@tcrawley: this is the exception I get when the connection drops -- java.io.IOException: UT002044: Compressed message payload is corrupted And this is how I'm using the extension

(.addExtension
              (.getAttachment handler UndertowWebsocket/HANDSHAKE_ATTACHMENT_KEY)
              (PerMessageDeflateHandshake.
                false Deflater/BEST_COMPRESSION false false))

no connection drops happen when I dont use the extension

@tcrawley: the above could possibly be a misconfiguration on my part because when I switch to the following setting I dont see any connection drops or exceptions

(PerMessageDeflateHandshake.
                false Deflater/BEST_COMPRESSION false true)

unless you think this is a bug, I am going to go with the latter setting. i am thinking its the right config based on how our browser client JS works. So if you dont think this is a bug with the extension, kindly make a 2.1.4 available as soon as is convenient for you. Thanks! @tcrawley