How to connect a java client to SignalR Hub using only websockets?

Question

I need to access a websocket server that runs with SignalR Hub, from my Java desktop application.

• There is a library that does exactly that, but it's dead. There are lots of issues and pull requests and it hasn't been updated since 2015.
• I also found another library but, as far as I can tell, it's only for Android projects.
• I found a SO question that says it's possible to talk directly to the SignalR server (standard websocket calls) with some workarounds, but the given link is dead.

When I tried to access the server directly with websocket, the HTTP handshaking fails (I get HTTP 200 instead of 101).

Can anyone help ?

Curtsy

Answer 1

You will not be able to connect to SignalR 2.x with just bare webSocket. The reason for that is that starting the connection requires a few HTTP requests which have to be sent with in a specific order and contain specific content. I described the SignalR protocol in a blog post. After reading this post you will understand why dedicated client for SignalR 2.x existed.

Having said that - the new version of SignalR for ASP.NET Core no longer has this protocol and requirements and it is possible to connect to the server with just bare websockets. I created a demo a while ago showing how to do this - you can find details here. I also started working on an example for the hubs layer but need to finish it.

Cove

Your sample repo doesn't seem to have an example of connecting to SignalR using websockets - perhaps you've changed this since? – Murielmurielle

There is a social weather sample that uses just webSockets: github.com/aspnet/SignalR/blob/dev/samples/SocialWeather/…. It is actually more than that - you can read the entire story here: blog.3d-logic.com/2017/01/15/… – Cove

The URL is dead, and the server at github.com/aspnet/SignalR/tree/master/samples/SocialWeather doesn't use SignalR at all. (And the repo is archived and read-only.) – Lucy

Folow-up: the WebSocket->SignalR example is at github.com/aspnet/SignalR-samples/tree/pawelka/ticker-ws/… . – Lucy

@Cove And there is no possibility to check when a user lost internet connection by timeout. Again. Right? – Xanthine