Introducing Spring Framework

Chapter 8 ■ Give Advice to Your Spring Application
Figure 8-1. Tangling and Scattering Code
Figure 8-1 shows how your logging mechanism is in every method of your SearchEngine implementation, and
that it could be in other classes like the DocumentService or MediaService classes. The code is all over the place! This
is called scattering and its implementation is not modular. But that’s not all. As I mentioned before, you can have the
same code, such as authorization or audit, in places where there is a particular business logic happening, making it
not cohesive. This is called tangling. There should be a better way to solve these issues.
AOP to the Rescue
You need to start thinking about how to modularize your code into independent modules. But how can you
accomplish that? Aspect-oriented programming (AOP) was created to accomplish this hard task by modularizing
this cross-cutting functionality into better manageable modules. In other words, AOP is going to take care of your
concerns (such as logging, authorization, and audit, in your case), so you can focus only on the business logic without
having to worry about checkpoints or logging.
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