SignalR not firing "disconnected" event

Question

I'm using SignalR to push updates out to connected web clients. I listen to the disconnected event in order to know when I should start my reconnection logic

$.connection.hub.disconnected(function() {
    // Initiate my own reconnection logic
});

The SignalR hub is hosted in in IIS (along with my site)

[assembly: OwinStartup(typeof(Startup))]
namespace MyNamespace.SignalR
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.MapSignalR();
        }
    }
}

Upon connection, the client calls a server method to join a group

public class MyHub : Hub
{
    public void JoinGroup(string groupName)
    {
        Groups.Add(Context.ConnectionId, groupName);
    }
}

And then I push messages to this group:

context.Clients.Group(groupName).sendMessage();

If I manually recycle the application pool in IIS, SignalR starts trying to reconnect and I eventually receive a disconnected event on the client side if it fails (after the timeout).

However, my problem is that if I manually restart the website in IIS, I do not receive any disconnected event at all, and I can't see in the logs that SignalR has detected any connection problem at all. How can I detect that I have been disconnected?

I know I should probably persist the group connections somehow, since that is saved in memory I guess. But that shouldn't affect the initial problem that the client receives no notification of the disconnection? Shouldn't the client side signalr code throw some kind of exception/event?

Answer 1

So I finally found out what the problem is and how to solve it. Some background though:

At the moment we manually release new versions of our application by going to "Basic settings..." under the website in IIS and changing the "Physical Path" from C:\websites\version1 to C:\websites\version2. Apparently this gives the same behavior as doing a restart of the website in IIS (not a hard reset, not stopping the website, not recycling the app pool) and according to this: "does NOT shut the site down, it merely removes the Http.sys binding for that port". And no matter how long we wait, the connected clients never receive any kind of indication that they should reconnect.

So the solution is to recycle the application pool after each release. The "lost" clients will receive disconnected events and reconnect to the new version of the site.

Answer 2

disconnected fires first when the built in logic for reconnection have timed out. You also need to listen to the recconect event, something like i did here

https://github.com/AndersMalmgren/SignalR.EventAggregatorProxy/blob/ReconnectOnClosed/SignalR.EventAggregatorProxy.Client.JS/jquery.signalR.eventAggregator.js#L157