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• Combining template method with strategy

  - by Mekswoll

  An assignment in my software engineering class is to design an application which can play different forms a particular game. The game in question is Mancala, some of these games are called Wari or Kalah. These games differ in some aspects but for my question it's only important to know that the games could differ in the following: The way in which the result of a move is handled The way in which the end of the game is determined The way in which the winner is determined The first thing that came to my mind to design this was to use the strategy pattern, I have a variation in algorithms (the actual rules of the game). The design could look like this: I then thought to myself that in the game of Mancala and Wari the way the winner is determined is exactly the same and the code would be duplicated. I don't think this is by definition a violation of the 'one rule, one place' or DRY principle seeing as a change in rules for Mancala wouldn't automatically mean that rule should be changed in Wari as well. Nevertheless from the feedback I got from my professor I got the impression to find a different design. I then came up with this: Each game (Mancala, Wari, Kalah, ...) would just have attribute of the type of each rule's interface, i.e. WinnerDeterminer and if there's a Mancala 2.0 version which is the same as Mancala 1.0 except for how the winner is determined it can just use the Mancala versions. I think the implementation of these rules as a strategy pattern is certainly valid. But the real problem comes when I want to design it further. In reading about the template method pattern I immediately thought it could be applied to this problem. The actions that are done when a user makes a move are always the same, and in the same order, namely: deposit stones in holes (this is the same for all games, so would be implemented in the template method itself) determine the result of the move determine if the game has finished because of the previous move if the game has finished, determine who has won Those three last steps are all in my strategy pattern described above. I'm having a lot of trouble combining these two. One possible solution I found would be to abandon the strategy pattern and do the following: I don't really see the design difference between the strategy pattern and this? But I am certain I need to use a template method (although I was just as sure about having to use a strategy pattern). I also can't determine who would be responsible for creating the TurnTemplate object, whereas with the strategy pattern I feel I have families of objects (the three rules) which I could easily create using an abstract factory pattern. I would then have a MancalaRuleFactory, WariRuleFactory, etc. and they would create the correct instances of the rules and hand me back a RuleSet object. Let's say that I use the strategy + abstract factory pattern and I have a RuleSet object which has algorithms for the three rules in it. The only way I feel I can still use the template method pattern with this is to pass this RuleSet object to my TurnTemplate. The 'problem' that then surfaces is that I would never need my concrete implementations of the TurnTemplate, these classes would become obsolete. In my protected methods in the TurnTemplate I could just call ruleSet.determineWinner(). As a consequence, the TurnTemplate class would no longer be abstract but would have to become concrete, is it then still a template method pattern? To summarize, am I thinking in the right way or am I missing something easy? If I'm on the right track, how do I combine a strategy pattern and a template method pattern? This is part of a homework assignment but I'm not looking to be gifted the answer, I have deliberately been very verbose in my question to show that I have thought about it before coming here to ask a question

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• Page output caching for dynamic web applications

  - by Mike Ellis

  I am currently working on a web application where the user steps (forward or back) through a series of pages with "Next" and "Previous" buttons, entering data until they reach a page with the "Finish" button. Until finished, all data is stored in Session state, then sent to the mainframe database via web services at the end of the process. Some of the pages display data from previous pages in order to collect additional information. These pages can never be cached because they are different for every user. For pages that don't display this dynamic data, they can be cached, but only the first time they load. After that, the data that was previously entered needs to be displayed. This requires Page_Load to fire, which means the page can't be cached at that point. A couple of weeks ago, I knew almost nothing about implementing page caching. Now I still don't know much, but I know a little bit, and here is the solution that I developed with the help of others on my team and a lot of reading and trial-and-error. We have a base page class defined from which all pages inherit. In this class I have defined a method that sets the caching settings programmatically. For pages that can be cached, they call this base page method in their Page_Load event within a if(!IsPostBack) block, which ensures that only the page itself gets cached, not the data on the page. if(!IsPostBack) {     ...     SetCacheSettings();     ... } protected void SetCacheSettings() {     Response.Cache.AddValidationCallback(new HttpCacheValidateHandler(Validate), null);     Response.Cache.SetExpires(DateTime.Now.AddHours(1));     Response.Cache.SetSlidingExpiration(true);     Response.Cache.SetValidUntilExpires(true);     Response.Cache.SetCacheability(HttpCacheability.ServerAndNoCache); } The AddValidationCallback sets up an HttpCacheValidateHandler method called Validate which runs logic when a cached page is requested. The Validate method signature is standard for this method type. public static void Validate(HttpContext context, Object data, ref HttpValidationStatus status) {     string visited = context.Request.QueryString["v"];     if (visited != null && "1".Equals(visited))     {         status = HttpValidationStatus.IgnoreThisRequest; //force a page load     }     else     {         status = HttpValidationStatus.Valid; //load from cache     } } I am using the HttpValidationStatus values IgnoreThisRequest or Valid which forces the Page_Load event method to run or allows the page to load from cache, respectively. Which one is set depends on the value in the querystring. The value in the querystring is set up on each page in the "Next" and "Previous" button click event methods based on whether the page that the button click is taking the user to has any data on it or not. bool hasData = HasPageBeenVisited(url); if (hasData) {     url += VISITED; } Response.Redirect(url); The HasPageBeenVisited method determines whether the destination page has any data on it by checking one of its required data fields. (I won't include it here because it is very system-dependent.) VISITED is a string constant containing "?v=1" and gets appended to the url if the destination page has been visited. The reason this logic is within the "Next" and "Previous" button click event methods is because 1) the Validate method is static which doesn't allow it to access non-static data such as the data fields for a particular page, and 2) at the time at which the Validate method runs, either the data has not yet been deserialized from Session state or is not available (different AppDomain?) because anytime I accessed the Session state information from the Validate method, it was always empty.

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• 256 Worker Role 3D Rendering Demo is now a Lab on my Azure Course

  - by Alan Smith

  Ever since I came up with the crazy idea of creating an Azure application that would spin up 256 worker roles (please vote if you like it ) to render a 3D animation created using the Kinect depth camera I have been trying to think of something useful to do with it. I have also been busy working on developing training materials for a Windows Azure course that I will be delivering through a training partner in Stockholm, and for customers wanting to learn Windows Azure. I hit on the idea of combining the render demo and a course lab and creating a lab where the students would create and deploy their own mini render farms, which would participate in a single render job, consisting of 2,000 frames. The architecture of the solution is shown below. As students would be creating and deploying their own applications, I thought it would be fun to introduce some competitiveness into the lab. In the 256 worker role demo I capture the rendering statistics for each role, so it was fairly simple to include the students name in these statistics. This allowed the process monitor application to capture the number of frames each student had rendered and display a high-score table. When I demoed the application I deployed one instance that started rendering a frame every few minutes, and the challenge for the students was to deploy and scale their applications, and then overtake my single role instance by the end of the lab time. I had the process monitor running on the projector during the lab so the class could see the progress of their deployments, and how they were performing against my implementation and their classmates. When I tested the lab for the first time in Oslo last week it was a great success, the students were keen to be the first to build and deploy their solution and then watch the frames appear. As the students mostly had MSDN suspicions they were able to scale to the full 20 worker role instances and before long we had over 100 worker roles working on the animation. There were, however, a few issues who the couple of issues caused by the competitive nature of the lab. The first student to scale the application to 20 instances would render the most frames and win; there was no way for others to catch up. Also, as they were competing against each other, there was no incentive to help others on the course get their application up and running. I have now re-written the lab to divide the student into teams that will compete to render the most frames. This means that if one developer on the team can deploy and scale quickly, the other team still has a chance to catch up. It also means that if a student finishes quickly and puts their team in the lead they will have an incentive to help the other developers on their team get up and running. As I was using “Sharks with Lasers” for a lot of my demos, and reserved the sharkswithfreakinlasers namespaces for some of the Azure services (well somebody had to do it), the students came up with some creative alternatives, like “Camels with Cannons” and “Honey Badgers with Homing Missiles”. That gave me the idea for the teams having to choose a creative name involving animals and weapons. The team rendering architecture diagram is shown below.   Render Challenge Rules In order to ensure fair play a number of rules are imposed on the lab. ·         The class will be divided into teams, each team choses a name. ·         The team name must consist of a ferocious animal combined with a hazardous weapon. ·         Teams can allocate as many worker roles as they can muster to the render job. ·         Frame processing statistics and rendered frames will be vigilantly monitored; any cheating, tampering, and other foul play will result in penalties. The screenshot below shows an example of the team render farm in action, Badgers with Bombs have taken a lead over Camels with Cannons, and both are  leaving the Sharks with Lasers standing. If you are interested in attending a scheduled delivery of my Windows Azure or Windows Azure Service bus courses, or would like on-site training, more details are here.

