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From Aki Yoshida <elak...@gmail.com>
Subject Re: Question about WS-RM
Date Tue, 04 Jun 2013 16:17:30 GMT
Hi Juan,

It looks like the problem occurs after the response retransmission from the
server at the client side at its decoupled receiving port. Because you have
a request-response call, there is a step to correlate this response message
to the original exchange. But the old exchange was gone when the old client
died. As this condition is not handled correctly, it results in an
unexpected exception and terminating the processing. As a consequence, the
client can never return an ack to the server, so the server will keep
resending the response to the client.

While getting this exception and unexpectedly terminating the process is a
bug, it is probably correct to reject the response from the server because
the client cannot deliver this response to the original requester. The only
information useful in the response is the ack for the original request.
This ack should be processed at the client to clean up any resource
associated with the original source sequence status. But there is no place
for the response payload to go.

If we could use a different programming model, the new client could pull
the old response using the persisted key of the old request. But for the
request response model, there is no way to deliver the response to the
original requester when it is permanently gone.

So basically, if you have a request-response service, there can be some
network errors any time during the calls but your client needs to remain
alive after transmitting a request until it receives its response.

I don't know your requirement from your scenario. What do you expect at the
client?  Typically, people use oneway calls and do any correlation needed
in the application level using two oneway calls. In that case, you don't
have this limitation.

