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    Q. [JBoss AOP 1.x] I get a NullPointerException when calling compile time instrumented classes , why does it happen?

    R. This can often happen when the JBoss AOP client libraries used for instrumentation and the ones used at run time differ. Please double check compile time classpath dependencies and runtime ones.

    Q. [JBoss AOP 1.x] I get an ArrayIndexOutOfBoundsException when calling either compile time or load time instrumented classes, why does it happen?

    R. One of the possibilities is that instance variables are prefixed with an underscore ('_'). See JBAOP-264. To fix it, either upgrade JBoss AOP library or avoid using underscores at the beginning of your instance variables.

    Q. Can calls to libraries in server/xyz/lib, such as hibernate3.jar or jboss-common-jdbc-wrapper.jar, be intercepted?

    R. No, this is not possible because these classes are loaded before server/xxx/deploy/jboss-aop.deployer is deployed. Unfortunately, even if you use compile-time weaving, you will still have problems since any jar in lib/ directory is deployed in a classloader that is the parent of loader containing the aop stuff. So basically on AS 4 you can only really aspectize the classes deployed as part of a deployment in the serve/xxx/deploy folder.