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• Simple task framework - building software from reusable pieces

  - by RuslanD

  I'm writing a web service with several APIs, and they will be sharing some of the implementation code. In order not to copy-paste, I would like to ideally implement each API call as a series of tasks, which are executed in a sequence determined by the business logic. One obvious question is whether that's the best strategy for code reuse, or whether I can look at it in a different way. But assuming I want to go with tasks, several issues arise: What's a good task interface to use? How do I pass data computed in one task to another task in the sequence that might need it? In the past, I've worked with task interfaces like: interface Task<T, U> { U execute(T input); } Then I also had sort of a "task context" object which had getters and setters for any kind of data my tasks needed to produce or consume, and it gets passed to all tasks. I'm aware that this suffers from a host of problems. So I wanted to figure out a better way to implement it this time around. My current idea is to have a TaskContext object which is a type-safe heterogeneous container (as described in Effective Java). Each task can ask for an item from this container (task input), or add an item to the container (task output). That way, tasks don't need to know about each other directly, and I don't have to write a class with dozens of methods for each data item. There are, however, several drawbacks: Each item in this TaskContext container should be a complex type that wraps around the actual item data. If task A uses a String for some purpose, and task B uses a String for something entirely different, then just storing a mapping between String.class and some object doesn't work for both tasks. The other reason is that I can't use that kind of container for generic collections directly, so they need to be wrapped in another object. This means that, based on how many tasks I define, I would need to also define a number of classes for the task items that may be consumed or produced, which may lead to code bloat and duplication. For instance, if a task takes some Long value as input and produces another Long value as output, I would have to have two classes that simply wrap around a Long, which IMO can spiral out of control pretty quickly as the codebase evolves. I briefly looked at workflow engine libraries, but they kind of seem like a heavy hammer for this particular nail. How would you go about writing a simple task framework with the following requirements: Tasks should be as self-contained as possible, so they can be composed in different ways to create different workflows. That being said, some tasks may perform expensive computations that are prerequisites for other tasks. We want to have a way of storing the results of intermediate computations done by tasks so that other tasks can use those results for free. The task framework should be light, i.e. growing the code doesn't involve introducing many new types just to plug into the framework.

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• Templated Razor Delegates – Phil Haack

  - by nmarun

  This post is largely based off of Phil Haack’s article titled Templated Razor Delegates. I strongly recommend reading this article first. Here’s a sample code for the same, so you can have a look at. I also have a custom type being rendered as a table. 1: // my custom type 2: public class Device 3: { 4: public int Id { get; set; } 5: public string Name { get; set; } 6: public DateTime MfgDate { get; set; } 7: } Now I can write an extension method just for this type. 1: public static class RazorExtensions 2: { 3: public static HelperResult List(this IList<Models.Device> devices, Func<Models.Device, HelperResult> template) 4: { 5: return new HelperResult(writer => 6: { 7: foreach (var device in devices) 8: { 9: template(device).WriteTo(writer); 10: } 11: }); 12: } 13: // ... 14: } Modified my view to make it a strongly typed one and included html to render my custom type collection in a table. 1: @using TemplatedRazorDelegates 2: @model System.Collections.Generic.IList<TemplatedRazorDelegates.Models.Device> 3:  4: @{ 5: ViewBag.Title = "Home Page"; 6: } 7:  8: <h2>@ViewBag.Message</h2> 9:  10: @{ 11: var items = new[] { "one", "two", "three" }; 12: IList<int> ints = new List<int> { 1, 2, 3 }; 13: } 14:  15: <ul> 16: @items.List(@<li>@item</li>) 17: </ul> 18: <ul> 19: @ints.List(@<li>@item</li>) 20: </ul> 21:  22: <table> 23: <tr><th>Id</th><th>Name</th><th>Mfg Date</th></tr> 24: @Model.List(@<tr><td>@item.Id</td><td>@item.Name</td><td>@item.MfgDate.ToShortDateString()</td></tr>) 25: </table> We get intellisense as well! Just added some items in the action method of the controller: 1: public ActionResult Index() 2: { 3: ViewBag.Message = "Welcome to ASP.NET MVC!"; 4: IList<Device> devices = new List<Device> 5: { 6: new Device {Id = 1, Name = "abc", MfgDate = new DateTime(2001, 10, 19)}, 7: new Device {Id = 2, Name = "def", MfgDate = new DateTime(2011, 1, 1)}, 8: new Device {Id = 3, Name = "ghi", MfgDate = new DateTime(2003, 3, 15)}, 9: new Device {Id = 4, Name = "jkl", MfgDate = new DateTime(2007, 6, 6)} 10: }; 11: return View(devices); 12: } Running this I get the output as: Absolutely brilliant! Thanks to both Phil Haack and to David Fowler for bringing this out to us. Download the code for this from here. Verdict: RazorViewEngine.Points += 1;

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• SharePoint 2010 Hosting :: Setting Default Column Values on a Folder Programmatically

  - by mbridge

  The reason I write this post today is because my initial searches on the Internet provided me with nothing on the topic.  I was hoping to find a reference to the SDK but I didn’t have any luck.  What I want to do is set a default column value on an existing folder so that new items in that folder automatically inherit that value.  It’s actually pretty easy to do once you know what the class is called in the API.  I did some digging and discovered that class is MetadataDefaults. It can be found in Microsoft.Office.DocumentManagement.dll.  Note: if you can’t find it in the GAC, this DLL is in the 14/CONFIG/BIN folder and not the 14/ISAPI folder.  Add a reference to this DLL in your project.  In my case, I am building a console application, but you might put this in an event receiver or workflow. In my example today, I have simple custom folder and document content types.  I have one shared site column called DocumentType.  I have a document library which each of these content types registered.  In my document library, I have a folder named Test and I want to set its default column values using code.  Here is what it looks like.  Start by getting a reference to the list in question.  This assumes you already have a SPWeb object.  In my case I have created it and it is called site. SPList customDocumentLibrary = site.Lists["CustomDocuments"]; You then pass the SPList object to the MetadataDefaults constructor. MetadataDefaults columnDefaults = new MetadataDefaults(customDocumentLibrary); Now I just need to get my SPFolder object in question and pass it to the meethod SetFieldDefault.  This takes a SPFolder object, a string with the name of the SPField to set the default on, and finally the value of the default (in my case “Memo”). SPFolder testFolder = customDocumentLibrary.RootFolder.SubFolders["Test"]; columnDefaults.SetFieldDefault(testFolder, "DocumentType", "Memo"); You can set multiple defaults here.  When you’re done, you will need to call .Update(). columnDefaults.Update(); Here is what it all looks like together. using (SPSite siteCollection = new SPSite("http://sp2010/sites/ECMSource")) {     using (SPWeb site = siteCollection.OpenWeb())     {         SPList customDocumentLibrary = site.Lists["CustomDocuments"];         MetadataDefaults columnDefaults = new MetadataDefaults(customDocumentLibrary);          SPFolder testFolder = customDocumentLibrary.RootFolder.SubFolders["Test"];         columnDefaults.SetFieldDefault(testFolder, "DocumentType", "Memo");         columnDefaults.Update();     } } You can verify that your property was set correctly on the Change Default Column Values page in your list This is something that I could see used a lot on an ItemEventReceiver attached to a folder to do metadata inheritance.  Whenever, the user changed the value of the folder’s property, you could have it update the default.  Your code might look something columnDefaults.SetFieldDefault(properties.ListItem.Folder, "MyField", properties.ListItem[" This is a great way to keep the child items updated any time the value a folder’s property changes.  I’m also wondering if this can be done via CAML.  I tried saving a site template, but after importing I got an error on the default values page.  I’ll keep looking and let you know what I find out.

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• Jersey non blocking client

  - by Pavel Bucek

  Although Jersey already have support for making asynchronous requests, it is implemented by standard blocking way - every asynchronous request is handled by one thread and that thread is released only after request is completely processed. That is OK for lots of cases, but imagine how that will work when you need to do lots of parallel requests. Of course you can limit (and its really wise thing to do, you do want control your resources) number of threads used for asynchronous requests, but you'll get another maybe not pleasant consequence - obviously processing time will incerase. There are few projects which are trying to deal with that problem, commonly named as async http clients. I didn't want to "re-implement a wheel" and I decided I'll use AHC - Async Http Client made by Jeanfrancois Arcand. There is also interesting implementation from Apache - HttpAsyncClient, but it is still in "very early stages of development" and others haven't been in similar or better shape as AHC. How this works? Non-blocking clients allow users to make same asynchronous requests as we can do with standard approach but implementation is different - threads are better utilized, they don't spend most of time in idle state. Simply described - when you make a request (send it over the network), you are waiting for reply from other side. And there comes main advantage of non-blocking approach - it uses these threads for further work, like making other requests or processing responses etc.. Idle time is minimized and your resources (threads) will be far better used. Who should consider using this? Everyone who is making lots of asynchronous requests. I haven't done proper benchmark yet, but some simple dumb tests are showing huge improvement in cases where lots of concurrent asynchronous requests are made in short period. Last but not least - this module is still experimental, so if you don't like something or if you have ideas for improvements/any feedback, feel free to comment this blog post, send mail to [email protected] or contact me personally. All feedback is greatly appreciated! maven dependency (will be present in java.net maven 2 repo by the end of the day): link: http://download.java.net/maven/2/com/sun/jersey/experimental/jersey-non-blocking-client <dependency> <groupId>com.sun.jersey.experimental</groupId> <artifactId>jersey-non-blocking-client</artifactId> <version>1.9-SNAPSHOT</version> </dependency> code snippet: ClientConfig cc = new DefaultNonBlockingClientConfig(); cc.getProperties().put(NonBlockingClientConfig.PROPERTY_THREADPOOL_SIZE, 10); // default value, feel free to change Client c = NonBlockingClient.create(cc); AsyncWebResource awr = c.asyncResource("http://oracle.com"); Future<ClientResponse> responseFuture = awr.get(ClientResponse.class); // or awr.get(new TypeListener<ClientResponse>(ClientResponse.class) { @Override public void onComplete(Future<ClientResponse> f) throws InterruptedException { ... } }); javadoc (temporary location, won't be updated): http://anise.cz/~paja/jersey-non-blocking-client/

