7 Replies Latest reply on Aug 8, 2011 6:59 AM by Daniel Bevenius

    Should a deployment fail if duplicate Transformers are detected

    Daniel Bevenius Master

      Hi,

       

      I'm running into this issue at the moment upon deployment of a quickstart I get the following error in AS 7:

       

      15:00:36,315 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-1) MSC00001: Failed to start service jboss.deployment.unit."switchyard-quickstarts-hornetq-binding-0.2.0-SNAPSHOT.jar".SwitchYardService: org.jboss.msc.service.StartException in service jboss.deployment.unit."switchyard-quickstarts-hornetq-binding-0.2.0-SNAPSHOT.jar".SwitchYardService: org.switchyard.exception.SwitchYardException: Failed to register Transformer 'org.switchyard.component.hornetq.transformer.ByteArrayToStringTransformer(java:byte[], java:java.lang.String)'.  A Transformer for these types is already registered: 'org.switchyard.component.camel.transformer.CamelTransformer(java:byte[], java:java.lang.String)'.
              at org.switchyard.as7.extension.services.SwitchYardService.start(SwitchYardService.java:90)
              at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1765)
              at org.jboss.msc.service.ServiceControllerImpl$ClearTCCLTask.run(ServiceControllerImpl.java:2291)
              at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [:1.6.0_26]
              at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [:1.6.0_26]
              at java.lang.Thread.run(Thread.java:680) [:1.6.0_26]
      Caused by: org.switchyard.exception.SwitchYardException: Failed to register Transformer 'org.switchyard.component.hornetq.transformer.ByteArrayToStringTransformer(java:byte[], java:java.lang.String)'.  A Transformer for these types is already registered: 'org.switchyard.component.camel.transformer.CamelTransformer(java:byte[], java:java.lang.String)'.
              at org.switchyard.transform.TransformerRegistryLoader.registerTransformers(TransformerRegistryLoader.java:88)
              at org.switchyard.transform.TransformerRegistryLoader.loadOOTBTransforms(TransformerRegistryLoader.java:131)
              at org.switchyard.deploy.internal.AbstractDeployment.init(AbstractDeployment.java:148)
              at org.switchyard.as7.extension.deployment.SwitchYardDeployment.start(SwitchYardDeployment.java:89)
              at org.switchyard.as7.extension.services.SwitchYardService.start(SwitchYardService.java:83)
              ... 5 more
      
      

      Now this is correct and I think this situation might arise now and again. In this case the hornetq component has a transformer and so does the camel component for the same types. But if the camel component is not installed as a subsystem the hornetq one would be used instead.

      Could we change this into logging a  warning instead so that the deployment does not fail?

       

      Regards,

       

      /Daniel

        • 1. Re: Should a deployment fail if duplicate Transformers are detected
          Keith Babo Master

          Hmm ... this is an interesting situation.  There are actually two possible scenarios here:

           

          1)  One or more runtime components (including the core runtime's OOTB stuff) have transformers which overlap.  This is what you're hitting now. 

          2) An application is deployed with a transformer which conflicts with an existing transformer.

           

          For #1, I agree with you that it should be logged as a warning.  For #2, I think this should result in a deployment error.  If the user is explicitly including a transformer for a set of types where a transformer already exists, then we should fail fast and raise a deployment exception.

           

          So what if the transformer registry threw a DuplicateTransformerException from the register method?  The code which loads the OOTB transformers could catch this exception and print a warning message.  The code which loads application transformers can treat it as an error.

           

          Thoughts?

          • 2. Re: Should a deployment fail if duplicate Transformers are detected
            Tom Fennelly Master

            We could try it for a while anyway and see how it works.  I purposely coded it to fail fast, but it has caused me a PITA on a few occassions too.

            • 3. Re: Should a deployment fail if duplicate Transformers are detected
              Keith Babo Master

              This is why I like the idea of throwing an explicit exception related to a duplicate entry.  That way, the code handling the registration can decide whether it's fatal or not.

              • 5. Re: Should a deployment fail if duplicate Transformers are detected
                Tom Fennelly Master

                Looks good Dan.  However... I would have it extend SwitchYardException.  I'd guess that SwitchYardException will become a checked exception at some point.

                • 7. Re: Should a deployment fail if duplicate Transformers are detected
                  Daniel Bevenius Master

                  However... I would have it extend SwitchYardException.  I'd guess that SwitchYardException will become a checked exception at some point.

                  I started out doing that but was not sure about what to do in the catch clause in registerTransformers:

                   

                  try {
                              for (TransformModel transformModel : transforms.getTransforms()) {
                                  Collection<Transformer<?, ?>> transformers = TransformerUtil.newTransformers(transformModel);
                  
                                  for (Transformer<?, ?> transformer : transformers) {
                                      if (_transformerRegistry.hasTransformer(transformer.getFrom(), transformer.getTo())) {
                                          Transformer<?, ?> registeredTransformer = _transformerRegistry.getTransformer(transformer.getFrom(), transformer.getTo());
                                          throw new DuplicateTransformerException("Failed to register Transformer '" + toDescription(transformer)
                                                  + "'.  A Transformer for these types is already registered: '"
                                                  + toDescription(registeredTransformer) + "'.");
                                      }
                  
                                      _log.debug("Adding transformer =>"
                                              + " From: " + transformer.getFrom()
                                              + ", To:" + transformer.getTo());
                                      _transformerRegistry.addTransformer(transformer);
                                      _transformers.add(transformer);
                                  }
                              }
                          } catch (RuntimeException e) {
                              // If there was an exception for any reason... remove all Transformer instance that have
                              // already been registered with the domain...
                              unregisterTransformers();
                              throw e;
                          }
                  
                  

                  When I made DuplicateTransformerException extends SwitchYardException the catch clause is entered which is not really what we want. Should this be changed now or should we wait until SwitchYardException is a checked exception?

                   

                  I created a jira for this now.