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https://issues.apache.org/jira/browse/CXF-5417?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13869449#comment-13869449
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Sergey Beryozkin commented on CXF-5417:
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Hi Andriy
Thanks for your analysis, it's been helpful. I've checked some resources as
well.
I think the obvious fact is that people who would like to write effective
asynchronous applications are keen to ensure the thread doing some work for the
already disconnected client does not spend another 1/5/etc seconds - especially
if a lot of clients are there and the percentage of the disconnected ones is
bigger.
I can see the people go at some length to write the code doing the heart-beat
messages with keep-alive, etc, as in
http://stackoverflow.com/questions/12085235/servlet-3-async-context-how-to-do-asynchronous-writes
So the good thing about ConnectionCallback is that JAX-RS 2.0 developers will
register it and that is it, CXF will do the rest, the solution can not be
perfect, and may be not guaranteed to work 100%, I agree :-), but I think in
case of CXF it should be straightforward to implement. This would also be of
help to users working directly with the CXF Continuations API.
The other thing is that implementing it would help to keep some users with CXF
JAX-RS. The way it often works, due to the fact we have 3+ JAX-RS
implementations, is that users can migrate to the implementation where a given
feature is available - so if we have CXF JAX-RS devs doing a pure portable
async code and keen to optimize then they can be tempted to migrate, so in the
end it is in our interests to implement it.
I'd like to propose to start with Servlet3Continuation.class, I can then do the
same with JettyContinuationWrapper and we can ignore JMSContinuation. So:
1. Add CXF ConnectionCallback interface - will be the same as JAX-RS one,
single method only.
2. in Servlet3Continuation constructor:
{code:java}
private ConnectionCallback connectionCallback;
private Timer timer;
// constructor:
connectionCallback = message.getExchange().get(ConnectionCallback.class);
if (connectionCallback != null) {
// init timer and start a basic timer task which will send a keep-alive say
every 0.5 sec (we can later configure this timeout)
// and callback into connectionCallback in case of IO exception; all of it
can be done if the continuation has not been reset/completed, i.e, if
AsyncResponse is not null
}
{code}
3. Servlet3Continuation.reset method will stop the timer if it is not null
IMHO it is worth doing it. I'm happy to continue from here but may be you'd
like to try it ? We can test it with deploying a basic JAX-RS 2.0 application
to Tomcat where AsyncResponse is saved into some map and then it is removed on
a client disconnect. I think I have an existing test project somewhere I can
update it and attach it here
Cheers, Sergey
> Support optional JAX-RS 2.0 ConnectionCallback
> ----------------------------------------------
>
> Key: CXF-5417
> URL: https://issues.apache.org/jira/browse/CXF-5417
> Project: CXF
> Issue Type: Improvement
> Components: JAX-RS, Transports
> Reporter: Sergey Beryozkin
> Priority: Minor
>
> https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/container/ConnectionCallback.html
> lets JAX-RS 2.0 applications receive the notifications when a given client
> has disconnected.
> We can probably build something on top of the Jetty-specific connector and
> also enhance CXF Continuation API.
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