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• persian transliteration java api

  - by New-To-Java

  I need to transliterate to Persian and I want to use it offline , is there any free api that I use offline ?

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• What's wrong with this function?

  - by ct2k7

  Hello, I'm using this function to determine whether my application should be online or offline: function online() { if ($online == "0") { if($_SESSION['exp_user']['userlevel'] != "1") { include("error/offline.php"); exit(); } } } However, with the data value set to 0 in the database, and $online does = '0', why is error/offline.php not included for those whoose user level is not 1? Thanks :)

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• Rails test across multiple environments

  - by DSimon

  Is there some way to change Rails environments mid-way through a test? Or, alternately, what would be the right way to set up a test suite that can start up Rails in one environment, run the first half of my test in it, then restart Rails in another environment to finish the test? The two environments have separate databases. Some necessary context: I'm writing a Rails plugin that allows multiple installations of a Rails app to communicate with each other with user assistance, so that a user without Internet access can still use the app. They'll run a local version of an app, and upload their work to the online app by saving a file to a thumbdrive and taking it to an Internet cafe. The plugin adds two special environments to Rails: "offline-production" and "offline-test". I want to write functional tests that involve both the "test" and "offline-test" environments, to represent the main online version of the app and the local offline version of the app respectively.

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• Custom Content-Type for File in Rails 'public' Folder

  - by Kevin Sylvestre

  For assets stored in the 'public' folder of a ruby-on-rails application is it possible to change the 'Content-Type' when running 'script/server'? For example, I am attempting to create an HTML5 application supporting offline mode, and have an 'offline.manifest'. When I run: curl -I localhost:3000/offline.mainfest The following header information is returned: HTTP/1.1 200 OK ... Content-Type: text/plain ... However, HTML5 specifications require: HTTP/1.1 200 OK ... Content-Type: text/cache-manifest ...

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• Building an HTML5 App with ASP.NET

  - by Stephen Walther

  I’m teaching several JavaScript and ASP.NET workshops over the next couple of months (thanks everyone!) and I thought it would be useful for my students to have a really easy to use JavaScript reference. I wanted a simple interactive JavaScript reference and I could not find one so I decided to put together one of my own. I decided to use the latest features of JavaScript, HTML5 and jQuery such as local storage, offline manifests, and jQuery templates. What could be more appropriate than building a JavaScript Reference with JavaScript? You can try out the application by visiting: http://Superexpert.com/JavaScriptReference Because the app takes advantage of several advanced features of HTML5, it won’t work with Internet Explorer 6 (but really, you should stop using that browser). I have tested it with IE 8, Chrome 8, Firefox 3.6, and Safari 5. You can download the source for the JavaScript Reference application at the end of this article. Superexpert JavaScript Reference Let me provide you with a brief walkthrough of the app. When you first open the application, you see the following lookup screen: As you type the name of something from the JavaScript language, matching results are displayed: You can click the details link for any entry to view details for an entry in a modal dialog: Alternatively, you can click on any of the tabs -- Objects, Functions, Properties, Statements, Operators, Comments, or Directives -- to filter results by type of syntax. For example, you might want to see a list of all JavaScript built-in objects: You can login to the application to make modification to the application: After you login, you can add, update, or delete entries in the reference database: HTML5 Local Storage The application takes advantage of HTML5 local storage to store all of the reference entries on the local browser. IE 8, Chrome 8, Firefox 3.6, and Safari 5 all support local storage. When you open the application for the first time, all of the reference entries are transferred to the browser. The data is stored persistently. Even if you shutdown your computer and return to the application many days later, the data does not need to be transferred again. Whenever you open the application, the app checks with the server to see if any of the entries have been updated on the server. If there have been updates, then only the updates are transferred to the browser and the updates are merged with the existing entries in local storage. After the reference database has been transferred to your browser once, only changes are transferred in the future. You get two benefits from using local storage. First, the application loads very fast and works very fast after the data has been loaded once. The application does not query the server whenever you filter or view entries. All of the data is persisted in the browser. Second, you can browse the JavaScript reference even when you are not connected to the Internet (when you are on the proverbial airplane). The JavaScript Reference works as an offline application for browsers that support offline applications (unfortunately, not IE). When using Google Chrome, you can easily view the contents of local storage by selecting Tools, Developer Tools (CTRL-SHIFT I) and selecting Storage, Local Storage: The JavaScript Reference app stores two items in local storage: entriesLastUpdated and entries. HTML5 Offline App For browsers that support HTML5 offline applications – Chrome 8 and Firefox 3.6 but not Internet Explorer – you do not need to be connected to the Internet to use the JavaScript Reference. The JavaScript Reference can execute entirely on your machine just like any other desktop application. When you first open the application with Firefox, you are presented with the following warning: Notice the notification bar that asks whether you want to accept offline content. If you click the Allow button then all of the files (generated ASPX, images, CSS, JavaScript) needed for the JavaScript Reference will be stored on your local computer. Automatic Script Minification and Combination All of the custom JavaScript files are combined and minified automatically whenever the application is built with Visual Studio. All of the custom scripts are contained in a folder named App_Scripts: When you perform a build, the combine.js and combine.debug.js files are generated. The Combine.config file contains the list of files that should be combined (importantly, it specifies the order in which the files should be combined). Here’s the contents of the Combine.config file:   <?xml version="1.0"?> <combine> <scripts> <file path="compat.js" /> <file path="storage.js" /> <file path="serverData.js" /> <file path="entriesHelper.js" /> <file path="authentication.js" /> <file path="default.js" /> </scripts> </combine>   jQuery and jQuery UI The JavaScript Reference application takes heavy advantage of jQuery and jQuery UI. In particular, the application uses jQuery templates to format and display the reference entries. Each of the separate templates is stored in a separate ASP.NET user control in a folder named Templates: The contents of the user controls (and therefore the templates) are combined in the default.aspx page: <!-- Templates --> <user:EntryTemplate runat="server" /> <user:EntryDetailsTemplate runat="server" /> <user:BrowsersTemplate runat="server" /> <user:EditEntryTemplate runat="server" /> <user:EntryDetailsCloudTemplate runat="server" /> When the default.aspx page is requested, all of the templates are retrieved in a single page. WCF Data Services The JavaScript Reference application uses WCF Data Services to retrieve and modify database data. The application exposes a server-side WCF Data Service named EntryService.svc that supports querying, adding, updating, and deleting entries. jQuery Ajax calls are made against the WCF Data Service to perform the database operations from the browser. The OData protocol makes this easy. Authentication is handled on the server with a ChangeInterceptor. Only authenticated users are allowed to update the JavaScript Reference entry database. JavaScript Unit Tests In order to build the JavaScript Reference application, I depended on JavaScript unit tests. I needed the unit tests, in particular, to write the JavaScript merge functions which merge entry change sets from the server with existing entries in browser local storage. In order for unit tests to be useful, they need to run fast. I ran my unit tests after each build. For this reason, I did not want to run the unit tests within the context of a browser. Instead, I ran the unit tests using server-side JavaScript (the Microsoft Script Control). The source code that you can download at the end of this blog entry includes a project named JavaScriptReference.UnitTests that contains all of the JavaScripts unit tests. JavaScript Integration Tests Because not every feature of an application can be tested by unit tests, the JavaScript Reference application also includes integration tests. I wrote the integration tests using Selenium RC in combination with ASP.NET Unit Tests. The Selenium tests run against all of the target browsers for the JavaScript Reference application: IE 8, Chrome 8, Firefox 3.6, and Safari 5. For example, here is the Selenium test that checks whether authenticating with a valid user name and password correctly switches the application to Admin Mode: [TestMethod] [HostType("ASP.NET")] [UrlToTest("http://localhost:26303/JavaScriptReference")] [AspNetDevelopmentServerHost(@"C:\Users\Stephen\Documents\Repos\JavaScriptReference\JavaScriptReference\JavaScriptReference", "/JavaScriptReference")] public void TestValidLogin() { // Run test for each controller foreach (var controller in this.Controllers) { var selenium = controller.Value; var browserName = controller.Key; // Open reference page. selenium.Open("http://localhost:26303/JavaScriptReference/default.aspx"); // Click login button displays login form selenium.Click("btnLogin"); Assert.IsTrue(selenium.IsVisible("loginForm"), "Login form appears after clicking btnLogin"); // Enter user name and password selenium.Type("userName", "Admin"); selenium.Type("password", "secret"); selenium.Click("btnDoLogin"); // Should set adminMode == true selenium.WaitForCondition("selenium.browserbot.getCurrentWindow().adminMode==true", "30000"); } }   The results for running the Selenium tests appear in the Test Results window just like the unit tests: The Selenium tests take much longer to execute than the unit tests. However, they provide test coverage for actual browsers. Furthermore, if you are using Visual Studio ALM, you can run the tests automatically every night as part of your standard nightly build. You can view the Selenium tests by opening the JavaScriptReference.QATests project. Summary I plan to write more detailed blog entries about this application over the next week. I want to discuss each of the features – HTML5 local storage, HTML5 offline apps, jQuery templates, automatic script combining and minification, JavaScript unit tests, Selenium tests -- in more detail. You can download the source control for the JavaScript Reference Application by clicking the following link: Download You need Visual Studio 2010 and ASP.NET 4 to build the application. Before running the JavaScript unit tests, install the Microsoft Script Control. Before running the Selenium tests, start the Selenium server by running the StartSeleniumServer.bat file located in the JavaScriptReference.QATests project.

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• AppFabric OutputCaching for ASP.NET Web API

  - by cibrax

  ASP.NET Web API does not provide any output caching capabilities out of the box other than the ones you would traditionally find in the ASP.NET caching module. Fortunately, Filip wrote a very nice library that you can use to decorate your Web API controller methods with an [OutputCaching] attribute, which is similar to the one you can find in ASP.NET MVC. This library provides a way to configure different persistence storages for the cached data, which uses memory by default. As part of this post, I will show how you can implement your own persistence provider for AppFabric in order to support distributed caching on web applications running on premises. Read more here  

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• Windows.Threading.Dispatcher' does not contain a definition for 'RunAsync' and no extension method 'RunAsync' accepting a first argument of type

  - by suhail mehdi

  public MainPage() { InitializeComponent(); offline.Visibility = (Network.IsConnected ? Visibility.Collapsed : Visibility.Visible); Network.InternetConnectionChanged += async (s, e) => { await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => { offline.Visibility = (e.IsConnected ? Visibility.Collapsed : Visibility.Visible); }); }; }

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• Powershell, SMO and Database Files

  - by dbaduck

  In response to some questions about renaming a physical file for a database, I have 2 versions of Powershell scripts that do this for you, including taking the database offline and then online to make the physical change match the meta-data. First, there is an article about this at http://msdn.microsoft.com/en-us/library/ms345483.aspx . This explains that you start by setting the database offline, then alter the database and modify the filename then set it back online. This particular article does...(read more)

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• Bring the Dragonborn to Your Desktop with the Elder Scrolls – Skyrim Theme for Windows 7

  - by Asian Angel

  Prepare your desktop for the journey to the world of Tamriel and the epic quest to defeat Alduin with the Elder Scrolls – Skyrim Theme for Windows 7. The theme comes with 16 Hi-Res wallpapers, custom icons, and system sounds from the game that will fill your desktop with legendary adventure. View Additional Screenshots of the Theme Download the Theme HTG Explains: Understanding Routers, Switches, and Network Hardware How to Use Offline Files in Windows to Cache Your Networked Files Offline How to See What Web Sites Your Computer is Secretly Connecting To

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• Performing a clean database build with MSBuild part 2

  - by Robert May

  In part 1, I showed a complicated mechanism for performing a clean database build. There’s an easier way.  The easier way is to use the msbuild extension tasks out on codeplex.  While you’ll still need to forcibly take the database offline (ALTER DATABASE [mydb] SET OFFLINE WITH ROLLBACK IMMEDIATE), the other msbuild tasks more easily allow you to create and delete the database.  Eventually, I’ll post an example. Technorati Tags: MSBuild

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• Password protected website

  - by danie7L T

  I need to add a user authentication page before the actual homepage of the website. In Joomla! I just set the website offline and the offline page loads in place of the homepage but then it's automatically throwing a "503 Service Temporarily Unavailable" error which I would like to avoid. That's why I would like to know the other ways to load an authentication page before the homepage. NB: I'm using Apache servers if that's relevant Thank you

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• Hosting the Razor Engine for Templating in Non-Web Applications