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• Thread safe double buffering

  - by kdavis8

  I am trying to implement a draw map method that will draw the tiled image across the surface of the component. I'm having issue with this code. The double buffering does not seem to be working, because the sprite flickers like crazy; my source code: package myPackage; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import javax.swing.JFrame; public class GameView extends JFrame implements Runnable { public BufferedImage backbuffer; public Graphics2D g2d; public Image img; Thread gameloop; Scene scene; public GameView() { super("Game View"); setSize(600, 600); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); backbuffer = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB); g2d = backbuffer.createGraphics(); Toolkit tk = Toolkit.getDefaultToolkit(); img = tk.getImage(this.getClass().getResource("cage.png")); scene = new Scene(g2d, this); gameloop = new Thread(this); gameloop.start(); } public static void main(String args[]) { new GameView(); } public void paint(Graphics g) { g.drawImage(backbuffer, 0, 0, this); repaint(); } @Override public void run() { // TODO Auto-generated method stub Thread t = Thread.currentThread(); while (t == gameloop) { scene.getScene("dirtmap"); g2d.drawImage(img, 80, 80,this![enter image description here][1]); } } private void drawScene(String string) { // TODO Auto-generated method stub // g2d.setColor(Color.white); // g2d.fillRect(0, 0, getWidth(), getHeight()); scene.getScene(string); } } package myPackage; import java.awt.Color; import java.awt.Component; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; public class Scene { Graphics g2d; Component c; boolean loaded = false; public Scene(Graphics2D gr, Component co) { g2d = gr; c = co; } public void getScene(String mapName) { Toolkit tk = Toolkit.getDefaultToolkit(); Image tile = tk.getImage(this.getClass().getResource("dirt.png")); // g2d.setColor(Color.red); for (int y = 0; y <= 18; y++) { for (int x = 0; x <= 18; x += 1) { g2d.drawImage(tile, x * 32, y * 32, c); } } loaded = true; } }

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• Binding a select in a client template

  - by Bertrand Le Roy

  I recently got a question on one of my client template posts asking me how to bind a select tag’s value to data in client templates. I was surprised not to find anything on the web addressing the problem, so I thought I’d write a short post about it. It really is very simple once you know where to look. You just need to bind the value property of the select tag, like this: <select sys:value="{binding color}"> If you do it from markup like here, you just need to use the sys: prefix. It just works. Here’s the full source code for my sample page: <!DOCTYPE html> <html> <head> <title>Binding a select tag</title> <script src=http://ajax.microsoft.com/ajax/beta/0911/Start.js type="text/javascript"></script> <script type="text/javascript"> Sys.require(Sys.scripts.Templates, function() { var colors = [ "red", "green", "blue", "cyan", "purple", "yellow" ]; var things = [ { what: "object", color: "blue" }, { what: "entity", color: "purple" }, { what: "thing", color: "green" } ]; Sys.create.dataView("#thingList", { data: things, itemRendered: function(view, ctx) { Sys.create.dataView( Sys.get("#colorSelect", ctx), { data: colors }); } }); }); </script> <style type="text/css"> .sys-template {display: none;} </style> </head> <body xmlns:sys="javascript:Sys"> <div> <ul id="thingList" class="sys-template"> <li> <span sys:id="thingName" sys:style-color="{binding color}" >{{what}}</span> <select sys:id="colorSelect" sys:value="{binding color}" class="sys-template"> <option sys:value="{{$dataItem}}" sys:style-background-color="{{$dataItem}}" >{{$dataItem}}</option> </select> </li> </ul> </div> </body> </html> This produces the following page: Each of the items sees its color change as you select a different color in the drop-down. Other details worth noting in this page are the use of the script loader to get the framework from the CDN, and the sys:style-background-color syntax to bind the background color style property from markup. Of course, I’ve used a fair amount of custom ASP.NET Ajax markup in here, but everything could be done imperatively and with completely clean markup from the itemRendered event using Sys.bind.

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• Copy New Files Only in .NET

  - by psheriff

  Recently I had a client that had a need to copy files from one folder to another. However, there was a process that was running that would dump new files into the original folder every minute or so. So, we needed to be able to copy over all the files one time, then also be able to go back a little later and grab just the new files. After looking into the System.IO namespace, none of the classes within here met my needs exactly. Of course I could build it out of the various File and Directory classes, but then I remembered back to my old DOS days (yes, I am that old!). The XCopy command in DOS (or the command prompt for you pure Windows people) is very powerful. One of the options you can pass to this command is to grab only newer files when copying from one folder to another. So instead of writing a ton of code I decided to simply call the XCopy command using the Process class in .NET. The command I needed to run at the command prompt looked like this: XCopy C:\Original\*.* D:\Backup\*.* /q /d /y What this command does is to copy all files from the Original folder on the C drive to the Backup folder on the D drive. The /q option says to do it quitely without repeating all the file names as it copies them. The /d option says to get any newer files it finds in the Original folder that are not in the Backup folder, or any files that have a newer date/time stamp. The /y option will automatically overwrite any existing files without prompting the user to press the "Y" key to overwrite the file. To translate this into code that we can call from our .NET programs, you can write the CopyFiles method presented below. C# using System.Diagnostics public void CopyFiles(string source, string destination){  ProcessStartInfo si = new ProcessStartInfo();  string args = @"{0}\*.* {1}\*.* /q /d /y";   args = string.Format(args, source, destination);   si.FileName = "xcopy";  si.Arguments = args;  Process.Start(si);} VB.NET Imports System.Diagnostics Public Sub CopyFiles(source As String, destination As String)  Dim si As New ProcessStartInfo()  Dim args As String = "{0}\*.* {1}\*.* /q /d /y"   args = String.Format(args, source, destination)   si.FileName = "xcopy"  si.Arguments = args  Process.Start(si)End Sub The CopyFiles method first creates a ProcessStartInfo object. This object is where you fill in name of the command you wish to run and also the arguments that you wish to pass to the command. I created a string with the arguments then filled in the source and destination folders using the string.Format() method. Finally you call the Start method of the Process class passing in the ProcessStartInfo object. That's all there is to calling any command in the operating system. Very simple, and much less code than it would have taken had I coded it using the various File and Directory classes. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free video on Silverlight entitled Silverlight XAML for the Complete Novice - Part 1.  

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• JMSContext, @JMSDestinationDefintion, DefaultJMSConnectionFactory with simplified JMS API: TOTD #213

  - by arungupta

  "What's New in JMS 2.0" Part 1 and Part 2 provide comprehensive introduction to new messaging features introduced in JMS 2.0. The biggest improvement in JMS 2.0 is introduction of the "new simplified API". This was explained in the Java EE 7 Launch Technical Keynote. You can watch a complete replay here. Sending and Receiving a JMS message using JMS 1.1 requires lot of boilerplate code, primarily because the API was designed 10+ years ago. Here is a code that shows how to send a message using JMS 1.1 API: @Statelesspublic class ClassicMessageSender { @Resource(lookup = "java:comp/DefaultJMSConnectionFactory") ConnectionFactory connectionFactory; @Resource(mappedName = "java:global/jms/myQueue") Queue demoQueue; public void sendMessage(String payload) { Connection connection = null; try { connection = connectionFactory.createConnection(); connection.start(); Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); MessageProducer messageProducer = session.createProducer(demoQueue); TextMessage textMessage = session.createTextMessage(payload); messageProducer.send(textMessage); } catch (JMSException ex) { ex.printStackTrace(); } finally { if (connection != null) { try { connection.close(); } catch (JMSException ex) { ex.printStackTrace(); } } } }} There are several issues with this code: A JMS ConnectionFactory needs to be created in a application server-specific way before this application can run. Application-specific destination needs to be created in an application server-specific way before this application can run. Several intermediate objects need to be created to honor the JMS 1.1 API, e.g. ConnectionFactory -> Connection -> Session -> MessageProducer -> TextMessage. Everything is a checked exception and so try/catch block must be specified. Connection need to be explicitly started and closed, and that bloats even the finally block. The new JMS 2.0 simplified API code looks like: @Statelesspublic class SimplifiedMessageSender { @Inject JMSContext context; @Resource(mappedName="java:global/jms/myQueue") Queue myQueue; public void sendMessage(String message) { context.createProducer().send(myQueue, message); }} The code is significantly improved from the previous version in the following ways: The JMSContext interface combines in a single object the functionality of both the Connection and the Session in the earlier JMS APIs.  You can obtain a JMSContext object by simply injecting it with the @Inject annotation.  No need to explicitly specify a ConnectionFactory. A default ConnectionFactory under the JNDI name of java:comp/DefaultJMSConnectionFactory is used if no explicit ConnectionFactory is specified. The destination can be easily created using newly introduced @JMSDestinationDefinition as: @JMSDestinationDefinition(name = "java:global/jms/myQueue",        interfaceName = "javax.jms.Queue") It can be specified on any Java EE component and the destination is created during deployment. JMSContext, Session, Connection, JMSProducer and JMSConsumer objects are now AutoCloseable. This means that these resources are automatically closed when they go out of scope. This also obviates the need to explicitly start the connection JMSException is now a runtime exception. Method chaining on JMSProducers allows to use builder patterns. No need to create separate Message object, you can specify the message body as an argument to the send() method instead. Want to try this code ? Download source code! Download Java EE 7 SDK and install. Start GlassFish: bin/asadmin start-domain Build the WAR (in the unzipped source code directory): mvn package Deploy the WAR: bin/asadmin deploy <source-code>/jms/target/jms-1.0-SNAPSHOT.war And access the application at http://localhost:8080/jms-1.0-SNAPSHOT/index.jsp to send and receive a message using classic and simplified API. A replay of JMS 2.0 session from Java EE 7 Launch Webinar provides complete details on what's new in this specification: Enjoy!

