I have just looked into the code of cxf to find out how it handles
incoming JMS Messages. In JMSDestination a listener thread is created
that reads from the queue and then dispatches the call to an
AutomaticWorkQueue. The default implementation of this is not
configurable and uses several threads. But I think if I write my own
AutomaticWorkQueue that makes sure one message is processed at a time I
could get nearer to what I want. What do you think?
Greetings
Christian
Christian Schneider schrieb:
Daniel Kulp schrieb:
On Jun 11, 2008, at 2:16 AM, Christian Schneider wrote:
Hi,
I am building webservice adapters for a legacy system. The system
can be accessed with a java api but is not multi threaded. So my
problem is
that I want to offer several services in one process and still make
sure only one service is called at a time. To make this scalable I
will then run this processes several
times on the same and different machines.
So my question is:
Can I offer several services with cxf on the same jms queue in one
process
I think so, yes. With configuration, you can use message selectors
to put multiple endpoints on the same queue and have the messages
dispatched correctly.
I am not sure if message selectors are what I want. If I have two
services on a queue and use message selectors, what will happen if I
have two messages in the queue one for each service? Let´s assume the
first message is for service 1 and the second for service2.
What I want is that the engine listens on the queue with one thread,
takes one message, finds out, which service it should be routed to and
calls the service. When the service returns it should take the next
message and route it to service 2. I guess with selectors both
messages would be processed in parallel. Can´t I simply configure both
services on the same queue and cxf routes the message like I wrote
using the SoapAction? Or will cxf automatically start a new thread for
each service it hosts? Is this behaviour configurable?
and make sure the whole process works only on one request at a time
and routes the reuqest to the right service?
This one I'm not sure about. Good question. CXF is definitely
designed for high scalability and mutlti-threaded cases.
Hmmmm.... One option, I guess, would be to write a custom invoker
that syncronizes things and use a single instance of that invoker for
all the endpoints. Might be harder for dynamic deployments though.
Another option might be to write a pair of interceptors, one for the
IN chain and one for the out/out fault chains that just
aquire/release a lock of some sort.
The interceptor solution sounds quite good to me. Though I would
prefer that cxf simply uses one thread only for both services. Then I
guess no interceptor and synchronizing would be necessary.
I also would like to make management of this system as easy as
possible. Ideally I would like this process to be a kind of
application server where I can install and deinstall services while
it is running.
Still they should listen on one queue and work single threaded. I
imagined doing this with an osgi server. The problem is that
probably then each bundle will have it´s own cxf and they are not
single threaded anymore.
Does cxf already run on osgi servers as a bundle? If I install several
of my own bundles and they all offer services using cxf. Will there be
only one instance of cxf in the osgi system then or one per bundle
that uses cxf? If there would be only one instance synchronizing the
requests would probably be quite easy. Perhaps even the one thread
strategy from above would work.
What osgi server would you recommand for my setup. A natural guess for
me would be servicemix 4. But it is not finished till now.
Greetings and thanks for the help
Christian
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