[undertow-dev] JSR WebSocket onMessage called out-of-order

[Stuart Douglas]

I think this is a bug, I will have a look. 

Stuart

----- Original Message -----
> From: "Stephan Mehlhase" <stephan.mehlhase at eml.org>
> To: undertow-dev at lists.jboss.org
> Sent: Wednesday, 18 March, 2015 12:36:31 AM
> Subject: [undertow-dev] JSR WebSocket onMessage called out-of-order
> 
> Hi,
> 
> I ran into an issue with the Undertow JSR WebSocket implementation: the
> message handler's @OnMessage method is not called with messages in the
> same order as these were sent. I encountered this problem first with the
> current WildFly 8.2.0.Final version. I posted about it in the forums
> [1]. But since I got no replies there and can reproduce this problem
> with Undertow 1.2.0.Beta4 (from maven) alone, I thought this might be
> the right place to ask about it.
> 
> I am developing a @ServerEndpoint which needs to handle clients sending
> unfragmented messages in rapid succession. These messages are not always
> delivered in the order as they were sent. Since WebSocket is based on
> HTTP, I assume that the messages arrive in the "correct" order at the
> server. However, from time to time two messages appear switched (e.g.
> message no. 4 arrives at @OnMessage before message no. 3). If I fragment
> the messages (according to RFC 6455), the order of all messages is
> always correct.
> 
> I have uploaded an example application which reproduces this to
> 
> http://pastebin.com/tcm6ZnsB
> 
> It uses some Guava classes for checking the order of messages.
> 
> I can also reproduce this problem with another (non-public but RFC
> compliant) WebSocket library.
> 
> My first question is, if that is intended behavior or a bug? The
> WebSocket RFC  does not explicitly forbid this kind of behavior, however
> for me it was very surprising given that
> 	1. the underlying protocols deliver everything in order,
> 	2. this works as I expected it for fragmented messages and
> 	3. I haven't seen this for other implementations.
> 
> If this is not considered a bug, is there an option which basically
> forces in-order delivery of messages? Ideally even accessible in
> WildFly. If not, does opening a feature request for this make sense
> (i.e. does it have a realistic chance of being addressed)?
> 
> 
> Best,
> Stephan
> 
> 
> 
> [1]: https://developer.jboss.org/message/921226#921226
> 
> --
> 
> Stephan Mehlhase
> Email: stephan.mehlhase at eml.org
> 
> EML European Media Laboratory GmbH
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