    - by K_naille
    when I'm launch skype, it crashes immediatly. Error: mathieu@mathieu-desktop:~$ skype `menu_proxy_module_load': skype: undefined symbol: menu_proxy_module_load (skype:10442): Gtk-WARNING **: Failed to load type module: (null) `menu_proxy_module_load': skype: undefined symbol: menu_proxy_module_load (skype:10442): Gtk-WARNING **: Failed to load type module: (null) `menu_proxy_module_load': skype: undefined symbol: menu_proxy_module_load (skype:10442): Gtk-WARNING **: Failed to load type module: (null) `menu_proxy_module_load': skype: undefined symbol: menu_proxy_module_load (skype:10442): Gtk-WARNING **: Failed to load type module: (null) Abandon (core dumped) mathieu@mathieu-desktop:~$ Can you help me? Thank.

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  • Built-in card-reader doesn't work. HP Compaq nx6325 notebook

    - by user10940
    I have a HP-Compaq nx6325 notebook with an built-in card-reader (SD, MS/Pro, MMC, SM, XD) and the ubuntu (10.10.) don't see it. I've tried to install it manually, with this steps (and with this tifmxx driver), but doesn't work. The compile log: $ echo /home/tvera/downloads/cr_install /home/tvera/downloads/cr_install $ make -C /lib/modules/2.6.35-25-generic/build M=/home/tvera/downloads/cr_install make[1]: Entering directory `/usr/src/linux-headers-2.6.35-25-generic' CC [M] /home/tvera/downloads/cr_install/tifm_core.o In file included from /home/tvera/downloads/cr_install/tifm_core.c:12: /home/tvera/downloads/cr_install/linux/tifm.h:128: error: field ‘cdev’ has incomplete type /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_uevent’: /home/tvera/downloads/cr_install/tifm_core.c:69: warning: passing argument 1 of ‘add_uevent_var’ from incompatible pointer type include/linux/kobject.h:244: note: expected ‘struct kobj_uevent_env *’ but argument is of type ‘char **’ /home/tvera/downloads/cr_install/tifm_core.c:69: warning: passing argument 2 of ‘add_uevent_var’ makes pointer from integer without a cast include/linux/kobject.h:244: note: expected ‘const char *’ but argument is of type ‘int’ /home/tvera/downloads/cr_install/tifm_core.c: At top level: /home/tvera/downloads/cr_install/tifm_core.c:161: warning: initialization from incompatible pointer type /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_free’: /home/tvera/downloads/cr_install/tifm_core.c:170: warning: type defaults to ‘int’ in declaration of ‘__mptr’ /home/tvera/downloads/cr_install/tifm_core.c:170: warning: initialization from incompatible pointer type /home/tvera/downloads/cr_install/tifm_core.c: At top level: /home/tvera/downloads/cr_install/tifm_core.c:177: error: unknown field ‘release’ specified in initializer /home/tvera/downloads/cr_install/tifm_core.c:178: warning: initialization from incompatible pointer type /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_alloc_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:190: error: implicit declaration of function ‘class_device_initialize’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_add_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:211: error: ‘BUS_ID_SIZE’ undeclared (first use in this function) /home/tvera/downloads/cr_install/tifm_core.c:211: error: (Each undeclared identifier is reported only once /home/tvera/downloads/cr_install/tifm_core.c:211: error: for each function it appears in.) /home/tvera/downloads/cr_install/tifm_core.c:212: error: implicit declaration of function ‘class_device_add’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_remove_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:237: error: implicit declaration of function ‘class_device_del’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_free_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:243: error: implicit declaration of function ‘class_device_put’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_alloc_device’: /home/tvera/downloads/cr_install/tifm_core.c:275: error: ‘struct device’ has no member named ‘bus_id’ /home/tvera/downloads/cr_install/tifm_core.c:275: error: ‘BUS_ID_SIZE’ undeclared (first use in this function) make[2]: *** [/home/tvera/downloads/cr_install/tifm_core.o] Error 1 make[1]: *** [_module_/home/tvera/downloads/cr_install] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-2.6.35-25-generic' make: *** [all] Error 2 The output of lsusb: Bus 001 Device 005: ID 05e3:0702 Genesys Logic, Inc. USB 2.0 IDE Adapter Bus 003 Device 003: ID 0458:003a KYE Systems Corp. (Mouse Systems) NetScroll+ Mini Traveler Bus 003 Device 002: ID 08ff:2580 AuthenTec, Inc. AES2501 Fingerprint Sensor Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

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  • How to Upload a file from client to server using OFBIZ?

