Give details about J2EE?

Answer 1

J2EE (Java 2 Enterprise Edition) is actually called JavaEE (Java Enterprise Edition) in the most recent release. JavaEE itself is not an application, but a set of application programming interfaces (APIs) developed by Sun Microsystems that are actually implemented by JavaEE application servers such as BEA WebLogic, JBoss, and IBM WebSphere.

It is composed of the following APIs:
- Enterprise Java Beans (EJB): To many, EJB is synonymous with JavaEE. In Java lingo a "bean" is a component object and follows certain rules of behavior. EJBs are distributed object beans that are held in a "container" mechanism provided by the app server. EJBs are accessed via remote procedure calls or message passing. The app server provide container services that are "wrapped around" the EJB, usually including services for verification, security, persistence, etc. EJBs come in a wide variety of colors and styles, including:
. . -- Entity Beans which encapsulate stored data (usually in a database) using either Container-managed persistence (CMP) or Bean-managed persistence (BMP).
. . -- Stateful Session Beans (SfSBs) which manage state across the course of an entire usage session.
. . -- Stateless Session Beans (SlSBs) which track usage sessions, but do not maintain state within the bean
. . -- Message-driven Beans (MDBs) which are activated in response to receipt of a JMS (see below) message
Many, including myself, think EJBs are a bloated nightmare and avoid them whenever possible.

- Servlets, JavaServer Pages, and JavaServer Faces: Perhaps the most widely used JavaEE APIs. A servlet is an object that implements request-response behavior, almost always within the HTTP (web) or HTTPS (secure web) protocol. JavaServer Pages are a refinement of Servlets that allow you to make template response web pages with server-side Java code imbedded within them. JavaServer Faces are designed to add component-based programming layers on top of JSPs. Servlets/JSPs are also managed by the app server in a Servlet container that is separate from the EJB container.

- Java Database Connectivity (JDBC): Provides methods for querying and updating a database. It is mostly for relational databases. The app server provides a "data source" mechanism to manage connection configuration and pooling. The connections themselves are created DBMS-specific "drivers" (DBMS clients). All major RDBMS vendors (even Microsoft) provide JDBC drivers for their DBMS servers.

- Java Naming and Directory Interface (JNDI): Provides a directory lookup mechanism for Java Objects. It supports several common directory standards, such as LDAP, DNS, or NIS. The actual directory service used is implementation-specific and is usually provided as a container service.

- Java API for XML Processing (JAXP): Provides a Java-based factory mechanism for accessing DOM, SAX, XPath, and XSLT. The factory interface allows the developer to configure whatever implementation is desired through properties, without having to change code.

- Java Message Service (JMS): Provides a Java-based factory mechanism for accessing message-oriented middleware (MOM). Message passing is loosely-coupled asynchronous communication, unlike the request-response of servlets or the remote procedure calls used on most EJBs. The factory interface allows developer configuration of different implementations. Since JMS does not specify the underlying message protocol, all endpoints in the JMS distributed application must be running the same vendor's messaging system (though not all endpoints need to be JMS-based or even Java-based).

- Java Transaction API (JTA): Provides ACID-level transaction integrity using a separate transaction processing monitor (TPM), following the X/Open XA transaction architecture. I have never had need of it so the above statement exhausts all my knowledge on the subject.

There are other APIs I have not mentioned, but those are the biggies.

Answer 2

For having more information you can get into Sun web site and there are lots of things about j2ee or even in theserverside.com

Answer 3

j2ee is an enterprise edition that is uses for developing management software or business related software .it provides server side security.