  - by Rick Strahl

  Microsoft’s new Razor HTML Rendering Engine that is currently shipping with ASP.NET MVC previews can be used outside of ASP.NET. Razor is an alternative view engine that can be used instead of the ASP.NET Page engine that currently works with ASP.NET WebForms and MVC. It provides a simpler and more readable markup syntax and is much more light weight in terms of functionality than the full blown WebForms Page engine, focusing only on features that are more along the lines of a pure view engine (or classic ASP!) with focus on expression and code rendering rather than a complex control/object model. Like the Page engine though, the parser understands .NET code syntax which can be embedded into templates, and behind the scenes the engine compiles markup and script code into an executing piece of .NET code in an assembly. Although it ships as part of the ASP.NET MVC and WebMatrix the Razor Engine itself is not directly dependent on ASP.NET or IIS or HTTP in any way. And although there are some markup and rendering features that are optimized for HTML based output generation, Razor is essentially a free standing template engine. And what’s really nice is that unlike the ASP.NET Runtime, Razor is fairly easy to host inside of your own non-Web applications to provide templating functionality. Templating in non-Web Applications? Yes please! So why might you host a template engine in your non-Web application? Template rendering is useful in many places and I have a number of applications that make heavy use of it. One of my applications – West Wind Html Help Builder - exclusively uses template based rendering to merge user supplied help text content into customizable and executable HTML markup templates that provide HTML output for CHM style HTML Help. This is an older product and it’s not actually using .NET at the moment – and this is one reason I’m looking at Razor for script hosting at the moment. For a few .NET applications though I’ve actually used the ASP.NET Runtime hosting to provide templating and mail merge style functionality and while that works reasonably well it’s a very heavy handed approach. It’s very resource intensive and has potential issues with versioning in various different versions of .NET. The generic implementation I created in the article above requires a lot of fix up to mimic an HTTP request in a non-HTTP environment and there are a lot of little things that have to happen to ensure that the ASP.NET runtime works properly most of it having nothing to do with the templating aspect but just satisfying ASP.NET’s requirements. The Razor Engine on the other hand is fairly light weight and completely decoupled from the ASP.NET runtime and the HTTP processing. Rather it’s a pure template engine whose sole purpose is to render text templates. Hosting this engine in your own applications can be accomplished with a reasonable amount of code (actually just a few lines with the tools I’m about to describe) and without having to fake HTTP requests. It’s also much lighter on resource usage and you can easily attach custom properties to your base template implementation to easily pass context from the parent application into templates all of which was rather complicated with ASP.NET runtime hosting. Installing the Razor Template Engine You can get Razor as part of the MVC 3 (RC and later) or Web Matrix. Both are available as downloadable components from the Web Platform Installer Version 3.0 (!important – V2 doesn’t show these components). If you already have that version of the WPI installed just fire it up. You can get the latest version of the Web Platform Installer from here: http://www.microsoft.com/web/gallery/install.aspx Once the platform Installer 3.0 is installed install either MVC 3 or ASP.NET Web Pages. Once installed you’ll find a System.Web.Razor assembly in C:\Program Files\Microsoft ASP.NET\ASP.NET Web Pages\v1.0\Assemblies\System.Web.Razor.dll which you can add as a reference to your project. Creating a Wrapper The basic Razor Hosting API is pretty simple and you can host Razor with a (large-ish) handful of lines of code. I’ll show the basics of it later in this article. However, if you want to customize the rendering and handle assembly and namespace includes for the markup as well as deal with text and file inputs as well as forcing Razor to run in a separate AppDomain so you can unload the code-generated assemblies and deal with assembly caching for re-used templates little more work is required to create something that is more easily reusable. For this reason I created a Razor Hosting wrapper project that combines a bunch of this functionality into an easy to use hosting class, a hosting factory that can load the engine in a separate AppDomain and a couple of hosting containers that provided folder based and string based caching for templates for an easily embeddable and reusable engine with easy to use syntax. If you just want the code and play with the samples and source go grab the latest code from the Subversion Repository at: http://www.west-wind.com:8080/svn/articles/trunk/RazorHosting/ or a snapshot from: http://www.west-wind.com/files/tools/RazorHosting.zip Getting Started Before I get into how hosting with Razor works, let’s take a look at how you can get up and running quickly with the wrapper classes provided. It only takes a few lines of code. The easiest way to use these Razor Hosting Wrappers is to use one of the two HostContainers provided. One is for hosting Razor scripts in a directory and rendering them as relative paths from these script files on disk. The other HostContainer serves razor scripts from string templates… Let’s start with a very simple template that displays some simple expressions, some code blocks and demonstrates rendering some data from contextual data that you pass to the template in the form of a ‘context’. Here’s a simple Razor template: @using System.Reflection Hello @Context.FirstName! Your entry was entered on: @Context.Entered @{ // Code block: Update the host Windows Form passed in through the context Context.WinForm.Text = "Hello World from Razor at " + DateTime.Now.ToString(); } AppDomain Id: @AppDomain.CurrentDomain.FriendlyName Assembly: @Assembly.GetExecutingAssembly().FullName Code based output: @{ // Write output with Response object from code string output = string.Empty; for (int i = 0; i < 10; i++) { output += i.ToString() + " "; } Response.Write(output); } Pretty easy to see what’s going on here. The only unusual thing in this code is the Context object which is an arbitrary object I’m passing from the host to the template by way of the template base class. I’m also displaying the current AppDomain and the executing Assembly name so you can see how compiling and running a template actually loads up new assemblies. Also note that as part of my context I’m passing a reference to the current Windows Form down to the template and changing the title from within the script. It’s a silly example, but it demonstrates two-way communication between host and template and back which can be very powerful. The easiest way to quickly render this template is to use the RazorEngine<TTemplateBase> class. The generic parameter specifies a template base class type that is used by Razor internally to generate the class it generates from a template. The default implementation provided in my RazorHosting wrapper is RazorTemplateBase. Here’s a simple one that renders from a string and outputs a string: var engine = new RazorEngine<RazorTemplateBase>(); // we can pass any object as context - here create a custom context var context = new CustomContext() { WinForm = this, FirstName = "Rick", Entered = DateTime.Now.AddDays(-10) }; string output = engine.RenderTemplate(this.txtSource.Text new string[] { "System.Windows.Forms.dll" }, context); if (output == null) this.txtResult.Text = "*** ERROR:\r\n" + engine.ErrorMessage; else this.txtResult.Text = output; Simple enough. This code renders a template from a string input and returns a result back as a string. It  creates a custom context and passes that to the template which can then access the Context’s properties. Note that anything passed as ‘context’ must be serializable (or MarshalByRefObject) – otherwise you get an exception when passing the reference over AppDomain boundaries (discussed later). Passing a context is optional, but is a key feature in being able to share data between the host application and the template. Note that we use the Context object to access FirstName, Entered and even the host Windows Form object which is used in the template to change the Window caption from within the script! In the code above all the work happens in the RenderTemplate method which provide a variety of overloads to read and write to and from strings, files and TextReaders/Writers. Here’s another example that renders from a file input using a TextReader: using (reader = new StreamReader("templates\\simple.csHtml", true)) { result = host.RenderTemplate(reader, new string[] { "System.Windows.Forms.dll" }, this.CustomContext); } RenderTemplate() is fairly high level and it handles loading of the runtime, compiling into an assembly and rendering of the template. If you want more control you can use the lower level methods to control each step of the way which is important for the HostContainers I’ll discuss later. Basically for those scenarios you want to separate out loading of the engine, compiling into an assembly and then rendering the template from the assembly. Why? So we can keep assemblies cached. In the code above a new assembly is created for each template rendered which is inefficient and uses up resources. Depending on the size of your templates and how often you fire them you can chew through memory very quickly. This slighter lower level approach is only a couple of extra steps: // we can pass any object as context - here create a custom context var context = new CustomContext() { WinForm = this, FirstName = "Rick", Entered = DateTime.Now.AddDays(-10) }; var engine = new RazorEngine<RazorTemplateBase>(); string assId = null; using (StringReader reader = new StringReader(this.txtSource.Text)) { assId = engine.ParseAndCompileTemplate(new string[] { "System.Windows.Forms.dll" }, reader); } string output = engine.RenderTemplateFromAssembly(assId, context); if (output == null) this.txtResult.Text = "*** ERROR:\r\n" + engine.ErrorMessage; else this.txtResult.Text = output; The difference here is that you can capture the assembly – or rather an Id to it – and potentially hold on to it to render again later assuming the template hasn’t changed. The HostContainers take advantage of this feature to cache the assemblies based on certain criteria like a filename and file time step or a string hash that if not change indicate that an assembly can be reused. Note that ParseAndCompileTemplate returns an assembly Id rather than the assembly itself. This is done so that that the assembly always stays in the host’s AppDomain and is not passed across AppDomain boundaries which would cause load failures. We’ll talk more about this in a minute but for now just realize that assemblies references are stored in a list and are accessible by this ID to allow locating and re-executing of the assembly based on that id. Reuse of the assembly avoids recompilation overhead and creation of yet another assembly that loads into the current AppDomain. You can play around with several different versions of the above code in the main sample form:   Using Hosting Containers for more Control and Caching The above examples simply render templates into assemblies each and every time they are executed. While this works and is even reasonably fast, it’s not terribly efficient. If you render templates more than once it would be nice if you could cache the generated assemblies for example to avoid re-compiling and creating of a new assembly each time. Additionally it would be nice to load template assemblies into a separate AppDomain optionally to be able to be able to unload assembli es and also to protect your host application from scripting attacks with malicious template code. Hosting containers provide also provide a wrapper around the RazorEngine<T> instance, a factory (which allows creation in separate AppDomains) and an easy way to start and stop the container ‘runtime’. The Razor Hosting samples provide two hosting containers: RazorFolderHostContainer and StringHostContainer. The folder host provides a simple runtime environment for a folder structure similar in the way that the ASP.NET runtime handles a virtual directory as it’s ‘application' root. Templates are loaded from disk in relative paths and the resulting assemblies are cached unless the template on disk is changed. The string host also caches templates based on string hashes – if the same string is passed a second time a cached version of the assembly is used. Here’s how HostContainers work. I’ll use the FolderHostContainer because it’s likely the most common way you’d use templates – from disk based templates that can be easily edited and maintained on disk. The first step is to create an instance of it and keep it around somewhere (in the example it’s attached as a property to the Form): RazorFolderHostContainer Host = new RazorFolderHostContainer(); public RazorFolderHostForm() { InitializeComponent(); // The base path for templates - templates are rendered with relative paths // based on this path. Host.TemplatePath = Path.Combine(Environment.CurrentDirectory, TemplateBaseFolder); // Add any assemblies you want reference in your templates Host.ReferencedAssemblies.Add("System.Windows.Forms.dll"); // Start up the host container Host.Start(); } Next anytime you want to render a template you can use simple code like this: private void RenderTemplate(string fileName) { // Pass the template path via the Context var relativePath = Utilities.GetRelativePath(fileName, Host.TemplatePath); if (!Host.RenderTemplate(relativePath, this.Context, Host.RenderingOutputFile)) { MessageBox.Show("Error: " + Host.ErrorMessage); return; } this.webBrowser1.Navigate("file://" + Host.RenderingOutputFile); } You can also render the output to a string instead of to a file: string result = Host.RenderTemplateToString(relativePath,context); Finally if you want to release the engine and shut down the hosting AppDomain you can simply do: Host.Stop(); Stopping the AppDomain and restarting it (ie. calling Stop(); followed by Start()) is also a nice way to release all resources in the AppDomain. The FolderBased domain also supports partial Rendering based on root path based relative paths with the same caching characteristics as the main templates. From within a template you can call out to a partial like this: @RenderPartial(@"partials\PartialRendering.cshtml", Context) where partials\PartialRendering.cshtml is a relative to the template root folder. The folder host example lets you load up templates from disk and display the result in a Web Browser control which demonstrates using Razor HTML output from templates that contain HTML syntax which happens to me my target scenario for Html Help Builder.   