WebSocket handshake: Unexpected response code: 404 -

Question

I am learning about websockets and followed the instructions here: http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/HomeWebsocket/WebsocketHome.html

I' using tomcat v8.0.21 to deploy my webapp but get the following error

My JavaScript Project looks fine, when I visit the webapp: my localhost and visit WebSocketJavaScriptProject

Although in the console window get the error: WebSocket connection to 'ws://localhost:8080/WebsocketHome/actions' failed: Error during WebSocket handshake: Unexpected response code: 404

My code lives here: https://github.com/darkcloudi/WebSocketProject

Difference between my app and the example on Oracle is I have split it as two projects one service and the other webapp.

I cannot figure out why I would be getting a 404 as the service .war file is called WebsocketHome. Any ideas what would be causing this issue? Usually a 404 is not found so guessing it cannot finding the service , i'm sure i'm doing something stupid but cannot figure out where the problem is

Thanks

Solution

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:

<!-- Provided Websocket API, because tomcat has its own implementation -->
<dependency>
    <groupId>javax.websocket</groupId>
    <artifactId>javax.websocket-api</artifactId>
    <version>1.1</version>
    <scope>provided</scope>
</dependency>

Comments

[sam]

Thanks for responding. So I tried what you suggested and it worked. Thanks :) I can see in the console that I get Status Code:101 Switching Protocols so thats good. But now get a different error in the logs (see below), need to look into why, main thing the service is running. 08-Jun-2015 20:40:31.276 SEVERE [http-nio-8080-exec-13] org.example.websocket.DeviceWebSocketServer.onError null java.lang.NullPointerException

[sam]

Appears the first error is when its opening connection so need to do some more debugging. duffy - thanks again as I never realised that Tomcat had its own implementation. 08-Jun-2015 20:55:41.287 SEVERE [http-nio-8080-exec-26] org.example.websocket.DeviceWebSocketServer.onError null java.lang.NullPointerException at org.example.websocket.DeviceWebSocketServer.open(DeviceWebSo‌​cketServer.java:29)

[Ishmael]

This is the holy grail of answers. I've spent days finding this answer.

[raksheetbhat]

This isn't helpful.

[Abdul Majid Bajwa]

Thanks buddy. I was added wesocket api jar and also add this jar in deployment assembly. But I should add websocket api for compile time usage but for runtime I need to remove from deployment assembly as TOMCAT server have already contain websocket api. Great help man thanks