views:

1058

answers:

4

Can ASP.Net routing (not MVC) be used to serve static files?

Say I want to route

http://domain.tld/static/picture.jpg

to

http://domain.tld/a/b/c/picture.jpg

and I want to do it dynamically in the sense that the rewritten URL is computed on the fly. I cannot set up a static route once and for all.

Anyway, I can create a route like this:

routes.Add(
  "StaticRoute", new Route("static/{file}", new FileRouteHandler())
);

In the FileRouteHandler.ProcessRequest method I can rewrite the path from /static/picture.jpg to /a/b/c/picture.jpg. I then want to create a handler for static files. ASP.NET uses the StaticFileHandler for this purpose. Unfortunately, this class is internal. I have tried to create the handler using reflection and it actually works:

Assembly assembly = Assembly.GetAssembly(typeof(IHttpHandler));
Type staticFileHandlerType = assembly.GetType("System.Web.StaticFileHandler");
ConstructorInfo constructorInfo = staticFileHandlerType.GetConstructor(BindingFlags.NonPublic | BindingFlags.Instance, null, Type.EmptyTypes, null);
return (IHttpHandler) constructorInfo.Invoke(null);

But using internal types doesn't seem to be the proper solution. Another option is to implement my own StaticFileHandler, but doing so properly (supporting HTTP stuff like ranges and etags) is non-trivial.

How should I approach routing of static files in ASP.NET?

+2  A: 

Why not use IIS to do this? You could just create redirect rule to point any requests from the first route to the second one before the request even gets to your application. Because of this, it would be a quicker method for redirecting requests.

Assuming you have IIS7, you do something like...

<rule name="Redirect Static Images" stopProcessing="true">
  <match url="^static/?(.*)$" />
  <action type="Redirect" url="/a/b/c/{R:1}" redirectType="Permanent" />
</rule>
Dan Atkinson
I would prefer this approach, as well. Moving it out to the pipeline and let the IIS worker process handle the redirect is more efficient than spinning cycles actually processing the route via the runtime, I would assume. Even if the amount of churn on the server is about the same, I would go the route (pun intended) of not using the routes and keep the redirect outside of the application itself.
joseph.ferris
What wasn't clear from my initial version of the question was that the rewritten URL is computed on the fly (I'm not concerned about performance here). I have updated the question to clarify that. Anyway, thanks for replying.
Martin Liversage
Martin, Performance issues aside, why would you want to handle this url in the application, when handling it outside would be better? I suppose that you could create a controller action which handles this, but here - http://bit.ly/SAav - is something you could have a look at.
Dan Atkinson
+1  A: 

I came up with an alternative to using the internal StaticFileHandler. In the IRouteHandler I call HttpServerUtility.Transfer:

public class FileRouteHandler : IRouteHandler {

  public IHttpHandler GetHttpHandler(RequestContext requestContext) {
    String fileName = (String) requestContext.RouteData.Values["file"];
    // Contrived example of mapping.
    String routedPath = String.Format("/a/b/c/{0}", fileName);
    HttpContext.Current.Server.Transfer(routedPath);
    return null; // Never reached.
  }

}

This is a hack. The IRouteHandler is supposed to return an IHttpHandler and not abort and transfer the current request. However, it does actually achieve what I want.

Using the internal StaticFileHandler is also somewhat a hack since I need reflection to get access to it, but at least there is some documentation on StaticFileHandler on MSDN making it a slightly more "official" class. Unfortunately I don't think it is possible to reflect on internal classes in a partial trust environment.

I will stick to using StaticFileHandler as I don't think it will get removed from ASP.NET in the foreseeable future.

Martin Liversage
+2  A: 

After dig this problem for a few hours, I found simply adding ignore rules will get your static files served.

In RegisterRoutes(RouteCollection routes), add following ignore rules:

routes.IgnoreRoute("{file}.js");
routes.IgnoreRoute("{file}.html");
Robert Mao
A: 

I've had a similar problem. I ended up using HttpContext.RewritePath:

public class MyApplication : HttpApplication
{
    private readonly Regex r = new Regex("^/static/(.*)$", RegexOptions.IgnoreCase);

    public override void Init()
    {
        BeginRequest += OnBeginRequest;
    }

    protected void OnBeginRequest(object sender, EventArgs e)
    {
        var match = r.Match(Request.Url.AbsolutePath);
        if (match.Success)
        {
            var fileName = match.Groups[1].Value;
            Context.RewritePath(string.Format("/a/b/c/{0}", fileName));
        }
    }
}
sheikhomar