Q&A...

Server side hub events (OnReconnected/OnDisconnected/OnConnected) not fired

Solution

hub = $.connection.myHub;
            // dummy call to force the [OnConnected()] method on signalR hub
            hub.client.foo = function () { };
            $.connection.hub.start().done( ... )
            

Refs

ref: http://elbruno.com/2014/07/25/signalr-error-html-client-does-not-raise-onconnected-method-on-server-hub-2/

DI not working

Solution

Bootstrap/Unity Config

container.RegisterType<IHubActivator, UnityHubActivator>(new ContainerControlledLifetimeManager());
GlobalHost.DependencyResolver.Register(typeof(IHubActivator), () => new UnityHubActivator(container));

UnityHubActivator.cs

using System;
using Microsoft.AspNet.SignalR.Hubs;
using Microsoft.Practices.Unity;

namespace DerivcoApps.Alerter.WebApi.Infrastructure
{
  public class UnityHubActivator : IHubActivator
  {
    private readonly IUnityContainer _container;

    public UnityHubActivator(IUnityContainer container)
    {
      _container = container;
    }

    public IHub Create(HubDescriptor descriptor)
    {
      if (descriptor == null)
      {
        throw new ArgumentNullException("descriptor");
      }

      if (descriptor.HubType == null)
      {
        return null;
      }

      object hub = _container.Resolve(descriptor.HubType) ?? Activator.CreateInstance(descriptor.HubType);
      return hub as IHub;
    }
  }
}

Refs

ref: http://elbruno.com/2014/07/25/signalr-error-html-client-does-not-raise-onconnected-method-on-server-hub-2/

Disocnnections use cases

When I Mention the following i am referring to the server side Hub method - OnConnected

  • OnDisconnected
  • OnReconnected
0:00 - Client connects to server, OnConnected is triggered
0:10 - Client loses connection due to ISP issues (and realizes it loses connection)
0:15 - Client Regains connectivity
0:16 - OnReconnected event is triggered
0:00 - Client connects to server, OnConnected is triggered
0:10 - Client loses connection due to pulling ethernet cable (doesn't realize it's disconnected)
0:15 - Client Regains connectivity
Two things can happen here
A: 0:16 - Nothing happens and client continues on with its previous connection
B: 0:~45 - Client Realizes its disconnected *
B: 0:46 - Client transitions into the reconnecting state
B: 0:47 - Client successfully reconnects and the OnReconnected event is triggered.
0:00 - Client connects to server, OnConnected is triggered
0:10 - Client loses connection due to pulling ethernet cable (doesn't realize it's disconnected)
0:~45 - Client Realizes its disconnected *
0:46 - Client transitions into the reconnecting state
1:15 - Server determines that client has been gone for too long and then forgets about it, queuing up a "disconnect" command for the client to receive if it reconnects slightly later. ***
1:15 - OnDisconnected is triggered
1:16 - Client regains connectivity
1:17 - Client does a "soft" reconnect (does not trigger OnReconnected)
1:18 - Client retrieves the "disconnect" command
1:19 - Client calls "stop" and does a soft disconnect (does not trigger OnDisconnected)
0:00 - Client connects to server, OnConnected is triggered
0:10 - Client loses connection due to pulling ethernet cable (doesn't realize it's disconnected)
0:~45 - Client Realizes its disconnected *
0:46 - Client transitions into the reconnecting state
1:15 - Server determines that client has been gone for too long and then forgets about it, queuing up a "disconnect" command for the client to receive if it reconnects slightly later. ***
1:15 - OnDisconnected is triggered
1:30 - Client stops trying to reconnect (been trying too long) **
1:30 - Client transitions into disconnected state
  • Due to client side keep alive check: Used to determine when a client is offline due to lack of keep alives. Not utilized for the long polling transport

** Due to client side disconnect timeout: Used to determine when a client has been reconnecting for too long of a period and chances are the server has forgotten about the client during the time

*** Due to server disconnect timeout: Used to determine when a client should be forgotten about. It's a time span that starts accruing once a connection is tagged as dead on the server. Ultimately the server queues a disconnect command for the client's topic which tells the client (if it reconnects) that it needs to start a fresh connection. The command will disappear from the server when the topic is cleaned up.

Hope this helps!

Transport protocols

Refs

Websockets [webSockets]

Prerequisite

  • IIS 8+
  • Latest version of any modern browser, IE10+
  • CORS : Cross Resource Sharing Enabled

web.config


  <system.webServer>

      <modules runAllManagedModulesForAllRequests="true">
      </modules>
    
  </system.webServer>
  

IIS Setup

  1. "Turn Windows features on or off"
  2. Internet Information Services
  3. World Wide Web Services
  4. Application Development Features
  5. WebSocket Protocol (or the equivalent if you are on a server SKU).

ServerSourceEvent (SSE) [serverSentEvents]

Prerequisite

  • FF, Chrome, (anything but IE)

foreverFrame

longPolling