Websocket example won't work

Question

I try run this example:

import java.util.logging.Level;
import java.util.logging.Logger;
import javax.websocket.OnClose;
import javax.websocket.OnError;
impo         


        

Answer 1

I had the same problem trying to use WebSocket API on Tomcat 7.0.47. The error message being displayed client side wasn't any help at all and my server side endpoint was never being created.

After much wasted time I found it was due to way I had set the dependency for javax.websocket-api. I'm using Maven which has the default scope as compile which causes problems as Tomcat has the websocket-api.jar in its lib folder. Setting the dependency to provided solved it.

    <dependency>
      <groupId>javax.websocket</groupId>
      <artifactId>javax.websocket-api</artifactId>
      <version>1.0</version>
      <scope>provided</scope>
    </dependency>

Hope this helps

It's also worth noting that if running behind Apache you will need mod_proxy_wstunnel and if using IIS you will need version 8.0 as anything prior does not support websockets.