regards, aki




2013/6/4 Aki Yoshida <elakito@gmail.com>

> Hi Juan,
> Thanks for uploading the logs. I am not yet 100% sure but it looks like
> there is an issue in the response delivery for request-response ws-rm case
> after an error.
>
> As we have several persistent recovery tests for ws-rm, I thought
> initially the problem after a successful response retransmission from the
> server (hence my question about how the client was configured) but the
> problem is occurring before. I'll look into it today.
>
> regards, aki
>
>
> 2013/6/3 Juan Alberto Lopez Cavallotti <juan.cavallotti@mulesoft.com>
>
>> Hi Aki,
>>
>> Please find the log here: http://pastebin.com/B0TtSduG
>>
>> About the client, it works correctly all the time when I use the CXF
>> facilities outside Mule, this is, connecting to a spring webapp with the
>> same service configured, my goal is to solve this for any type of client,
>> correct or incorrect.
>>
>> Thanks,
>> Juan
>> MuleSoft
>>
>>
>> On Mon, Jun 3, 2013 at 10:14 AM, Aki Yoshida <elakito@gmail.com> wrote:
>>
>> > Hi Juan,
>> > your attachment didn't get to the list. Maybe you should put it at some
>> > remote storage that hat the http access.
>> >
>> > and how is your client configured? can you make sure that you configured
>> > the decoupled endpoint and persistence at the client?
>> >
>> > regards, aki
>> >
>> >
>> > 2013/5/31 Juan Alberto Lopez Cavallotti <juan.cavallotti@mulesoft.com>
>> >
>> > > Hi Aki,
>> > >
>> > > Thank you for your reponse.
>> > >
>> > > Yes, I have a decoupled endpoint, I have a standalone client based on
>> > > cxf's sample projects (nothing fancy added) which is currently working
>> > > fine, I'm killing it randomly so I can handle that kind of outages I'm
>> > > aware that you also have a custom interceptor for generating
>> > communication
>> > > errors.
>> > >
>> > > My problem context is the following:
>> > >
>> > > I have exposed a service through Mule ESB facilities (I'm currently
>> > trying
>> > > to fix a bug in Mule's code) which exposes a service as described on
>> this
>> > > section on the doc
>> > >
>> >
>> http://www.mulesoft.org/documentation/display/current/Building+Web+Services+with+CXF#BuildingWebServiceswithCXF-CreatingaJAX-WSService
>> > > .
>> > >
>> > > Also I have enabled WS-RM on the server via spring configuration file
>> as
>> > I
>> > > showed before, so in this case Mule is responsible for building and
>> > > exposing the server endpoint though HTTP. This facility is powered by
>> our
>> > > UniversalConduit (source code link is on the previous comment).
>> > >
>> > > I also have to note that when is no outage on either the client or the
>> > > server side, everything is works perfectly. Server receives the
>> requests
>> > > through its endpoint and answers to the client through the decoupled
>> > > endpoint.
>> > >
>> > > Now the problem is:
>> > > When there is an outage on the backchannel (I.E client dies) then the
>> > > message is put in a retransmission queue (which is actually a good
>> thing)
>> > > but  for some reason the redelivery queue isn't able to even attempt
>> to
>> > > resend the retries and also never gives up.
>> > >
>> > > Please find attached an execution log in debug level so you get the
>> sense
>> > > of what is going on. The last log sentences would repeat at-infinitum
>> > until
>> > > I kill the server.
>> > >
>> > > Now, I know there is a bug on our conduit (or any other part of our
>> code)
>> > > so I'm trying to understand why I'm having this behavior and
>> hopefully be
>> > > able to fix it.
>> > >
>> > > Please let me know if you need more detailed information.
>> > >
>> > > About upgrading the version, currently it is not so easy. We have
>> > upgraded
>> > > to 2.5.9 for our latest release so maybe upgrading to 2.5.10 could be
>> an
>> > > option but for future releases.
>> > >
>> > > Thanks for your help,
>> > >
>> > > Regards,
>> > > Juan
>> > >
>> > >
>> > >
>> > > On Fri, May 31, 2013 at 6:00 AM, Aki Yoshida <elakito@gmail.com>
>> wrote:
>> > >
>> > >> Hi Juan,
>> > >> I have a couple of questions.
>> > >>
>> > >> You mention of the backchannel, that means you have configured a
>> > decoupled
>> > >> endpoint where the server can asynchronously deliver ack messages
>> to? I
>> > >> didn't see it at least in your beans.xml file. And you have a
>> > >> request-response service right? That means there are application
>> > messages
>> > >> going in both directions.
>> > >>
>> > >> And when you say no retry is happening back to the client after
>> restart,
>> > >> have you enabled the persistence? If the client didn't persist the
>> > >> sequence, it cannot handle the messages sent back on that sequence.
I
>> > >> didn't see the persistence enabled in your beans.xml. So it's not