The Razor Engine Wrapper Project The project I created to wrap Razor hosting has a fair bit of code and a number of classes associated with it. Most of the components are internally used and as you can see using the final RazorEngine<T> and HostContainer classes is pretty easy. The classes are extensible and I suspect developers will want to build more customized host containers for their applications. Host containers are the key to wrapping up all functionality – Engine, BaseTemplate, AppDomain Hosting, Caching etc in a logical piece that is ready to be plugged into an application. When looking at the code there are a couple of core features provided: Core Razor Engine Hosting This is the core Razor hosting which provides the basics of loading a template, compiling it into an assembly and executing it. This is fairly straightforward, but without a host container that can cache assemblies based on some criteria templates are recompiled and re-created each time which is inefficient (although pretty fast). The base engine wrapper implementation also supports hosting the Razor runtime in a separate AppDomain for security and the ability to unload it on demand. Host Containers The engine hosting itself doesn’t provide any sort of ‘runtime’ service like picking up files from disk, caching assemblies and so forth. So my implementation provides two HostContainers: RazorFolderHostContainer and RazorStringHostContainer. The FolderHost works off a base directory and loads templates based on relative paths (sort of like the ASP.NET runtime does off a virtual). The HostContainers also deal with caching of template assemblies – for the folder host the file date is tracked and checked for updates and unless the template is changed a cached assembly is reused. The StringHostContainer similiarily checks string hashes to figure out whether a particular string template was previously compiled and executed. The HostContainers also act as a simple startup environment and a single reference to easily store and reuse in an application. TemplateBase Classes The template base classes are the base classes that from which the Razor engine generates .NET code. A template is parsed into a class with an Execute() method and the class is based on this template type you can specify. RazorEngine<TBaseTemplate> can receive this type and the HostContainers default to specific templates in their base implementations. Template classes are customizable to allow you to create templates that provide application specific features and interaction from the template to your host application. How does the RazorEngine wrapper work? You can browse the source code in the links above or in the repository or download the source, but I’ll highlight some key features here. Here’s part of the RazorEngine implementation that can be used to host the runtime and that demonstrates the key code required to host the Razor runtime. The RazorEngine class is implemented as a generic class to reflect the Template base class type: public class RazorEngine<TBaseTemplateType> : MarshalByRefObject where TBaseTemplateType : RazorTemplateBase The generic type is used to internally provide easier access to the template type and assignments on it as part of the template processing. The class also inherits MarshalByRefObject to allow execution over AppDomain boundaries – something that all the classes discussed here need to do since there is much interaction between the host and the template. The first two key methods deal with creating a template assembly: /// <summary> /// Creates an instance of the RazorHost with various options applied. /// Applies basic namespace imports and the name of the class to generate /// </summary> /// <param name="generatedNamespace"></param> /// <param name="generatedClass"></param> /// <returns></returns> protected RazorTemplateEngine CreateHost(string generatedNamespace, string generatedClass) { Type baseClassType = typeof(TBaseTemplateType); RazorEngineHost host = new RazorEngineHost(new CSharpRazorCodeLanguage()); host.DefaultBaseClass = baseClassType.FullName; host.DefaultClassName = generatedClass; host.DefaultNamespace = generatedNamespace; host.NamespaceImports.Add("System"); host.NamespaceImports.Add("System.Text"); host.NamespaceImports.Add("System.Collections.Generic"); host.NamespaceImports.Add("System.Linq"); host.NamespaceImports.Add("System.IO"); return new RazorTemplateEngine(host); } /// <summary> /// Parses and compiles a markup template into an assembly and returns /// an assembly name. The name is an ID that can be passed to /// ExecuteTemplateByAssembly which picks up a cached instance of the /// loaded assembly. /// /// </summary> /// <param name="namespaceOfGeneratedClass">The namespace of the class to generate from the template</param> /// <param name="generatedClassName">The name of the class to generate from the template</param> /// <param name="ReferencedAssemblies">Any referenced assemblies by dll name only. Assemblies must be in execution path of host or in GAC.</param> /// <param name="templateSourceReader">Textreader that loads the template</param> /// <remarks> /// The actual assembly isn't returned here to allow for cross-AppDomain /// operation. If the assembly was returned it would fail for cross-AppDomain /// calls. /// </remarks> /// <returns>An assembly Id. The Assembly is cached in memory and can be used with RenderFromAssembly.</returns> public string ParseAndCompileTemplate( string namespaceOfGeneratedClass, string generatedClassName, string[] ReferencedAssemblies, TextReader templateSourceReader) { RazorTemplateEngine engine = CreateHost(namespaceOfGeneratedClass, generatedClassName); // Generate the template class as CodeDom GeneratorResults razorResults = engine.GenerateCode(templateSourceReader); // Create code from the codeDom and compile CSharpCodeProvider codeProvider = new CSharpCodeProvider(); CodeGeneratorOptions options = new CodeGeneratorOptions(); // Capture Code Generated as a string for error info // and debugging LastGeneratedCode = null; using (StringWriter writer = new StringWriter()) { codeProvider.GenerateCodeFromCompileUnit(razorResults.GeneratedCode, writer, options); LastGeneratedCode = writer.ToString(); } CompilerParameters compilerParameters = new CompilerParameters(ReferencedAssemblies); // Standard Assembly References compilerParameters.ReferencedAssemblies.Add("System.dll"); compilerParameters.ReferencedAssemblies.Add("System.Core.dll"); compilerParameters.ReferencedAssemblies.Add("Microsoft.CSharp.dll"); // dynamic support! // Also add the current assembly so RazorTemplateBase is available compilerParameters.ReferencedAssemblies.Add(Assembly.GetExecutingAssembly().CodeBase.Substring(8)); compilerParameters.GenerateInMemory = Configuration.CompileToMemory; if (!Configuration.CompileToMemory) compilerParameters.OutputAssembly = Path.Combine(Configuration.TempAssemblyPath, "_" + Guid.NewGuid().ToString("n") + ".dll"); CompilerResults compilerResults = codeProvider.CompileAssemblyFromDom(compilerParameters, razorResults.GeneratedCode); if (compilerResults.Errors.Count > 0) { var compileErrors = new StringBuilder(); foreach (System.CodeDom.Compiler.CompilerError compileError in compilerResults.Errors) compileErrors.Append(String.Format(Resources.LineX0TColX1TErrorX2RN, compileError.Line, compileError.Column, compileError.ErrorText)); this.SetError(compileErrors.ToString() + "\r\n" + LastGeneratedCode); return null; } AssemblyCache.Add(compilerResults.CompiledAssembly.FullName, compilerResults.CompiledAssembly); return compilerResults.CompiledAssembly.FullName; } Think of the internal CreateHost() method as setting up the assembly generated from each template. Each template compiles into a separate assembly. It sets up namespaces, and assembly references, the base class used and the name and namespace for the generated class. ParseAndCompileTemplate() then calls the CreateHost() method to receive the template engine generator which effectively generates a CodeDom from the template – the template is turned into .NET code. The code generated from our earlier example looks something like this: //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:4.0.30319.1 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ namespace RazorTest { using System; using System.Text; using System.Collections.Generic; using System.Linq; using System.IO; using System.Reflection; public class RazorTemplate : RazorHosting.RazorTemplateBase { #line hidden public RazorTemplate() { } public override void Execute() { WriteLiteral("Hello "); Write(Context.FirstName); WriteLiteral("! Your entry was entered on: "); Write(Context.Entered); WriteLiteral("\r\n\r\n"); // Code block: Update the host Windows Form passed in through the context Context.WinForm.Text = "Hello World from Razor at " + DateTime.Now.ToString(); WriteLiteral("\r\nAppDomain Id:\r\n "); Write(AppDomain.CurrentDomain.FriendlyName); WriteLiteral("\r\n \r\nAssembly:\r\n "); Write(Assembly.GetExecutingAssembly().FullName); WriteLiteral("\r\n\r\nCode based output: \r\n"); // Write output with Response object from code string output = string.Empty; for (int i = 0; i < 10; i++) { output += i.ToString() + " "; } } } } Basically the template’s body is turned into code in an Execute method that is called. Internally the template’s Write method is fired to actually generate the output. Note that the class inherits from RazorTemplateBase which is the generic parameter I used to specify the base class when creating an instance in my RazorEngine host: var engine = new RazorEngine<RazorTemplateBase>(); This template class must be provided and it must implement an Execute() and Write() method. Beyond that you can create any class you chose and attach your own properties. My RazorTemplateBase class implementation is very simple: public class RazorTemplateBase : MarshalByRefObject, IDisposable { /// <summary> /// You can pass in a generic context object /// to use in your template code /// </summary> public dynamic Context { get; set; } /// <summary> /// Class that generates output. Currently ultra simple /// with only Response.Write() implementation. /// </summary> public RazorResponse Response { get; set; } public object HostContainer {get; set; } public object Engine { get; set; } public RazorTemplateBase() { Response = new RazorResponse(); } public virtual void Write(object value) { Response.Write(value); } public virtual void WriteLiteral(object value) { Response.Write(value); } /// <summary> /// Razor Parser implements this method /// </summary> public virtual void Execute() {} public virtual void Dispose() { if (Response != null) { Response.Dispose(); Response = null; } } } Razor fills in the Execute method when it generates its subclass and uses the Write() method to output content. As you can see I use a RazorResponse() class here to generate output. This isn’t necessary really, as you could use a StringBuilder or StringWriter() directly, but I prefer using Response object so I can extend the Response behavior as needed. The RazorResponse class is also very simple and merely acts as a wrapper around a TextWriter: public class RazorResponse : IDisposable { /// <summary> /// Internal text writer - default to StringWriter() /// </summary> public TextWriter Writer = new StringWriter(); public virtual void Write(object value) { Writer.Write(value); } public virtual void WriteLine(object value) { Write(value); Write("\r\n"); } public virtual void WriteFormat(string format, params object[] args) { Write(string.Format(format, args)); } public override string ToString() { return Writer.ToString(); } public virtual void Dispose() { Writer.Close(); } public virtual void SetTextWriter(TextWriter writer) { // Close original writer if (Writer != null) Writer.Close(); Writer = writer; } } The Rendering Methods of RazorEngine At this point I’ve talked about the assembly generation logic and the template implementation itself. What’s left is that once you’ve generated the assembly is to execute it. The code to do this is handled in the various RenderXXX methods of the RazorEngine class. Let’s look at the lowest level one of these which is RenderTemplateFromAssembly() and a couple of internal support methods that handle instantiating and invoking of the generated template method: public string RenderTemplateFromAssembly( string assemblyId, string generatedNamespace, string generatedClass, object context, TextWriter outputWriter) { this.SetError(); Assembly generatedAssembly = AssemblyCache[assemblyId]; if (generatedAssembly == null) { this.SetError(Resources.PreviouslyCompiledAssemblyNotFound); return null; } string className = generatedNamespace + "." + generatedClass; Type type; try { type = generatedAssembly.GetType(className); } catch (Exception ex) { this.SetError(Resources.UnableToCreateType + className + ": " + ex.Message); return null; } // Start with empty non-error response (if we use a writer) string result = string.Empty; using(TBaseTemplateType instance = InstantiateTemplateClass(type)) { if (instance == null) return null; if (outputWriter != null) instance.Response.SetTextWriter(outputWriter); if (!InvokeTemplateInstance(instance, context)) return null; // Capture string output if implemented and return // otherwise null is returned if (outputWriter == null) result = instance.Response.ToString(); } return result; } protected virtual TBaseTemplateType InstantiateTemplateClass(Type type) { TBaseTemplateType instance = Activator.CreateInstance(type) as TBaseTemplateType; if (instance == null) { SetError(Resources.CouldnTActivateTypeInstance + type.FullName); return null; } instance.Engine = this; // If a HostContainer was set pass that to the template too instance.HostContainer = this.HostContainer; return instance; } /// <summary> /// Internally executes an instance of the template, /// captures errors on execution and returns true or false /// </summary> /// <param name="instance">An instance of the generated template</param> /// <returns>true or false - check ErrorMessage for errors</returns> protected virtual bool InvokeTemplateInstance(TBaseTemplateType instance, object context) { try { instance.Context = context; instance.Execute(); } catch (Exception ex) { this.SetError(Resources.TemplateExecutionError + ex.Message); return false; } finally { // Must make sure Response is closed instance.Response.Dispose(); } return true; } The RenderTemplateFromAssembly method basically requires the namespace and class to instantate and creates an instance of the class using InstantiateTemplateClass(). It then invokes the method with InvokeTemplateInstance(). These two methods are broken out because they are re-used by various other rendering methods and also to allow subclassing and providing additional configuration tasks to set properties and pass values to templates at execution time. In the default mode instantiation sets the Engine and HostContainer (discussed later) so the template can call back into the template engine, and the context is set when the template method is invoked. The various RenderXXX methods use similar code although they create the assemblies first. If you’re after potentially cashing assemblies the method is the one to call and that’s exactly what the two HostContainer classes do. More on that in a minute, but before we get into HostContainers let’s talk about AppDomain hosting and the like. Running Templates in their own AppDomain With the RazorEngine class above, when a template is parsed into an assembly and executed the assembly is created (in memory or on disk – you can configure that) and cached in the current AppDomain. In .NET once an assembly has been loaded it can never be unloaded so if you’re loading lots of templates and at some time you want to release them there’s no way to do so. If however you load the assemblies in a separate AppDomain that new AppDomain can be unloaded and the assemblies loaded in it with it. In order to host the templates in a separate AppDomain the easiest thing to do is to run the entire RazorEngine in a separate AppDomain. Then all interaction occurs in the other AppDomain and no further changes have to be made. To facilitate this there is a RazorEngineFactory which has methods that can instantiate the RazorHost in a separate AppDomain as well as in the local AppDomain. The host creates the remote instance and then hangs on to it to keep it alive as well as providing methods to shut down the AppDomain and reload the engine. Sounds complicated but cross-AppDomain invocation is actually fairly easy to implement. Here’s some of the relevant code from the RazorEngineFactory class. Like the RazorEngine this class is generic and requires a template base type in the generic class name: public class RazorEngineFactory<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase Here are the key methods of interest: /// <summary> /// Creates an instance of the RazorHost in a new AppDomain. This /// version creates a static singleton that that is cached and you /// can call UnloadRazorHostInAppDomain to unload it. /// </summary> /// <returns></returns> public static RazorEngine<TBaseTemplateType> CreateRazorHostInAppDomain() { if (Current == null) Current = new RazorEngineFactory<TBaseTemplateType>(); return Current.GetRazorHostInAppDomain(); } public static void UnloadRazorHostInAppDomain() { if (Current != null) Current.UnloadHost(); Current = null; } /// <summary> /// Instance method that creates a RazorHost in a new AppDomain. /// This method requires that you keep the Factory around in /// order to keep the AppDomain alive and be able to unload it. /// </summary> /// <returns></returns> public RazorEngine<TBaseTemplateType> GetRazorHostInAppDomain() { LocalAppDomain = CreateAppDomain(null); if (LocalAppDomain == null) return null; /// Create the instance inside of the new AppDomain /// Note: remote domain uses local EXE's AppBasePath!!! RazorEngine<TBaseTemplateType> host = null; try { Assembly ass = Assembly.GetExecutingAssembly(); string AssemblyPath = ass.Location; host = (RazorEngine<TBaseTemplateType>) LocalAppDomain.CreateInstanceFrom(AssemblyPath, typeof(RazorEngine<TBaseTemplateType>).FullName).Unwrap(); } catch (Exception ex) { ErrorMessage = ex.Message; return null; } return host; } /// <summary> /// Internally creates a new AppDomain in which Razor templates can /// be run. /// </summary> /// <param name="appDomainName"></param> /// <returns></returns> private AppDomain CreateAppDomain(string appDomainName) { if (appDomainName == null) appDomainName = "RazorHost_" + Guid.NewGuid().ToString("n"); AppDomainSetup setup = new AppDomainSetup(); // *** Point at current directory setup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory; AppDomain localDomain = AppDomain.CreateDomain(appDomainName, null, setup); return localDomain; } /// <summary> /// Allow unloading of the created AppDomain to release resources /// All internal resources