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• xna orbit camera troubles

  - by user17753

  I have a Model named cube to which I load in LoadContent(): cube = Content.Load<Model>("untitled");. In the Draw Method I call DrawModel: private void DrawModel(Model m, Matrix world) { foreach (ModelMesh mesh in m.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.View = camera.View; effect.Projection = camera.Projection; effect.World = world; } mesh.Draw(); } } camera is of the Camera type, a class I've setup. Right now it is instantiated in the initialization section with the graphics aspect ratio and the translation (world) vector of the model, and the Draw loop calls the camera.UpdateCamera(); before drawing the models. class Camera { #region Fields private Matrix view; // View Matrix for Camera private Matrix projection; // Projection Matrix for Camera private Vector3 position; // Position of Camera private Vector3 target; // Point camera is "aimed" at private float aspectRatio; //Aspect Ratio for projection private float speed; //Speed of camera private Vector3 camup = Vector3.Up; #endregion #region Accessors /// <summary> /// View Matrix of the Camera -- Read Only /// </summary> public Matrix View { get { return view; } } /// <summary> /// Projection Matrix of the Camera -- Read Only /// </summary> public Matrix Projection { get { return projection; } } #endregion /// <summary> /// Creates a new Camera. /// </summary> /// <param name="AspectRatio">Aspect Ratio to use for the projection.</param> /// <param name="Position">Target coord to aim camera at.</param> public Camera(float AspectRatio, Vector3 Target) { target = Target; aspectRatio = AspectRatio; ResetCamera(); } private void Rotate(Vector3 Axis, float Amount) { position = Vector3.Transform(position - target, Matrix.CreateFromAxisAngle(Axis, Amount)) + target; } /// <summary> /// Resets Default Values of the Camera /// </summary> private void ResetCamera() { speed = 0.05f; position = target + new Vector3(0f, 20f, 20f); projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, aspectRatio, 0.5f, 100f); CalculateViewMatrix(); } /// <summary> /// Updates the Camera. Should be first thing done in Draw loop /// </summary> public void UpdateCamera() { Rotate(Vector3.Right, speed); CalculateViewMatrix(); } /// <summary> /// Calculates the View Matrix for the camera /// </summary> private void CalculateViewMatrix() { view = Matrix.CreateLookAt(position,target, camup); } I'm trying to create the camera so that it can orbit the center of the model. For a test I am calling Rotate(Vector3.Right, speed); but it rotates almost right but gets to a point where it "flips." If I rotate along a different axis Rotate(Vector3.Up, speed); everything seems OK in that direction. So I guess, can someone tell me what I'm not accounting for in the above code I wrote? Or point me to an example of an orbiting camera that can be fixed on an arbitrary point?

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• Help me get my 3D camera to look like the ones in RTS

  - by rFactor

  I am a newbie in 3D game development and I am trying to make a real-time strategy game. I am struggling with the camera currently as I am unable to make it look like they do in RTS games. Here is my Camera.cs class using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Input; namespace BB { public class Camera : Microsoft.Xna.Framework.GameComponent { public Matrix view; public Matrix projection; protected Game game; KeyboardState currentKeyboardState; Vector3 cameraPosition = new Vector3(600.0f, 0.0f, 600.0f); Vector3 cameraForward = new Vector3(0, -0.4472136f, -0.8944272f); BoundingFrustum cameraFrustum = new BoundingFrustum(Matrix.Identity); // Light direction Vector3 lightDir = new Vector3(-0.3333333f, 0.6666667f, 0.6666667f); public Camera(Game game) : base(game) { this.game = game; } public override void Initialize() { this.view = Matrix.CreateLookAt(this.cameraPosition, this.cameraPosition + this.cameraForward, Vector3.Up); this.projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, this.game.renderer.aspectRatio, 1, 10000); base.Initialize(); } /* Handles the user input * @ param GameTime gameTime */ private void HandleInput(GameTime gameTime) { float time = (float)gameTime.ElapsedGameTime.TotalMilliseconds; currentKeyboardState = Keyboard.GetState(); } void UpdateCamera(GameTime gameTime) { float time = (float)gameTime.ElapsedGameTime.TotalMilliseconds; // Check for input to rotate the camera. float pitch = 0.0f; float turn = 0.0f; if (currentKeyboardState.IsKeyDown(Keys.Up)) pitch += time * 0.001f; if (currentKeyboardState.IsKeyDown(Keys.Down)) pitch -= time * 0.001f; if (currentKeyboardState.IsKeyDown(Keys.Left)) turn += time * 0.001f; if (currentKeyboardState.IsKeyDown(Keys.Right)) turn -= time * 0.001f; Vector3 cameraRight = Vector3.Cross(Vector3.Up, cameraForward); Vector3 flatFront = Vector3.Cross(cameraRight, Vector3.Up); Matrix pitchMatrix = Matrix.CreateFromAxisAngle(cameraRight, pitch); Matrix turnMatrix = Matrix.CreateFromAxisAngle(Vector3.Up, turn); Vector3 tiltedFront = Vector3.TransformNormal(cameraForward, pitchMatrix * turnMatrix); // Check angle so we cant flip over if (Vector3.Dot(tiltedFront, flatFront) > 0.001f) { cameraForward = Vector3.Normalize(tiltedFront); } // Check for input to move the camera around. if (currentKeyboardState.IsKeyDown(Keys.W)) cameraPosition += cameraForward * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.S)) cameraPosition -= cameraForward * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.A)) cameraPosition += cameraRight * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.D)) cameraPosition -= cameraRight * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.R)) { cameraPosition = new Vector3(0, 50, 50); cameraForward = new Vector3(0, 0, -1); } cameraForward.Normalize(); // Create the new view matrix view = Matrix.CreateLookAt(cameraPosition, cameraPosition + cameraForward, Vector3.Up); // Set the new frustum value cameraFrustum.Matrix = view * projection; } public override void Update(Microsoft.Xna.Framework.GameTime gameTime) { HandleInput(gameTime); UpdateCamera(gameTime); } } } The problem is that the initial view is looking in a horizontal direction. I would like to have an RTS like top down view (but with a slight pitch). Can you help me out?

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• Ubuntu + Wacom Intuos 4 + MyPaint HELP!

