I haven't really had time to look at this at all, but a couple comments.....
On Friday, July 08, 2011 9:23:05 PM Guillaume Sauthier wrote: > If you look at the global picture: > http://wiki.jonas.ow2.org/xwiki/bin/download/Main/ReliableJMS_Transport_CXF/ > cxf-reliablejms-execution-flow-simple-english.png > > you'll notice that the client is split in 2 parts: the initiator (initiates > the call) and the handler (process the result). > > We don't use the JAXWS AsyncHandler API because it is tightly coupled to the > execution context of the client initiator: maybe the handler has some ref > to live objects that we cannot persist and/or recreate if the initiator JVM > crashes. > In order to bypass this issue, we had to tweak the jaxws development model a > little bit: > * on initiator side, we use the normal (synchronous) generated API, but the > stub always returns null (as the call was synchronous, the answer is not > there yet) This is what concerns me the most and would be my #1 complaint. This really kind of abuses the JAX-WS API's quite a bit which makes me a bit uncomfortable. I think I'd really prefer something that doesn't really abuse the JAX-WS API's like that. For the most part, I'd want to keep the API's working as advertised, but possibly with extended behavior. I'd also DEFINITELY prefer a solution that doesn't require spring or is very easily to decouple from Spring. A lot of work was put into 2.4 to minimize the Spring requirements. There are three types of JAX-WS methods we need to consider. For the Async methods that return a Response<Foo> type thing, we're completely in control of that return object. Thus, that object can be restoreable (serializable or similar) and passed back. The client can use it to poll when the response is there, etc... The non-async method should, IMO, just work as designed. It should block until the return is avail. It COULD be implemented in terms of the Response<Foo> thing above. For the Async method that takes the AsyncHandler, we should use it. It COULD also optionally implement additional CXF specific interfaces to help handle saving/restoring it. Anyway, those are my initial thoughts. I also agree with Christian that having a single JMS transport is also preferred, but not a "huge" requirement. Dan > * the initiator provides an AsynchHandler through the Spring application > context, this handler will be notified when a response will be posted on the > response queue. As this object is created from Spring beans, it is > decoupled from the initiator execution context and can be safely used. > * The request flow is quite normal: we define a <jaxws:client> on the client > side, a <jaxws:endpoint> on the server side > * But the response flow is different than what we could expect: the client > also defines a <jaxws:endpoint> that will be invoked when JMS messages will > be posted on the response queue. > > As everything is transactional, we have dead message queues, so that we > never lost any messages. > > Hope that helps to understand this potential contribution. > > Thanks > --Guillaume > > > 2011/7/8 Christian Schneider <[email protected]> > > > Yes request / response correlation is definately a place where we > > currently loose message when the client goes down. > > > > I think this is o big issue though as you typically only use request > > response when you wait for the response. So normally you will even want > > the responses to be lost when the client goes down. In the one way case > > we should not loose messages as we can also use transactions. > > > > Still your JMS transport my be interesting. When doing the refactoring > > to > > spring jms templates and message listener I also thought about making > > the > > transport more asynchronous but never really did it. > > So I would like to compare your implementation with the current one in > > cxf. > > > > I would not like to have both though. If your transport is more suitable > > we should throw the other away. In any case we should only have one JMS > > transport. > > > > Christian > > > > Am 08.07.2011 14:39, schrieb Florent BENOIT: > > Hi, > >> > >> One example about the "reliable" stuff is that we should include > >> "recovery". > >> For example the correlation map used to match JMS replies is stored in > >> memory [1] > >> 341 Exchange exchange = correlationMap.remove(**correlationId); > >> 342 if (exchange == null) { > >> 343 LOG.log(Level.WARNING, "Could not correlate message with > >> correlationId " + correlationId); > >> 344 return; > >> 345 } > >> > >> > >> So, if the JVM of the client is restarted, we will loose any replies > >> as we won't know how to match the reply. > >> Also, there is no JTA used with the current JMS transport. It means > >> that > >> we can loose data or to get some messages twice or so one. > >> > >> So even by using ActiveMQ with the messages being stored on the disk, > >> this won't work after a restart. > >> > >> [1] : > >> http://svn.apache.org/viewvc/**cxf/trunk/rt/transports/jms/** > >> src/main/java/org/apache/cxf/**transport/jms/JMSConduit.java?