    - by SIVAKUMAR.J
    I'm new to ofbiz so try to keep your answer as simple as possibly. If you can give examples that would be kind. My problem is I created a project inside the ofbiz/hot-deploy folder namely productionmgntSystem. Inside the folder ofbiz\hot-deploy\productionmgntSystem\webapp\productionmgntSystem I created a file app_details_1.ftl. The following are the code of this file <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> <script TYPE="TEXT/JAVASCRIPT" language=""JAVASCRIPT"> function uploadFile() { //alert("Before calling upload.jsp"); window.location='<@ofbizUrl>testing_service1</@ofbizUrl>' } </script> </head> <!-- <form action="<@ofbizUrl>testing_service1</@ofbizUrl>" enctype="multipart/form-data" name="app_details_frm"> --> <form action="<@ofbizUrl>logout1</@ofbizUrl>" enctype="multipart/form-data" name="app_details_frm"> <center style="height: 299px; "> <table border="0" style="height: 177px; width: 788px"> <tr style="height: 115px; "> <td style="width: 103px; "> <td style="width: 413px; "><h1>APPLICATION DETAILS</h1> <td style="width: 55px; "> </tr> <tr> <td style="width: 125px; ">Application name : </td> <td> <input name="app_name_txt" id="txt_1" value=" " /> </td> </tr> <tr> <td style="width: 125px; ">Excell sheet &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: </td> <td> <input type="file" name="filename"/> </td> </tr> <tr> <td> <!-- <input type="button" name="logout1_cmd" value="Logout" onclick="logout1()"/> --> <input type="submit" name="logout_cmd" value="logout"/> </td> <td> <!-- <input type="submit" name="upload_cmd" value="Submit" /> --> <input type="button" name="upload1_cmd" value="Upload" onclick="uploadFile()"/> </td> </tr> </table> </center> </form> </html> the following coding is present in the file ofbiz\hot-deploy\productionmgntSystem\webapp\productionmgntSystem\WEB-INF\controller.xml ...... ....... ........ <request-map uri="testing_service1"> <security https="true" auth="true"/> <event type="java" path="org.ofbiz.productionmgntSystem.web_app_req.WebServices1" invoke="testingService"/> <response name="ok" type="view" value="ok_view"/> <response name="exception" type="view" value="exception_view"/> </request-map> .......... ............ .......... <view-map name="ok_view" type="ftl" page="ok_view.ftl"/> <view-map name="exception_view" type="ftl" page="exception_view.ftl"/> ................ ............. ............. The following are the coding present in the file ofbiz\hot-deploy\productionmgntSystem\src\org\ofbiz\productionmgntSystem\web_app_req\WebServices1.java package org.ofbiz.productionmgntSystem.web_app_req; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.DataInputStream; import java.io.FileOutputStream; import java.io.IOException; public class WebServices1 { public static String testingService(HttpServletRequest request, HttpServletResponse response) { //int i=0; String result="ok"; System.out.println("\n\n\t*************************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response)- Start"); String contentType=request.getContentType(); System.out.println("\n\n\t*************************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response)- contentType : "+contentType); String str=new String(); // response.setContentType("text/html"); //PrintWriter writer; if ((contentType != null) && (contentType.indexOf("multipart/form-data") >= 0)) { System.out.println("\n\n\t**********************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response) after if (contentType != null)"); try { // writer=response.getWriter(); System.out.println("\n\n\t**********************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response) - try Start"); DataInputStream in = new DataInputStream(request.getInputStream()); int formDataLength = request.getContentLength(); byte dataBytes[] = new byte[formDataLength]; int byteRead = 0; int totalBytesRead = 0; //this loop converting the uploaded file into byte code while (totalBytesRead < formDataLength) { byteRead = in.read(dataBytes, totalBytesRead,formDataLength); totalBytesRead += byteRead; } String file = new String(dataBytes); //for saving the file name String saveFile = file.substring(file.indexOf("filename=\"") + 10); saveFile = saveFile.substring(0, saveFile.indexOf("\n")); saveFile = saveFile.substring(saveFile.lastIndexOf("\\")+ 1,saveFile.indexOf("\"")); int lastIndex = contentType.lastIndexOf("="); String boundary = contentType.substring(lastIndex + 1,contentType.length()); int pos; //extracting the index of file pos = file.indexOf("filename=\""); pos = file.indexOf("\n", pos) + 1; pos = file.indexOf("\n", pos) + 1; pos = file.indexOf("\n", pos) + 1; int boundaryLocation = file.indexOf(boundary, pos) - 4; int startPos = ((file.substring(0, pos)).getBytes()).length; int endPos = ((file.substring(0, boundaryLocation)).getBytes()).length; //creating a new file with the same name and writing the content in new file FileOutputStream fileOut = new FileOutputStream("/"+saveFile); fileOut.write(dataBytes, startPos, (endPos - startPos)); fileOut.flush(); fileOut.close(); System.out.println("\n\n\t**********************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response) - try End"); } catch(IOException ioe) { System.out.println("\n\n\t*********************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response) - Catch IOException"); //ioe.printStackTrace(); return("exception"); } catch(Exception ex) { System.out.println("\n\n\t*********************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response) - Catch Exception"); return("exception"); } } else { System.out.println("\n\n\t********************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response) else part"); result="exception"; } System.out.println("\n\n\t*************************************\n\tInside WebServices1.testingService(HttpServletRequest request, HttpServletResponse response)- End"); return(result); } } I want to upload a file to the server. The file is get from user " tag in the "app_details_1.ftl" file & it is updated into the server by using the method "testingService(HttpServletRequest request, HttpServletResponse response)" in the class "WebServices1". But the file is not uploaded. Give me a good solution for uploading a file to the server.

