J2EE : Java 2 Enterprise Edition
J2EE is a platform-independent, Java-centric environment from Sun for developing, building and deploying Web-based enterprise applications online. The J2EE platform consists of a set of services, APIs, and protocols that provide the functionality for developing multitiered, Web-based applications.
The Java™ 2 Platform, Enterprise Edition (J2EE) provides a standard for developing multitier, enterprise services.
J2EE architecture supports component-based development of multi-tier enterprise applications. A J2EE application system typically includes the following tiers:
• Client tier: In the client tier, Web components, such as Servlets and JavaServer Pages (JSPs), or standalone Java applications provide a dynamic interface to the middle tier.
• Middle tier: In the server tier, or middle tier, enterprise beans and Web Services encapsulate reusable, distributable business logic for the application. These server-tier components are contained on a J2EE Application Server, which provides the platform for these components to perform actions and store data.
• Enterprise data tier: In the data tier, the enterprise's data is stored and persisted, typically in a relational database.
J2EE applications are comprised of components, containers, and services. Components are application-level components. Web components, such as Servlets and JSPs, provide dynamic responses to requests from a Web page. EJB components contain server-side business logic for enterprise applications. Web and EJB component containers host services that support Web and EJB modules.
The J2EE platform uses a distributed multitiered application model for enterprise applications. Application logic is divided into components according to function, and the various application components that make up a J2EE application are installed on different machines depending on the tier in the multitiered J2EE environment to which the application component belongs.
The J2EE application parts are presented in J2EE Components.
• Client-tier components run on the client machine.
• Web-tier components run on the J2EE server.
• Business-tier components run on the J2EE server.
• Enterprise information system (EIS)-tier software runs on the EIS server.
J2EE multitiered applications are generally considered to be three-tiered applications because they are distributed over three locations: client machines, the J2EE server machine, and the database or legacy machines at the back end. Three-tiered applications that run in this way extend the standard two-tiered client and server model by placing a multithreaded application server between the client application and back-end storage.
What is J2EE?
The Java 2 Platform Enterprise Edition (J2EE) technology provides a component-based approach to the design,development,assembly,and deployment of enterprise applications. The J2EE platform provides the ability to reuse components in different applications. J2EE is made up of 13 different technologies including JavaServer Pages,Servlets,Enterprise JavaBeans,JavaMail,XML,JavaMail and many more.
You can check out this article :J2EE OverviewWhat are the benefits of using J2EE?
There are several reasons for using the J2EE set of technologies:
What are JavaServer Pages?
- Extensibility and maintainability
- Division of work along skill lines
- Code reuse.
- Interoperability – legacy integration
- Focus on implementing business logic
- Separation of code with differing rates of change.
JavaServer Pages (JSP) is a technology based on the Java language and enables the development of dynamic web sites. JSP was developed by Sun Microsystems to allow server side development. JSP files are HTML files with special Tags containing Java source code that provide the dynamic content.
You can check out this article : Java Server PagesWhat are Servlets?
A Servlet is a Java class that provides special server side service. To display any information on a web page,HTML code is embedded in “println” statements. JSP technology is an extension of Servlets. It is easier to generate GUI pages using JSP because a web page editor (such as Macromedia DreamWeaver ) can be used to create simple pages.
You can check out this article : Java Servlet Technology.