How to determine server disconnection from SignalR

问题:

The question is how can SignalR JavaScript client detect when connection with server is lost?

Thanks for any reply!

回答1:

A hub has a method disconnect which will allow you to add a callback when disconnection takes place:

myHub.disconnect(function() {
  alert('Server has disconnected');
});

If you aren't using hubs then the code for the disconnect method will help you out:

$(connection).bind("onDisconnect", function (e, data) {
  callback.call(connection);
});

This shows the syntax for hooking onto the onDisconnect event of the underlying connection.

回答2:

If you are using hubs then implement the IDisconnect interface.

public class ChatHub : Hub, IDisconnect
{
    public void Disconnect()
    {
        Debug.WriteLine(Context.ConnectionId + " disconnected");
    }
}

On persistent connections you can override OnDisconnectAsync, (from the SignalR wiki at https://github.com/SignalR/SignalR/wiki/PersistentConnection )

public class MyEndPoint : PersistentConnection 
{
    protected override Task OnDisconnectAsync(string clientId) 
    {
        return Connection.Broadcast("Client " + clientId + " disconncted");   
    }
}

回答3:

Starting with SignalR v0.5.1 it works this way:

$.connection.hub.stateChanged(function (change) {
    if (change.newState === $.signalR.connectionState.reconnecting) {
        console.log("liveFeed is reconnecting!");
    }
    else if (change.newState === $.signalR.connectionState.connected) {
        console.log("liveFeed is connected!");
    }
});

For more details check this website:

http://weblogs.asp.net/davidfowler/archive/2012/06/10/signalr-0-5-1-released.aspx

回答4:

The SignalR 2.0 way of doing this is like so:

$.connection.hub.disconnected(function () {
    console.log('Connection disconnected')
});

http://www.asp.net/signalr/overview/signalr-20/hubs-api/hubs-api-guide-javascript-client#connectionlifetime

回答5:

The below, worked for me:

var connection = $.hubConnection('signalrConnectionUrl');

connection.disconnected(function() {
    console.log('Connection disconnected');
});

I'm using version: 2.1.2

See the following link for reference: Link

回答6:

This worked for me using "@aspnet/signalr": "^1.0.0" npm package

const connection = new signalr.HubConnectionBuilder()
    .withUrl('url')
    .configureLogging(signalr.LogLevel.Information)
    .build()

connection.onclose(() => {
   // close logic goes here
})