EJB interview questions

What are the different kinds of enterprise beans?

- Different kind of enterrise beans are Stateless session bean, Stateful session bean, Entity bean, Message-driven bean.

What is Session Bean?

- A session bean is a non-persistent object that implements some business logic running on the server. One way to think of a session object.

What is Entity Bean?

- The entity bean is used to represent data in the database. It provides an object-oriented interface to ____.

What are the methods of Entity Bean?

- An entity bean consists of 4 groups of methods, create methods.

What is the difference between Container-Managed Persistent (CMP) bean and Bean-Managed Persistent(BMP) ?

- Container-managed persistence (CMP) and bean-managed persistence (BMP). With CMP, the container manages the persistence of the entity bean.

What are the callback methods in Entity beans?

- Callback methods allows the container to notify the bean of events in its life cycle. The callback methods are defined in the javax.ejb.EntityBean interface.

What is software architecture of EJB?

- Session and Entity EJBs consist of 4 and 5 parts respectively, a remote interface.

Can Entity Beans have no create() methods?

- Yes. In some cases the data is inserted NOT using Java application,.

What is bean managed transaction?

- If a developer doesn’t want a Container to manage transactions, it’s possible to implement all database operations manually.

What are transaction attributes?

- The transaction attribute specifies how the Container must manage transactions for a method when a client invokes the method via the enterprise bean’s home or.

What are transaction isolation levels in EJB?

- Transaction_read_uncommitted, Transaction_read_committed, Transaction_repeatable_read.