** > >> view=markup<http://svn.apache.org/viewvc/cxf/trunk/rt/transports/jms/s > >> rc/main/java/org/apache/cxf/transport/jms/JMSConduit.java?view=markup> > >> > >> Regards, > >> > >> Florent > >> > >> On 07/08/2011 02:25 PM, Benson Margulies wrote: > >>> I'm confused. If you use AMQ configured for reliable storage on > >>> disk, > >>> how do you lose things with the existing CXF transport? > >>> > >>> On Fri, Jul 8, 2011 at 8:23 AM, Florent > >>> BENOIT<[email protected]> > >>> > >>> wrote: > >>>> Hi CXF guys, > >>>> > >>>> I would like to introduce a new CXF transport that we've developed > >>>> and > >>>> that > >>>> could be contributed back to the CXF community. It is called > >>>> "Reliable > >>>> JMS > >>>> transport" > >>>> > >>>> When this transport has been designed, the goal was to have a > >>>> reliable > >>>> transport that we could called "Enterprise Transport" as we wanted > >>>> to > >>>> use > >>>> transactions and JMS by using containers like Java EE EJB or > >>>> Spring MDP (we > >>>> support both). We don't want to loose any requests or answers and > >>>> we > >>>> want to > >>>> avoid waiting threads. This transport has not been designed from > >>>> scratch as > >>>> it is using the JMS layer and share some classes with the current > >>>> CXF > >>>> JMS > >>>> transport but there are some differences between them. But we > >>>> couldn't > >>>> change the current transport as the design is not the same. > >>>> > >>>> First, let me give you details about this transport and why it's > >>>> different > >>>> from the current JMS CXF transport. > >>>> > >>>> The current CXF JMS transport is not reliable. For example, if you > >>>> restart a > >>>> client or a server you may loose some requests/answers. This is > >>>> because the > >>>> mechanism that is used is keeping data in memory. So after a JVM > >>>> crash, all > >>>> the data are lost. > >>>> Also, for this new transport, we wanted to guarantee the delivery > >>>> so it is > >>>> using transactions. (A transaction manager is then required). > >>>> As said before, we wanted to avoid the use of threads waiting for > >>>> an > >>>> answer. > >>>> If there are 100 requests, we don't want 100 threads waiting their > >>>> answer. > >>>> This is because we can use either EJB MDB or Spring MDP to handle > >>>> the > >>>> answer. In this way, resources are allocated only if an answer is > >>>> handled > >>>> and not during all the waiting time. So the number of threads is > >>>> dramatically reduced. Also by relying on EJB MDB or Spring MDP > >>>> we're > >>>> based > >>>> on existing patterns. > >>>> > >>>> Here is a link to the documentation of this transport and pictures > >>>> that are > >>>> illustrating this solution : > >>>> http://wiki.jonas.ow2.org/**xwiki/bin/view/Main/** > >>>> ReliableJMS_Transport_CXF<http://wiki.jonas.ow2.org/xwiki/bin/view > >>>> /Main/ReliableJMS_Transport_CXF> This illustrates how the > >>>> > >>>> And the errors handling that is working with all kind of JVM crash > >>>> : > >>>> http://wiki.jonas.ow2.org/**xwiki/bin/download/Main/** > >>>> ReliableJMS_Transport_CXF/cxf-**reliablejms-execution-flow-** > >>>> simple-failure-english.png<http://wiki.jonas.ow2.org/xwiki/bin/dow > >>>> nload/Main/ReliableJMS_Transport_CXF/cxf-reliablejms-execution-flo > >>>> w-simple-failure-english.png> > >>>> > >>>> There are integration tests included in this transport that are > >>>> launched through our continous integration tool on > >>>> http://bamboo.ow2.org For now, they're using JOnAS as Java EE > >>>> server as we need a JTA manager and > >>>> we test both EJB MDB and Spring MDP providers. > >>>> > >>>> To sum up, is there an interest in CXF to integrate this transport > >>>> ? > >>>> What > >>>> kind of changes need to be done, etc. > >>>> Also I hope to get some feedback about this protocol. > >>>> > >>>> Regards, > >>>> > >>>> Florent > > > > -- > > -- > > Christian Schneider > > http://www.liquid-reality.de > > > > Open Source Architect > > Talend Application Integration Division http://www.talend.com -- Daniel Kulp [email protected] http://dankulp.com/blog Talend - http://www.talend.com
