Can ASP.NET Routing be used to create “clean” URLs for .ashx (IHttpHander) handlers?

Question

I have some REST services using plain old IHttpHandlers. I\'d like to generate cleaner URLs, so that I don\'t have the .ashx in the path. Is there a way to us

Answer 1

Yeah, I noticed that, too. Perhaps there is a built-in ASP.NET way to do this, but the trick for me was to create a new class derived from IRouteHandler:

using System;
using System.IO;
using System.Reflection;
using System.Text.RegularExpressions;
using System.Web;
using System.Web.Routing;

namespace MyNamespace
{
    class GenericHandlerRouteHandler : IRouteHandler
    {
        private string _virtualPath;
        private Type _handlerType;
        private static object s_lock = new object();

        public GenericHandlerRouteHandler(string virtualPath)
        {
            _virtualPath = virtualPath;
        }

        #region IRouteHandler Members

        public System.Web.IHttpHandler GetHttpHandler(RequestContext requestContext)
        {
            ResolveHandler();

            IHttpHandler handler = (IHttpHandler)Activator.CreateInstance(_handlerType);
            return handler;
        }

        #endregion

        private void ResolveHandler()
        {
            if (_handlerType != null)
                return;

            lock (s_lock)
            {
                // determine physical path of ashx
                string path = _virtualPath.Replace("~/", HttpRuntime.AppDomainAppPath);

                if (!File.Exists(path))
                    throw new FileNotFoundException("Generic handler " + _virtualPath + " could not be found.");

                // parse the class name out of the .ashx file
                // unescaped reg-ex: (?<=Class=")[a-zA-Z\.]*
                string className;
                Regex regex = new Regex("(?<=Class=\")[a-zA-Z\\.]*");
                using (var sr = new StreamReader(path))
                {
                    string str = sr.ReadToEnd();

                    Match match = regex.Match(str);
                    if (match == null)
                        throw new InvalidDataException("Could not determine class name for generic handler " + _virtualPath);

                    className = match.Value;
                }

                // get the class type from the name
                Assembly[] asms = AppDomain.CurrentDomain.GetAssemblies();
                foreach (Assembly asm in asms)
                {
                    _handlerType = asm.GetType(className);
                    if (_handlerType != null)
                        break;
                }

                if (_handlerType == null)
                    throw new InvalidDataException("Could not find type " + className + " in any loaded assemblies.");
            }
        }
    }
}

To create a route for an .ashx:

IRouteHandler routeHandler = new GenericHandlerRouteHandler("~/somehandler.ashx");
Route route = new Route("myroute", null, null, null, routeHandler);
RouteTable.Routes.Add(route);

The code above may need to be enhanced to work with your route arguments, but it's starting point. Comments welcome.