in the AppDomain are released including /// in memory compiled Razor assemblies. /// </summary> public void UnloadHost() { if (this.LocalAppDomain != null) { AppDomain.Unload(this.LocalAppDomain); this.LocalAppDomain = null; } } The static CreateRazorHostInAppDomain() is the key method that startup code usually calls. It uses a Current singleton instance to an instance of itself that is created cross AppDomain and is kept alive because it’s static. GetRazorHostInAppDomain actually creates a cross-AppDomain instance which first creates a new AppDomain and then loads the RazorEngine into it. The remote Proxy instance is returned as a result to the method and can be used the same as a local instance. The code to run with a remote AppDomain is simple: private RazorEngine<RazorTemplateBase> CreateHost() { if (this.Host != null) return this.Host; // Use Static Methods - no error message if host doesn't load this.Host = RazorEngineFactory<RazorTemplateBase>.CreateRazorHostInAppDomain(); if (this.Host == null) { MessageBox.Show("Unable to load Razor Template Host", "Razor Hosting", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); } return this.Host; } This code relies on a local reference of the Host which is kept around for the duration of the app (in this case a form reference). To use this you’d simply do: this.Host = CreateHost(); if (host == null) return; string result = host.RenderTemplate( this.txtSource.Text, new string[] { "System.Windows.Forms.dll", "Westwind.Utilities.dll" }, this.CustomContext); if (result == null) { MessageBox.Show(host.ErrorMessage, "Template Execution Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); return; } this.txtResult.Text = result; Now all templates run in a remote AppDomain and can be unloaded with simple code like this: RazorEngineFactory<RazorTemplateBase>.UnloadRazorHostInAppDomain(); this.Host = null; One Step further – Providing a caching ‘Runtime’ Once we can load templates in a remote AppDomain we can add some additional functionality like assembly caching based on application specific features. One of my typical scenarios is to render templates out of a scripts folder. So all templates live in a folder and they change infrequently. So a Folder based host that can compile these templates once and then only recompile them if something changes would be ideal. Enter host containers which are basically wrappers around the RazorEngine<t> and RazorEngineFactory<t>. They provide additional logic for things like file caching based on changes on disk or string hashes for string based template inputs. The folder host also provides for partial rendering logic through a custom template base implementation. There’s a base implementation in RazorBaseHostContainer, which provides the basics for hosting a RazorEngine, which includes the ability to start and stop the engine, cache assemblies and add references: public abstract class RazorBaseHostContainer<TBaseTemplateType> : MarshalByRefObject where TBaseTemplateType : RazorTemplateBase, new() { public RazorBaseHostContainer() { UseAppDomain = true; GeneratedNamespace = "__RazorHost"; } /// <summary> /// Determines whether the Container hosts Razor /// in a separate AppDomain. Seperate AppDomain /// hosting allows unloading and releasing of /// resources. /// </summary> public bool UseAppDomain { get; set; } /// <summary> /// Base folder location where the AppDomain /// is hosted. By default uses the same folder /// as the host application. /// /// Determines where binary dependencies are /// found for assembly references. /// </summary> public string BaseBinaryFolder { get; set; } /// <summary> /// List of referenced assemblies as string values. /// Must be in GAC or in the current folder of the host app/ /// base BinaryFolder /// </summary> public List<string> ReferencedAssemblies = new List<string>(); /// <summary> /// Name of the generated namespace for template classes /// </summary> public string GeneratedNamespace {get; set; } /// <summary> /// Any error messages /// </summary> public string ErrorMessage { get; set; } /// <summary> /// Cached instance of the Host. Required to keep the /// reference to the host alive for multiple uses. /// </summary> public RazorEngine<TBaseTemplateType> Engine; /// <summary> /// Cached instance of the Host Factory - so we can unload /// the host and its associated AppDomain. /// </summary> protected RazorEngineFactory<TBaseTemplateType> EngineFactory; /// <summary> /// Keep track of each compiled assembly /// and when it was compiled. /// /// Use a hash of the string to identify string /// changes. /// </summary> protected Dictionary<int, CompiledAssemblyItem> LoadedAssemblies = new Dictionary<int, CompiledAssemblyItem>(); /// <summary> /// Call to start the Host running. Follow by a calls to RenderTemplate to /// render individual templates. Call Stop when done. /// </summary> /// <returns>true or false - check ErrorMessage on false </returns> public virtual bool Start() { if (Engine == null) { if (UseAppDomain) Engine = RazorEngineFactory<TBaseTemplateType>.CreateRazorHostInAppDomain(); else Engine = RazorEngineFactory<TBaseTemplateType>.CreateRazorHost(); Engine.Configuration.CompileToMemory = true; Engine.HostContainer = this; if (Engine == null) { this.ErrorMessage = EngineFactory.ErrorMessage; return false; } } return true; } /// <summary> /// Stops the Host and releases the host AppDomain and cached /// assemblies. /// </summary> /// <returns>true or false</returns> public bool Stop() { this.LoadedAssemblies.Clear(); RazorEngineFactory<RazorTemplateBase>.UnloadRazorHostInAppDomain(); this.Engine = null; return true; } … } This base class provides most of the mechanics to host the runtime, but no application specific implementation for rendering. There are rendering functions but they just call the engine directly and provide no caching – there’s no context to decide how to cache and reuse templates. The key methods are Start and Stop and their main purpose is to start a new AppDomain (optionally) and shut it down when requested. The RazorFolderHostContainer – Folder Based Runtime Hosting Let’s look at the more application specific RazorFolderHostContainer implementation which is defined like this: public class RazorFolderHostContainer : RazorBaseHostContainer<RazorTemplateFolderHost> Note that a customized RazorTemplateFolderHost class template is used for this implementation that supports partial rendering in form of a RenderPartial() method that’s available to templates. The folder host’s features are: Render templates based on a Template Base Path (a ‘virtual’ if you will) Cache compiled assemblies based on the relative path and file time stamp File changes on templates cause templates to be recompiled into new assemblies Support for partial rendering using base folder relative pathing As shown in the startup examples earlier host containers require some startup code with a HostContainer tied to a persistent property (like a Form property): // The base path for templates - templates are rendered with relative paths // based on this path. HostContainer.TemplatePath = Path.Combine(Environment.CurrentDirectory, TemplateBaseFolder); // Default output rendering disk location HostContainer.RenderingOutputFile = Path.Combine(HostContainer.TemplatePath, "__Preview.htm"); // Add any assemblies you want reference in your templates HostContainer.ReferencedAssemblies.Add("System.Windows.Forms.dll"); // Start up the host container HostContainer.Start(); Once that’s done, you can render templates with the host container: // Pass the template path for full filename seleted with OpenFile Dialog // relativepath is: subdir\file.cshtml or file.cshtml or ..\file.cshtml var relativePath = Utilities.GetRelativePath(fileName, HostContainer.TemplatePath); if (!HostContainer.RenderTemplate(relativePath, Context, HostContainer.RenderingOutputFile)) { MessageBox.Show("Error: " + HostContainer.ErrorMessage); return; } webBrowser1.Navigate("file://" + HostContainer.RenderingOutputFile); The most critical task of the RazorFolderHostContainer implementation is to retrieve a template from disk, compile and cache it and then deal with deciding whether subsequent requests need to re-compile the template or simply use a cached version. Internally the GetAssemblyFromFileAndCache() handles this task: /// <summary> /// Internally checks if a cached assembly exists and if it does uses it /// else creates and compiles one. Returns an assembly Id to be /// used with the LoadedAssembly list. /// </summary> /// <param name="relativePath"></param> /// <param name="context"></param> /// <returns></returns> protected virtual CompiledAssemblyItem GetAssemblyFromFileAndCache(string relativePath) { string fileName = Path.Combine(TemplatePath, relativePath).ToLower(); int fileNameHash = fileName.GetHashCode(); if (!File.Exists(fileName)) { this.SetError(Resources.TemplateFileDoesnTExist + fileName); return null; } CompiledAssemblyItem item = null; this.LoadedAssemblies.TryGetValue(fileNameHash, out item); string assemblyId = null; // Check for cached instance if (item != null) { var fileTime = File.GetLastWriteTimeUtc(fileName); if (fileTime <= item.CompileTimeUtc) assemblyId = item.AssemblyId; } else item = new CompiledAssemblyItem(); // No cached instance - create assembly and cache if (assemblyId == null) { string safeClassName = GetSafeClassName(fileName); StreamReader reader = null; try { reader = new StreamReader(fileName, true); } catch (Exception ex) { this.SetError(Resources.ErrorReadingTemplateFile + fileName); return null; } assemblyId = Engine.ParseAndCompileTemplate(this.ReferencedAssemblies.ToArray(), reader); // need to ensure reader is closed if (reader != null) reader.Close(); if (assemblyId == null) { this.SetError(Engine.ErrorMessage); return null; } item.AssemblyId = assemblyId; item.CompileTimeUtc = DateTime.UtcNow; item.FileName = fileName; item.SafeClassName = safeClassName; this.LoadedAssemblies[fileNameHash] = item; } return item; } This code uses a LoadedAssembly dictionary which is comprised of a structure that holds a reference to a compiled assembly, a full filename and file timestamp and an assembly id. LoadedAssemblies (defined on the base class shown earlier) is essentially a cache for compiled assemblies and they are identified by a hash id. In the case of files the hash is a GetHashCode() from the full filename of the template. The template is checked for in the cache and if not found the file stamp is checked. If that’s newer than the cache’s compilation date the template is recompiled otherwise the version in the cache is used. All the core work defers to a RazorEngine<T> instance to ParseAndCompileTemplate(). The three rendering specific methods then are rather simple implementations with just a few lines of code dealing with parameter and return value parsing: /// <summary> /// Renders a template to a TextWriter. Useful to write output into a stream or /// the Response object. Used for partial rendering. /// </summary> /// <param name="relativePath">Relative path to the file in the folder structure</param> /// <param name="context">Optional context object or null</param> /// <param name="writer">The textwriter to write output into</param> /// <returns></returns> public bool RenderTemplate(string relativePath, object context, TextWriter writer) { // Set configuration data that is to be passed to the template (any object) Engine.TemplatePerRequestConfigurationData = new RazorFolderHostTemplateConfiguration() { TemplatePath = Path.Combine(this.TemplatePath, relativePath), TemplateRelativePath = relativePath, }; CompiledAssemblyItem item = GetAssemblyFromFileAndCache(relativePath); if (item == null) { writer.Close(); return false; } try { // String result will be empty as output will be rendered into the // Response object's stream output. However a null result denotes // an error string result = Engine.RenderTemplateFromAssembly(item.AssemblyId, context, writer); if (result == null) { this.SetError(Engine.ErrorMessage); return false; } } catch (Exception ex) { this.SetError(ex.Message); return false; } finally { writer.Close(); } return true; } /// <summary> /// Render a template from a source file on disk to a specified outputfile. /// </summary> /// <param name="relativePath">Relative path off the template root folder. Format: path/filename.cshtml</param> /// <param name="context">Any object that will be available in the template as a dynamic of this.Context</param> /// <param name="outputFile">Optional - output file where output is written to. If not specified the /// RenderingOutputFile property is used instead /// </param> /// <returns>true if rendering succeeds, false on failure - check ErrorMessage</returns> public bool RenderTemplate(string relativePath, object context, string outputFile) { if (outputFile == null) outputFile = RenderingOutputFile; try { using (StreamWriter writer = new StreamWriter(outputFile, false, Engine.Configuration.OutputEncoding, Engine.Configuration.StreamBufferSize)) { return RenderTemplate(relativePath, context, writer); } } catch (Exception ex) { this.SetError(ex.Message); return false; } return true; } /// <summary> /// Renders a template to string. Useful for RenderTemplate /// </summary> /// <param name="relativePath"></param> /// <param name="context"></param> /// <returns></returns> public string RenderTemplateToString(string relativePath, object context) { string result = string.Empty; try { using (StringWriter writer = new StringWriter()) { // String result will be empty as output will be rendered into the // Response object's stream output. However a null result denotes // an error if (!RenderTemplate(relativePath, context, writer)) { this.SetError(Engine.ErrorMessage); return null; } result = writer.ToString(); } } catch (Exception ex) { this.SetError(ex.Message); return null; } return result; } The idea is that you can create custom host container implementations that do exactly what you want fairly easily. Take a look at both the RazorFolderHostContainer and RazorStringHostContainer classes for the basic concepts you can use to create custom implementations. Notice also that you can set the engine’s PerRequestConfigurationData() from the host container: // Set configuration data that is to be passed to the template (any object) Engine.TemplatePerRequestConfigurationData = new RazorFolderHostTemplateConfiguration() { TemplatePath = Path.Combine(this.TemplatePath, relativePath), TemplateRelativePath = relativePath, }; which when set to a non-null value is passed to the Template’s InitializeTemplate() method. This method receives an object parameter which you can cast as needed: public override void InitializeTemplate(object configurationData) { // Pick up configuration data and stuff into Request object RazorFolderHostTemplateConfiguration config = configurationData as RazorFolderHostTemplateConfiguration; this.Request.TemplatePath = config.TemplatePath; this.Request.TemplateRelativePath = config.TemplateRelativePath; } With this data you can then configure any custom properties or objects on your main template class. It’s an easy way to pass data from the HostContainer all the way down into the template. The type you use is of type object so you have to cast it yourself, and it must be serializable since it will likely run in a separate AppDomain. This might seem like an ugly way to pass data around – normally I’d use an event delegate to call back from the engine to the host, but since this is running over AppDomain boundaries events get really tricky and passing a template instance back up into the host over AppDomain boundaries doesn’t work due to serialization issues. So it’s easier to pass the data from the host down into the template using this rather clumsy approach of set and forward. It’s ugly, but it’s something that can be hidden in the host container implementation as I’ve done here. It’s also not something you have to do in every implementation so this is kind of an edge case, but I know I’ll need to pass a bunch of data in some of my applications and this will be the easiest way to do so. Summing Up Hosting the Razor runtime is something I got jazzed up about quite a bit because I have an immediate need for this type of templating/merging/scripting capability in an application I’m working on. I’ve also been using templating in many apps and it’s always been a pain to deal with. The Razor engine makes this whole experience a lot cleaner and more light weight and with these wrappers I can now plug .NET based templating into my code literally with a few lines of code. That’s something to cheer about… I hope some of you will find this useful as well… Resources The examples and code require that you download the Razor runtimes. Projects are for Visual Studio 2010 running on .NET 4.0 Platform Installer 3.0 (install WebMatrix or MVC 3 for Razor Runtimes) Latest Code in Subversion Repository Download Snapshot of the Code Documentation (CHM Help File) © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  .NET  

