JBoss AOP Framework

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JBoss AOP Framework

• Version 1.1

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Elements of JBoss AOP I

• Joinpoints same as AOP concept.
• can be specified at both callee and caller side
  of an invocation.
• Caller side at method and constructor level
• Callee side at field, method and constructor
  level
• Plugged into the class by either aopc compiler or
  a load time transformation mechanism.

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Elements of JBoss AOP II

• Advice same as AOP concept
• Special advice Interceptor
• Pointcut regular expression string that is used
  to express a particular joinpoint.
• Bindings (advice bindings) contains pointcut,
  possible cflow, and the interceptor factory.
  (TBC)

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Elements of JBoss AOP III

• Aspect a plain java class that encapsulates any
  number of advices, pointcut definitions, mixins,
  and other aspect management elements.
• Scope of aspect PER_VM, PER_CLASS, PER_INSTANCE,
  PER_JOINPOINT
• Management elements advisor, instance advisor
  and joinpoint, aspect manager.

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Aspect Scope And Management Elements

• The ones marked with ) are not available when
  invoking a static method or reading/writing a
  static field.

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Demostration of JBoss aspect
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Elements of JBoss AOP IV

• Metadata very similar to JDKs annotation except
  that it is un-typed.
• Defined as annotations by adding Doclet tags
  first.
• Attached to a class, method, constructor, field
  or parameter.
• Annotation compiler (annotationc)
• Driven and applied through XML.

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Dynamic Aspect

• Dynamic insertion and deletion advices from
  specific joinpoints plugged into a class.
• Prepare phase an extra code transformation phase
  at compile time, used for making classes ready
  for further adaptation.
• PER_VM adaptation run-time insertion and
  deletion of bindings with advices to any prepared
  Java class.
• Ex Hot-deployment
• PER_INSTANCE adaptation run-time insertion of
  interceptors of a particular instance.
• Beginning, or end of the interceptor chain.
• Ex Per instance interception

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Per-VM adaptation Hot Deplyment

• An interceptor class has to be wrapped as binding
  (AdviceBinding)
• Add/remove binding with AspectManager API method
  addBinding( ) and removeBinding( ).

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PER-INSTANCE adaptation per instance
interception

• Get the instance advisor of the prepared java
  classes.
• Add new interceptor through the InstanceAdvisor
  API method insertInterceptor() /
  appendInterceptor().

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Demostartion of dynamic AOP