I am learning about websockets and followed the instructions here: http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/HomeWebsocket/WebsocketHome.html
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The Error during the handshake happens, because Tomcat has its own api for websockets. Thus you might have added the JSR implementation or something similar as javax.websocket-api in your pom.xml there comes a conflict at runtime.
Try to not export your Websocket-library to your webserver, thus it uses its own implementation.
If you use maven, set the websocket dependency as provided:
javax.websocket
javax.websocket-api
1.1
provided