Heather Heather - 3 months ago 124
C# Question

SignalR: detect connection state on client

I've seen how you can trap a disconnection event on the client side with SignalR by binding to the .disconnect event.

Now that I've done this, I want to put the client into a "waiting to reconnect cycle" where it continually tries to connect until it succeeds or the user cancels out. Does the hub expose a connection state property? I'm thinking something like (pseudo code)

var isConnected;

function onConnected() { isConnected = true; }

hub.disconnect = function() { while(hub.notconnected) { connect(); }

Answer

The JS client attempts to reconnect for a certain time period, which defaults to 110 seconds. You can subscribe to the connection.stateChanged event, and get updates on when the state changes so that you can display it to the user, or validate SignalR's response to different disconnection scenarios.

In my testing, the state was correctly updated to disconnected and reconnecting etc., as you would expect.

More information on signalr connections

function connectionStateChanged(state) {
    var stateConversion = {0: 'connecting', 1: 'connected', 2: 'reconnecting', 4: 'disconnected'};
    console.log('SignalR state changed from: ' + stateConversion[state.oldState]
     + ' to: ' + stateConversion[state.newState]);
}

connection = $.connection(signalR_Endpoint);
connection.stateChanged(connectionStateChanged);
connection.start({ waitForPageLoad: false });