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  • Using jQuery Live instead of jQuery Hover function

    - by hajan
    Let’s say we have a case where we need to create mouseover / mouseout functionality for a list which will be dynamically filled with data on client-side. We can use jQuery hover function, which handles the mouseover and mouseout events with two functions. See the following example: <!DOCTYPE html> <html lang="en"> <head id="Head1" runat="server">     <title>jQuery Mouseover / Mouseout Demo</title>     <script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.4.4.js"></script>     <style type="text/css">         .hover { color:Red; cursor:pointer;}     </style>     <script type="text/javascript">         $(function () {             $("li").hover(               function () {                   $(this).addClass("hover");               },               function () {                   $(this).removeClass("hover");               });         });     </script> </head> <body>     <form id="form2" runat="server">     <ul>         <li>Data 1</li>         <li>Data 2</li>         <li>Data 3</li>         <li>Data 4</li>         <li>Data 5</li>         <li>Data 6</li>     </ul>     </form> </body> </html> Now, if you have situation where you want to add new data dynamically... Lets say you have a button to add new item in the list. Add the following code right bellow the </ul> tag <input type="text" id="txtItem" /> <input type="button" id="addNewItem" value="Add New Item" /> And add the following button click functionality: //button add new item functionality $("#addNewItem").click(function (event) {     event.preventDefault();     $("<li>" + $("#txtItem").val() + "</li>").appendTo("ul"); }); The mouse over effect won't work for the newly added items. Therefore, we need to use live or delegate function. These both do the same job. The main difference is that for some cases delegate is considered a bit faster, and can be used in chaining. In our case, we can use both. I will use live function. $("li").live("mouseover mouseout",   function (event) {       if (event.type == "mouseover") $(this).addClass("hover");       else $(this).removeClass("hover");   }); The complete code is: <!DOCTYPE html> <html lang="en"> <head id="Head1" runat="server">     <title>jQuery Mouseover / Mouseout Demo</title>     <script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.4.4.js"></script>     <style type="text/css">         .hover { color:Red; cursor:pointer;}     </style>     <script type="text/javascript">         $(function () {             $("li").live("mouseover mouseout",               function (event) {                   if (event.type == "mouseover") $(this).addClass("hover");                   else $(this).removeClass("hover");               });             //button add new item functionality             $("#addNewItem").click(function (event) {                 event.preventDefault();                 $("<li>" + $("#txtItem").val() + "</li>").appendTo("ul");             });         });     </script> </head> <body>     <form id="form2" runat="server">     <ul>         <li>Data 1</li>         <li>Data 2</li>         <li>Data 3</li>         <li>Data 4</li>         <li>Data 5</li>         <li>Data 6</li>     </ul>          <input type="text" id="txtItem" />     <input type="button" id="addNewItem" value="Add New Item" />     </form> </body> </html> So, basically when replacing hover with live, you see we use the mouseover and mouseout names for both events. Check the working demo which is available HERE. Hope this was useful blog for you. Hope it’s helpful. HajanReference blog: http://codeasp.net/blogs/hajan/microsoft-net/1260/using-jquery-live-instead-of-jquery-hover-function

