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Enterprise Java Beans (EJB) Interview Questions
1. What is EJB?
EJB stands for Enterprise Java Bean 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?
There are three kinds of enterprise beans:
o Session Beans
o Entity Beans
o Message Driven Beans (MDB)
7. What is Message Driven Bean (MDB)?
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.
8. Is EJB a product?
No, EJB is a specification, Enterprise JavBeans defines the EJB component architecture and the
interfaces between the EJB enabled server and the component.
9. How does a Client find and connect to a specific enterprise bean?
A client accesses an Enterprise JavaBean by looking up the class implementing its home interface
by name through JNDI. It then uses methods of the home interface to acquire access to an
instance of the class implementing the remote interface.
10. How does a Client find and connect to a specific enterprise bean write the coding?
Context ct=new InitialContext();
HaiHome home=(HaiHome)ct.lookup("hai");
HaiRemote remote=home.create(); then remote.Business methods…
11. What general services does a container provide for an Enterprise JavaBean component?
A Container provides Enterprise JavaBeans Components with services of several types First it provides
services for lifecycle management and instance pooling, including creation, activation, passivation and destroy.
Second it interacts methods in a bean to enforce transaction and security constraints. It enforces policies and restrictions on bean instances, such as reentrance rules security polices and some others.
12. What are main interfaces in EJB required ?
javax.ejb pacakage contains mainly SessionBean, EntityBean Interfaces
EJB stands for Enterprise Java Bean 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?
- Rapid application development
- Broad industry adoption
- Application portability
- Protection of IT investment
There are three kinds of enterprise beans:
o Session Beans
o Entity Beans
o Message Driven Beans (MDB)
7. What is Message Driven Bean (MDB)?
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.
8. Is EJB a product?
No, EJB is a specification, Enterprise JavBeans defines the EJB component architecture and the
interfaces between the EJB enabled server and the component.
9. How does a Client find and connect to a specific enterprise bean?
A client accesses an Enterprise JavaBean by looking up the class implementing its home interface
by name through JNDI. It then uses methods of the home interface to acquire access to an
instance of the class implementing the remote interface.
10. How does a Client find and connect to a specific enterprise bean write the coding?
Context ct=new InitialContext();
HaiHome home=(HaiHome)ct.lookup("hai");
HaiRemote remote=home.create(); then remote.Business methods…
11. What general services does a container provide for an Enterprise JavaBean component?
A Container provides Enterprise JavaBeans Components with services of several types First it provides
services for lifecycle management and instance pooling, including creation, activation, passivation and destroy.
Second it interacts methods in a bean to enforce transaction and security constraints. It enforces policies and restrictions on bean instances, such as reentrance rules security polices and some others.
12. What are main interfaces in EJB required ?
javax.ejb pacakage contains mainly SessionBean, EntityBean Interfaces
