# ...And Finally, You Should Introduce A DAO If:

Your Services will not just degrade to a plain delegates after the DAO-introduction.You are really going to mock out the DAOs and test the Services (really = high code coverage of Service layer with serious unit tests).It is likely, that your persistence implementation will change next time (<few years).Your DAOs is not just a wrapper around the EntityManager - it provides additional value (fluent interface, query builder, domain specific queries etc).Your design remains DRY and KISS.What's KISS?: Keep it Simple, Stupid


Keep it Simple, Silly


Keep it Simple, Shithead


Keep it Simple & Stupid


Keep it Small & Simple


Keep it Sweet & Simple


Keep it Simple & Straightforward


Keep it Simple & Smart


Keep it Strictly Simple


From wikipedia.