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  • MySQL Cluster 7.2: Over 8x Higher Performance than Cluster 7.1

    - by Mat Keep
    0 0 1 893 5092 Homework 42 11 5974 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-US;} Summary The scalability enhancements delivered by extensions to multi-threaded data nodes enables MySQL Cluster 7.2 to deliver over 8x higher performance than the previous MySQL Cluster 7.1 release on a recent benchmark What’s New in MySQL Cluster 7.2 MySQL Cluster 7.2 was released as GA (Generally Available) in February 2012, delivering many enhancements to performance on complex queries, new NoSQL Key / Value API, cross-data center replication and ease-of-use. These enhancements are summarized in the Figure below, and detailed in the MySQL Cluster New Features whitepaper Figure 1: Next Generation Web Services, Cross Data Center Replication and Ease-of-Use Once of the key enhancements delivered in MySQL Cluster 7.2 is extensions made to the multi-threading processes of the data nodes. Multi-Threaded Data Node Extensions The MySQL Cluster 7.2 data node is now functionally divided into seven thread types: 1) Local Data Manager threads (ldm). Note – these are sometimes also called LQH threads. 2) Transaction Coordinator threads (tc) 3) Asynchronous Replication threads (rep) 4) Schema Management threads (main) 5) Network receiver threads (recv) 6) Network send threads (send) 7) IO threads Each of these thread types are discussed in more detail below. MySQL Cluster 7.2 increases the maximum number of LDM threads from 4 to 16. The LDM contains the actual data, which means that when using 16 threads the data is more heavily partitioned (this is automatic in MySQL Cluster). Each LDM thread maintains its own set of data partitions, index partitions and REDO log. The number of LDM partitions per data node is not dynamically configurable, but it is possible, however, to map more than one partition onto each LDM thread, providing flexibility in modifying the number of LDM threads. The TC domain stores the state of in-flight transactions. This means that every new transaction can easily be assigned to a new TC thread. Testing has shown that in most cases 1 TC thread per 2 LDM threads is sufficient, and in many cases even 1 TC thread per 4 LDM threads is also acceptable. Testing also demonstrated that in some instances where the workload needed to sustain very high update loads it is necessary to configure 3 to 4 TC threads per 4 LDM threads. In the previous MySQL Cluster 7.1 release, only one TC thread was available. This limit has been increased to 16 TC threads in MySQL Cluster 7.2. The TC domain also manages the Adaptive Query Localization functionality introduced in MySQL Cluster 7.2 that significantly enhanced complex query performance by pushing JOIN operations down to the data nodes. Asynchronous Replication was separated into its own thread with the release of MySQL Cluster 7.1, and has not been modified in the latest 7.2 release. To scale the number of TC threads, it was necessary to separate the Schema Management domain from the TC domain. The schema management thread has little load, so is implemented with a single thread. The Network receiver domain was bound to 1 thread in MySQL Cluster 7.1. With the increase of threads in MySQL Cluster 7.2 it is also necessary to increase the number of recv threads to 8. This enables each receive thread to service one or more sockets used to communicate with other nodes the Cluster. The Network send thread is a new thread type introduced in MySQL Cluster 7.2. Previously other threads handled the sending operations themselves, which can provide for lower latency. To achieve highest throughput however, it has been necessary to create dedicated send threads, of which 8 can be configured. It is still possible to configure MySQL Cluster 7.2 to a legacy mode that does not use any of the send threads – useful for those workloads that are most sensitive to latency. The IO Thread is the final thread type and there have been no changes to this domain in MySQL Cluster 7.2. Multiple IO threads were already available, which could be configured to either one thread per open file, or to a fixed number of IO threads that handle the IO traffic. Except when using compression on disk, the IO threads typically have a very light load. Benchmarking the Scalability Enhancements The scalability enhancements discussed above have made it possible to scale CPU usage of each data node to more than 5x of that possible in MySQL Cluster 7.1. In addition, a number of bottlenecks have been removed, making it possible to scale data node performance by even more than 5x. Figure 2: MySQL Cluster 7.2 Delivers 8.4x Higher Performance than 7.1 The flexAsynch benchmark was used to compare MySQL Cluster 7.2 performance to 7.1 across an 8-node Intel Xeon x5670-based cluster of dual socket commodity servers (6 cores each). As the results demonstrate, MySQL Cluster 7.2 delivers over 8x higher performance per data nodes than MySQL Cluster 7.1. More details of this and other benchmarks will be published in a new whitepaper – coming soon, so stay tuned! In a following blog post, I’ll provide recommendations on optimum thread configurations for different types of server processor. You can also learn more from the Best Practices Guide to Optimizing Performance of MySQL Cluster Conclusion MySQL Cluster has achieved a range of impressive benchmark results, and set in context with the previous 7.1 release, is able to deliver over 8x higher performance per node. As a result, the multi-threaded data node extensions not only serve to increase performance of MySQL Cluster, they also enable users to achieve significantly improved levels of utilization from current and future generations of massively multi-core, multi-thread processor designs.

