Reconnecting to an existing SignalR (.NET CORE) socket with Angular

Issue

In my project, I need to reconnect to a SignalR Web Socket if the internet connection is lost. I'm working with Angular Ionic V4, and I installed the Network Information plugin. On the plugin's "Connected" event - I'm trying to call this._hubConnection.start() with the original token. It appears a new connection is established, but every time I get data from the hub, the event runs twice ( or X times depending how many re-connections I've made).

I beleive what's happening is the SignalR creates another socket under the same key, and when a message is sent to the specified key - it is broadcasted to all connections with same key hence duplicates the events.

My question is - Is there a way to "reconnect" to an existing socket instead of "making an additional connection"?

EDIT:

After trying to upgrade to @microsoft/signalr, this is what I got:

chrome devtool console log

It appears it tries to reconnect while the network is offline, and when the network is back it connects and disconnects.

I tried debugging my SignalR server. This is the method that's invoking the events on the client:

 public async Task Enqueue(int processId)
    {
        var processEnqueueAppointmentResults = await _processesService.Enqueue<object>(processId);
        await Clients.User($"PROCESS_{processId}").SendAsync("ProcessEnqueued", processEnqueueAppointmentResults);
    }

The debugger entered Enqueue once, and on the client - I received 4 duplicate logs (meaning the event was fired 4 times)

Solution

Solved

The problem was that on my Internet connected event I called my createConnection() method which initializes the SignalR connection

this._hubConnection = new signalR.HubConnectionBuilder()
      .withUrl(`${this.env.testUrl}/hubs/patients`, {
        accessTokenFactory: () => token
      })
      .build();

Instead, just had to invoke the this._hubConnection.start(); method on my existing hubConnection which solved the duplicate invocation (Just as I thought, every reconnect event added another socket under the same key. When SignalR wanted to invoke the event on the client - it fired the number of times I invoked createConnection())

Answered By - Yoni Ziv