Re: [aspectj-users] LTW and build-time weaving used together result in a

[Matthew Webster <matthew_webster@xxxxxxxxxx>]

Seva,

You have encountered a restriction in
the current implementation of AspectJ that is described in https://bugs.eclipse.org/bugs/show_bug.cgi?id=104218.
Basically AspectJ cannot weave code that has already been woven. This causes
a problem for LTW when an application has already used aspects. The solution
is to use the reweavable mode of the compiler which stores an unwoven version
of the class when it is woven. When a reweavable class it woven again,
either statically or at load-time, the compiler retrieves the unwoven "vanilla"
version of the class then weaves it again with the original aspects plus
any new ones.

Therefore if your application uses aspects
that are woven at build-time they must all be declared in an aop.xml, perhaps
generated using the -outxml compiler option, that is available at runtime.
If you don't then the vanilla class will be used and you application will
not behave correctly. This is why the compiler issues an error.

Matthew Webster
AOSD Project
Java Technology Centre, MP146
IBM Hursley Park, Winchester,  SO21 2JN, England
Telephone: +44 196 2816139 (external) 246139 (internal) 
Email: Matthew Webster/UK/IBM @ IBMGB, matthew_webster@xxxxxxxxxx
http://w3.hursley.ibm.com/~websterm/

Please respond to aspectj-users@xxxxxxxxxxx

Sent by:        aspectj-users-bounces@xxxxxxxxxxx

To:        <aspectj-users@xxxxxxxxxxx>
cc:        
Subject:        [aspectj-users] LTW and build-time weaving used together result in        an unexpected org.aspectj.bridge.AbortException


Hi,

In our company we are considering the possibility to use LTW and  build-time weaving together with AspectJ 1.5.  What I mean is that we would like to allow LTW only for the "global" aspects (i.e. those that crosscut all our codebase) only in our system level jars (that are audited more carefully and owned by a more senior developers). At the same time we do not want to let the rest of our projects to have aspects that are weaved at load-time. However, we still want them to be able to use AspectJ at compile/build time should they have a need. The reason is that we just do not want some negligent, too broad pointcut definitions coming from some regular jar file with the LTW approach to "accidentally" harm/break other code in the system. This sounds like a safer approach for us.

Anyway, closer to my question.

>From what I know so far with the LTW  one has to declare all the aspects in the aop.xml files even if the aspect was already weaved into the desired classes. The AspectJ will issue an ERROR logging with the stack trace if some aspect is not declared.  In spite of that ERROR reporting, everything seems to work okay for us.

So, I'd like to understand why the described situation considered an error by AspectJ. I would expect just a warning message from AspectJ just saying that an aspect is found that is not declared (i.e. there is no LTW for this aspect).

Below is the relevent output from AspectJ with an error message and a stack trace:

info processing reweavable type com.metatv.user.hibernate.HibernateUserFactory: com\metatv\user\hibernate\HibernateUserFactory.java
error aspect 'com.metatv.user.hibernate.TransactionManager' woven into 'com.metatv.user.hibernate.HibernateUserFactory' must be declared in an aop.xml file.
Message: error aspect 'com.metatv.user.hibernate.TransactionManager' woven into 'com.metatv.user.hibernate.HibernateUserFactory' must be declared in an aop.xml file.
org.aspectj.bridge.AbortException: aspect 'com.metatv.user.hibernate.TransactionManager' woven into 'com.metatv.user.hibernate.HibernateUserFactory' must be declared in an aop.xml file.
       at org.aspectj.weaver.tools.WeavingAdaptor$WeavingAdaptorMessageHandler.handleMessage(WeavingAdaptor.java:413)
       at org.aspectj.weaver.World.showMessage(World.java:550)
       at org.aspectj.weaver.bcel.BcelWeaver.processReweavableStateIfPresent(BcelWeaver.java:1244)
       at org.aspectj.weaver.bcel.BcelWeaver.weave(BcelWeaver.java:1024)
       at org.aspectj.weaver.tools.WeavingAdaptor.getWovenBytes(WeavingAdaptor.java:277)
       at org.aspectj.weaver.tools.WeavingAdaptor.weaveClass(WeavingAdaptor.java:210)
       at org.aspectj.weaver.loadtime.Aj.preProcess(Aj.java:65)
       at org.aspectj.weaver.loadtime.ClassPreProcessorAgentAdapter.transform(ClassPreProcessorAgentAdapter.java:52)
       at sun.instrument.TransformerManager.transform(TransformerManager.java:122)

Thanks,
Seva
_______________________________________________
aspectj-users mailing list
aspectj-users@xxxxxxxxxxx
https://dev.eclipse.org/mailman/listinfo/aspectj-users