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  • Is INT_MIN-1 an underflow or overflow?

    - by Johannes Schaub - litb
    I seem to remember that I was reading that underflow means you have a too small magnitude that cannot be presented anymore in a type overflow means you have a too large magnitude that cannot be presented anymore in a type However, in practice I perceive that the terms are used such that underflow means you have a too small value that cannot be presented anymore in a type overflow means you have a too large value that cannot be presented anymore in a type What is the correct meaning to use here? Are the terms defined differently for integer and floating point types?

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  • Retrieving Custom Attributes Using Reflection

    - by Scott Dorman
    The .NET Framework allows you to easily add metadata to your classes by using attributes. These attributes can be ones that the .NET Framework already provides, of which there are over 300, or you can create your own. Using reflection, the ways to retrieve the custom attributes of a type are: System.Reflection.MemberInfo public abstract object[] GetCustomAttributes(bool inherit); public abstract object[] GetCustomAttributes(Type attributeType, bool inherit); public abstract bool IsDefined(Type attributeType, bool inherit); System.Attribute public static Attribute[] GetCustomAttributes(MemberInfo member, bool inherit); public static bool IsDefined(MemberInfo element, Type attributeType, bool inherit); If you take the following simple class hierarchy: public abstract class BaseClass { private bool result;   [DefaultValue(false)] public virtual bool SimpleProperty { get { return this.result; } set { this.result = value; } } }   public class DerivedClass : BaseClass { public override bool SimpleProperty { get { return true; } set { base.SimpleProperty = value; } } } Given a PropertyInfo object (which is derived from MemberInfo, and represents a propery in reflection), you might expect that these methods would return the same result. Unfortunately, that isn’t the case. The MemberInfo methods strictly reflect the metadata definitions, ignoring the inherit parameter and not searching the inheritance chain when used with a PropertyInfo, EventInfo, or ParameterInfo object. It also returns all custom attribute instances, including those that don’t inherit from System.Attribute. The Attribute methods are closer to the implied behavior of the language (and probably closer to what you would naturally expect). They do respect the inherit parameter for PropertyInfo, EventInfo, and ParameterInfo objects and search the implied inheritance chain defined by the associated methods (in this case, the property accessors). These methods also only return custom attributes that inherit from System.Attribute. This is a fairly subtle difference that can produce very unexpected results if you aren’t careful. For example, to retrieve the custom  attributes defined on SimpleProperty, you could use code similar to this: PropertyInfo info = typeof(DerivedClass).GetProperty("SimpleProperty"); var attributeList1 = info.GetCustomAttributes(typeof(DefaultValueAttribute), true)); var attributeList2 = Attribute.GetCustomAttributes(info, typeof(DefaultValueAttribute), true));   The attributeList1 array will be empty while the attributeList2 array will contain the attribute instance, as expected. Technorati Tags: Reflection,Custom Attributes,PropertyInfo