  - by Sativa

  Please keep in mind I'm not that computer savvy, but I will try any suggestion so please help me out! My tablet will stop working if the USB connection is ever broken, or the Ubuntu software is being updated. Sometimes it will stop working for no reason that I can see. The lights will still be on, but it won't be responsive. It doesn't work again until I restart the laptop with the tablet plugged in, which is grating if you have to do it every 25 min. or so... I'm not sure if the issue is with the port, the tablet/cable or the driver but any suggestions would be very welcome! Also, MyPaint is frequently having hiccups. It seems to save fine but at times it will randomly close down and when I open files they're often empty. They turn into 0Kb files and only contain a single empty layer. Also very grating, considering I lose days of work for no clear reason and without any heads up. Again, I'm not sure if the issue is with the port, the tablet/cable or the driver but any suggestions would be very welcome! The error message reads; Traceback (most recent call last): File "/usr/share/mypaint/gui/application.py", line 177, at_application_start(*junk=()) else: self.filehandler.open_file(fn) variables: {'fn': ('local', u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora'), 'self.filehandler.open_file': ('local', <bound method FileHandler.wrapper of <gui.filehandling.FileHandler object at 0x7fdb89063a10>>)} File "/usr/share/mypaint/gui/drawwindow.py", line 60, wrapper(self=<gui.filehandling.FileHandler object>, *args=(u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora',), **kwargs={}) try: func(self, *args, **kwargs) # gtk main loop may be called in here... variables: {'self': ('local', <gui.filehandling.FileHandler object at 0x7fdb89063a10>), 'args': ('local', (u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora',)), 'func': ('local', <function open_file at 0x7fdb8b397b90>), 'kwargs': ('local', {})} File "/usr/share/mypaint/gui/filehandling.py", line 231, open_file(self=<gui.filehandling.FileHandler object>, filename=u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora') try: self.doc.model.load(filename, feedback_cb=self.gtk_main_tick) except document.SaveLoadError, e: variables: {'self.doc.model.load': ('local', <bound method Document.load of <lib.document.Document instance at 0x7fdb8ab4f8c0>>), 'feedback_cb': (None, []), 'self.gtk_main_tick': ('local', <function gtk_main_tick at 0x7fdb8b397b18>), 'filename': ('local', u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora')} File "/usr/share/mypaint/lib/document.py", line 544, load(self=<lib.document.Document instance>, filename=u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora', **kwargs={'feedback_cb': <function gtk_main_tick>}) try: load(filename, **kwargs) except gobject.GError, e: variables: {'load': ('local', <bound method Document.load_ora of <lib.document.Document instance at 0x7fdb8ab4f8c0>>), 'kwargs': ('local', {'feedback_cb': <function gtk_main_tick at 0x7fdb8b397b18>}), 'filename': ('local', u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora')} File "/usr/share/mypaint/lib/document.py", line 772, load_ora(self=<lib.document.Document instance>, filename=u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora', feedback_cb=<function gtk_main_tick>) tempdir = tempdir.decode(sys.getfilesystemencoding()) z = zipfile.ZipFile(filename) print 'mimetype:', z.read('mimetype').strip() variables: {'zipfile.ZipFile': ('global', <class 'zipfile.ZipFile'>), 'z': (None, []), 'filename': ('local', u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora')} File "/usr/lib/python2.7/zipfile.py", line 770, __init__(self=<zipfile.ZipFile object>, file=u'/home/maria/Desktop/Drawings/WIPs/Sativa Chibi.ora', mode='r', compression=0, allowZip64=False) if key == 'r': self._RealGetContents() elif key == 'w': variables: {'self._RealGetContents': ('local', <bound method ZipFile._RealGetContents of <zipfile.ZipFile object at 0x7fdb9b952790>>)} File "/usr/lib/python2.7/zipfile.py", line 811, _RealGetContents(self=<zipfile.ZipFile object>) if not endrec: raise BadZipfile, "File is not a zip file" if self.debug > 1: variables: {'BadZipfile': ('global', <class 'zipfile.BadZipfile'>)} BadZipfile: File is not a zip file

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• Why you shouldn't add methods to interfaces in APIs

  - by Simon Cooper

  It is an oft-repeated maxim that you shouldn't add methods to a publically-released interface in an API. Recently, I was hit hard when this wasn't followed. As part of the work on ApplicationMetrics, I've been implementing auto-reporting of MVC action methods; whenever an action was called on a controller, ApplicationMetrics would automatically report it without the developer needing to add manual ReportEvent calls. Fortunately, MVC provides easy hook when a controller is created, letting me log when it happens - the IControllerFactory interface. Now, the dll we provide to instrument an MVC webapp has to be compiled against .NET 3.5 and MVC 1, as the lowest common denominator. This MVC 1 dll will still work when used in an MVC 2, 3 or 4 webapp because all MVC 2+ webapps have a binding redirect redirecting all references to previous versions of System.Web.Mvc to the correct version, and type forwards taking care of any moved types in the new assemblies. Or at least, it should. IControllerFactory In MVC 1 and 2, IControllerFactory was defined as follows: public interface IControllerFactory { IController CreateController(RequestContext requestContext, string controllerName); void ReleaseController(IController controller); } So, to implement the logging controller factory, we simply wrap the existing controller factory: internal sealed class LoggingControllerFactory : IControllerFactory { private readonly IControllerFactory m_CurrentController; public LoggingControllerFactory(IControllerFactory currentController) { m_CurrentController = currentController; } public IController CreateController( RequestContext requestContext, string controllerName) { // log the controller being used FeatureSessionData.ReportEvent("Controller used:", controllerName); return m_CurrentController.CreateController(requestContext, controllerName); } public void ReleaseController(IController controller) { m_CurrentController.ReleaseController(controller); } } Easy. This works as expected in MVC 1 and 2. However, in MVC 3 this type was throwing a TypeLoadException, saying a method wasn't implemented. It turns out that, in MVC 3, the definition of IControllerFactory was changed to this: public interface IControllerFactory { IController CreateController(RequestContext requestContext, string controllerName); SessionStateBehavior GetControllerSessionBehavior( RequestContext requestContext, string controllerName); void ReleaseController(IController controller); } There's a new method in the interface. So when our MVC 1 dll was redirected to reference System.Web.Mvc v3, LoggingControllerFactory tried to implement version 3 of IControllerFactory, was missing the GetControllerSessionBehaviour method, and so couldn't be loaded by the CLR. Implementing the new method Fortunately, there was a workaround. Because interface methods are normally implemented implicitly in the CLR, if we simply declare a virtual method matching the signature of the new method in MVC 3, then it will be ignored in MVC 1 and 2 and implement the extra method in MVC 3: internal sealed class LoggingControllerFactory : IControllerFactory { ... public virtual SessionStateBehaviour GetControllerSessionBehaviour( RequestContext requestContext, string controllerName) {} ... } However, this also has problems - the SessionStateBehaviour type only exists in .NET 4, and we're limited to .NET 3.5 by support for MVC 1 and 2. This means that the only solutions to support all MVC versions are: Construct the LoggingControllerFactory type at runtime using reflection Produce entirely separate dlls for MVC 1&2 and MVC 3. Ugh. And all because of that blasted extra method! Another solution? Fortunately, in this case, there is a third option - System.Web.Mvc also provides a DefaultControllerFactory type that can provide the implementation of GetControllerSessionBehaviour for us in MVC 3, while still allowing us to override CreateController and ReleaseController. However, this does mean that LoggingControllerFactory won't be able to wrap any calls to GetControllerSessionBehaviour. This is an acceptable bug, given the other options, as very few developers will be overriding GetControllerSessionBehaviour in their own custom controller factory. So, if you're providing an interface as part of an API, then please please please don't add methods to it. Especially if you don't provide a 'default' implementing type. Any code compiled against the previous version that can't be updated will have some very tough decisions to make to support both versions.

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• Code Contracts: validating arrays and collections

  - by DigiMortal

  Validating collections before using them is very common task when we use built-in generic types for our collections. In this posting I will show you how to validate collections using code contracts. It is cool how much awful looking code you can avoid using code contracts. Failing code Let’s suppose we have method that calculates sum of all invoices in collection. We have class Invoice and one of properties it has is Sum. I don’t introduce here any complex calculations on invoices because we have another problem to solve in this topic. Here is our code. public static decimal CalculateTotal(IList<Invoice> invoices) {     var sum = invoices.Sum(p => p.Sum);     return sum; } This method is very simple but it fails when invoices list contains at least one null. Of course, we can test if invoice is null but having nulls in lists like this is not good idea – it opens green way for different coding bugs in system. Our goal is to react to bugs ASAP at the nearest place they occur. There is one more way how to make our method fail. It happens when invoices is null. I thing it is also one common bugs during development and it even happens in production environments under some conditions that are usually hardly met. Now let’s protect our little calculation method with code contracts. We need two contracts: invoices cannot be null invoices cannot contain any nulls Our first contract is easy but how to write the second one? Solution: Contract.ForAll Preconditions in code are checked using Contract.Ensures method. This method takes boolean value as argument that sais if contract holds or not. There is also method Contract.ForAll that takes collection and predicate that must hold for that collection. Nice thing is ForAll returns boolean. So, we have very simple solution. public static decimal CalculateTotal(IList<Invoice> invoices) {     Contract.Requires(invoices != null);     Contract.Requires(Contract.ForAll<Invoice>(invoices, p => p != null));       var sum = invoices.Sum(p => p.Sum);     return sum; } And here are some lines of code you can use to test the contracts quickly. var invoices = new List<Invoice>(); invoices.Add(new Invoice()); invoices.Add(null); invoices.Add(new Invoice()); //CalculateTotal(null); CalculateTotal(invoices); If your code is covered with unit tests then I suggest you to write tests to check that these contracts hold for every code run. Conclusion Although it seemed at first place that checking all elements in collection may end up with for-loops that does not look so nice we were able to solve our problem nicely. ForAll method of contract class offered us simple mechanism to check collections and it does it smoothly the code-contracts-way. P.S. I suggest you also read devlicio.us blog posting Validating Collections with Code Contracts by Derik Whittaker.

