Re: [aspectj-users] joinpoint in interface

[aXXa <borlin@xxxxxxxxxxx>]

Hi ,

Thanks Adrian, the pointcuts worked fine but not exactly in the way I need
them to work. I'll try to explain my situation: 

We're using Hibernate (and Spring) and Hibernate transactions start in the
facade layer. One part of our errorhandling involves "translating" any
exceptions into internal ones (with a sweet looking message code,
configurable via the annotation TranslateExceptionToInternal, e.g
TranslateExceptionToInternal(defaultMess="error.db.unavailable") ).
For some peculiar reason Hibernate exceptions (thanks to Spring?) does not
propagate up the chain of method calls to the start of the transaction (so I
cannot write an 'after throwing' advice pointcutting the execution of a
facade method), but rather quite miraculously appears at the method call
just before the start of the transaction, in my example in the client
package.

Since I prefer not to redesign the entire error handling I need a pointcut
that, in the client package, triggers on method calls to annotated facade
methods. AND I need access to the annotation (in one way or the other,
through reflection if I cannot bind it via a pointcut).

package com.salestool.client;
public class MyController {
  private UserServiceFacade userFacade;

  public void myMethodA() {
    UserServiceFacadeImpl userFacadeImpl = new UserServiceFacadeImpl();
    userFacadeImpl.saveUpdateUser(user); //should be adviced, and I need
access to the annotation on the saveUpdateUser method in the
UserServiceFacadeImpl class
  }
  public void myMethodB() {
	    userFacade.saveUpdateUser(user); //should be adviced, and I need access
to the annotation on the saveUpdateUser method in the UserServiceFacadeImpl
class
	}  
}

package com.salestool.facade;
public class UserServiceFacadeImpl implements UserServiceFacade {

  @TranslateExceptionToInternal(
  	ConstraintViolationException="error.db.duplicate.user",
  	NullpointerException="error.user.not.available",
  	DefaultMess="error.db.generic")
  @Transactional(readOnly = false, propagation = Propagation.REQUIRED,
isolation = Isolation.DEFAULT)
  public StatusResult saveUpdateUser(user) { //should NOT be adviced since
I'm looking for exceptions thrown
  }
}

regards 
Martin



Adrian Colyer-2 wrote:
> 
> In your pointcut expression: 
> 
>>   pointcut annotatedFacadeCall(TranslateExceptionToInternal
>> translateExceptionToInternal) :
>>     @annotation(translateExceptionToInternal)
>>     && within(com.salestool.client..*)
>>     && call(@TranslateExceptionToInternal StatusResult+
>> com.salestool.facade.*.*(..));
> 
> Annotation matching in both @annotation and in call is based on the
> static type of the receiver - the "subject" of the join point as the
> aspectj docs call it. When you change to declare the variable to have
> the interface type, the subject of the join point changes (it becomes
> the interface operation). 
> 
> Changing to use the execution join point is probably what you want
> here - this will match annotations based on the thing that actually
> gets to execute (the implementation method). It would read something
> like this:
> 
> pointcut inClientControlFlow() : 
>   cflow(execution(* com.salestool.client..*(..));
> 
> pointcut annotatedFacadeCall(TranslateExceptionToInternal
> translateExceptionToInternal) :
>   @annotation(translateExceptionToInternal) &&
>   execution(StatusResult+ com.salestool.facade.*.*(..)) &&
>   inClientControlFlow();
> 
> Regards, Adrian.
> 
> On Mon, Feb 12, 2007 at 04:24:47AM -0800, aXXa wrote:
>> 
>> All!
>> My question:
>> In the following example, how do I write my pointcut to trigger on any
>> implementing classes annotation, i.e. so BOTH A) and B) are adviced
>> (without
>> having to annotate the interface) 
>> 
>> I have the following pointcut defined:
>> /** 
>>   any method call to facade package returning a subclass of StatusResult
>> and 
>>   annotated with TranslateExceptionToInternal
>>   from within the client package
>> */
>>   pointcut annotatedFacadeCall(TranslateExceptionToInternal
>> translateExceptionToInternal) :
>>     @annotation(translateExceptionToInternal)
>>     && within(com.salestool.client..*)
>>     && call(@TranslateExceptionToInternal StatusResult+
>> com.salestool.facade.*.*(..));
>> 
>> 
>> a method of a class in facade package is annotated...
>> public class UserServiceFacadeImpl implements UserServiceFacade {
>> 
>>   @TranslateExceptionToInternal()
>>   public StatusResult saveUpdateUser(user) {
>>   }
>> }
>> 
>> ...but NOT its corresponding method in the interface
>> public interface UserServiceFacade {
>>   public StatusResult saveUpdateUser(user);
>> }
>> 
>> The following works fine, A):
>> 
>> package com.salestool.client;
>> public class MyController {
>>   public void myMethod() {
>>     UserServiceFacadeImpl userFacadeImpl = new UserServiceFacadeImpl();
>>     userFacadeImpl.saveUpdateUser(user); //is adviced
>>   }
>> 
>> BUT since programming against interfaces is good manners I changed the
>> code
>> to, B)
>> 
>>   public void myMethod2() {
>>     UserServiceFacade userFacade = new UserServiceFacadeImpl();
>>     userFacade.saveUpdateUser(user); //is NOT adviced
>>   }  
>> }
>> 
>> 
> 
> -- 
> Adrian Colyer
> CTO
> Interface21 Limited
> http://www.interface21.com
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