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  • Can't see Windows partition in Nautilus

    - by Anders Feder
    I am on Ubuntu 11.10. I used to be able to access my Windows partion from the list of devices in Nautilus, but I no longer see it. What might be wrong? Running sudo blkid gives the following: /dev/loop0: UUID="ef34b449-1330-4ac5-bb69-e1475c0b91da" TYPE="ext4" /dev/sda1: LABEL="PQSERVICE" UUID="D04C76D04C76B138" TYPE="ntfs" /dev/sda2: LABEL="SYSTEM RESERVED" UUID="EC4878594878248C" TYPE="ntfs" /dev/sda3: LABEL="Acer" UUID="54947A5A947A3E94" TYPE="ntfs" Thanks.

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  • Master-slave vs. peer-to-peer archictecture: benefits and problems

    - by Ashok_Ora
    Normal 0 false false false EN-US X-NONE X-NONE Almost two decades ago, I was a member of a database development team that introduced adaptive locking. Locking, the most popular concurrency control technique in database systems, is pessimistic. Locking ensures that two or more conflicting operations on the same data item don’t “trample” on each other’s toes, resulting in data corruption. In a nutshell, here’s the issue we were trying to address. In everyday life, traffic lights serve the same purpose. They ensure that traffic flows smoothly and when everyone follows the rules, there are no accidents at intersections. As I mentioned earlier, the problem with typical locking protocols is that they are pessimistic. Regardless of whether there is another conflicting operation in the system or not, you have to hold a lock! Acquiring and releasing locks can be quite expensive, depending on how many objects the transaction touches. Every transaction has to pay this penalty. To use the earlier traffic light analogy, if you have ever waited at a red light in the middle of nowhere with no one on the road, wondering why you need to wait when there’s clearly no danger of a collision, you know what I mean. The adaptive locking scheme that we invented was able to minimize the number of locks that a transaction held, by detecting whether there were one or more transactions that needed conflicting eyou could get by without holding any lock at all. In many “well-behaved” workloads, there are few conflicts, so this optimization is a huge win. If, on the other hand, there are many concurrent, conflicting requests, the algorithm gracefully degrades to the “normal” behavior with minimal cost. We were able to reduce the number of lock requests per TPC-B transaction from 178 requests down to 2! Wow! This is a dramatic improvement in concurrency as well as transaction latency. The lesson from this exercise was that if you can identify the common scenario and optimize for that case so that only the uncommon scenarios are more expensive, you can make dramatic improvements in performance without sacrificing correctness. So how does this relate to the architecture and design of some of the modern NoSQL systems? NoSQL systems can be broadly classified as master-slave sharded, or peer-to-peer sharded systems. NoSQL systems with a peer-to-peer architecture have an interesting way of handling changes. Whenever an item is changed, the client (or an intermediary) propagates the changes synchronously or asynchronously to multiple copies (for availability) of the data. Since the change can be propagated asynchronously, during some interval in time, it will be the case that some copies have received the update, and others haven’t. What happens if someone tries to read the item during this interval? The client in a peer-to-peer system will fetch the same item from multiple copies and compare them to each other. If they’re all the same, then every copy that was queried has the same (and up-to-date) value of the data item, so all’s good. If not, then the system provides a mechanism to reconcile the discrepancy and to update stale copies. So what’s the problem with this? There are two major issues: First, IT’S HORRIBLY PESSIMISTIC because, in the common case, it is unlikely that the same data item will be updated and read from different locations at around the same time! For every read operation, you have to read from multiple copies. That’s a pretty expensive, especially if the data are stored in multiple geographically separate locations and network latencies are high. Second, if the copies are not all the same, the application has to reconcile the differences and propagate the correct value to the out-dated copies. This means that the application program has to handle discrepancies in the different versions of the data item and resolve the issue (which can further add to cost and operation latency). Resolving discrepancies is only one part of the problem. What if the same data item was updated independently on two different nodes (copies)? In that case, due to the asynchronous nature of change propagation, you might land up with different versions of the data item in different copies. In this case, the application program also has to resolve conflicts and then propagate the correct value to the copies that are out-dated or have incorrect versions. This can get really complicated. My hunch is that there are many peer-to-peer-based applications that don’t handle this correctly, and worse, don’t even know it. Imagine have 100s of millions of records in your database – how can you tell whether a particular data item is incorrect or out of date? And what price are you willing to pay for ensuring that the data can be trusted? Multiple network messages per read request? Discrepancy and conflict resolution logic in the application, and potentially, additional messages? All this overhead, when all you were trying to do was to read a data item. Wouldn’t it be simpler to avoid this problem in the first place? Master-slave architectures like the Oracle NoSQL Database handles this very elegantly. A change to a data item is always sent to the master copy. Consequently, the master copy always has the most current and authoritative version of the data item. The master is also responsible for propagating the change to the other copies (for availability and read scalability). Client drivers are aware of master copies and replicas, and client drivers are also aware of the “currency” of a replica. In other words, each NoSQL Database client knows how stale a replica is. This vastly simplifies the job of the application developer. If the application needs the most current version of the data item, the client driver will automatically route the request to the master copy. If the application is willing to tolerate some staleness of data (e.g. a version that is no more than 1 second out of date), the client can easily determine which replica (or set of replicas) can satisfy the request, and route the request to the most efficient copy. This results in a dramatic simplification in application logic and also minimizes network requests (the driver will only send the request to exactl the right replica, not many). So, back to my original point. A well designed and well architected system minimizes or eliminates unnecessary overhead and avoids pessimistic algorithms wherever possible in order to deliver a highly efficient and high performance system. If you’ve every programmed an Oracle NoSQL Database application, you’ll know the difference! /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