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• Surviving MATLAB and R as a Hardcore Programmer

  - by dsimcha

  I love programming in languages that seem geared towards hardcore programmers. (My favorites are Python and D.) MATLAB is geared towards engineers and R is geared towards statisticians, and it seems like these languages were designed by people who aren't hardcore programmers and don't think like hardcore programmers. I always find them somewhat awkward to use, and to some extent I can't put my finger on why. Here are some issues I have managed to identify: (Both): The extreme emphasis on vectors and matrices to the extent that there are no true primitives. (Both): The difficulty of basic string manipulation. (Both): Lack of or awkwardness in support for basic data structures like hash tables and "real", i.e. type-parametric and nestable, arrays. (Both): They're really, really slow even by interpreted language standards, unless you bend over backwards to vectorize your code. (Both): They seem to not be designed to interact with the outside world. For example, both are fairly bulky programs that take a while to launch and seem to not be designed to make simple text filter programs easy to write. Furthermore, the lack of good string processing makes file I/O in anything but very standard forms near impossible. (Both): Object orientation seems to have a very bolted-on feel. Yes, you can do it, but it doesn't feel much more idiomatic than OO in C. (Both): No obvious, simple way to get a reference type. No pointers or class references. For example, I have no idea how you roll your own linked list in either of these languages. (MATLAB): You can't put multiple top level functions in a single file, encouraging very long functions and cut-and-paste coding. (MATLAB): Integers apparently don't exist as a first class type. (R): The basic builtin data structures seem way too high level and poorly documented, and never seem to do quite what I expect given my experience with similar but lower level data structures. (R): The documentation is spread all over the place and virtually impossible to browse or search. Even D, which is often knocked for bad documentation and is still fairly alpha-ish, is substantially better as far as I can tell. (R): At least as far as I'm aware, there's no good IDE for it. Again, even D, a fairly alpha-ish language with a small community, does better. In general, I also feel like MATLAB and R could be easily replaced by plain old libraries in more general-purpose langauges, if sufficiently comprehensive libraries existed. This is especially true in newer general purpose languages that include lots of features for library writers. Why do R and MATLAB seem so weird to me? Are there any other major issues that you've noticed that may make these languages come off as strange to hardcore programmers? When their use is necessary, what are some good survival tips? Edit: I'm seeing one issue from some of the answers I've gotten. I have a strong personal preference, when I analyze data, to have one script that incorporates the whole pipeline. This implies that a general purpose language needs to be used. I hate having to write a script to "clean up" the data and spit it out, then another to read it back in a completely different environment, etc. I find the friction of using MATLAB/R for some of my work and a completely different language with a completely different address space and way of thinking for the rest to be a huge source of friction. Furthermore, I know there are glue layers that exist, but they always seem to be horribly complicated and a source of friction.

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• Silverlight Cream for June 01, 2010 -- #874

  - by Dave Campbell

  In this Issue: Michael Washington, Alan Beasley and Michael Washington, Miroslav Miroslavov, Max Paulousky, Teresa and Ronald Burger, Laurent Duveau, Tim Heuer, Jeff Brand, Mike Snow, and John Papa. Shoutouts: To pay homage to the Advanced Options button in Expression Blend, Adam Kinney posted: Expression Blend Advanced Options square wallpaper SilverLaw stood his drag and drop ripple on it's head for this one: Silver Soccer - A Case Study for the Flexible Surface Effect (Silverlight 4) From SilverlightCream.com: Expression Blend DataStore - A Powerful Tool For Designers Michael Washington dug into the documentation and with some Microsoft assistance has figured out how to use the SetDataStoreAction in SketchFlow... good tutorial and a game to demonstrate it's use. Windows Phone 7 View Model Style Video Player Alan Beasley and Michael Washington teamed up again to produce a ViewModel-Style Video Player for WP7 ... very nice interface I might add... very detailed tutorial and all the code... oh, and did you notice it uses MVVMLight... on WP7? ... just thought I'd mention that :) Navigation in 3D world of 2D objects In part 7 of the CompleteIT code explenation, Miroslav Miroslavov is discussing some of the very cool animation they did... 3D, moving camera... cool stuff! Search Engine Optimization (SEO) for Silverlight Applications. Part 2 Max Paulousky has part 2 of his Silverlight 4 and SEO series up. In part 2 he's discussing sitemaps and html content providing. He also has good links showing where to submit your sitemaps and information. Mousin’ down the PathListBox Teresa and Ronald Burger (not sure which) has a post up about the PathListBox and how they drew the path that they ended up using, and the code used to enable animation. Dynamically apply and change Theme with the Silverlight Toolkit We've all had fun playing with themes, but Laurent Duveau has an example up of letting your users change the theme at run-time. Microsoft Translator client library for Silverlight Tim Heuer has been playing with the Microsoft Translator for Silverlight and he has a "Works on My Machine" license on what he's making available .. but considering his access to resources... I'd say go for it :) Custom Per-Page Transitions in Windows Phone 7 Jeff Brand has a follow-on to his other WP7 post about page transitions and is now discussing per-page transitions Silverlight Tip of the Day #26 – Changing the Startup Class Mike Snow's latest 'tip' is a little more involved than a tip ... changing the startup class and actually removing (in his example), the page and app classes... code and xaml! I've seen this before but never explained as clean... fun stuff. Behaviors in Blend 4 (Silverlight TV #30) Episode 30 of Silverlight TV (now a tag at Silverlight Cream) finds John Papa talking to Adam Kinney about Behaviors in Blend 4... not only using them but creating a custom one. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• The WaitForAll Roadshow

  - by adweigert

  OK, so I took for granted some imaginative uses of WaitForAll but lacking that, here is how I am using. First, I have a nice little class called Parallel that allows me to spin together a list of tasks (actions) and then use WaitForAll, so here it is, WaitForAll's 15 minutes of fame ... First Parallel that allows me to spin together several Action delegates to execute, well in parallel.   public static class Parallel { public static ParallelQuery Task(Action action) { return new Action[] { action }.AsParallel(); } public static ParallelQuery> Task(Action action) { return new Action[] { action }.AsParallel(); } public static ParallelQuery Task(this ParallelQuery actions, Action action) { var list = new List(actions); list.Add(action); return list.AsParallel(); } public static ParallelQuery> Task(this ParallelQuery> actions, Action action) { var list = new List>(actions); list.Add(action); return list.AsParallel(); } }   Next, this is an example usage from an app I'm working on that just is rendering some basic computer information via WMI and performance counters. The WMI calls can be expensive given the distance and link speed of some of the computers it will be trying to communicate with. This is the actual MVC action from my controller to return the data for an individual computer.  public PartialViewResult Detail(string computerName) { var computer = this.Computers.Get(computerName); var perf = Factory.GetInstance(); var detail = new ComputerDetailViewModel() { Computer = computer }; try { var work = Parallel .Task(delegate { // Win32_ComputerSystem var key = computer.Name + "_Win32_ComputerSystem"; var system = this.Cache.Get(key); if (system == null) { using (var impersonation = computer.ImpersonateElevatedIdentity()) { system = computer.GetWmiContext().GetInstances().Single(); } this.Cache.Set(key, system); } detail.TotalMemory = system.TotalPhysicalMemory; detail.Manufacturer = system.Manufacturer; detail.Model = system.Model; detail.NumberOfProcessors = system.NumberOfProcessors; }) .Task(delegate { // Win32_OperatingSystem var key = computer.Name + "_Win32_OperatingSystem"; var os = this.Cache.Get(key); if (os == null) { using (var impersonation = computer.ImpersonateElevatedIdentity()) { os = computer.GetWmiContext().GetInstances().Single(); } this.Cache.Set(key, os); } detail.OperatingSystem = os.Caption; detail.OSVersion = os.Version; }) // Performance Counters .Task(delegate { using (var impersonation = computer.ImpersonateElevatedIdentity()) { detail.AvailableBytes = perf.GetSample(computer, "Memory", "Available Bytes"); } }) .Task(delegate { using (var impersonation = computer.ImpersonateElevatedIdentity()) { detail.TotalProcessorUtilization = perf.GetValue(computer, "Processor", "% Processor Time", "_Total"); } }).WithExecutionMode(ParallelExecutionMode.ForceParallelism); if (!work.WaitForAll(TimeSpan.FromSeconds(15), task => task())) { return PartialView("Timeout"); } } catch (Exception ex) { this.LogException(ex); return PartialView("Error.ascx"); } return PartialView(detail); }