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• Load and Web Performance Testing using Visual Studio Ultimate 2010-Part 3

  - by Tarun Arora

  Welcome back once again, in Part 1 of Load and Web Performance Testing using Visual Studio 2010 I talked about why Performance Testing the application is important, the test tools available in Visual Studio Ultimate 2010 and various test rig topologies, in Part 2 of Load and Web Performance Testing using Visual Studio 2010 I discussed the details of web performance & load tests as well as why it’s important to follow a goal based pattern while performance testing your application. In part 3 I’ll be discussing Test Result Analysis, Test Result Drill through, Test Report Generation, Test Run Comparison, Asp.net Profiler and some closing thoughts. Test Results – I see some creepy worms! In Part 2 we put together a web performance test and a load test, lets run the test to see load test to see how the Web site responds to the load simulation. While the load test is running you will be able to see close to real time analysis in the Load Test Analyser window. You can use the Load Test Analyser to conduct load test analysis in three ways: Monitor a running load test - A condensed set of the performance counter data is maintained in memory. To prevent the results memory requirements from growing unbounded, up to 200 samples for each performance counter are maintained. This includes 100 evenly spaced samples that span the current elapsed time of the run and the most recent 100 samples.         After the load test run is completed - The test controller spools all collected performance counter data to a database while the test is running. Additional data, such as timing details and error details, is loaded into the database when the test completes. The performance data for a completed test is loaded from the database and analysed by the Load Test Analyser. Below you can see a screen shot of the summary view, this provides key results in a format that is compact and easy to read. You can also print the load test summary, this is generated after the test has completed or been stopped.         Analyse the load test results of a previously run load test – We’ll see this in the section where i discuss comparison between two test runs. The performance counters can be plotted on the graphs. You also have the option to highlight a selected part of the test and view details, drill down to the user activity chart where you can hover over to see more details of the test run.   Generate Report => Test Run Comparisons The level of reports you can generate using the Load Test Analyser is astonishing. You have the option to create excel reports and conduct side by side analysis of two test results or to track trend analysis. The tools also allows you to export the graph data either to MS Excel or to a CSV file. You can view the ASP.NET profiler report to conduct further analysis as well. View Data and Diagnostic Attachments opens the Choose Diagnostic Data Adapter Attachment dialog box to select an adapter to analyse the result type. For example, you can select an IntelliTrace adapter, click OK and open the IntelliTrace summary for the test agent that was used in the load test.   Compare results This creates a set of reports that compares the data from two load test results using tables and bar charts. I have taken these screen shots from the MSDN documentation, I would highly recommend exploring the wealth of knowledge available on MSDN. Leaving Thoughts While load testing the application with an excessive load for a longer duration of time, i managed to bring the IIS to its knees by piling up a huge queue of requests waiting to be processed. This clearly means that the IIS had run out of threads as all the threads were busy processing existing request, one easy way of fixing this is by increasing the default number of allocated threads, but this might escalate the problem. The better suggestion is to try and drill down to the actual root cause of the problem. When ever the garbage collection runs it stops processing any pages so all requests that come in during that period are queued up, but realistically the garbage collection completes in fraction of a a second. To understand this better lets look at the .net heap, it is divided into large heap and small heap, anything greater than 85kB in size will be allocated to the Large object heap, the Large object heap is non compacting and remember large objects are expensive to move around, so if you are allocating something in the large object heap, make sure that you really need it! The small object heap on the other hand is divided into generations, so all objects that are supposed to be short-lived are suppose to live in Gen-0 and the long living objects eventually move to Gen-2 as garbage collection goes through.  As you can see in the picture below all < 85 KB size objects are first assigned to Gen-0, when Gen-0 fills up and a new object comes in and finds Gen-0 full, the garbage collection process is started, the process checks for all the dead objects and assigns them as the valid candidate for deletion to free up memory and promotes all the remaining objects in Gen-0 to Gen-1. So in the future when ever you clean up Gen-1 you have to clean up Gen-0 as well. When you fill up Gen – 0 again, all of Gen – 1 dead objects are drenched and rest are moved to Gen-2 and Gen-0 objects are moved to Gen-1 to free up Gen-0, but by this time your Garbage collection process has started to take much more time than it usually takes. Now as I mentioned earlier when garbage collection is being run all page requests that come in during that period are queued up. Does this explain why possibly page requests are getting queued up, apart from this it could also be the case that you are waiting for a long running database process to complete.      Lets explore the heap a bit more… What is really a case of crisis is when the objects are living long enough to make it to Gen-2 and then dying, this is definitely a high cost operation. But sometimes you need objects in memory, for example when you cache data you hold on to the objects because you need to use them right across the user session, which is acceptable. But if you wanted to see what extreme caching can do to your server then write a simple application that chucks in a lot of data in cache, run a load test over it for about 10-15 minutes, forcing a lot of data in memory causing the heap to run out of memory. If you get to such a state where you start running out of memory the IIS as a mode of recovery restarts the worker process. It is great way to free up all your memory in the heap but this would clear the cache. The problem with this is if the customer had 10 items in their shopping basket and that data was stored in the application cache, the user basket will now be empty forcing them either to get frustrated and go to a competitor website or if the customer is really patient, give it another try! How can you address this, well two ways of addressing this; 1. Workaround – A x86 bit processor only allows a maximum of 4GB of RAM, this means the machine effectively has around 3.4 GB of RAM available, the OS needs about 1.5 GB of RAM to run efficiently, the IIS and .net framework also need their share of memory, leaving you a heap of around 800 MB to play with. Because Team builds by default build your application in ‘Compile as any mode’ it means the application is build such that it will run in x86 bit mode if run on a x86 bit processor and run in a x64 bit mode if run on a x64 but processor. The problem with this is not all applications are really x64 bit compatible specially if you are using com objects or external libraries. So, as a quick win if you compiled your application in x86 bit mode by changing the compile as any selection to compile as x86 in the team build, you will be able to run your application on a x64 bit machine in x86 bit mode (WOW – By running Windows on Windows) and what that means is, you could use 8GB+ worth of RAM, if you take away everything else your application will roughly get a heap size of at least 4 GB to play with, which is immense. If you need a heap size of more than 4 GB you have either build a software for NASA or there is something fundamentally wrong in your application. 2. Solution – Now that you have put a workaround in place the IIS will not restart the worker process that regularly, which means you can take a breather and start working to get to the root cause of this memory leak. But this begs a question “How do I Identify possible memory leaks in my application?” Well i won’t say that there is one single tool that can tell you where the memory leak is, but trust me, ‘Performance Profiling’ is a great start point, it definitely gets you started in the right direction, let’s have a look at how. Performance Wizard - Start the Performance Wizard and select Instrumentation, this lets you measure function call counts and timings. Before running the performance session right click the performance session settings and chose properties from the context menu to bring up the Performance session properties page and as shown in the screen shot below, check the check boxes in the group ‘.NET memory profiling collection’ namely ‘Collect .NET object allocation information’ and ‘Also collect the .NET Object lifetime information’.    Now if you fire off the profiling session on your pages you will notice that the results allows you to view ‘Object Lifetime’ which shows you the number of objects that made it to Gen-0, Gen-1, Gen-2, Large heap, etc. Another great feature about the profile is that if your application has > 5% cases where objects die right after making to the Gen-2 storage a threshold alert is generated to alert you. Since you have the option to also view the most expensive methods and by capturing the IntelliTrace data you can drill in to narrow down to the line of code that is the root cause of the problem. Well now that we have seen how crucial memory management is and how easy Visual Studio Ultimate 2010 makes it for us to identify and reproduce the problem with the best of breed tools in the product. Caching One of the main ways to improve performance is Caching. Which basically means you tell the web server that instead of going to the database for each request you keep the data in the webserver and when the user asks for it you serve it from the webserver itself. BUT that can have consequences! Let’s look at some code, trust me caching code is not very intuitive, I define a cache key for almost all searches made through the common search page and cache the results. The approach works fine, first time i get the data from the database and second time data is served from the cache, significant performance improvement, EXCEPT when two users try to do the same operation and run into each other. But it is easy to handle this by adding the lock as you can see in the snippet below. So, as long as a user comes in and finds that the cache is empty, the user locks and starts to get the cache no more concurrency issues. But lets say you are processing 10 requests per second, by the time i have locked the operation to get the results from the database, 9 other users came in and found that the cache key is null so after i have come out and populated the cache they will still go in to get the results again. The application will still be faster because the next set of 10 users and so on would continue to get data from the cache. BUT if we added another null check after locking to build the cache and before actual call to the db then the 9 users who follow me would not make the extra trip to the database at all and that would really increase the performance, but didn’t i say that the code won’t be very intuitive, may be you should leave a comment you don’t want another developer to come in and think what a fresher why is he checking for the cache key null twice !!! The downside of caching is, you are storing the data outside of the database and the data could be wrong because the updates applied to the database would make the data cached at the web server out of sync. So, how do you invalidate the cache? Well if you only had one way of updating the data lets say only one entry point to the data update you can write some logic to say that every time new data is entered set the cache object to null. But this approach will not work as soon as you have several ways of feeding data to the system or your system is scaled out across a farm of web servers. The perfect solution to this is Micro Caching which means you cache the query for a set time duration and invalidate the cache after that set duration. The advantage is every time the user queries for that data with in the time span for which you have cached the results there are no calls made to the database and the data is served right from the server which makes the response immensely quick. Now figuring out the appropriate time span for which you micro cache the query results really depends on the application. Lets say your website gets 10 requests per second, if you retain the cache results for even 1 minute you will have immense performance gains. You would reduce 90% hits to the database for searching. Ever wondered why when you go to e-bookers.com or xpedia.com or yatra.com to book a flight and you click on the book button because the fare seems too exciting and you get an error message telling you that the fare is not valid any more. Yes, exactly => That is a cache failure! These travel sites or price compare engines are not going to hit the database every time you hit the compare button instead the results will be served from the cache, because the query results are micro cached, its a perfect trade-off, by micro caching the results the site gains 100% performance benefits but every once in a while annoys a customer because the fare has expired. But the trade off works in the favour of these sites as they are still able to process up to 30+ page requests per second which means cater to the site traffic by may be losing 1 customer every once in a while to a competitor who is also using a similar caching technique what are the odds that the user will not come back to their site sooner or later? Recap   Resources Below are some Key resource you might like to review. I would highly recommend the documentation, walkthroughs and videos available on MSDN. You can always make use of Fiddler to debug Web Performance Tests. Some community test extensions and plug ins available on Codeplex might also be of interest to you. The Road Ahead Thank you for taking the time out and reading this blog post, you may also want to read Part I and Part II if you haven’t so far. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Questions/Feedback/Suggestions, etc please leave a comment. Next ‘Load Testing in the cloud’, I’ll be working on exploring the possibilities of running Test controller/Agents in the Cloud. See you on the other side! Thank You!   Share this post : CodeProject

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• Loosely coupled .NET Cache Provider using Dependency Injection

