How do I configure IIS 7.5 for SSE (Server Sent Events) and SignalR

Question

I have tested my Asp.NET MVC application to run SignalR and it properly handles the text/event-stream MIME with a serverSentEvents connection, using Visual Studio 2012, IIS Express (Microsoft-IIS/8.0) and Chrome.

Now that I am deploying to production environment (IIS 7.5, .NET Framework 4.5, Windows Server 2008R2), I've noticed that SignalR always falls back to LongPolling transport, since the signalr/connect?transport=serverSentEvents etc times out.

Is there a way to configure Microsoft-IIS/7.5 to make ServerSentEvents work? Or is this possible only on 8.0+?

When I try to directly access the url 'http://my.webapp.com/MyHub/signalr/connect?transport=serverSentEvents&connectionId=624849a4-45c6-458b-b6d0-f7cb023ab226&connectionData=%5B%7B%22name%22%3A%22myHub%22%7D%5D&tid=2' I am getting a file which contains what looks like a SSE data packet:

data: initialized

id: 14476
data: {"MessageId":"14476","Messages":[],"Disconnect":false,"TimedOut":false,"TransportData":{}}

so I am not sure why the timeout is hitting the request.

Answer 1

Turns out that no specific configuration was required in my case - SignalR falling back to longPolling depended on the fact that my server is evidently behind a proxy.

To test this, I suggest to try the connection to the hub server on server using localhost as web address - in my case the transport is correctly set up as serverSentEvents (when using Chrome) or foreverFrame (when using IE)

Credit to user dfowler for the heads up (more here)

Answer 2

What might be happening that the server is compressing the dynamic content generated before sending it to client. Add this in your web.config to fix

   <location path="signalr">
    <system.webServer>
      <urlCompression doDynamicCompression="false"/>
    </system.webServer>
  </location>