EJB Section Index | Page 5
The ejbCreate() methods is part of the bean's lifecycle, so, the compiler will not return an error because there is no ejbCreate() method. However, the J2EE spec is explicit: the home interface of...more
Why the Session beans should not be re-entrant and the same way entity bean should be re-entrant? Why the container manages the thread synchronization then what is the point in having a separate property called re-entrant ?
Except for the JMS part of EJBs, Enterprise Java beans have synchronous interfaces, meaning that a response to a request on a bean must be sent before another request is sent to the bean. Entity E...more
You shouldn't. What will happen depends on the implementation, but the call will most likely be ignored.
An Entity Bean represents data in a persistent storage like a database and it caches the data. If X clients connect (via a findXXX method to the same Entity EJB, will there be X copies of the cach...more
A Primary Key Class is a class that follows few simple rules: it has to implement the java.io.Serializable interface. all its fields have to be made public, to allow the container to use the Relfe...more
The idea of the "Pooled State" is to allow a container to maintain a pool of entity beans that has been created, but has not been yet "synchronized" or assigned to an EJBObject. This mean that the...more
Actually the answer is no, you cannot map more than one table to a single CMP Entity Bean. CMP has been, in fact, designed to map a single table. Said so, we can see that there could be some work...more
Stateless Session Bean member variable modification. If a client is calling two methods f1() and f2() of a Stateless SB, one after another, is it possible that if f1() modified some member variable of the bean it may reflect in method f2().
Note that here is no guarantee that the variable still has the value, so don't rely on it. Variables in stateless session beans should only contain state which can be used by any client instance ...more
Developing a application using EJB-CMP, automatically does the persistence of data in a RDBMS without the developer writing any JDBC code. In this case, what type of projects should utiltize OR M...more
Additional info: When I run my client, I get javax.naming.CommunicationException: org.omg.CORBA.NO_PERMISSION for the "lookup" statement in the client. The deployment was success...more
Why does the Sun j2EE Reference Implementation invoke ejbLoad() and ejbStore() twice in a row? Whenever I find an EJB (either BMP or CMP), the container calls ejbLoad(), then ejbStore(), then ejbLo...more
Storing the Remote Reference to a Stateless Session Bean. In an application with several Stateless Session EJB, we are debating the best approach with reference to performance on how to do the calls to our Stateless Session Beans.
Does it make sense to cache the reference we would get from using the EJBObject.getHandle(), then use this reference when attempting to access the bean from here on? - Absolutely. Does the ...more
The short, practical answer is... because it makes your entity beans useless as a reusable component. Also, transaction management is best left to the application server - that's what they're ther...more
What is PortableRemoteObject.narrow() method and what is used for? I found somewhere that it is "CORBA compliant". Why?
Hi, When you execute a lookup to get the home interface of your bean, you normally use the lookup() method of the javax.naming.Context interface. This method will return you an Object that needs t...more
According to Richard Monson Haefel's book (Enterprise Java Beans, O'Reilly), Stateful Session Bean conceptually doesn't have instance pooling. But some container implement pooling internally. Acc...more