Why use service layer?

Question

I looked at the example on http://solitarygeek.com/java/developing-a-simple-java-application-with-spring/comment-page-1#comment-1639

I\'m trying to figure out why t

Answer 1

Take a look at the following article:

http://www.martinfowler.com/bliki/AnemicDomainModel.html

It all depends on where you want to put your logic - in your services or your domain objects.

The service layer approach is appropriate if you have a complex architecture and require different interfaces to your DAO's and data. It's also good to provide course grained methods for clients to call - which call out to multiple DAO's to get data.

However, in most cases what you want is a simple architecture so skip the service layer and look at a domain model approach. Domain Driven Design by Eric Evans and the InfoQ article here expand on this:

http://www.infoq.com/articles/ffffd-in-practice