James.Strachan wrote:
>
> On 8/7/07, James Strachan <[EMAIL PROTECTED]> wrote:
>
> I've just added to trunk a little try/catch style routing DSL.
>
> In Java we can't use try/catch/finally words so I've initially gone with
> this
>
> from("direct:start").
> tryBlock().
> process(validator).
> to("mock:valid").
> handle(ValidationException.class).to("mock:invalid");
>
> which is maybe not the easiest thing to read; but tryBlock / handle is
> a replacement for try/catch. (Maybe tryBlock/catchBlock is more
> consistent?). Any name suggestions most welcome! (Its often the
> hardest part of programming, coming up with good names for things).
>
> In XML its a little easier on the eye. e.g. here's a validation test
> case to ensure that messages are delivered to different endpoints
> depending on whether they are valid or not...
> https://svn.apache.org/repos/asf/activemq/camel/trunk/components/camel-spring/src/test/resources/org/apache/camel/component/validator/camelContext.xml
>
> In Java we could even use the real try/catch handling using an inline
> Processor
>
> e.g.
>
> fromC
>
>
Hmm, not sure about the try/catch approach :confused: as it makes the DSL a
bit verbose. I think I'd prefer the implicit try/catch that we already have
with the ErrorHandler; more of an AOP approach. How about using an
ErrorRoute instead of an ErrorHandler? Once an error is on the ErrorRoute it
has the full semantics of the DSL available for filtering/splitting etc.
We'd have to add semantics to allow retry to an endpoint. Something like:
from("error:start").
.choice()
.when(error(ValidationException.class)).to("seda:a")
.when(error(BusinessDataException.class)).to("seda:b")
.when(error(SystemException.class)).retry().useCollisionAvoidance().maximumRedeliveries(0)
.useExponentialBackOff()
.when(error(PooException.class)).retry().useCollisionAvoidance().maximumRedeliveries(-1)
.useExponentialBackOff()
.otherwise().to("seda:c");
Where the retry() will post the message back to the route that generated the
error...
I just threw the 'when(error(...' semantic in to make it explicit but maybe
the exception class is already available in the context?
As in this example I'd want to be able to separately configure the retry
behaviour for different exceptions.
Thoughts?
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