WebSocket compression support is broken

[robert-s-ubi]

Unfortunately, the recently added WebSocket compression support is broken due to a bug in the Java-WebSocket library (TooTallNate/Java-WebSocket#1496).

If WebSocket compression is enabled on a MultiProtocolJSONClient, the second message exchange with the MultiProtocolJSONServer yields an exception:

org.java_websocket.exceptions.InvalidDataException: invalid distance too far back
at org.java_websocket.extensions.permessage_deflate.PerMessageDeflateExtension.decodeFrame(PerMessageDeflateExtension.java:193)
at org.java_websocket.drafts.Draft_6455.translateSingleFrame(Draft_6455.java:589)
at org.java_websocket.drafts.Draft_6455.translateFrame(Draft_6455.java:762)
at org.java_websocket.WebSocketImpl.decodeFrames(WebSocketImpl.java:394)
at org.java_websocket.WebSocketImpl.decode(WebSocketImpl.java:229)

This can be worked around by changing the PerMessageDeflation configuration in MultiProtocolJSONClient perMessageDeflateExtension.setServerNoContextTakeover(false -> true), but that yields a much lower compression efficiency.

[robert-s-ubi]

I have submitted a PR to the Java-WebSocket library to fix the issue on their end:

TooTallNate/Java-WebSocket#1497

I don't know if or when this PR will be picked up, and when that might be released. In the meantime, if you want to use WebSocket compression, you can either compile this library from source with the modification mentioned above, or compile the Java-WebSocket library from source with the above PR patched in and use this library unmodified. The latter solution yields much higher compression efficiency (at the cost of higher memory usage).