Introduction to J2EE APIS

 

(Servlet, JSP, EJB, JMS, JavaMail, JSF, JNDI)

1)       Java Servlet :The Java Servlets provides object oriented abstractions for building dynamic web applications. Servlets are server side components that are a platform independent high  performance  replacement for CGI. Like CGI, Servlets dynamically generate HEML as a result  of  a  HTTP request.

2)      Java Server Pages [JSP]

The Java Server Pages are an extension of the Servlet API that simplifies the generation of dynamic web pages by providing template driven web application development. It uses XML/HTML like tags and Java Scrip lets to encapsulate the logic required to generate pages in a platform independent way.

3)      Enterprise Java Beans [EJB]

Enterprise Java Beans are a distributed component based framework. It provides  a  standard means of defining server-side components, and specifies a run-time environment for hosting the components on the server side. There are 3 main types of EJBs : Session beans, Entity beans and Message driven beans.

4)      Java Database Connectivity :

JDBC provides platform and vendor independent access to SQL compliant databases. Basic JDBC (version 2.0) is J2SE. The J2EE platform requires, besides the basic APIs, also the JDBC 2.0 Optional Package. JDBC allows transactional querying, retrieval and manipulation of data in a JDBC drivers or you can use a ODBC-to-JDBC bridge. This means that almost every relational database available can be used on J2EE platform.

5)      Java Message Service (JMS) :

JMS provides a Java API for message queuing, and publish and subscribe types of message- oriented middleware (MOM). This API is to use if applications in a distributed environment cannot be connected all the time and the handling of the communication should be a synchronous.

6)      Java Mail :

This API provides a platform independent and protocol independent framework to build Java  based email applications. Although platform independent, Java Mail depends on an underlying email server like Send Mail or MS Exchange Server for the actual sending of an email. It uses IMAP4, POP3 and SMTP as its underlying transport mechanisms.

7)      Java Beans Activation Framework (JAF) :

The Java Beans Activation Framework is required for Java Mail. Java Mail uses JAF to determine the contents of a Multiple Internet Main Extension (MIME) message and what appropriate actions can be done accordingly.

8)      Java Naming and Directory Interface (JNDI) :

JNDI standardizes access to different types of naming services. The API is designed to be independent of any specific naming or directory service implementation.  J2SE also specifies a  JNDI service provider interface (SPI) for naming and directory service providers to implement. JNDI is not a J2EE API but a J2SE API.

9)      Java Transaction API (JTA) :

This API is for implementing distributed transactional applications.

10)   The Java Connector Architecture (JCA) :

This API has recently been included in J2EE, and provides a means to integrate J2EE application components to legacy information systems.