Hi
What Camel does is correct there was an exception and it was handled, and
you could build a custom response in the onException block as you did. And
then the routing stops and returns to the caller.
The first route does not see the exception, so either you turn off error
handling in the second route, or make it return the proper response. Or you
can use onCompletion in the first route to change the response as you
desire.
On Wed, Feb 12, 2025 at 3:06 PM Fabien Arrault <
farra...@consulting-for.d-edge.com> wrote:
> Hello Raymond,
>
> The default Error Handler
> (org.apache.camel.processor.errorhandler.DefaultErrorHandler) is already
> fine to make the redeliveries and calling the exception policy without
> explicitly specifying it
> ( and I don't need the Deadletter capable error handler
> (org.apache.camel.processor.errorhandler.DeadLetterChannel) as my use case
> is fully synchronous )
> I did try though : and it doesn't change anything.
>
> Also, I do think that my issue is very specific to the use of a DIRECT
> channel between my two routes
>
> To make my requirement more clear, here a test case : the
> retryAndFallBack method
> shows the expected versus current behaviour :
> ( I also forbid to state that I am currently using Camel 4.7.0 )
>
> @Slf4j
> public class TestCaseErrorHandling extends CamelTestSupport {
>
> record IntermediateResult(String val) {}
>
> @Override
> protected RoutesBuilder createRouteBuilder() {
> return new RouteBuilder() {
> @Override
> public void configure() throws Exception {
> from("direct:firstRoute").routeId("firstRoute")
> .onException(Exception.class).log("NEVER
> called here").end()
> .log(LoggingLevel.INFO,"firstRoute - BEGIN")
> .to("direct:secondRoute")
> .transform().simple("TRANSFORMED-${body.val}")
> // IntermediateResult to String
> .log(LoggingLevel.INFO,"firstRoute - END");
>
> from("direct:secondRoute").routeId("secondRoute")
> // .errorHandler(defaultErrorHandler())
> .onException(IOException.class)
> .handled(true)
> .maximumRedeliveries(3)
> .log("SecondRoute exception handler called
> for ${exception}")
> .transform().constant(new
> IntermediateResult("FALLBACK VALUE"))
> .end()
> .log(LoggingLevel.INFO,"secondRoute - BEGIN")
> .choice()
> .when(simple("${body} == 'pass'"))
> .transform().constant(new
> IntermediateResult("SOME REAL VALUE")).endChoice()
> .otherwise()
> .process( e -> {
> log.info("in failing processor");
> throw new IOException("some failure");
> })
> .end()
> .log(LoggingLevel.INFO,"secondRoute - END");
> }
> };
> }
>
> @Test
> public void pass() throws Exception {
> var resultBody = template.requestBody("direct:firstRoute","pass");
> assertThat(resultBody).isEqualTo("TRANSFORMED-SOME REAL
> VALUE"); // firstRoute Enriched the message
> }
>
> @Test
> public void retryAndFallBack() throws Exception {
> var resultBody = template.requestBody("direct:firstRoute","error");
> // Expected result :
> // assertThat(resultBody).isInstanceOf(String.class);
> // assertThat(resultBody).isEqualTo("TRANSFORMED-FALLBACK VALUE");
> // Current result :
> assertThat(resultBody).isInstanceOf(IntermediateResult.class);
> assertThat(resultBody).isEqualTo(new
> IntermediateResult("FALLBACK VALUE"));
> }
>
> }
>
> Regards,
> Fabien
>
> On Wed, 12 Feb 2025 at 14:05, ski n <raymondmees...@gmail.com> wrote:
>
> > Did you try to use an errorHandler? Some like this:
> >
> > from("seda:a")
> > // here we configure the error handler
> > .errorHandler(deadLetterChannel("seda:error"))
> > // and we continue with the routing here
> > .to("seda:b");
> >
> > Then you can set the errorHandler direct on the route (you can also add
> > redeliveries etc). Also check:
> >
> > https://camel.apache.org/manual/route-configuration.html
> >
> > In het routeConfiguration you can set specific error handler per route.
> >
> > Raymond
> >
> >
> >
> >
> >
> >
> > On Wed, Feb 12, 2025 at 12:00 PM Fabien Arrault <
> > farra...@consulting-for.d-edge.com> wrote:
> >
> > > Hello,
> > >
> > > In our application, we have factored out some common behaviour in a
> > direct:
> > > route called synchronously by other routes
> > > This sub-route needs to handle exception by first making retries ; and
> > > then, when retry are exhausted, by returning **to the caller route** a
> > > default intermediary response.
> > >
> > > Playing around with onException directive on this direct sub-route, I
> did
> > > not succeed to achieve the last part :
> > > * the retries do work correctly ( with required redelivery policy
> > > directive : maximumRedeliveries in particular )
> > > * when retries are exhausted the custom exception policy is correctly
> > > executed : it marks the exception as "handled" and set the body on the
> > > exchange with the default intermediary response
> > > * BUT the processing of the exchange completely ends after that : the
> > > parent route didn't continue its processing based on this intermediary
> > > response
> > > * and in the ends the caller of the main route receives an
> intermediary
> > > response, which is not in the format it expects.
> > >
> > > I know there is doTry/doCatch directives, which would allow to return a
> > > default response without involing errorHandler, but we can't use them
> > here
> > > as we also do need the redelivery behaviour of the default error
> handler.
> > >
> > > Digging a little into the camel source code, I understand that this
> > > behaviour is caused by the fact that both routes (main route /
> sub-route)
> > > are sharing the same Exchange when using direct: endpoint,
> > > and that in this case, the error handler of the sub-route flags the
> > > Exchange has errorHandlerHandled which caused BOTH routes to stop their
> > > processing.
> > >
> > >
> > > I didn't succeed to find reference material on this specific behaviour
> on
> > > direct endpoint.
> > > It seems to me to be a fairly reasonable requirement though.
> > > Is it possible to achieve what we need here ?
> > >
> > > Thanks in advance for your advices
> > >
> > > Regards,
> > > Fabien Arrault
> > >
> > > --
> > >
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--
Claus Ibsen
-----------------
@davsclaus
Camel in Action 2: https://www.manning.com/ibsen2
