[jboss-user] [EJB 3.0] - Re: @EJB injection in JBoss 5 application clients?

[henk53]

"ALRubinger" wrote : Jaikiran, you give a good example of why the spec dictates the fields must be injected into static members.  But it's OK to criticize something for being stupid.
  | 
  | "bcn" wrote : In real-world application that would make it almost useless.
  | 
  | Yep.
  | 
  | Imagine if MC or Spring or any injection container limited you in this regard.  The difference is whether your object is managed or not; if you create your own objects, they're not managed and you can't expect injection.  If you get it from a container or other lookup store, then that's another story.
  | 

Indeed, the thing is that the main class in a client application is really the only place where a class is loaded and a method is called by the runtime, so this also basically makes it the only candidate for an injection target. Unless, you would accept to run your application in a modified JVM where the new operator is somehow intercepted by the client container. Personally I wouldn't mind that, but I guess a lot of people would object to that.

anonymous wrote : 
  | I've never liked Application Clients as they are.  In addition to these programmatic limitations with injection into the Main class (which completely destroys good program design), you're limited to obtaining services from only one host.
  | 

I'm not sure if it's really limiting. The idea seems to be to separate your application code from details of where the AS is located. If you inject your main class with a factory EJB that serves to give you other EJBs at any location in your client code that you desire, than I don't really see the problem with that.

Something like:


  | public class MainClass {
  | 
  |  @EJB
  |  public EJBFactory factory;
  | 
  |  public static void main(String args[]) {
  |     MyApp theApp = new MyApp();
  |     theApp.run();
  |  }
  | }
  | 
  | ...
  | 
  | public class SomeClass {
  | 
  |    public void SomeMethod() {
  |        EJBFooBean bean = MainClass.factory.getEJBFooBean();
  |        bean.invokeBar(); // results in RMI class to AS
  |    }
  | }
  | 

There's always room for improvement of course, and being able to use @EJB EJBFooBean in SomeClass would be superb, but for the time being the pattern shown above seems to do the trick.



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