Top EJB Interview Questions and Answers: A Comprehensive Guide for Freshers and Experienced Developers

Enterprise JavaBeans (EJBs) are an important part of Java EE because they make it possible to build scalable, reliable, and safe business apps. Java developers who want to do well in this field need to understand EJB concepts. This complete guide goes into detail about the most common EJB interview questions and gives you helpful answers and explanations to help you do well.

What is EJB?

EJB stands for Enterprise JavaBeans, a server-side component model within the Java EE platform EJBs encapsulate business logic and manage the lifecycle of enterprise applications, simplifying development and ensuring scalability

Types of Enterprise Beans

EJBs are categorized into three primary types

• Session Beans: Stateless and stateful session beans manage business logic and provide services to clients. Stateless beans are short-lived and do not maintain conversational state, while stateful beans preserve state across multiple client interactions.
• Message-Driven Beans (MDBs): Asynchronous message consumers, MDBs process messages delivered through messaging systems like JMS.
• Entity Beans: Representing persistent data, entity beans manage data access and provide object-relational mapping capabilities.

Advantages of EJB

EJBs offer numerous advantages for enterprise application development:

• Scalability: EJBs can be easily scaled to meet increasing demand by deploying them on multiple servers.
• Transaction Management: EJBs provide automatic transaction management, ensuring data consistency and integrity.
• Security: EJBs offer built-in security mechanisms, protecting applications from unauthorized access.
• Portability: EJBs are platform-independent, enabling deployment on various operating systems and application servers.

EJB Architecture

The EJB architecture comprises several key components:

• EJB Container: Manages the lifecycle of EJBs, providing services like transaction management, security, and resource pooling.
• EJB Client: Interacts with EJBs through remote interfaces, invoking business logic and accessing data.
• Deployment Descriptor: An XML file configuring EJB properties, including transaction attributes, security settings, and resource references.

EJB Interview Questions and Answers

1. What is the difference between stateless and stateful session beans?

Stateless session beans do not maintain conversational state, while stateful session beans preserve state across multiple client interactions.

2. What are the advantages of using message-driven beans?

MDBs enable asynchronous message processing, improving application responsiveness and scalability.

3. Explain the role of entity beans in EJB architecture.

Entity beans represent persistent data, providing object-relational mapping capabilities and managing data access.

4. How does EJB handle transactions?

EJBs provide automatic transaction management, ensuring data consistency and integrity. Transactions can be configured as mandatory, required, requires_new, supports, not_supported, or never.

5. What are the different types of EJB containers?

EJB containers include WebLogic Server, JBoss Application Server, and GlassFish Server.

6. Explain the concept of EJB deployment descriptors.

EJB deployment descriptors are XML files configuring EJB properties, including transaction attributes, security settings, and resource references.

7. What are the benefits of using EJBs in enterprise application development?

EJBs offer scalability, transaction management, security, and portability, simplifying development and ensuring robust application design.

Mastering EJB concepts is crucial for Java developers seeking to excel in enterprise application development. This comprehensive guide has equipped you with the knowledge and understanding to confidently answer EJB interview questions and demonstrate your expertise in this essential technology.