CODEWITHSUNDEEP
c#asp.netiiswebsocket
joox
joox

Reputation: 253

How to track 500 errors on WebSockets (ws://)

I'm trying to play around with WebSockets on IIS 8.5. I started off with a couple of very basic C# classes from a lesson:

using Microsoft.Web.WebSockets;
using System.Web;

public class ChatHttpHandler : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        if (context.IsWebSocketRequest)
            context.AcceptWebSocketRequest(new WebSocketChatHandler());
    }

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

public class WebSocketChatHandler : WebSocketHandler
{
    private static WebSocketCollection clients = new WebSocketCollection();
    private string name;

    public override void OnOpen()
    {
        this.name = this.WebSocketContext.QueryString["username"];
        clients.Add(this);
        clients.Broadcast(string.Format("{0} joined.", name));
    }

    public override void OnMessage(string message)
    {
        clients.Broadcast(string.Format("{0}: {1}", name, message));
    }

    public override void OnClose()
    {
        clients.Remove(this);
        clients.Broadcast(string.Format("{0} left.", name));
    }
}

and a simple HTML client. The project builds ok, but when I try to connect to the handler, it returns error 500. The problem is that I cannot see what the exact error is, because neither Chrome nor FF load the response body for ws:// scheme, so i cannot even see it in the Network tab of Developer Tools (though IIS provides the body, as I can see from from the response' Content-Length). Is there a way to see the response body in this situation? Or what am I missing with WebSockets in IIS?

Upvotes: 1

Views: 1818

Answers (2)

joox
joox

Reputation: 253

The problem was with web.config. I added

<httpRuntime targetFramework="4.5.1" />

to system.web section and it finally began to work

Upvotes: 1

Stephen Kennedy
Stephen Kennedy

Reputation: 21548

You should be able to see the cause of the error in the Windows Event Viewer.

Fiddler will show you the connection and that it has upgraded to web socket so you can use that tool to at least show you if the connection worked or not. I'm not aware of a tool which can show you the traffic flowing over the socket once it has been upgraded although there might be one.

Better still, debug it in Visual Studio with breakpoints and 'break on exception' set. You can tell VS to use IIS as the server by right clicking the web site and going to Property Pages then Start Options. Tick Use custom server and put your URL into the textbox. Click Specific page and choose your default page.

Comparing it to my working solution using the same DLL, I don't spot any obvious issues with the handling of the socket, so I would suggest commenting out this.name = this.WebSocketContext.QueryString["username"]; for now and replacing it with this.name = "TEST"; as that appears to be about the only code which deviates from the samples. Keep it simple until its working!

Upvotes: 0

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