  - by Rhames

  I have recently been reading the excellent book “Dependency Injection in .NET”, written by Mark Seemann. I do not generally buy software development related books, as I never seem to have the time to read them, but I have found the time to read Mark’s book, and it was time well spent I think. Reading the ideas around Dependency Injection made me realise that the Cache Provider code I wrote about earlier (see http://geekswithblogs.net/Rhames/archive/2011/01/10/using-the-asp.net-cache-to-cache-data-in-a-model.aspx) could be refactored to use Dependency Injection, which should produce cleaner code. The goals are to: Separate the cache provider implementation (using the ASP.NET data cache) from the consumers (loose coupling). This will also mean that the dependency on System.Web for the cache provider does not ripple down into the layers where it is being consumed (such as the domain layer). Provide a decorator pattern to allow a consumer of the cache provider to be implemented separately from the base consumer (i.e. if we have a base repository, we can decorate this with a caching version). Although I used the term repository, in reality the cache consumer could be just about anything. Use constructor injection to provide the Dependency Injection, with a suitable DI container (I use Castle Windsor). The sample code for this post is available on github, https://github.com/RobinHames/CacheProvider.git ICacheProvider In the sample code, the key interface is ICacheProvider, which is in the domain layer. 1: using System; 2: using System.Collections.Generic; 3:   4: namespace CacheDiSample.Domain 5: { 6: public interface ICacheProvider<T> 7: { 8: T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); 9: IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); 10: } 11: }   This interface contains two methods to retrieve data from the cache, either as a single instance or as an IEnumerable. the second paramerter is of type Func<T>. This is the method used to retrieve data if nothing is found in the cache. The ASP.NET implementation of the ICacheProvider interface needs to live in a project that has a reference to system.web, typically this will be the root UI project, or it could be a separate project. The key thing is that the domain or data access layers do not need system.web references adding to them. In my sample MVC application, the CacheProvider is implemented in the UI project, in a folder called “CacheProviders”: 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Web; 5: using System.Web.Caching; 6: using CacheDiSample.Domain; 7:   8: namespace CacheDiSample.CacheProvider 9: { 10: public class CacheProvider<T> : ICacheProvider<T> 11: { 12: public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) 13: { 14: return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry); 15: } 16:   17: public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) 18: { 19: return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry); 20: } 21:   22: #region Helper Methods 23:   24: private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) 25: { 26: U value; 27: if (!TryGetValue<U>(key, out value)) 28: { 29: value = retrieveData(); 30: if (!absoluteExpiry.HasValue) 31: absoluteExpiry = Cache.NoAbsoluteExpiration; 32:   33: if (!relativeExpiry.HasValue) 34: relativeExpiry = Cache.NoSlidingExpiration; 35:   36: HttpContext.Current.Cache.Insert(key, value, null, absoluteExpiry.Value, relativeExpiry.Value); 37: } 38: return value; 39: } 40:   41: private bool TryGetValue<U>(string key, out U value) 42: { 43: object cachedValue = HttpContext.Current.Cache.Get(key); 44: if (cachedValue == null) 45: { 46: value = default(U); 47: return false; 48: } 49: else 50: { 51: try 52: { 53: value = (U)cachedValue; 54: return true; 55: } 56: catch 57: { 58: value = default(U); 59: return false; 60: } 61: } 62: } 63:   64: #endregion 65:   66: } 67: }   The FetchAndCache helper method checks if the specified cache key exists, if it does not, the Func<U> retrieveData method is called, and the results are added to the cache. Using Castle Windsor to register the cache provider In the MVC UI project (my application root), Castle Windsor is used to register the CacheProvider implementation, using a Windsor Installer: 1: using Castle.MicroKernel.Registration; 2: using Castle.MicroKernel.SubSystems.Configuration; 3: using Castle.Windsor; 4:   5: using CacheDiSample.Domain; 6: using CacheDiSample.CacheProvider; 7:   8: namespace CacheDiSample.WindsorInstallers 9: { 10: public class CacheInstaller : IWindsorInstaller 11: { 12: public void Install(IWindsorContainer container, IConfigurationStore store) 13: { 14: container.Register( 15: Component.For(typeof(ICacheProvider<>)) 16: .ImplementedBy(typeof(CacheProvider<>)) 17: .LifestyleTransient()); 18: } 19: } 20: }   Note that the cache provider is registered as a open generic type. Consuming a Repository I have an existing couple of repository interfaces defined in my domain layer: IRepository.cs 1: using System; 2: using System.Collections.Generic; 3:   4: using CacheDiSample.Domain.Model; 5:   6: namespace CacheDiSample.Domain.Repositories 7: { 8: public interface IRepository<T> 9: where T : EntityBase 10: { 11: T GetById(int id); 12: IList<T> GetAll(); 13: } 14: }   IBlogRepository.cs 1: using System; 2: using CacheDiSample.Domain.Model; 3:   4: namespace CacheDiSample.Domain.Repositories 5: { 6: public interface IBlogRepository : IRepository<Blog> 7: { 8: Blog GetByName(string name); 9: } 10: }   These two repositories are implemented in the DataAccess layer, using Entity Framework to retrieve data (this is not important though). One important point is that in the BaseRepository implementation of IRepository, the methods are virtual. This will allow the decorator to override them. The BlogRepository is registered in a RepositoriesInstaller, again in the MVC UI project. 1: using Castle.MicroKernel.Registration; 2: using Castle.MicroKernel.SubSystems.Configuration; 3: using Castle.Windsor; 4:   5: using CacheDiSample.Domain.CacheDecorators; 6: using CacheDiSample.Domain.Repositories; 7: using CacheDiSample.DataAccess; 8:   9: namespace CacheDiSample.WindsorInstallers 10: { 11: public class RepositoriesInstaller : IWindsorInstaller 12: { 13: public void Install(IWindsorContainer container, IConfigurationStore store) 14: { 15: container.Register(Component.For<IBlogRepository>() 16: .ImplementedBy<BlogRepository>() 17: .LifestyleTransient() 18: .DependsOn(new 19: { 20: nameOrConnectionString = "BloggingContext" 21: })); 22: } 23: } 24: }   Now I can inject a dependency on the IBlogRepository into a consumer, such as a controller in my sample code: 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Web; 5: using System.Web.Mvc; 6:   7: using CacheDiSample.Domain.Repositories; 8: using CacheDiSample.Domain.Model; 9:   10: namespace CacheDiSample.Controllers 11: { 12: public class HomeController : Controller 13: { 14: private readonly IBlogRepository blogRepository; 15:   16: public HomeController(IBlogRepository blogRepository) 17: { 18: if (blogRepository == null) 19: throw new ArgumentNullException("blogRepository"); 20:   21: this.blogRepository = blogRepository; 22: } 23:   24: public ActionResult Index() 25: { 26: ViewBag.Message = "Welcome to ASP.NET MVC!"; 27:   28: var blogs = blogRepository.GetAll(); 29:   30: return View(new Models.HomeModel { Blogs = blogs }); 31: } 32:   33: public ActionResult About() 34: { 35: return View(); 36: } 37: } 38: }   Consuming the Cache Provider via a Decorator I used a Decorator pattern to consume the cache provider, this means my repositories follow the open/closed principle, as they do not require any modifications to implement the caching. It also means that my controllers do not have any knowledge of the caching taking place, as the DI container will simply inject the decorator instead of the root implementation of the repository. The first step is to implement a BlogRepository decorator, with the caching logic in it. Note that this can reside in the domain layer, as it does not require any knowledge of the data access methods. BlogRepositoryWithCaching.cs 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5:   6: using CacheDiSample.Domain.Model; 7: using CacheDiSample.Domain; 8: using CacheDiSample.Domain.Repositories; 9:   10: namespace CacheDiSample.Domain.CacheDecorators 11: { 12: public class BlogRepositoryWithCaching : IBlogRepository 13: { 14: // The generic cache provider, injected by DI 15: private ICacheProvider<Blog> cacheProvider; 16: // The decorated blog repository, injected by DI 17: private IBlogRepository parentBlogRepository; 18:   19: public BlogRepositoryWithCaching(IBlogRepository parentBlogRepository, ICacheProvider<Blog> cacheProvider) 20: { 21: if (parentBlogRepository == null) 22: throw new ArgumentNullException("parentBlogRepository"); 23:   24: this.parentBlogRepository = parentBlogRepository; 25:   26: if (cacheProvider == null) 27: throw new ArgumentNullException("cacheProvider"); 28:   29: this.cacheProvider = cacheProvider; 30: } 31:   32: public Blog GetByName(string name) 33: { 34: string key = string.Format("CacheDiSample.DataAccess.GetByName.{0}", name); 35: // hard code 5 minute expiry! 36: TimeSpan relativeCacheExpiry = new TimeSpan(0, 5, 0); 37: return cacheProvider.Fetch(key, () => 38: { 39: return parentBlogRepository.GetByName(name); 40: }, 41: null, relativeCacheExpiry); 42: } 43:   44: public Blog GetById(int id) 45: { 46: string key = string.Format("CacheDiSample.DataAccess.GetById.{0}", id); 47:   48: // hard code 5 minute expiry! 49: TimeSpan relativeCacheExpiry = new TimeSpan(0, 5, 0); 50: return cacheProvider.Fetch(key, () => 51: { 52: return parentBlogRepository.GetById(id); 53: }, 54: null, relativeCacheExpiry); 55: } 56:   57: public IList<Blog> GetAll() 58: { 59: string key = string.Format("CacheDiSample.DataAccess.GetAll"); 60:   61: // hard code 5 minute expiry! 62: TimeSpan relativeCacheExpiry = new TimeSpan(0, 5, 0); 63: return cacheProvider.Fetch(key, () => 64: { 65: return parentBlogRepository.GetAll(); 66: }, 67: null, relativeCacheExpiry) 68: .ToList(); 69: } 70: } 71: }   The key things in this caching repository are: I inject into the repository the ICacheProvider<Blog> implementation, via the constructor. This will make the cache provider functionality available to the repository. I inject the parent IBlogRepository implementation (which has the actual data access code), via the constructor. This will allow the methods implemented in the parent to be called if nothing is found in the cache. I override each of the methods implemented in the repository, including those implemented in the generic BaseRepository. Each override of these methods follows the same pattern. It makes a call to the CacheProvider.Fetch method, and passes in the parentBlogRepository implementation of the method as the retrieval method, to be used if nothing is present in the cache. Configuring the Caching Repository in the DI Container The final piece of the jigsaw is to tell Castle Windsor to use the BlogRepositoryWithCaching implementation of IBlogRepository, but to inject the actual Data Access implementation into this decorator. This is easily achieved by modifying the RepositoriesInstaller to use Windsor’s implicit decorator wiring: 1: using Castle.MicroKernel.Registration; 2: using Castle.MicroKernel.SubSystems.Configuration; 3: using Castle.Windsor; 4:   5: using CacheDiSample.Domain.CacheDecorators; 6: using CacheDiSample.Domain.Repositories; 7: using CacheDiSample.DataAccess; 8:   9: namespace CacheDiSample.WindsorInstallers 10: { 11: public class RepositoriesInstaller : IWindsorInstaller 12: { 13: public void Install(IWindsorContainer container, IConfigurationStore store) 14: { 15:   16: // Use Castle Windsor implicit wiring for the block repository decorator 17: // Register the outermost decorator first 18: container.Register(Component.For<IBlogRepository>() 19: .ImplementedBy<BlogRepositoryWithCaching>() 20: .LifestyleTransient()); 21: // Next register the IBlogRepository inmplementation to inject into the outer decorator 22: container.Register(Component.For<IBlogRepository>() 23: .ImplementedBy<BlogRepository>() 24: .LifestyleTransient() 25: .DependsOn(new 26: { 27: nameOrConnectionString = "BloggingContext" 28: })); 29: } 30: } 31: }   This is all that is needed. Now if the consumer of the repository makes a call to the repositories method, it will be routed via the caching mechanism. You can test this by stepping through the code, and seeing that the DataAccess.BlogRepository code is only called if there is no data in the cache, or this has expired. The next step is to add the SQL Cache Dependency support into this pattern, this will be a future post.

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• From Pocket to Instapaper

  - by Michael Freidgeim

  Some time ago I’ve described the issues that I’ve had since a new version of Read It Later, named Pocket, was introduced.I’ve waited with hope for a new upgrade, but I had a huge disappointment with the latest version 16 June 2012. It didn’t fixed any of the two major problems, that I  experienced since new Pocket was introduced-  1. iPad app still didn’t show many of the saved links. 2. ability to rename articles on iPad still wasn’t restored.I’ve posted the message into their forum. They did not show my comment on their forum( I would name it censorship, not moderation), but a few days ago I’ve received an email, recommending “try logging out of the app on your iPad, and back in again.” Their suggestion helped,  but I don’t understand, why it is not posted as a recommendation on their support site.So I decided to try InstAPaper on my iPad, Previously I’ve used it for Kindle. I never considered it before on iPad, because there were no free demo and I was very satisfied with RIL free and then RIL Pro. Currently InstAPaper cost $3, so the price is not an issue.I’ve checked that it has most of features that I am using(e.g. renaming, folders) and I am quite happy with it now. Actually I am using Pocket (or RIL free) for old bookmarks( I have 1000+ stored on my iPad) and for new bookmarks I am using InstAPaper.Having a solid experience with RIL/Pocket I’ve created a list of suggestions to Marco Arment to implement.1. Some pages stored in InstAPaper have removed essential sections of the text. E.g in many blogs comments are not stored in  InstAPaper. Some pages lost almost all of important links (e.g. http://www.lib.rus.ec/a/32416 -sorry, in Russian). RIL/Pocket has 2 modes to store offline- Web view and Article view. Web View includes all links/images of the original page, but it’s very reliable. Article view suppose to strip unrelated information, but often corrupts the content. I prefer to use offline Web view.InstAPaper should also support offline Web view, in case if stripped view removes important part of content.2.  Black full screen Saving on iPad Safari is very annoying. After user pressed a bookmark, the saving has some delay and then for a few seconds prevents from reading the text.Would be better to show as message on the top part(as in Pocket ). I am surprised, that  a full screen popup was  implemented recently as a desired feature. 3.There are no comments allowed on http://blog.instapaper.com/. I would prefer to post some of these notes as comments on http://blog.instapaper.com/ rather than write them in my blog and then send link to Marco.(I found recommendation how to add support of comments on tumblr at http://www.tumblr.com/help, but then realized that Marko was the lead developer ofTumblr.)4. Also there is no support forum. I understand that maintenance of the forum ican be a hassle, but stackexchange fSome time ago I’ve described the issues that I’ve had since a new version of Read It Later, named Pocket, was introduced.I’ve waited with hope for a new upgrade, but I had a huge disappointment with the latest version 16 June 2012. It didn’t fixed any of the two major problems, that I  experienced since new Pocket was introduced- orums can be referred on  http://www.instapaper.com/main/support page, i.e.http://webapps.stackexchange.com/search?q=Instapaper  or http://apple.stackexchange.com/search?q=Instapaper 5. Tags are more convenient than folders. i.e. an ability for the same article to have more than one tag. Also creating of new folders is not supported offline, which is an annoying limitation.6. I would like to have a narrow list - additionally to existing list modes have a subject only list or subject+site list to show more list items on a screen.7. Limit of 500 offline articles sounds quite big, but my RIL list exceeded 1000, so it could be a issue in the future.8. Search button on iPad version is visible, but doesn’t work- it forces to buy Premium subscription. I think, that it’s not correct. If the button in a paid version is visible and enabled, it should  provide  a working functionality, e.g. search in article names only. And leave full-text search for the premium support.9..Copy URL is an important operation and deserves to be in a first level of Action menu, rather than in Share sub-menu.I’ve also have comment re post http://www.marco.org/2011/04/28/removed-instapaper-free. Marco Arment  explained, why he doesn’t provide free version of Instapaper.  I believe that he is loosing essential part of his customers. When I decided which of iPad application to choose, I’ve selected RIL, because I was able to play with free version, and I liked it. I didn’t have a chance to compare RIL and InstAPaper on iPad, so I’ve bought  RIL pro. For a user there is no point to pay even $3 , if there are similar free product, that user can try and see, is it suitable for him/her.I’ve also played with Readability. It doesn’t have folders or tags(which is very important for me), but nicely supports full text search

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• Locking Cache Key without Locking the entire Cache

  - by Gandalf

  I have servlets that caches user information rather then retrieving it from the user store on every request (shared Ehcache). The issue I have is that if a client is multi-threaded and they make more then one simultaneous request, before they have been authenticated, then I get this in my log: Retrieving User [Bob] Retrieving User [Bob] Retrieving User [Bob] Returned [Bob] ...caching Returned [Bob] ...caching Returned [Bob] ...caching What I would want is that the first request would call the user service, while the other two requests get blocked - and when the first request returns, and then caches the object, the other two requests go through: Retrieving User [Bob] blocking... blocking... Returned [Bob] ...caching [Bob] found in cache [Bob] found in cache I've thought about locking on the String "Bob" (because due to interning it's always the same object right?). Would that work? And if so how do I keep track of the keys that actually exist in the cache and build a locking mechanism around them that would then return the valid object once it's retrieved. Thanks.