>> clear
>> > to
>> > >> me if that is your entire configuration or you are adding additional
>> > stuff
>> > >> programatically.
>> > >>
>> > >> So I still don't know if this is some inconsistent configuration or
a
>> > >> known
>> > >> bug or a new bug/limitation.
>> > >>
>> > >> regards, aki
>> > >> p.s. In 2.6.x, there is an option to set the maximum number of
>> > >> retransmission and there is also a way to terminate a message or a
>> > >> sequence
>> > >> permanently from the persistence over JMX. 2.5.1 is really old. Do
>> you
>> > >> need
>> > >> to stick to it or can you at least get to a more recent 2.5.10 or to
>> > >> 2.6.8?
>> > >>
>> > >>
>> > >>
>> > >> 2013/5/29 Juan Alberto Lopez Cavallotti <
>> juan.cavallotti@mulesoft.com>
>> > >>
>> > >> > Hi Aki,
>> > >> >
>> > >> > Thanks for getting back to me, if you wish to see the
>> implementation
>> > of
>> > >> the
>> > >> > conduit, here is a github link for it:
>> > >> >
>> > >> >
>> > >> >
>> > >>
>> >
>> https://github.com/mulesoft/mule/blob/mule-3.3.2/modules/cxf/src/main/java/org/mule/module/cxf/transport/MuleUniversalConduit.java
>> > >> >
>> > >> > What I'm trying to do is to make this conduit to handle outages
on
>> the
>> > >> > backchannel correctly. The CXF version we're using is 2.5.1. The
>> > >> scenario
>> > >> > is the following:
>> > >> >
>> > >> > I have WS-RM working, on the happy path:
>> > >> >
>> > >> > - Client creates a sequence.
>> > >> > - Server acknowledges on the backchannel.
>> > >> > - Client sends the request.
>> > >> > - Server answers on the backchannel.
>> > >> > - Client acknowledges the answer.
>> > >> >
>> > >> > What is happening here is that when I have some outage on the
>> client.
>> > >> For
>> > >> > example client dies suddenly. The message gets in the redelivery
>> queue
>> > >> and
>> > >> > it gets stuck forever logging constantly that message.
>> > >> >
>> > >> > I would like to understand how I can make the redelivery queue
to
>> give
>> > >> up
>> > >> > after a certain amount of retries but I believe currently is not
>> being
>> > >> able
>> > >> > to retry so, I would like to understand the reason why.
>> > >> >
>> > >> > Regards,
>> > >> > Juan
>> > >> >
>> > >> >
>> > >> > On Wed, May 29, 2013 at 2:50 PM, Aki Yoshida <elakito@gmail.com>
>> > wrote:
>> > >> >
>> > >> > > I suppose you are seeing this warning because you have
>> configured no
>> > >> > > separate channel (i.e.d, decoupled endpoint) for acks or
response
>> > >> > delivery.
>> > >> > > So when the http response connection is gone, you will get
some
>> kind
>> > >> of
>> > >> > > stuck message until at least the next message comes in.
>> > >> > >
>> > >> > > Can't say anything about the line 101 if we don't know the
cxf
>> > >> version.
>> > >> > >
>> > >> > > In any case, if you don't (or can't configure a decoupled
ep
>> because
>> > >> of
>> > >> > > your firewall rules), you should stick to oneway calls and
>> > >> > > setting AcknowledgementInterval to 0 so that you get your
request
>> > >> ack'ed
>> > >> > in
>> > >> > > its response.
>> > >> > >
>> > >> > > If you have further questions, please describe your scenario
in
>> more
>> > >> > > details (version, req/resp or oneway, etc). And i don't know
what
>> > your
>> > >> > > conduit is doing. So it's really hard what to say based on
the
>> info
>> > >> you
>> > >> > > provided so far.
>> > >> > >
>> > >> > >
>> > >> > >
>> > >> > > 2013/5/29 Juan Alberto Lopez Cavallotti <
>> > juan.cavallotti@mulesoft.com
>> > >> >
>> > >> > >
>> > >> > > > Hello,
>> > >> > > >
>> > >> > > >
>> > >> > > > I have a custom conduit implementation which takes care
of the
>> > >> > > integration
>> > >> > > > of CXF and MuleESB. I am able to use the WS-RM functionality
on
>> > the
>> > >> > happy
>> > >> > > > path over this conduit but when something goes wrong
on the
>> > >> > backchannel I
>> > >> > > > get the message stuck on the redelivery queue and constantly
>> > >> printing
>> > >> > the
>> > >> > > > following log statement:
>> > >> > > >
>> > >> > > > WARN 2013-05-27 16:57:33,917 [RMManager-Timer-2051976295]
>> > >> > > org.apache.cxf.endpoint.DeferredConduitSelector:
>> > >> > > > MessageObserver not found This is actually happening
on line:
>> 101
>> > of
>> > >> > the
>> > >> > > > class org.apache.cxf.endpoint.AbstractConduitSelector
>> > >> > > >
>> > >> > > > I would like to diagnose the cause of this situation.
>> > >> > > >
>> > >> > > > Please find attached my configuration file.
>> > >> > > >
>> > >> > > > Thanks for your help in advance.
>> > >> > > >
>> > >> > > > Regards,
>> > >> > > > Juan Alberto López Cavallotti
>> > >> > > >
>> > >> > >
>> > >> >
>> > >>
>> > >
>> > >
>> >
>>
>
>

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