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• HTTP Module in detail

  - by Jalpesh P. Vadgama

  I know this post may sound like very beginner level. But I have already posted two topics regarding HTTP Handler and HTTP module and this will explain how http module works in the system. I have already posted What is the difference between HttpModule and HTTPHandler here. Same way I have posted about an HTTP Handler example here as people are still confused with it. In this post I am going to explain about HTTP Module in detail. What is HTTP Module As we all know that when ASP.NET Runtimes receives any request it will execute a series of HTTP Pipeline extensible objects. HTTP Module and HTTP handler play important role in extending this HTTP Pipelines. HTTP Module are classes that will pre and post process request as they pass into HTTP Pipelines.  So It’s one kind of filter we can say which will do some procession on begin request and end request. If we have to create HTTP Module we have to implement System.Web.IHttpModule interface in our custom class. An IHTTP Module contains two method dispose where you can write your clean up code and another is Init where your can write your custom code to handle request. Here you can your event handler that will execute at the time of begin request and end request. Let’s create an HTTP Module which will just print text in browser with every request. Here is the code for that. using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace Experiment { public class MyHttpModule:IHttpModule { public void Dispose() { //add clean up code here if required } public void Init(HttpApplication context) { context.BeginRequest+=new EventHandler(context_BeginRequest); context.EndRequest+=new EventHandler(context_EndRequest); } public void context_BeginRequest(object o, EventArgs args) { HttpApplication app = (HttpApplication)o; if (app != null) { app.Response.Write("<h1>Begin Request Executed</h1>"); } } public void context_EndRequest(object o, EventArgs args) { HttpApplication app = (HttpApplication)o; if (app != null) { app.Response.Write("<h1>End Request Executed</h1>"); } } } } Here in above code you can see that I have created two event handler context_Beginrequest and context_EndRequest which will execute at begin request and end request when request are processed. In this event handler I have just written a code to print text on browser. Now In order enable this HTTP Module in HTTP pipeline we have to put a settings in web.config  HTTPModules section to tell which HTTPModule is enabled. Below is code for HTTPModule. <configuration> <system.web> <compilation debug="true" targetFramework="4.0" /> <httpModules> <add name="MyHttpModule" type="Experiment.MyHttpModule,Experiment"/> </httpModules> </system.web> </configuration> Now I just have created a sample webform with following code in HTML like following. <form id="form1" runat="server"> <B>test of HTTP Module</B> </form> Now let’s run this web form in browser and you can see here it the output as expected.   Technorati Tags: HTTPModule,ASP.NET,Request

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• Thoughts on C# Extension Methods

  - by Damon

  I'm not a huge fan of extension methods.  When they first came out, I remember seeing a method on an object that was fairly useful, but when I went to use it another piece of code that method wasn't available.  Turns out it was an extension method and I hadn't included the appropriate assembly and imports statement in my code to use it.  I remember being a bit confused at first about how the heck that could happen (hey, extension methods were new, cut me some slack) and it took a bit of time to track down exactly what it was that I needed to include to get that method back.  I just imagined a new developer trying to figure out why a method was missing and fruitlessly searching on MSDN for a method that didn't exist and it just didn't sit well with me. I am of the opinion that if you have an object, then you shouldn't have to include additional assemblies to get additional instance level methods out of that object.  That opinion applies to namespaces as well - I do not like it when the contents of a namespace are split out into multiple assemblies.  I prefer to have static utility classes instead of extension methods to keep things nicely packaged into a cohesive unit.  It also makes it abundantly clear where utility methods are used in code.  I will concede, however, that it can make code a bit more verbose and lengthy.  There is always a trade-off. Some people harp on extension methods because it breaks the tenants of object oriented development and allows you to add methods to sealed classes.  Whatever.  Extension methods are just utility methods that you can tack onto an object after the fact.  Extension methods do not give you any more access to an object than the developer of that object allows, so I say that those who cry OO foul on extension methods really don't have much of an argument on which to stand.  In fact, I have to concede that my dislike of them is really more about style than anything of great substance. One interesting thing that I found regarding extension methods is that you can call them on null objects. Take a look at this extension method: namespace ExtensionMethods {   public static class StringUtility   {     public static int WordCount(this string str)     {       if(str == null) return 0;       return str.Split(new char[] { ' ', '.', '?' },         StringSplitOptions.RemoveEmptyEntries).Length;     }   }   } Notice that the extension method checks to see if the incoming string parameter is null.  I was worried that the runtime would perform a check on the object instance to make sure it was not null before calling an extension method, but that is apparently not the case.  So, if you call the following code it runs just fine. string s = null; int words = s.WordCount(); I am a big fan of things working, but this seems to go against everything I've come to know about instance level methods.  However, an extension method is really a static method masquerading as an instance-level method, so I suppose it would be far more frustrating if it failed since there is really no reason it shouldn't succeed. Although I'm not a fan of extension methods, I will say that if you ever find yourself at an impasse with a die-hard fan of either the utility class or extension method approach, then there is a common ground.  Extension methods are defined in static classes, and you call them from those static classes as well as directly from the objects they extend.  So if you build your utility classes using extension methods, then you can have it your way and they can have it theirs. 

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• Physics like asteroides

  - by user2933016

  I try to make a ship that has the physic properties like asteroides. I have this for now(All in Java): Ship.class public class Ship { public static final float sMaxHealth = 0.1F; public static final float sMaxMoveVelocity = 5.0F; public static final float sMaxAngleVelocity = 20.0F; public static final float sRadius = 1.0F; public static final float sMoveDeceleration = 10.0F; public static final float sMoveAcceleration = 2.0F; public static final float sAngleDeceleration = 15.0F; public static final float sAngleAcceleration = 20.0F; private float mHealth; private float mXVelocity; private float mYVelocity; private float mAngleVelocity; private float mX; private float mY; private float mAngle; } (I let the getter and setter away for now) Controller code // Player input if(Gdx.input.isKeyPressed(Keys.UP)) { mPlayer.setXVelocity(mPlayer.getXVelocity() + (float) Math.cos(mPlayer.getAngle()) * Ship.sMoveAcceleration); mPlayer.setYVelocity(mPlayer.getYVelocity() + (float) Math.sin(mPlayer.getAngle()) * Ship.sMoveAcceleration); } if(Gdx.input.isKeyPressed(Keys.LEFT)) { mPlayer.setAngleVelocity(mPlayer.getAngleVelocity() + Ship.sAngleAcceleration * pDeltaTime); } if(Gdx.input.isKeyPressed(Keys.RIGHT)) { mPlayer.setAngleVelocity(mPlayer.getAngleVelocity() - Ship.sAngleAcceleration * pDeltaTime); } // X velocity if(mPlayer.getXVelocity() < 0) { if(-mPlayer.getXVelocity() > Ship.sMaxMoveVelocity) { mPlayer.setXVelocity(-Ship.sMaxMoveVelocity); } mPlayer.setXVelocity(mPlayer.getXVelocity() + Ship.sMoveDeceleration * pDeltaTime); if(mPlayer.getXVelocity() > 0) { mPlayer.setXVelocity(0); } } else if(mPlayer.getXVelocity() > 0) { if(mPlayer.getXVelocity() > Ship.sMaxMoveVelocity) { mPlayer.setXVelocity(Ship.sMaxMoveVelocity); } mPlayer.setXVelocity(mPlayer.getXVelocity() - Ship.sMoveDeceleration * pDeltaTime); if(mPlayer.getXVelocity() < 0) { mPlayer.setXVelocity(0); } } // Y velocity if(mPlayer.getYVelocity() < 0) { if(-mPlayer.getYVelocity() > Ship.sMaxMoveVelocity) { mPlayer.setYVelocity(-Ship.sMaxMoveVelocity); } mPlayer.setYVelocity(mPlayer.getYVelocity() + Ship.sMoveDeceleration * pDeltaTime); if(mPlayer.getYVelocity() > 0) { mPlayer.setYVelocity(0); } } else if(mPlayer.getYVelocity() > 0) { if(mPlayer.getYVelocity() > Ship.sMaxMoveVelocity) { mPlayer.setYVelocity(Ship.sMaxMoveVelocity); } mPlayer.setYVelocity(mPlayer.getYVelocity() - Ship.sMoveDeceleration * pDeltaTime); if(mPlayer.getYVelocity() < 0) { mPlayer.setYVelocity(0); } } // Angle velocity if(mPlayer.getAngleVelocity() < 0) { if(-mPlayer.getAngleVelocity() > Ship.sMaxAngleVelocity) { mPlayer.setAngleVelocity(-Ship.sMaxAngleVelocity); } mPlayer.setAngleVelocity(mPlayer.getAngleVelocity() + Ship.sAngleDeceleration * pDeltaTime); if(mPlayer.getAngleVelocity() > 0) { mPlayer.setAngleVelocity(0); } } else if(mPlayer.getAngleVelocity() > 0) { if(mPlayer.getAngleVelocity() > Ship.sMaxAngleVelocity) { mPlayer.setAngleVelocity(Ship.sMaxAngleVelocity); } mPlayer.setAngleVelocity(mPlayer.getAngleVelocity() - Ship.sAngleDeceleration * pDeltaTime); if(mPlayer.getAngleVelocity() < 0) { mPlayer.setAngleVelocity(0); } } mPlayer.setX(mPlayer.getX() + mPlayer.getXVelocity() * pDeltaTime); mPlayer.setY(mPlayer.getY() + mPlayer.getYVelocity() * pDeltaTime); mPlayer.setAngle(mPlayer.getAngle() + mPlayer.getAngleVelocity() * pDeltaTime); Why the ship does not behave like in asteroides ? What do I wrong?

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• Thoughts on my new template language/HTML generator?