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• Adding OutputCache to a WebForm crashes my site :(

  - by Pure.Krome

  Hi folks, When I add either ... <%@ OutputCache Duration="600" Location="Any" VaryByParam="*" %> or <%@ OutputCache CacheProfile="CmsArticlesListOrItem" %> (.. and this into the web.config file...) <caching> <outputCacheSettings> <outputCacheProfiles> <add name="CmsArticlesListOrItem" duration="600" varyByParam="*" /> </outputCacheProfiles> </outputCacheSettings> <sqlCacheDependency ........ ></sqlCacheDependency </caching> my page/site crashes with the following error:- Source: System.Web ---------------------------------------------------------------------------- TargetSite: System.Web.DirectoryMonitor FindDirectoryMonitor(System.String, Boolean, Boolean) ---------------------------------------------------------------------------- Message:System.Web.HttpException: Directory 'C:\Web Sites\My Site Foo - Main Site\Controls\InfoAdvice' does not exist. Failed to start monitoring file changes. at System.Web.FileChangesMonitor.FindDirectoryMonitor(String dir, Boolean addIfNotFound, Boolean throwOnError) at System.Web.FileChangesMonitor.StartMonitoringPath(String alias, FileChangeEventHandler callback, FileAttributesData& fad) at System.Web.Caching.CacheDependency.Init(Boolean isPublic, String[] filenamesArg, String[] cachekeysArg, CacheDependency dependency, DateTime utcStart) at System.Web.Caching.CacheDependency..ctor(Int32 dummy, String[] filenames, DateTime utcStart) at System.Web.Hosting.MapPathBasedVirtualPathProvider.GetCacheDependency(String virtualPath, IEnumerable virtualPathDependencies, DateTime utcStart) at System.Web.ResponseDependencyList.CreateCacheDependency(CacheDependencyType dependencyType, CacheDependency dependency) at System.Web.HttpResponse.CreateCacheDependencyForResponse(CacheDependency dependencyVary) at System.Web.Caching.OutputCacheModule.InsertResponse(HttpResponse response, HttpContext context, String keyRawResponse, HttpCachePolicySettings settings, CachedVary cachedVary, CachedRawResponse memoryRawResponse) at System.Web.Caching.OutputCacheModule.OnLeave(Object source, EventArgs eventArgs) at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Ok .. so for some reason, the OutputCache wants a folder/file to be there? Well, i've had this site live for around 3 years and i'm pretty sure that the folders \Controls and \Controls\InfoAdvice doesn't exist on my production server. On my localhost, it sure does .. and contains a large list of ascx controls. But they don't exist on my live server. So ... what is going on here? Can anyone please help? Oh :) Before someone suggests I create those two folders and even stick a random file in those folders .. and have some random text in those random files .. i've done that and it doesn't seem to work, still :( Please Help !

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• Entity Framework 4 and Velocity

  - by Feryt

  Hi. Did you ever used EF4 and Velocity(or other caching framework) together? I found this blog post Tracing and Caching EF.

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• Adding OutputCache to an ASP.NET WebForm crashes my site :(

  - by Pure.Krome

  Hi folks, When I add either one of these ... <%@ OutputCache Duration="600" Location="Any" VaryByParam="*" %> or <%@ OutputCache CacheProfile="CmsArticlesListOrItem" %> (.. and this into the web.config file...) <caching> <outputCacheSettings> <outputCacheProfiles> <add name="CmsArticlesListOrItem" duration="600" varyByParam="*" /> </outputCacheProfiles> </outputCacheSettings> <sqlCacheDependency ........ ></sqlCacheDependency </caching> my page/site crashes with the following error:- Source: System.Web ---------------------------------------------------------------------------- TargetSite: System.Web.DirectoryMonitor FindDirectoryMonitor(System.String, Boolean, Boolean) ---------------------------------------------------------------------------- Message:System.Web.HttpException: Directory 'C:\Web Sites\My Site Foo - Main Site\Controls\InfoAdvice' does not exist. Failed to start monitoring file changes. at System.Web.FileChangesMonitor.FindDirectoryMonitor(String dir, Boolean addIfNotFound, Boolean throwOnError) at System.Web.FileChangesMonitor.StartMonitoringPath(String alias, FileChangeEventHandler callback, FileAttributesData& fad) at System.Web.Caching.CacheDependency.Init(Boolean isPublic, String[] filenamesArg, String[] cachekeysArg, CacheDependency dependency, DateTime utcStart) at System.Web.Caching.CacheDependency..ctor(Int32 dummy, String[] filenames, DateTime utcStart) at System.Web.Hosting.MapPathBasedVirtualPathProvider.GetCacheDependency(String virtualPath, IEnumerable virtualPathDependencies, DateTime utcStart) at System.Web.ResponseDependencyList.CreateCacheDependency(CacheDependencyType dependencyType, CacheDependency dependency) at System.Web.HttpResponse.CreateCacheDependencyForResponse(CacheDependency dependencyVary) at System.Web.Caching.OutputCacheModule.InsertResponse(HttpResponse response, HttpContext context, String keyRawResponse, HttpCachePolicySettings settings, CachedVary cachedVary, CachedRawResponse memoryRawResponse) at System.Web.Caching.OutputCacheModule.OnLeave(Object source, EventArgs eventArgs) at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Ok .. so for some reason, the OutputCache wants a folder/file to be there? Well, i've had this site live for around 3 years and i'm pretty sure that the folders \Controls and \Controls\InfoAdvice doesn't exist on my production server. On my localhost, it sure does .. and contains a large list of ascx controls. But they don't exist on my live server. So ... what is going on here? Can anyone please help? Oh :) Before someone suggests I create those two folders and even stick a random file in those folders .. and have some random text in those random files .. i've done that and it doesn't seem to work, still :( Please Help !

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• How to cache render :json

  - by ash34

  Hi, I have a controller index action which returns json output. render :json => my_array.to_json What type of caching do I have to use here. Does 'page caching' make sense for this. Or do I have to do action caching like below caches_action :index thanks, ash

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• PHP cache header override

  - by Soyo

  I've been through over 100 answers here, lots to try, NOTHING working?? Have a PHP based site. I need caching OFF for all .php files EXCEPT A SELECT FEW. So, in .htaccess, I have the following: ExpiresActive On # Eliminate caching for certain dynamic files <FilesMatch "\.(php|cgi|pl)$"> ExpiresDefault A0 Header set Cache-Control "no-cache, no-store, must-revalidate, max-age=0, proxy-revalidate, no-transform" Header set Pragma "no-cache" </FilesMatch> Using Firebug, I see the following: Cache-Control no-cache, no-store, must-revalidate, max-age=0, proxy-revalidate, no-transform Connection Keep-Alive Content-Type text/html Date Sun, 02 Sep 2012 19:22:27 GMT Expires Sun, 02 Sep 2012 19:22:27 GMT Keep-Alive timeout=3, max=100 Pragma no-cache Server Apache Transfer-Encoding chunked X-Powered-By PHP/5.2.17 Hey, Looks great! BUT, I have a couple .php pages I need some very short caching on. I thought the simple answer was having this added to the very top of each php page in which I want caching enabled: <?php header("Cache-Control: max-age=360"); ?> Nope. Then I tried various versions of the above. Nope. Then I tried meta http-equiv variations. Nope. Then I tried variations of the .htaccess code along with the above variations, such as limiting it to: # Eliminate caching for certain dynamic files <FilesMatch "\.(php|cgi|pl)$"> Header set Cache-Control "no-cache, max-age=0" </FilesMatch> Nope. It seems nothing I do will allow a single .php to be cache enabled with the .htaccess code in place, short of removing the statements from the .htaccess file altogether. Where am I going wrong? What do I have to do to get individual php pages to be cacheable while the rest remain off?? Thank you for any thoughts.

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• ASP.NET GZip Encoding Caveats

  - by Rick Strahl

  GZip encoding in ASP.NET is pretty easy to accomplish using the built-in GZipStream and DeflateStream classes and applying them to the Response.Filter property.  While applying GZip and Deflate behavior is pretty easy there are a few caveats that you have watch out for as I found out today for myself with an application that was throwing up some garbage data. But before looking at caveats let’s review GZip implementation for ASP.NET. ASP.NET GZip/Deflate Basics Response filters basically are applied to the Response.OutputStream and transform it as data is written to it through the ASP.NET Response object. So a Response.Write eventually gets written into the output stream which if a filter is also written through the filter stream’s interface. To perform the actual GZip (and Deflate) encoding typically used by Web pages .NET includes the GZipStream and DeflateStream stream classes which can be readily assigned to the Repsonse.OutputStream. With these two stream classes in place it’s almost trivially easy to create a couple of reusable methods that allow you to compress your HTTP output. In my standard WebUtils utility class (from the West Wind West Wind Web Toolkit) created two static utility methods – IsGZipSupported and GZipEncodePage – that check whether the client supports GZip encoding and then actually encodes the current output (note that although the method includes ‘Page’ in its name this code will work with any ASP.NET output). /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("deflate")) { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "deflate"); } else { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "gzip"); } } } As you can see the actual assignment of the Filter is as simple as: Response.Filter = new DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); which applies the filter to the OutputStream. You also need to ensure that your response reflects the new GZip or Deflate encoding and ensure that any pages that are cached in Proxy servers can differentiate between pages that were encoded with the various different encodings (or no encoding). To use this utility function now is trivially easy: In any ASP.NET code that wants to compress its Response output you simply use: protected void Page_Load(object sender, EventArgs e) { WebUtils.GZipEncodePage(); Entry = WebLogFactory.GetEntry(); var entries = Entry.GetLastEntries(App.Configuration.ShowEntryCount, "pk,Title,SafeTitle,Body,Entered,Feedback,Location,ShowTopAd", "TEntries"); if (entries == null) throw new ApplicationException("Couldn't load WebLog Entries: " + Entry.ErrorMessage); this.repEntries.DataSource = entries; this.repEntries.DataBind(); } Here I use an ASP.NET page, but the above WebUtils.GZipEncode() method call will work in any ASP.NET application type including HTTP Handlers. The only requirement is that the filter needs to be applied before any other output is sent to the OutputStream. For example, in my CallbackHandler service implementation by default output over a certain size is GZip encoded. The output that is generated is JSON or XML and if the output is over 5k in size I apply WebUtils.GZipEncode(): if (sbOutput.Length > GZIP_ENCODE_TRESHOLD) WebUtils.GZipEncodePage(); Response.ContentType = ControlResources.STR_JsonContentType; HttpContext.Current.Response.Write(sbOutput.ToString()); Ok, so you probably get the idea: Encoding GZip/Deflate content is pretty easy. Hold on there Hoss –Watch your Caching Or is it? There are a few caveats that you need to watch out for when dealing with GZip content. The fist issue is that you need to deal with the fact that some clients don’t support GZip or Deflate content. Most modern browsers support it, but if you have a programmatic Http client accessing your content GZip/Deflate support is by no means guaranteed. For example, WinInet Http clients don’t support GZip out of the box – it has to be explicitly implemented. Other low level HTTP clients on other platforms too don’t support GZip out of the box. The problem is that your application, your Web Server and Proxy Servers on the Internet might be caching your generated content. If you return content with GZip once and then again without, either caching is not applied or worse the wrong type of content is returned back to the client from a cache or proxy. The result is an unreadable response for *some clients* which is also very hard to debug and fix once in production. You already saw the issue of Proxy servers addressed in the GZipEncodePage() function: // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); This ensures that any Proxy servers also check for the Content-Encoding HTTP Header to cache their content – not just the URL. The same thing applies if you do OutputCaching in your own ASP.NET code. If you generate output for GZip on an OutputCached page the GZipped content will be cached (either by ASP.NET’s cache or in some cases by the IIS Kernel Cache). But what if the next client doesn’t support GZip? She’ll get served a cached GZip page that won’t decode and she’ll get a page full of garbage. Wholly undesirable. To fix this you need to add some custom OutputCache rules by way of the GetVaryByCustom() HttpApplication method in your global_ASAX file: public override string GetVaryByCustomString(HttpContext context, string custom) { // Override Caching for compression if (custom == "GZIP") { string acceptEncoding = HttpContext.Current.Response.Headers["Content-Encoding"]; if (string.IsNullOrEmpty(acceptEncoding)) return ""; else if (acceptEncoding.Contains("gzip")) return "GZIP"; else if (acceptEncoding.Contains("deflate")) return "DEFLATE"; return ""; } return base.GetVaryByCustomString(context, custom); } In a page that use Output caching you then specify: <%@ OutputCache Duration="180" VaryByParam="none" VaryByCustom="GZIP" %> To use that custom rule. It’s all Fun and Games until ASP.NET throws an Error Ok, so you’re up and running with GZip, you have your caching squared away and your pages that you are applying it to are jamming along. Then BOOM, something strange happens and you get a lovely garbled page that look like this: Lovely isn’t it? What’s happened here is that I have WebUtils.GZipEncode() applied to my page, but there’s an error in the page. The error falls back to the ASP.NET error handler and the error handler removes all existing output (good) and removes all the custom HTTP headers I’ve set manually (usually good, but very bad here). Since I applied the Response.Filter (via GZipEncode) the output is now GZip encoded, but ASP.NET has removed my Content-Encoding header, so the browser receives the GZip encoded content without a notification that it is encoded as GZip. The result is binary output. Here’s what Fiddler says about the raw HTTP header output when an error occurs when GZip encoding was applied: HTTP/1.1 500 Internal Server Error Cache-Control: private Content-Type: text/html; charset=utf-8 Date: Sat, 30 Apr 2011 22:21:08 GMT Content-Length: 2138 Connection: close ?`I?%&/m?{J?J??t??` … binary output striped here Notice: no Content-Encoding header and that’s why we’re seeing this garbage. ASP.NET has stripped the Content-Encoding header but left our filter intact. So how do we fix this? In my applications I typically have a global Application_Error handler set up and in this case I’ve been using that. One thing that you can do in the Application_Error handler is explicitly clear out the Response.Filter and set it to null at the top: protected void Application_Error(object sender, EventArgs e) { // Remove any special filtering especially GZip filtering Response.Filter = null; … } And voila I get my Yellow Screen of Death or my custom generated error output back via uncompressed content. BTW, the same is true for Page level errors handled in Page_Error or ASP.NET MVC Error handling methods in a controller. Another and possibly even better solution is to check whether a filter is attached just before the headers are sent to the client as pointed out by Adam Schroeder in the comments: protected void Application_PreSendRequestHeaders() { // ensure that if GZip/Deflate Encoding is applied that headers are set // also works when error occurs if filters are still active HttpResponse response = HttpContext.Current.Response; if (response.Filter is GZipStream && response.Headers["Content-encoding"] != "gzip") response.AppendHeader("Content-encoding", "gzip"); else if (response.Filter is DeflateStream && response.Headers["Content-encoding"] != "deflate") response.AppendHeader("Content-encoding", "deflate"); } This uses the Application_PreSendRequestHeaders() pipeline event to check for compression encoding in a filter and adjusts the content accordingly. This is actually a better solution since this is generic – it’ll work regardless of how the content is cleaned up. For example, an error Response.Redirect() or short error display might get changed and the filter not cleared and this code actually handles that. Sweet, thanks Adam. It’s unfortunate that ASP.NET doesn’t natively clear out Response.Filters when an error occurs just as it clears the Response and Headers. I can’t see where leaving a Filter in place in an error situation would make any sense, but hey - this is what it is and it’s easy enough to fix as long as you know where to look. Riiiight! IIS and GZip I should also mention that IIS 7 includes good support for compression natively. If you can defer encoding to let IIS perform it for you rather than doing it in your code by all means you should do it! Especially any static or semi-dynamic content that can be made static should be using IIS built-in compression. Dynamic caching is also supported but is a bit more tricky to judge in terms of performance and footprint. John Forsyth has a great article on the benefits and drawbacks of IIS 7 compression which gives some detailed performance comparisons and impact reviews. I’ll post another entry next with some more info on IIS compression since information on it seems to be a bit hard to come by. Related Content Built-in GZip/Deflate Compression in IIS 7.x HttpWebRequest and GZip Responses © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET   IIS7  

