SignalR

SignalR is a WebSockets implementation for dotnet applications. I used the frontend client for this which was @aspnet/signalr, this version is for dotnet core 2.0 and the version for 3.0 is @microsoft/signalr

Basics#

Building a connection first, can pass multiple different params to it for logging and other features

let connection = new SignalR.HubConnectionBuilder()
    .withUrl('https://api.forcespenpals.net/signalhub', {
      accessTokenFactory: () => token
    })
    .configureLogging(SignalR.LogLevel.Debug)
    .build()

Starting the connection

    connection
      .start()
      .then(() => {
        console.log('SignalR: STARTED!@!#!@#!@#!')
        setInterval((): void => {
          if (connection.state) {
            connection.invoke('heartbeat')
            console.log('HeartBeat')
          }
        }, 15000)
      })
      .catch(err => console.log('Error while establishing connection :(', err))

Listening to events sent from server SignalR uses the on method to listen to methods coming from server and off method to close the connection

connection.on('messageReceived', (data: any) => {
    console.log(data);        
})

connection.off('messageReceived', c => {
    console.log('messageRecieved Off', c)
})

Sending events to server SignalR uses the invoke method to call methods on the server,

A simple way to keep the server alive is sending a heartbeat

connection.invoke('heartbeat')

Wrapping this in an interval and calling it constantly would do the trick (code above in starting a connection)

|| Note: in the 3.0 version a simple .withAutomaticReconnect() can be passed in the HubConnectionBuilder() chain and it would do. -- Ref

Callback if connection closes

For running any processes and logging errors if the connection drops, there's a onclose method

connection.onclose((error: any) => {
    console.log('Connection closed', JSON.stringify(error))
})

Basics#

Referrences#