How do you design a services layer that's not all try/catch blocks?

Question

When designing a SpringMVC application the @ExceptionHandler annotation is at our disposal in the REST layer. This greatly de-clutters controller methods by offloading exception handling to a set of semi-generic handlers.

The basic architecture of our services is this:

[REST API] <==> [Application Services] <==> [Data Layer]

I'm of the belief that a REST layer controller should not be dealing directly with Data layer exceptions, instead it should be dealing with Application Service exceptions only.

However, that means all my Application Services methods basically have to look like this:

public DomainObject getSomeDomainObjectById(String id) {
   DomainObject retVal = null;
   try {
      myDomainDao.getSomeDomainObjectById(id);
   } catch (DataLayerExceptionOfSomeSort ex) {
      throw translateToAppropriateServiceException(ex);
   }
   //do some further processing
   return retVal;
}

To me, that's a lot of in-your-face exception handling, which I don't care for. How else could I solve this? Is there an easy way to achieve the same thing in the Application Services layer as there is in the Rest layer?

My first thought is AOP. I'm open to this providing it doesn't add a lot of cruft and is easy to configure.

Answer 1

You should use AOP, with or without Spring and do in your aspects this kind of work (like exception translation, transaction management, etc).