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• Inside the DLR – Invoking methods

  - by Simon Cooper

  So, we’ve looked at how a dynamic call is represented in a compiled assembly, and how the dynamic lookup is performed at runtime. The last piece of the puzzle is how the resolved method gets invoked, and that is the subject of this post. Invoking methods As discussed in my previous posts, doing a full lookup and bind at runtime each and every single time the callsite gets invoked would be far too slow to be usable. The results obtained from the callsite binder must to be cached, along with a series of conditions to determine whether the cached result can be reused. So, firstly, how are the conditions represented? These conditions can be anything; they are determined entirely by the semantics of the language the binder is representing. The binder has to be able to return arbitary code that is then executed to determine whether the conditions apply or not. Fortunately, .NET 4 has a neat way of representing arbitary code that can be easily combined with other code – expression trees. All the callsite binder has to return is an expression (called a ‘restriction’) that evaluates to a boolean, returning true when the restriction passes (indicating the corresponding method invocation can be used) and false when it does’t. If the bind result is also represented in an expression tree, these can be combined easily like so: if ([restriction is true]) { [invoke cached method] } Take my example from my previous post: public class ClassA { public static void TestDynamic() { CallDynamic(new ClassA(), 10); CallDynamic(new ClassA(), "foo"); } public static void CallDynamic(dynamic d, object o) { d.Method(o); } public void Method(int i) {} public void Method(string s) {} } When the Method(int) method is first bound, along with an expression representing the result of the bind lookup, the C# binder will return the restrictions under which that bind can be reused. In this case, it can be reused if the types of the parameters are the same: if (thisArg.GetType() == typeof(ClassA) && arg1.GetType() == typeof(int)) { thisClassA.Method(i); } Caching callsite results So, now, it’s up to the callsite to link these expressions returned from the binder together in such a way that it can determine which one from the many it has cached it should use. This caching logic is all located in the System.Dynamic.UpdateDelegates class. It’ll help if you’ve got this type open in a decompiler to have a look yourself. For each callsite, there are 3 layers of caching involved: The last method invoked on the callsite. All methods that have ever been invoked on the callsite. All methods that have ever been invoked on any callsite of the same type. We’ll cover each of these layers in order Level 1 cache: the last method called on the callsite When a CallSite<T> object is first instantiated, the Target delegate field (containing the delegate that is called when the callsite is invoked) is set to one of the UpdateAndExecute generic methods in UpdateDelegates, corresponding to the number of parameters to the callsite, and the existance of any return value. These methods contain most of the caching, invoke, and binding logic for the callsite. The first time this method is invoked, the UpdateAndExecute method finds there aren’t any entries in the caches to reuse, and invokes the binder to resolve a new method. Once the callsite has the result from the binder, along with any restrictions, it stitches some extra expressions in, and replaces the Target field in the callsite with a compiled expression tree similar to this (in this example I’m assuming there’s no return value): if ([restriction is true]) { [invoke cached method] return; } if (callSite._match) { _match = false; return; } else { UpdateAndExecute(callSite, arg0, arg1, ...); } Woah. What’s going on here? Well, this resulting expression tree is actually the first level of caching. The Target field in the callsite, which contains the delegate to call when the callsite is invoked, is set to the above code compiled from the expression tree into IL, and then into native code by the JIT. This code checks whether the restrictions of the last method that was invoked on the callsite (the ‘primary’ method) match, and if so, executes that method straight away. This means that, the next time the callsite is invoked, the first code that executes is the restriction check, executing as native code! This makes this restriction check on the primary cached delegate very fast. But what if the restrictions don’t match? In that case, the second part of the stitched expression tree is executed. What this section should be doing is calling back into the UpdateAndExecute method again to resolve a new method. But it’s slightly more complicated than that. To understand why, we need to understand the second and third level caches. Level 2 cache: all methods that have ever been invoked on the callsite When a binder has returned the result of a lookup, as well as updating the Target field with a compiled expression tree, stitched together as above, the callsite puts the same compiled expression tree in an internal list of delegates, called the rules list. This list acts as the level 2 cache. Why use the same delegate? Stitching together expression trees is an expensive operation. You don’t want to do it every time the callsite is invoked. Ideally, you would create one expression tree from the binder’s result, compile it, and then use the resulting delegate everywhere in the callsite. But, if the same delegate is used to invoke the callsite in the first place, and in the caches, that means each delegate needs two modes of operation. An ‘invoke’ mode, for when the delegate is set as the value of the Target field, and a ‘match’ mode, used when UpdateAndExecute is searching for a method in the callsite’s cache. Only in the invoke mode would the delegate call back into UpdateAndExecute. In match mode, it would simply return without doing anything. This mode is controlled by the _match field in CallSite<T>. The first time the callsite is invoked, _match is false, and so the Target delegate is called in invoke mode. Then, if the initial restriction check fails, the Target delegate calls back into UpdateAndExecute. This method sets _match to true, then calls all the cached delegates in the rules list in match mode to try and find one that passes its restrictions, and invokes it. However, there needs to be some way for each cached delegate to inform UpdateAndExecute whether it passed its restrictions or not. To do this, as you can see above, it simply re-uses _match, and sets it to false if it did not pass the restrictions. This allows the code within each UpdateAndExecute method to check for cache matches like so: foreach (T cachedDelegate in Rules) { callSite._match = true; cachedDelegate(); // sets _match to false if restrictions do not pass if (callSite._match) { // passed restrictions, and the cached method was invoked // set this delegate as the primary target to invoke next time callSite.Target = cachedDelegate; return; } // no luck, try the next one... } Level 3 cache: all methods that have ever been invoked on any callsite with the same signature The reason for this cache should be clear – if a method has been invoked through a callsite in one place, then it is likely to be invoked on other callsites in the codebase with the same signature. Rather than living in the callsite, the ‘global’ cache for callsite delegates lives in the CallSiteBinder class, in the Cache field. This is a dictionary, typed on the callsite delegate signature, providing a RuleCache<T> instance for each delegate signature. This is accessed in the same way as the level 2 callsite cache, by the UpdateAndExecute methods. When a method is matched in the global cache, it is copied into the callsite and Target cache before being executed. Putting it all together So, how does this all fit together? Like so (I’ve omitted some implementation & performance details): That, in essence, is how the DLR performs its dynamic calls nearly as fast as statically compiled IL code. Extensive use of expression trees, compiled to IL and then into native code. Multiple levels of caching, the first of which executes immediately when the dynamic callsite is invoked. And a clever re-use of compiled expression trees that can be used in completely different contexts without being recompiled. All in all, a very fast and very clever reflection caching mechanism.

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• Prevent auto mounting Android sdcard under Linux Mint

  - by BullShark

  I recently obtained an older Android phone, so that I could test Android Apps on it. I've needed it because I have a Nexus 7 but not older Android versions, hardware, etc. to test on. I'm having a problem with it under Linux Mint with Cinnamon. When I plug the phone in, or remove and plug the sdcard from the phone back to it while the phone is plugged in, Linux automatically mounts the sdcard. This is a problem because once it is mounted under Linux, it dismounts from the phone running Android 2.3.5, and I can no longer test Android Apps I write that require the sdcard to be present, writable. I went to Menu System Tools System Settings System Details Removable Media, and it brings up this window. I have changed the settings to always "Ask what to do" on "Select how media should be handled". However, the sdcard still gets mounted and then I am asked how I want to open these files (media players, photo importers, file browser, etc.). If I click the checkbox for "Never prompt or start programs on media insertion", then the sdcard is mounted, and I am not asked how to open these files. Eject is just a noob word for Ubuntu users that means umount (unmount) like "Adminstrator" is another ubuntu noob word for the root user. And if I unmount the sdcard, the phone doesn't recognize it again until I take the sdcard out and plug it back in. The phone sees it for a brief moment until Linux Mint takes it over. There are 2 possible solutions and maybe more: 1) Prevent Linux from automounting sdcards some how 2) Tell Android not to allow the computer it is plugged into to take over the sdcard, HOW? Edit: I found out how to prevent the sdcard from being automatically mounted: Now it gets recognized by Linux: bullshark@beastlinux ~ $ dmesg | tail -n 25 [597212.218323] sd 21:0:0:0: [sde] Attached SCSI removable disk [597212.218639] sr 21:0:0:1: Attached scsi CD-ROM sr2 [597212.218910] sr 21:0:0:1: Attached scsi generic sg7 type 5 [597217.139373] sd 21:0:0:0: [sde] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB) [597217.140726] sd 21:0:0:0: [sde] No Caching mode page present [597217.140735] sd 21:0:0:0: [sde] Assuming drive cache: write through [597217.143595] sd 21:0:0:0: [sde] No Caching mode page present [597217.143602] sd 21:0:0:0: [sde] Assuming drive cache: write through [597217.152240] sde: sde1 [597389.751008] 4:2:1: cannot get freq at ep 0x84 [597390.238742] 4:2:1: cannot get freq at ep 0x84 [597624.903132] sde: detected capacity change from 1977614336 to 0 [597637.677763] sd 21:0:0:0: [sde] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB) [597637.679616] sd 21:0:0:0: [sde] No Caching mode page present [597637.679626] sd 21:0:0:0: [sde] Assuming drive cache: write through [597637.682508] sd 21:0:0:0: [sde] No Caching mode page present [597637.682515] sd 21:0:0:0: [sde] Assuming drive cache: write through [597637.692758] sde: sde1 [597661.857979] sde: detected capacity change from 1977614336 to 0 [597688.775455] sd 21:0:0:0: [sde] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB) [597688.776814] sd 21:0:0:0: [sde] No Caching mode page present [597688.776823] sd 21:0:0:0: [sde] Assuming drive cache: write through [597688.780055] sd 21:0:0:0: [sde] No Caching mode page present [597688.780062] sd 21:0:0:0: [sde] Assuming drive cache: write through [597688.788639] sde: sde1 bullshark@beastlinux ~ $ However, the phone still unmounts the sdcard upon being detected by Linux. Linux detects but does not mount, and a few seconds later: Edit #2 (Solution): I solved this one by changing the usb connection type (was usb mass storage) :

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• Sync iPod Touch's calendar to Google Calendar

  - by Masi

  How can you sync your calendar of iPod Touch to Google Calendar? I have rarely internet connection at my iPod Touch. It has my calendar as "offline". I cannot share it with my friends. I would like to use "Google Calendar" in a offline mode such that I can more easily sync my calendar, every time my iPod is online. So problems are to sync iPod Touch's calendar to Google Calendar to be able to use Google calendar offline in iPod touch to put iPod sync Gcal every time it observes a network

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