J2EE Interview Questions

by Shabina Siddique Software Engineer

Java 2 Platform Enterprise Edition (J2EE) is a platform, used to develop and deploy enterprise applications. It is comprised of a set of services, application programming interfaces (APIs) and protocols that offers features of multi-tier web based applications.

Using J2EE, application development process becomes easy and it decreases the need for programmer training by creating standardized, reusable modular components and by enabling the tier to handle many aspects of programming automatically.

What are the Unit testing frameworks you have used for Java?

1. JUnit
2. Cactus
3. Struts Test Case
   
4. JFC Unit
   
5. TestNG
   
6. JMock
7. Grinder
   

J2EE – Distributed Multi-tier Application Model

J2EE is a multi-tiered platform divided into three or four tiers based on the application requirements. Generally, it is considered as three-tiered application because J2EE is distributed over three different locations. The locations are: Client machines, J2EE server machine and database machine. It can be extended to four tiered based application by placing a multi-threaded application server between the client application and back-end storage.

J2EE – Components

J2EE component is referred to as a self-contained functional unit of software that is part of J2EE application. With its related classes and files, the component communicates to other components. Below are the J2EE components:

·      Application clients and Applets

·      Java Servlets and Java Server Pages (JSPs)

·      Enterprise Java Beans (EJB)

J2EE Application Clients and Applets

J2EE client enables the user to handle user interface related tasks provided by markup language. Application clients access enterprise beans running in the business tier.

An applet is a small client application that executes in Java Virtual Machine (JVM) installed in the web browser. In order to successfully execute applet in the web browser, Java plugin or security files are required on the end user’s system.

J2EE Servlets and JSPs

J2EE servlets are classes that dynamically process requests and generate responses. JSPs are text based documents that are used to create static content.

J2EE Enterprise Java Beans (EJB)

J2EE are enterprise beans run in the business tier. It retrieves data from the client programs, processes it in the business tier and sends to back-end for storage. It also retrieves data from back-end, processes it and sends it to the client program. It is middle tier and important for domains that demands business logic.

J2EE Containers

J2EE container refers to a component and a part of the server that manages life cycle of Web applications. The containers are Java Servlets, Java Server Pages (JSPs) and Java Server Faces (JSFs). The containers are responsible for for initializing Web application components and invoking client requests on the components.

They may also be used to generate XML or other format data that is consumed by other application components.

J2EE Application Program Interfaces (APIs)

Application Programming Interface is a piece of program that is used for accessing Web applications. There are some APIs available in J2EE as listed below:

·      Java Message Service (JMS): The JMS API is used for sending and receiving messages via enterprise messaging systems

·      JDBC: The JDBC API is used for accessing database from Java using a call level interface.

·      Java Authentication and Authorization Service (JAAS): The JAAS API is used to authenticate and authorize access controls on users.

JDO: The JDBC API is used for accessing database from Java using persistence interface.

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Created on Sep 27th 2020 15:54. Viewed 284 times.

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