El Bruno

Hello!

Today something that can be quite annoying with signalR:

The need for a signalR hub from a web client, hosted on a different server from SignalR address

When we have something like this in WPF, Win8, or other .Net client; the solution is quite easy: declare 2 connections and 2 different hubs

   1: _connection = new HubConnection("http://localhost:50000/");

   2: _myHub = _connection.CreateHubProxy("MyHub");

   3: _connection.Start().Wait();

   4:  

   5: _connection2 = new HubConnection("http://localhost:50001/");

   6: _myHub2 = _connection2.CreateHubProxy("MyHub");

   7: _connection2.Start().Wait();

However in JavaScript, si not that easy . Let’s see the following example. In this case, from a local url httl://localhost:1234, I need to use an external Hub signalR hosted at http://localhost:4316.

   1: $(function () {

   2:     $.support.cors = true;

   3:     $.connection.hub.url = 'http://localhost:4316/signalr/hubs';

   4:     var chat = $.connection.myHub;

   5:     $.connection.hub.start({ jsonp: true}).done(function () {

   6:         console.log("connection started");

   7:         $('#sendmessage').click(function () {

   8:             chat.server.publishMessage($('#message').val());

   9:         });

  10:     });

  11: });

A summary of this javascript client, can be::

• Enable JQuery CORS in javascript (line 3)
• Define the url of the connection (line 4)
• Start the connection, using jsonp (only necessary with Chrome)

However, this solution is only 50%. The next thing is to enable cross-domain calls into the server. Prior to version 2.0, there was a property of the fairly self-explanatory hub:

var config = new HubConfiguration {EnableCrossDomain = true};

Now with SignalR 2.0, also we must modify the configuration by default of Hubs, but in this case enabling JSONP.

   1: public partial class Startup

   2: {

   3:     public void Configuration(IAppBuilder app)

   4:     {

   5:         var configuration = new HubConfiguration

   6:         {

   7:             EnableJSONP = true

   8:         };

   9:         app.MapSignalR(configuration);

  10:         ConfigureAuth(app);

  11:     }

  12: }

Done !!! We have cross domain enabled for calls to SignalR hubs.   

Saludos @ La Finca

El Bruno

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