EJB 3.0 , are thread safe?

0
votes

Hy,

I am a newbie in EJB. Now I am studying the EJB 3.0 specification. If I have two different JSF managed beans like the next ones: 

 @ManagedBean
 public class CocheBean {   
      @EJB 
      private ICochesService cochesService = null;
 }

 @ManagedBean
 public class UsuarioBean {     
      @EJB 
      private ICochesService cochesService = null;
 }

  1. The injecteds implementations for cochesService are the same in both cases?, I mean, for each annotation, the ejb container gets back a new object or is the same object?

  2. Why do they refer to EJBs as session beans? Are they session scoped? Do they exist till the session of a user expires?

  3. Its said that you dont have to worry if the stateless EJB are thread safe because the container has a pool of different instances for each request but if they are stateless and there is no danger that multiple threads access to just one ejb, why the container creates a pool of them and not just one?

  4. Using JSF managed beans, if this bean is request or session scoped and because we inject the ejbs in this beans, they cannot be called more than once per user or per request at the same time, right?

  5. How to specify the transactional atributes to EJB bean methods, with JPA annotations?

Thanks

1
thread-safetyejbejb-3.0

1 Answers

1
votes

  1. This depends - if ICochesService is stateless than each of them will have different object. If it's stateful or singleton than both beans will have the same object injected

  2. Answer to both questions is no :) See the Oracle docs

  3. Exactly

  4. You can call as many beans as you want per each request.

  5. See the Oracle tutorial for Java Transaction API.