Skip to main content

Learnings from a discussion on EJB 3.0

Yesterday I had a learning discussion session with some developers on EJB 3.0 It was a very interesting discussion and we all took home some new and interesting stuff. The key learnings were:

  1. EJB 2.1 was a 300 lb gorilla that used a crane to lift a peanut. EJB 3.0 is a nimble chimpanzee :-)
  2. EJB 3.0 uses annotations instead on the xml deployment descriptors that were so hard to maintain. So beans, security constrains and everything that was earlier defined using the deployment descriptor can now be done in code using annotations. I think this is really neat, especially for small applications.
  3. We no longer need to define all the 2.1 interfaces to get an EJB working. In fact we need not define interfaces at all. A business interface will be automatically created for us by the annotation processor. I read somewhere on the net (do not remember where), that we must not generate the business interface automatically (but create it manually and have the EBJ implement it), because the automatically generated interaface will include every public method from the bean and make it available to client code. Now I think that should not be a problem. Public methods are meant to define the public interface of a class, so if we do not want client code to invoke a method, then it should not be public. So the existence of public methods that should not be available to client code, smells to me of bad design.
  4. EBJ 3.0 entity beans are now POJO's, which is again really nice and makes development light weight. Again a big plus for small applications, and for maintainability.
  5. EBJ 3.0 uses dependency injection. The container will inject environment related objects in the client automatically. Client code now does not need to do any complex JNDI lookups. By the way Martin Fowler has written an excellent article on dependency injection here.
  6. We can still use deployment descriptors to override annotations, but in my opinion this should be avoided (unless absolutely necessary), because it will make the application harder to maintain.
Overall EBJ 3.0 is a huge advancement towards easing enterprise development. I am certain this specification will be adopted and accepted by the developer community much better than the previous one.

Comments

Popular posts from this blog

Running your own one person company

Recently there was a post on PuneTech on mom's re-entering the IT work force after a break. Two of the biggest concerns mentioned were : Coping with vast advances (changes) in the IT landscape Balancing work and family responsibilities Since I have been running a one person company for a good amount of time, I suggested that as an option. In this post I will discuss various aspects of running a one person company. Advantages: You have full control of your time. You can choose to spend as much or as little time as you would like. There is also a good chance that you will be able to decide when you want to spend that time. You get to work on something that you enjoy doing. Tremendous work satisfaction. You have the option of working from home. Disadvantages: It can take a little while for the work to get set, so you may not be able to see revenues for some time. It takes a huge amount of discipline to work without a boss, and without deadlines. You will not get the benefits (insuran

Testing Groovy domain classes

If you are trying to test Grails domain class constraints by putting your unit test cases in the 'test/unit' directory, then your tests will fail because the domain objects will not have the 'valdate' method. This can be resolved in two ways: Place the test cases inside test/integration (which will slow things down) Use the method 'mockForConstraintsTests(Trail)' to create mock method in your domain class and continue writing your test cases in 'test/unit' What follows is some example code around this finding. I am working on a Groovy on Grails project for a website to help programmers keep up and refresh their skills. I started with some domain classes and then moved on to write some unit tests. When we create a Grails project using grails create-app , it creates several directories, one of which is a directory called 'test' for holding unit tests. This directory contains two directories, 'unit', and 'integration' for uni

Some thoughts on redesigning education

Some time back I read a blog post on redesigning education. It asked some very good questions. Stuff which I had been thinking of myself. I left my thoughts on the blog, but I would also like to start a conversation around these ideas with those who read this blog as well. I would like to know what other people think of the issue of redesigning (college) education. I have often thought about how college education can be improved. To answer this question, we first have to ask a very basic question. What is the purpose of education? To me, we need education for 3 things: To learn more about the world around us To lead positive constructive lives To earn a good living / fulfill our ambitions I think education has to a large extent evolved to fulfill #3 (with a bias towards earning a comfortable living). The semester system, along with multiple choice tests, and grading, has made our education system into an assembly line. Students are pushed into the assembly line, given classes, admini