Here is what I did... Web App with signalR .net4.0, then your SharePoint Web App .net 2. Add this to the global.asax in your Signalr project RouteTable.Routes.MapHttpHandlerRoute("spproxy","spproxy/{*operation}", new SharePointRProxyHandler()); If you want to raise an event from SharePoint you can do a http POST to this new route URL for example…

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace System.Web.Routing
{
public class HttpHandlerRoute : IRouteHandler
{
    private String _virtualPath = null;
    private IHttpHandler _handler = null;

    public HttpHandlerRoute(String virtualPath)
    {
        _virtualPath = virtualPath;
    }

    public HttpHandlerRoute(IHttpHandler handler)
    {
        _handler = handler;
    }

    public IHttpHandler GetHttpHandler(RequestContext requestContext)
    {
        IHttpHandler result;
        if (_handler == null)
        {
            result = (IHttpHandler)System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(_virtualPath, typeof(IHttpHandler));
        }
        else
        {
            result = _handler;
        }
        return result;
    }
}

public static class RoutingExtensions
{
    public static void MapHttpHandlerRoute(this RouteCollection routes, string routeName, string routeUrl, string physicalFile, RouteValueDictionary defaults = null, RouteValueDictionary constraints = null)
    {
        var route = new Route(routeUrl, defaults, constraints, new HttpHandlerRoute(physicalFile));
        RouteTable.Routes.Add(routeName, route);
    }

    public static void MapHttpHandlerRoute(this RouteCollection routes, string routeName, string routeUrl, IHttpHandler handler, RouteValueDictionary defaults = null, RouteValueDictionary constraints = null)
    {
        var route = new Route(routeUrl, defaults, constraints, new HttpHandlerRoute(handler));
        RouteTable.Routes.Add(routeName, route);
    }
}
}

gistfile2.cs

//Or you could just post directly to a httphandler and get the handler to do a connection.Broadcast
namespace SharePointRProxy
{
 /// <summary>
 /// Summary description for SharePointRProxyHandler
 /// </summary>
 public class SharePointRProxyHandler : IHttpHandler
 {

     public void ProcessRequest(HttpContext context)
     {
         context.Response.ContentType = "text/plain";
         IConnectionManager connectonManager = AspNetHost.DependencyResolver.Resolve<IConnectionManager>();
         IConnection connection = connectonManager.GetConnection<MyConnection>();

         object payload = null; //Add payload here 'context.Request.Params["data"] ?'

         JavaScriptSerializer jss = new JavaScriptSerializer();
         var payloadJSON = jss.Serialize(payload);

         connection.Broadcast(payloadJSON);
     }

     public bool IsReusable
     {
         get
         {
             return false;
         }
     }
 }
}