POJO

As a young newly minted software person, one of the first things I remember hearing was an engaging a talk on the issue of separating business logic from implementation. That was mumblety-mumble years ago. How times do not change. Tonight at the SDForum Java SIG we heard a talk on exactly the same subject.

This time the talk was wrapped around the subject of POJO, which stands for "Plain Old Java Objects". Chris Richardson, author of a new book "POJOs In Action" spent most of the talk telling us what POJO are not. In particular POJOs are not Enterprise Java Beans (EJB).

Underlying all the negativity was a positive message. Write your business logic as a set of plain old Java objects. Then implement the application through lightweight frameworks. Use Hibernate or JDO to make the objects persistent and Spring to provide transactions.

The important concept is that you do not change the business logic code. These frameworks are declarative specifications in XML that describe the implementation of the business logic without you having to change it. I know from my experience with JDO that it is not quite as easy as all that, however it seems like we are still headed in the right direction if not making a lot of progress.