  - by Ralph

  I guess I should have pre-faced this with: Yes, I know there is no need for a new templating language, but I want to make a new one anyway, because I'm a fool. That aside, how can I improve my language: Let's start with an example: using "html5" using "extratags" html { head { title "Ordering Notice" jsinclude "jquery.js" } body { h1 "Ordering Notice" p "Dear @name," p "Thanks for placing your order with @company. It's scheduled to ship on {@ship_date|dateformat}." p "Here are the items you've ordered:" table { tr { th "name" th "price" } for(@item in @item_list) { tr { td @item.name td @item.price } } } if(@ordered_warranty) p "Your warranty information will be included in the packaging." p(class="footer") { "Sincerely," br @company } } } The "using" keyword indicates which tags to use. "html5" might include all the html5 standard tags, but your tags names wouldn't have to be based on their HTML counter-parts at all if you didn't want to. The "extratags" library for example might add an extra tag, called "jsinclude" which gets replaced with something like <script type="text/javascript" src="@content"></script> Tags can be optionally be followed by an opening brace. They will automatically be closed at the closing brace. If no brace is used, they will be closed after taking one element. Variables are prefixed with the @ symbol. They may be used inside double-quoted strings. I think I'll use single-quotes to indicate "no variable substitution" like PHP does. Filter functions can be applied to variables like @variable|filter. Arguments can be passed to the filter @variable|filter:@arg1,arg2="y" Attributes can be passed to tags by including them in (), like p(class="classname"). You will also be able to include partial templates like: for(@item in @item_list) include("item_partial", item=@item) Something like that I'm thinking. The first argument will be the name of the template file, and subsequent ones will be named arguments where @item gets the variable name "item" inside that template. I also want to have a collection version like RoR has, so you don't even have to write the loop. Thoughts on this and exact syntax would be helpful :) Some questions: Which symbol should I use to prefix variables? @ (like Razor), $ (like PHP), or something else? Should the @ symbol be necessary in "for" and "if" statements? It's kind of implied that those are variables. Tags and controls (like if,for) presently have the exact same syntax. Should I do something to differentiate the two? If so, what? This would make it more clear that the "tag" isn't behaving like just a normal tag that will get replaced with content, but controls the flow. Also, it would allow name-reuse. Do you like the attribute syntax? (round brackets) How should I do template inheritance/layouts? In Django, the first line of the file has to include the layout file, and then you delimit blocks of code which get stuffed into that layout. In CakePHP, it's kind of backwards, you specify the layout in the controller.view function, the layout gets a special $content_for_layout variable, and then the entire template gets stuffed into that, and you don't need to delimit any blocks of code. I guess Django's is a little more powerful because you can have multiple code blocks, but it makes your templates more verbose... trying to decide what approach to take Filtered variables inside quotes: "xxx {@var|filter} yyy" "xxx @{var|filter} yyy" "xxx @var|filter yyy" i.e, @ inside, @ outside, or no braces at all. I think no-braces might cause problems, especially when you try adding arguments, like @var|filter:arg="x", then the quotes would get confused. But perhaps a braceless version could work for when there are no quotes...? Still, which option for braces, first or second? I think the first one might be better because then we're consistent... the @ is always nudged up against the variable. I'll add more questions in a few minutes, once I get some feedback.

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• 45 minutes to talk about C# [closed]

  - by Philip

  I have the opportunity to give a 45 minute talk on C# in the theory of programming languages class I'm taking. The college teaches Java almost exclusively, so that's what all the students are most familiar with. (There's a little C, assembly, Prolog and LISP as well.) I decide what to talk about. It seems to me the best approach is to focus on a few of the big, obvious differences between C# and Java. I don't intend it to be a recommendation to use C# -- there are reasons to use each, mostly because of their ecosystems. So I want to focus on C# as a language. I don't want to go too fast and end up listing a whole bunch of features without showing their usefulness. My current plan is this: Functions as first class objects. This is, in my opinion, one of the biggest differences between C# and Java. The professor briefly mentioned this notion and showed a LISP example, but many of the students have probably never used it. I can show real world examples where it's made my code more readable. Lambda expressions as concise syntax for anonymous functions. Obviously with examples to show how this is useful. The real hit-home examples will be at the end when it's combined with the rest. I don't see an advantage to first showing the old delegate syntax and then replacing it with lambdas -- most of us won't have ever seen delegates anyway so it would just be confusing. The yield keyword and how it's different from returning an array. I have the impression that a lot of C# developers aren't familiar with how to use this. It will likely be very foreign to Java developers. I have some examples from my own work where it was really useful, such as iterating over a tree traversal, or iterating over neighbors in a graph where the neighbors aren't stored in memory. In both cases, doing it in Java would likely mean returning a complete list -- with yield I can stop iterating if I find what I want early on, without using memory for superfluous lists or arrays. Extension methods as a way to write implementation on interfaces. We'll all be familiar with how interfaces don't allow method implementation, and how this leads to code duplication. I'll show a specific example of this and how the extension method can solve the problem. Demonstrate how the above can be combined by implementing some simple Linq methods and using them. Where, Select, First, maybe more depending on how much time is left. Ideas on which ones might 'hit home' the best? There are other things I could talk about such as generics, value types, properties and more. I haven't yet though of good ways to incorporate these. In the case of generics and value types, the advantages might not be obvious or as relevant. Properties are obviously useful, particularly since we're taught strict JavaBeans here, but I don't know if I could integrate it with the "path to Linq" discussion above without it feeling tacked on. So I'm looking for thoughts on how to talk about C#, and what to talk about. Even minor details. I'm sure there are more experienced C# developers than me here who have good insight about what's really important in the language, and what would miss the point.

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• An Unusual UpdatePanel

  - by João Angelo

  The code you are about to see was mostly to prove a point, to myself, and probably has limited applicability. Nonetheless, in the remote possibility this is useful to someone here it goes… So this is a control that acts like a normal UpdatePanel where all child controls are registered as postback triggers except for a single control specified by the TriggerControlID property. You could basically achieve the same thing by registering all controls as postback triggers in the regular UpdatePanel. However with this, that process is performed automatically. Finally, here is the code: public sealed class SingleAsyncTriggerUpdatePanel : WebControl, INamingContainer { public string TriggerControlID { get; set; } [TemplateInstance(TemplateInstance.Single)] [PersistenceMode(PersistenceMode.InnerProperty)] public ITemplate ContentTemplate { get; set; } public override ControlCollection Controls { get { this.EnsureChildControls(); return base.Controls; } } protected override void CreateChildControls() { if (string.IsNullOrWhiteSpace(this.TriggerControlID)) throw new InvalidOperationException( "The TriggerControlId property must be set."); this.Controls.Clear(); var updatePanel = new UpdatePanel() { ID = string.Concat(this.ID, "InnerUpdatePanel"), ChildrenAsTriggers = false, UpdateMode = UpdatePanelUpdateMode.Conditional, ContentTemplate = this.ContentTemplate }; updatePanel.Triggers.Add(new SingleControlAsyncUpdatePanelTrigger { ControlID = this.TriggerControlID }); this.Controls.Add(updatePanel); } } internal sealed class SingleControlAsyncUpdatePanelTrigger : UpdatePanelControlTrigger { private Control target; private ScriptManager scriptManager; public Control Target { get { if (this.target == null) { this.target = this.FindTargetControl(true); } return this.target; } } public ScriptManager ScriptManager { get { if (this.scriptManager == null) { var page = base.Owner.Page; if (page != null) { this.scriptManager = ScriptManager.GetCurrent(page); } } return this.scriptManager; } } protected override bool HasTriggered() { string asyncPostBackSourceElementID = this.ScriptManager.AsyncPostBackSourceElementID; if (asyncPostBackSourceElementID == this.Target.UniqueID) return true; return asyncPostBackSourceElementID.StartsWith( string.Concat(this.target.UniqueID, "$"), StringComparison.Ordinal); } protected override void Initialize() { base.Initialize(); foreach (Control control in FlattenControlHierarchy(this.Owner.Controls)) { if (control == this.Target) continue; bool isApplicableControl = false; isApplicableControl |= control is INamingContainer; isApplicableControl |= control is IPostBackDataHandler; isApplicableControl |= control is IPostBackEventHandler; if (isApplicableControl) { this.ScriptManager.RegisterPostBackControl(control); } } } private static IEnumerable<Control> FlattenControlHierarchy( ControlCollection collection) { foreach (Control control in collection) { yield return control; if (control.Controls.Count > 0) { foreach (Control child in FlattenControlHierarchy(control.Controls)) { yield return child; } } } } } You can use it like this, meaning that only the B2 button will trigger an async postback: <cc:SingleAsyncTriggerUpdatePanel ID="Test" runat="server" TriggerControlID="B2"> <ContentTemplate> <asp:Button ID="B1" Text="B1" runat="server" OnClick="Button_Click" /> <asp:Button ID="B2" Text="B2" runat="server" OnClick="Button_Click" /> <asp:Button ID="B3" Text="B3" runat="server" OnClick="Button_Click" /> <asp:Label ID="LInner" Text="LInner" runat="server" /> </ContentTemplate> </cc:SingleAsyncTriggerUpdatePanel>

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