Pragmatic AOP with Spring and AspectJ

The final afternoon talk on the final day of The Spring Experience is Pragmatic AOP with Spring and AspectJ.

Aspects are modular, enhancing the value of the software overall. Aspects lead to DRY SOCs (Don't Repeat Yourself, Separation of Concerns).

Join points are well defined points in the execution of the program.
Pointcuts are expressions that match join points.
Advice is action to take at those join points. Advice is not explicitly called, unlike methods.

Typical applications are Spring managed for data access, services, web controllers, transactions, etc. Up to now, the Domain Model has not been managed by Spring.

Spring AOP is a good fit for Spring managed beans, execution based join points, or coarser-grained service application. Or any time where the aspect is slower than the impact of the proxy itself (ie, transactions).

In Domain Driven Design, another separation of concern (SOC) is the Technical Concerns (transactions, auditing, etc) from the Business Concerns (the Ubiquitous Language, language of the business domain experts).

AspectJ is perfect for integration with the Domain Model, in contrast to Spring AOP which is good for advising the service layer.

What makes a good aspect? Does the aspect reduce coupling?

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