Error during WebSocket handshake: Unexpected response code: 302

Question

While connecting to REACT based WebSocket client to Java Jetty based Web Socket server, I am getting the error below -

WebSocket connection to 'ws://localhost:2319/ws' failed: Error during WebSocket handshake: Unexpected response code: 302

This error doesn't exist while connecting through Chrome's Smart Web Socket client.

I am trying to develop Web Socket Client based on REACT. Client code is -

var connection = new WebSocket('ws://localhost:2319/ws');
     connection.onopen = function () {
     // connection is opened and ready to use
    };

WebSocket Server has been based on Jetty. Server code is -

server = new Server();
    ServerConnector connector = new ServerConnector(server);
    connector.setPort(SSConstants.WWBSOCKET_PORT);
    server.addConnector(connector);

    // Setup the basic application "context" for this application at "/"
    // This is also known as the handler tree (in jetty speak)
    ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
    context.setContextPath("/ws"); // Set to "/ws" for future integration with the main jetty server.
    server.setHandler(context);

    try {
        // Initialize javax.websocket layer
        ServerContainer wsContainer = WebSocketServerContainerInitializer.configureContext(context);

        // Add WebSocket endpoint to javax.websocket layer
        wsContainer.addEndpoint(WebsocketListener.class);
        server.start();           
    }
    catch (Throwable t) {
        ssLogger.logInfo("Websocket Server start exp : ");
        t.printStackTrace(System.err);
    }

Output -

WebSocket connection to 'ws://localhost:2319/ws' failed: Error during WebSocket handshake: Unexpected response code: 302

Request URL:ws://localhost:2319/ws
Request Method:GET
Status Code:302 Found

Response Headers
view source
Content-Length:0
Date:Fri, 11 Aug 2017 18:51:42 GMT
Location:http://localhost:2319/ws/
Server:Jetty(9.3.8.v20160314)

Request Headers
view source
Accept-Encoding:gzip, deflate, br
Accept-Language:en-US,en;q=0.8
Cache-Control:no-cache
Connection:Upgrade
Host:localhost:2319
Origin:https://localhost:1338
Pragma:no-cache
Sec-WebSocket-Extensions:permessage-deflate; client_max_window_bits
Sec-WebSocket-Key:2OZooIjOX7G6kgNpPOz9Fw==
Sec-WebSocket-Version:13
Upgrade:websocket
User-Agent:Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.90 Safari/537.36
Name

Answer 1

ws://localhost:2319/ws is not the valid endpoint URL/URI, it wants to redirect to the correct one for your declared contextPath of /ws

That's what the 302 redirect is telling you ...

Location: http://localhost:2319/ws/

Lets say your WebsocketListener is declared as @ServerEndpoint("/ws"), and we use your ServletContext at contextPath of "/ws" that would mean your URL/URI to access that websocket endpoint is ...

ws://localhost:2319/ws/ws

Or said in a different way ...

ws://<host>:<port>/<contextPath>/<endpointPath>