On Mon, May 4, 2009 at 12:44 PM, Zhi Zhou <[email protected]> wrote:
> Great. it's closer to what I want now..Thanks Claus.
> However, my producer is a sync processor, which has finished processing that
> exchange, if I set the exception to the exchange, it seems no other way I
> can pass it to camel's control any more. I just cached the exchange in the
> timeout task when finishing producing.
>
> in another reply, Roman mentioned about AsyncProcessor. I think I do
> understand AsyncProcessor. but if I implement the producer as
> AsyncProcessor, it defeats the purpose of the whole route being async, as
> the jms consumer will still wait for the callback to be called at the
> producer side before processing the next exchange. I don't think the jms
> consumer is doing async, as I only consider InOnly for getting messages from
> queue.
Hi
Many solutions
a)
Put a seda queue in between JMS and your custom component. Then its
inOnly and the JMS listener do not expect a reply
from("jms:queue:foo").to("seda:foo")
from("seda:foo").to"(mycomponent:foo");
b)
Or you can use some of the DSLs to set the Message Exchange Pattern,
so its an Event Message EIP:
http://camel.apache.org/event-message.html
I do think the inOnly() is added to 1.6.0 also. But I cannot remember.
c)
The JMS consumer also have some option to not expect a reply AFAIR
For instance: disableReplyTo=true
>
>
> On Mon, May 4, 2009 at 6:32 PM, Claus Ibsen <[email protected]> wrote:
>
>> On Mon, May 4, 2009 at 11:40 AM, Zhi Zhou <[email protected]> wrote:
>> > Claus,
>> > Thank you very much for the quick response!
>> >
>> > On Mon, May 4, 2009 at 5:07 PM, Claus Ibsen <[email protected]>
>> wrote:
>> >
>> >> Hi
>> >>
>> >> What version of Camel are you using? Camel 2.0 has many improvments in
>> >> error handling and processing over 1.x.
>> >>
>> >
>> > Sorry that I forgot to mention I am using 1.x for now as 2.0 is still
>> going
>> > through milestone release stage.
>> >
>> >
>> >>
>> >> On Mon, May 4, 2009 at 10:54 AM, Zhi Zhou <[email protected]> wrote:
>> >> > Hello all,
>> >> >
>> >> > Camel's error handling is pretty powerful, but lately I am having two
>> >> > questions about it.
>> >> >
>> >> > 1) I am working a custom camel component, and not quite sure how to
>> >> handle
>> >> > certain error condition. I may be having wrong idea from the very
>> >> beginning
>> >> > but let me give you a simple scenario to describe the issue.
>> >> >
>> >> > from("jms:someQueue").to("myCustom:endpoint");
>> >> >
>> >> > My custom endpoint does some async message sending. For performance
>> >> reason,
>> >> > it should keep sending messages from the jms queue without waiting for
>> >> > responses. responses come back asynchronously from the remote host.
>> The
>> >> > question here is that if a response doesn't return without a timeout
>> >> period,
>> >> > I would like an exception to be thrown and hence to be captured by
>> >> camel's
>> >> > error handling where some redelivery logic is made possible.
>> >> unfortunately,
>> >> > with this async nature of producing, the timeout event will be
>> triggered
>> >> in
>> >> > a different thread and hence no way to have camel to capture my
>> created
>> >> > exception up to my limited camel knowledge.
>> >> We are planning to add a new Async API in Camel 2.0 so you leverage
>> >> Camel to do async routing much more easily.
>> >>
>> >
>> >> Anyway if you leverage the async task execution in the JDK 1.5
>> >> concurrent API then you can get a handle to your async task, known as
>> >> a Future handle.
>> >> With that you can test whether the task is complete, get the result,
>> >> get the result within a timeout period etc.
>> >>
>> > Exactly I am using the concurrent API to implement a timeout task. but my
>> > headache is how to have camel informed of the exception that's created in
>> my
>> > timeout task. it seems impossible to call any current 1.x API to align
>> this
>> > timeout exception with the camel's standard error handling yet.
>> You can set an exception on the Exchange to indicate a timeout
>>
>> exchange.setException(new ExchangeTimedOutException());
>> Or just set your own kind of time out exception.
>>
>> Then Camel standard error handling will notice the exception and take
>> it from there.
>>
>>
>>
>> >
>> > well look forward to the new Async API of 2.0. before having it on board,
>> I
>> > probably still need to think of a solution.
>> >
>> >
>> >>
>> >> >
>> >> >
>> >> > 2) my second question: is it possible that the error handling will
>> happen
>> >> in
>> >> > multiple threads in case of multi-threaded exchange processing. for
>> >> example,
>> >> > the following route:
>> >> >
>> >> > from("direct:start").thread(10).process(new Processor(){/*throw some
>> >> > exception*/});
>> >> >
>> >> > will the error handling happen in the same thread of the caller that
>> >> > produces message to "direct:start", or will happen concurrently in
>> >> multiple
>> >> > threads?
>> >> The thread is basically a worker pool, and since you use direct
>> >> component your route is synchronous all the way. Leveraging up till 10
>> >> worker threads.
>> >>
>> >> If you want to divide into async you should use the seda component.
>> >> But when you want to do request-reply over seda it gets complicated.
>> >>
>> >
>> > I am just wondering whether camel will spawn a thread for error handing
>> or
>> > it's just using the current thread context. my above example might not be
>> > exactly what I wanted to show. Put it more straightforward, if I have an
>> > event-driven consumer, it typically does:
>> >
>> > getProcessor().process(exchange);
>> >
>> > to have the exchange consumed. in case of an exception ocurred down the
>> > route, camel's error handling will be sharing the same thread as the
>> above
>> > call or executing in a separate thread? if it's the same thread, that
>> means
>> > my event-driven consumer will be delayed until the exchange gets clear on
>> > exception.
>> >
>> >
>> >
>> >> Hence we are planning a new Async API in Camel 2.0 that addresses this.
>> >> There is a discussion on this in the camel-dev forum.
>> >>
>> >>
>> >> >
>> >> >
>> >> > Zhi
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> Claus Ibsen
>> >> Apache Camel Committer
>> >>
>> >> Open Source Integration: http://fusesource.com
>> >> Blog: http://davsclaus.blogspot.com/
>> >> Twitter: http://twitter.com/davsclaus
>> >> Apache Camel Reference Card:
>> >> http://refcardz.dzone.com/refcardz/enterprise-integration
>> >>
>> >
>>
>>
>>
>> --
>> Claus Ibsen
>> Apache Camel Committer
>>
>> Open Source Integration: http://fusesource.com
>> Blog: http://davsclaus.blogspot.com/
>> Twitter: http://twitter.com/davsclaus
>> Apache Camel Reference Card:
>> http://refcardz.dzone.com/refcardz/enterprise-integration
>>
>
--
Claus Ibsen
Apache Camel Committer
Open Source Integration: http://fusesource.com
Blog: http://davsclaus.blogspot.com/
Twitter: http://twitter.com/davsclaus
Apache Camel Reference Card:
http://refcardz.dzone.com/refcardz/enterprise-integration
