EJB interview questions Part9

1. What is EJB?

EJB stands for Enterprise JavaBean and is the widely-adopted server side component architecture for J2EE. it enables rapid development of mission-critical application that are versatile, reusable and portable across middleware while protecting IT investment and preventing vendor lock-in.

2. What is EJB role in J2EE?

EJB technology is the core of J2EE. It enables developers to write reusable and portable server-side business logic for the J2EE platform.

3. What is the difference between EJB and Java beans?

EJB is a specification for J2EE server, not a product; Java beans may be a graphical component in IDE.

4. What are the key features of the EJB technology?

1. EJB components are server-side components written entirely in the Java programming language

2. EJB components contain business logic only - no system-level programming & services, such as transactions, security, life-cycle, threading, persistence, etc. are automatically managed for the EJB component by the EJB server.

3. EJB architecture is inherently transactional, distributed, portable multi-tier, scalable and secure.

4. EJB components are fully portable across any EJB server and any OS.

5. EJB architecture is wire-protocol neutral--any protocol can be utilized like IIOP,JRMP, HTTP, DCOM,etc.

5. What are the key benefits of the EJB technology?

o Rapid application development

o Broad industry adoption

o Application portability

o Protection of IT investment

6. How many enterprice beans?

There are three kinds of enterprise beans:

o session beans,

o entity beans, and

o message-driven beans.

7. What is message-driven bean?

A message-driven bean combines features of a session bean and a Java Message Service (JMS) message listener, allowing a business component to receive JMS. A message-driven bean enables asynchronous clients to access the business logic in the EJB tier.