WebSocketTransportHandler passes Collections.<String, Object>emptyMap() to HandshakeHandler [SPR-12716]

[spring-projects-issues]

Rob Winch opened SPR-12716 and commented

WebSocketTransportHandler passes in an empty Map into the delegate HandshakeHandler. This causes two problems:

• The first is that no attributes that are were copied from any HandshakeInterceptor instances are available. For example, TransportHandlingSockJsService will invoke the HandshakeInterceptor and then delegate to a WebSocketTransportHandler. Since the attributes provided by the HandshakeInterceptor are not passed into the delegate HandshakeHandler
• The second is that the delegate HandshakeHandler cannot populate any attributes to be provided in the WebSocket Session. For one Collections.<String, Object>emptyMap() is immutable. For two, the values are never copied to the WebSocket Session.

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Affects: 4.1.4

[spring-projects-issues]

Rossen Stoyanchev commented

With SockJS the actual "session" is of type SockJsSession and for the websocket transport that's WebSocketServerSockJsSession which wraps the underlying WebSocketSession instance.

The attributes map that is populated by HandshakeInterceptors is correctly passed to the SockJsSession (TransportHandlingSockJsService line 238) and that's all that should matter for the most part since no one should ever see the wrapped WebSocketSession. This is why we pass an empty map in WebSocketTransportHandler.

That said it is true that the delegate HandshakeHandler won't be able to add any attributes. Is that the actual issue you're running into? Now that I look at this again we might as well pass the attributes from the SockJsSession into the handshakeHandler, i.e. change from Collections.emptyMap to WebSocket wsSession.getAttributes.

Does that make sense?

[spring-projects-issues]

Rob Winch commented

Thanks for the response.

My actual issue is actually a bit incidental actually. I was using a TestHandshakeHandler to verify that a custom HandshakeInterceptor was properly integrated with the configuration. I felt that this is an actual issue.

I think that changing from Collections.emptyMap to wsSession.getAttributes would fix both issues.