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  • What is a good resource for learning how the .Net Framework works? [on hold]

    - by Till Death Developer
    I've been developing web apps, for a while now so i know how to get the job done, what i don't know is how every thing really works, i know some but the rest i can't get a grasp on like how abstract works, what happens when i instantiate an object from a class that inherits from an abstract class?, where things get stored Heap vs Stack?, in other words the Interview questions that i suck at, so any advice would be great, books, videos, online courses, whatever you can provide would really help me.

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  • How to know the number of pins on my laptop's ram?

    - by Rajat Saxena
    I am thinking about upgrading my laptop's ram.How can I get to know the number of pins on my ram without opening my laptop? I ran this command sudo dmidecode --type memory and got following info: Handle 0x0019, DMI type 17, 27 bytes Memory Device Array Handle: 0x0017 Error Information Handle: 0x001A Total Width: 64 bits Data Width: 64 bits Size: 1024 MB Form Factor: SODIMM Set: None Locator: DIMM0 Bank Locator: BANK 0 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: AD00000000000000 Serial Number: 04008104 Asset Tag: Unknown Part Number: 040404040404040404040404040404040404 Can anyone help?

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  • Speaking at PASS 2012… Exciting and Scary… As usual…

    - by drsql
    I have been selected this year at the PASS Summit 2012 to do two sessions, and they are both going to be interesting. Pre-Con: Relational Database Design Workshop - Abstract Triggers: Born Evil or Misunderstood? - Abstract The pre-con session entitled Relational Database Design Workshop will be (at least) the third time I will have done this pre-con session, and I am pretty excited to take it to a bit larger scale. The one big change that I am forcing this time is a limit on the lecture time. Each...(read more)

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