azureasp.net-corewebsocketsignalr

What means skipNegotiation in SignalR HubConnection?

What is the difference between:

this.hubConnection = new signalR.HubConnectionBuilder()
  .withUrl(environment.API_URL + "invoicinghub", {
    skipNegotiation: true,
    transport: signalR.HttpTransportType.WebSockets
  })
  .withAutomaticReconnect([0, 2000, 10000, 30000, null])
  .build();

and

this.hubConnection = new signalR.HubConnectionBuilder()
  .withUrl(environment.API_URL + "invoicinghub", {     
    transport: signalR.HttpTransportType.WebSockets
  })
  .withAutomaticReconnect([0, 2000, 10000, 30000, null])
  .build();

What does this skipNegotiation : true.

Thanks!

Solution

  • In SignalR, the client first sends a negotiation request to the server and the server responds with a redirect URL and an access token if there is one.

    Client Request

    {
  "connectionId":"807809a5-31bf-470d-9e23-afaee35d8a0d",
  "availableTransports":[
    {
      "transport": "WebSockets",
      "transferFormats": [ "Text", "Binary" ]
    },
    {
      "transport": "ServerSentEvents",
      "transferFormats": [ "Text" ]
    },
    {
      "transport": "LongPolling",
      "transferFormats": [ "Text", "Binary" ]
    }
  ]
}

    Server Response

    {
    "url":"https://test.service.signalr.net/client/?hub=chat&...",
    "accessToken":"<a typical JWT token>"
}

    Only after receiving the response from the server does the client establish a connection.

    In SignalR Core, but not in SignalR ASP, this requires sticky sessions. To avoid using sticky sessions, the client needs to skip negotiation but is restricted to only using websockets without Azure.

    Sources: