J2EE Interview questions and answers

Posted by Stephen thangaraj at 18:32

PART-I

1. What is J2EE?

J2EE is an environment for developing and deploying enterprise applications. The J2EE platform consists of a set of services, application programming interfaces (APIs), and protocols that provide the functionality for developing multitiered, web-based applications.

2. What is the J2EE module?

A J2EE module consists of one or more J2EE components for the same container type and one component deployment descriptor of that type.

3. What are the components of J2EE application?

A J2EE component is a self-contained functional software unit that is assembled into a J2EE
application with its related classes and files and communicates with other components. The J2EE
specification defines the following J2EE components:

Application clients and applets are client components.

Java Servlet and JavaServer PagesTM (JSPTM) technology components are web components.
Enterprise JavaBeansTM (EJBTM) components (enterprise beans) are business components.
Resource adapter components provided by EIS and tool vendors.

4. What are the four types of J2EE modules?

1. Application client module
2. Web module
3. Enterprise JavaBeans module
4. Resource adapter module

5. What does application client module contain?

The application client module contains:
--class files,
--an application client deployment descriptoor. Application client modules are packaged as JAR files with a .jar extension.

6. What does web module contain?

The web module contains:
--JSP files,
--class files for servlets,
--GIF and HTML files, and
--a Web deployment descriptor.
Web modules are packaged as JAR files with a .war (Web
ARchive) extension.

7. What are the differences between Ear, Jar and War
files? Under what circumstances should we use each one?
There are no structural differences between the files; they are all archived using zip-jar compression.
However, they are intended for different purposes.
--Jar files (files with a .jar extension) are intended to hold generic libraries of Java classes,
resources, auxiliary files, etc.
--War files (files with a .war extension) are intended to contain complete Web applications. In this context, a Web application is defined as a single group of files, classes, resources, .jar files that can be packaged and accessed as one servlet context. --Ear files (files with a .ear extension) are intended to contain complete enterprise applications. In this context, an enterprise application is defined as a collection of .jar files, resources, classes, and multiple Web applications. Each type of file (.jar, .war, .ear) is processed uniquely by application servers, servlet containers, EJB containers, etc.

8. What is the difference between Session bean and Entity bean?one?
The Session bean and Entity bean are two main parts of
EJB container.
Session Bean
--represents a workflow on behalf of a cliennt
--one-to-one logical mapping to a client. --created
and destroyed by a client
--not permanent objects
--lives its EJB container(generally) does noot survive system shut down
--two types: stateless and stateful beans Entity Bean
--represents persistent data and behavior off this data
--can be shared among multiple clients
--persists across multiple invocations
--findable permanent objects
--outlives its EJB container, survives system shutdown
--two types: container managed persistence(CCMP) and
bean managed persistence(BMP)

9. What is "applet"
A J2EE component that typically executes in a Web browser but can execute in a variety of other applications or devices that support the applet  programming model.
10. What is "applet container"
A container that includes support for the applet programming model.

21. What is authorization?
 The process by which access to a method or resource is determined. Authorization depends on the determination of whether the principal associated with a request
through authentication is in a given security role. A security role is a logical grouping of users defined
by the person who assembles the application. A deployer maps security roles to security identities.
Security identities may be principals or groups in the operational environment.

 22. What is authorization constraint

An authorization rule that determines who is permitted to access a Web resource collection.

23. What is B2B

B2B stands for Business-to-business.

24. What is backing bean

A JavaBeans component that corresponds to a JSP page that includes JavaServer Faces components. The backing bean defines properties for the components on the page and methods that perform processing for the component. This processing includes event handling, validation, and processing associated with navigation.

25. What is basic authentication
 An authentication mechanism in which a Web server authenticates an entity via a user name and password obtained using the Web application's built-in authentication mechanism.


26. What is bean-managed persistence

The mechanism whereby data transfer between an entity bean's variables and a resource manager is managed by the entity bean.

27. What is bean-managed transaction

A transaction whose boundaries are defined by an enterprise bean.


28. What is binding (XML)

Generating the code needed to process a well-defined portion of XML data.

29. What is binding (JavaServer Faces technology)

Wiring UI components to back-end data sources such as backing bean properties.

30. What is build file The XML file that contains one or more asant targets.
A target is a set of tasks you want to be executed. When starting asant, you can select which targets you want to have executed. When no target is given, the project's default target is executed.

31. What is business logic
The code that implements the functionality of an application. In the Enterprise JavaBeans architecture, this logic is implemented by the methods of an enterprise bean.

32.What is business method ?
A method of an enterprise bean that implements the business logic or rules of an application.



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1 comments:

Rajapriya R on 6 February 2017 at 22:45 said...

useful blog to java beginners and experienced professionals

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