How to add bundles with dynamic content to asp.net web optimization

Question

I'm using SignalR, which maps to asp.net application on virtual path "~/signalr". SignalR dynamically creates javascript proxy hubs on app start with virtual path "~/signalr/hubs".

So the url "[http://myapp]/signalr/hubs" is where dynamic javascript content is. How can I add this virtual path to Asp.Net Web Optimization Bundling?

Asp.Net Web Optimization Framework starting from 1.1 supports VirtuPathProvider's: ASP.NET bundling/minification: including dynamically generated Javascript

Actually I don't understand how to use these VPP's. Could somebody explain in details or better give an example?

Answer 1

Integration of dynamic content into the bundling process requires the following steps:

1. Writing the logic that requests / builds the required content. For SignalR you could use this code snippet:

   public static string GetSignalRContent()
   {
       var resolver = new DefaultHubManager(new DefaultDependencyResolver());
       var proxy = new DefaultJavaScriptProxyGenerator(resolver, new NullJavaScriptMinifier());
       return proxy.GenerateProxy("/signalr");
   }
   

2. Implement a virtual path provider that wraps the existing one and intercept all virtual paths that should deliver the dynamic content (just "~/signalr/hubs" in your case).

   public class CustomVirtualPathProvider : VirtualPathProvider
   {
       public CustomActionVirtualPathProvider(VirtualPathProvider virtualPathProvider)
       {
           // Wrap an existing virtual path provider
           VirtualPathProvider = virtualPathProvider;
       }
   
       protected VirtualPathProvider VirtualPathProvider { get; set; }
   
       public override string CombineVirtualPaths(string basePath, string relativePath)
       {
           return VirtualPathProvider.CombineVirtualPaths(basePath, relativePath);
       }
   
       public override bool DirectoryExists(string virtualDir)
       {
           return VirtualPathProvider.DirectoryExists(virtualDir);
       }
   
       public override bool FileExists(string virtualPath)
       {
           if (virtualPath == "~/signalr/hubs")
           {
               return true;
           }
   
           return VirtualPathProvider.FileExists(virtualPath);
       }
   
       public override CacheDependency GetCacheDependency(string virtualPath, IEnumerable virtualPathDependencies, DateTime utcStart)
       {
           // BaseClass can't create a CacheDependency for your content, remove it
           // You could also add your own CacheDependency and aggregate it with the base dependency
           List<string> virtualPathDependenciesCopy = virtualPathDependencies.Cast<string>().ToList();
           virtualPathDependenciesCopy.Remove("~/signalr/hubs");
   
           return VirtualPathProvider.GetCacheDependency(virtualPath, virtualPathDependenciesCopy, utcStart);
       }
   
       public override string GetCacheKey(string virtualPath)
       {
           return VirtualPathProvider.GetCacheKey(virtualPath);
       }
   
       public override VirtualDirectory GetDirectory(string virtualDir)
       {
           return VirtualPathProvider.GetDirectory(virtualDir);
       }
   
       public override VirtualFile GetFile(string virtualPath)
       {
           if (virtualPath == "~/signalr/hubs")
           {
               return new CustomVirtualFile(virtualPath,
                   new MemoryStream(Encoding.Default.GetBytes(GetSignalRContent())));
           }
   
           return VirtualPathProvider.GetFile(virtualPath);
       }
   
       public override string GetFileHash(string virtualPath, IEnumerable virtualPathDependencies)
       {
           return VirtualPathProvider.GetFileHash(virtualPath, virtualPathDependencies);
       }
   
       public override object InitializeLifetimeService()
       {
           return VirtualPathProvider.InitializeLifetimeService();
       }
   }
   
   public class CustomVirtualFile : VirtualFile
   {
       public CustomVirtualFile (string virtualPath, Stream stream)
           : base(virtualPath)
       {
           Stream = stream;
       }
   
       public Stream Stream { get; private set; }
   
       public override Stream Open()
       {
            return Stream;
       }
   }
   

3. Register your virtual path provider:

   public static void RegisterBundles(BundleCollection bundles)
   {
       // Set the virtual path provider
       BundleTable.VirtualPathProvider =
           new CustomVirtualPathProvider(BundleTable.VirtualPathProvider);
   
       Bundle include = new Bundle("~/bundle")
           .Include("~/Content/static.js")
           .Include("~/signalr/hubs");
   
       bundles.Add(include);
   }
   

For some samples of virtual path providers + bundling, see Bundling and Minification and Embedded Resources or Bundling Dynamic Generated Controller / Action Content for example.