How to keep SignalR connection alive on web page?

Question

I'm using ASP.NET MVC 5 and using SignalR v2.2.2 (the latest). My application is working all okay until the page has been idle for a while (not sure exactly now long but between 5 to 15 mins idle). Once it has been idle for this period of time, the buttons on the web page no longer work (as I assume they need an active connection).

My preferred way to solve this is to be able to increase the timeout of the connection. How can I do this?

If this is not possible, how can I detect that the connection has been dropped on the page and/or how can I re-establish connection if required?

My web page uses javascript and the code that establishes the connection to the SignalR hub is this:

$.connection.hub.start()
    .done(function () {
        // Does stuff here...
    })
    .fail(function (e) { console.log(e); });

Thank you

Answer 1

There are 2 recipes you can implement:

1.Reconnect if the connection drops:

$.connection.hub.disconnected(function () {

    setTimeout(function () {
        $.connection.hub.start();
    }, 5000);
});

2.Use the pingInterval so you try to keep the connection alive:

$.connection.hub.start({ pingInterval: 6000 })

Answer 2

From Microsoft Docs ,

Handle the connectionSlow event to display a message as soon as SignalR is aware of connection problems, before it goes into reconnecting mode.

Handle the reconnecting event to display a message when SignalR is aware of a disconnection and is going into reconnecting mode.

Handle the disconnected event to display a message when an attempt to reconnect has timed out. In this scenario, the only way to re-establish a connection with the server again is to restart the SignalR connection by calling the Start method, which will create a new connection ID.

Answer 3

There's a much simpler way now: .withAutomaticReconnect()

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