|
|
|
JSP
Java 2 Platform, Enterprise Edition (J2EE) is a set of coordinated specifications and practices that together enable solutions for developing, deploying, and managing multi-tier server-centric applications. Building on the Java 2 Platform, Standard Edition (J2SE), J2EE adds the capabilities necessary to provide a complete, stable, secure, and fast Java platform to the enterprise level. It provides value by significantly reducing the cost and complexity of developing and deploying multi-tier solutions, resulting in services that can be rapidly deployed and easily enhanced. J2EE provides the following: - Faster solutions delivery time to market. J2EE uses "containers" to simplify development. J2EE containers provide for the separation of business logic from resource and lifecycle management, which means that developers can focus on writing business logic -- their value add -- rather than writing enterprise infrastructure. For example, the Enterprise JavaBeans (EJB) container (implemented by J2EE technology vendors) handles distributed communication, threading, scaling, transaction management, etc. Similarly, Java Servlets simplify web development by providing infrastructure for component, communication, and session management in a web container that is integrated with a web server.
- Freedom of choice. J2EE technology is a set of standards that many vendors can implement. The vendors are free to compete on implementations but not on standards or APIs. Sun supplies a comprehensive J2EE Compatibility Test Suite (CTS) to J2EE licensees. The J2EE CTS helps ensure compatibility among the application vendors which helps ensure portability for the applications and components written for J2EE. J2EE brings Write Once, Run Anywhere (WORA) to the server.
- Simplified connectivity. J2EE technology makes it easier to connect the applications and systems you already have and bring those capabilities to the web, to cell phones, and to devices. J2EE offers Java Message Service for integrating diverse applications in a loosely coupled, asynchronous way. J2EE also offers CORBA support for tightly linking systems through remote method calls. In addition, J2EE 1.3 adds J2EE Connectors for linking to enterprise information systems such as ERP systems, packaged financial applications, and CRM applications.
- By offering one platform with faster solution delivery time to market, freedom of choice, and simplified connectivity, J2EE helps IT by reducing TCO and simultaneously avoiding single-source for their enterprise software needs.
The primary technologies in the J2EE platform are: Java API for XML-Based RPC (JAX-RPC), JavaServer Pages (JSPs), Java Servlets, Enterprise JavaBeans (EJBs), J2EE Connector Architecture, J2EE Management Model, J2EE Deployment API, Java Management Extensions (JMX), J2EE Authorization Contract for Containers, Java API for XML Registries (JAXR), Java Message Service (JMS), Java Naming and Directory Interface (JNDI), Java Transaction API (JTA), CORBA, and JDBC data access API. JavaServer™ Pages (JSP) is the Java™ 2 Platform, Enterprise Edition (J2EE) technology for building applications for generating dynamic web content, such as HTML, DHTML, XHTML, and XML. JSP technology enables the easy authoring of web pages that create dynamic content with maximum power and flexibility. General Concepts JSP technology provides the means for textual specification of the creation of a dynamic response to a request. The technology builds on the following concepts: - Template Data. A substantial portion of most dynamic content is fixed or template content. Text or XML fragments are typical template data. JSP technology supports natural manipulation of template data.
- Addition of Dynamic Data. JSP technology provides a simple, yet powerful, way to add dynamic data to template data.
- Encapsulation of Functionality. JSP technology provides two related mechanisms for the encapsulation of functionality: JavaBeans™ component architecture, and tag libraries delivering custom actions, functions, listener classes, and validation.
- Good Tool Support. Good tool support leads to significantly improved productivity. Accordingly, JSP technology has features that enable the creation of good authoring tools. Careful development of these concepts yields a flexible and powerful serverside technology.
Benefits of JavaServer Pages Technology JSP technology offers the following benefits: - Write Once, Run Anywhere™ properties. JSP technology is platform independent in its dynamic web pages, its web servers, and its underlying server components. JSP pages may be authored on any platform, run on any web server or web enabled application server, and accessed from any web browser. Server components can be built on any platform and run on any server.
- High quality tool support. Platform independence allows the JSP user to choose best-of-breed tools. Additionally, an explicit goal of the JavaServer Pages design is to enable the creation of high quality portable tools.
- Separation of Roles. JSP supports the separation of developer and author roles. Developers write components that interact with server-side objects. Authors put static data and dynamic content together to create presentations suited for their intended audience.
Each group may do their job without knowing the job of the other. Each role emphasizes different abilities and, although these abilities may be present in the same individual, they most commonly will not be. Separation allows a natural division of labor. A subset of the developer community may be engaged in developing reusable components intended to be used by authors. - Reuse of components and tag libraries. JavaServer Pages technology emphasizes the use of reusable components such as JavaBeans components, Enterprise JavaBeans™ components, and tag libraries. These components can be used with interactive tools for component development and page composition, yielding considerable development time savings. In addition, they provide the cross-platform power and flexibility of the Java programming language or other scripting languages.
- Separation of dynamic and static content. JavaServer Pages technology enables the separation of static content in a template from dynamic content that is inserted into the static template. This greatly simplifies the creation of content. The separation is supported by beans specifically designed for the interaction with server-side objects, and by the tag extension mechanism.
- Support for actions, expressions, and scripting. JavaServer Pages technology supports scripting elements as well as actions. Actions encapsulate useful functionality in a convenient form that can be manipulated by tools. Expressions are used to access data. Scripts can be used to glue together this functionality in a per-page manner.
The JSP 2.0 specification adds a simple expression language (EL) to Javabased scripts. Expressions in the EL directly express page author concepts like properties in beans and provide more controlled access to the Web Application data. Functions defined through the tag library mechanism can be accessed in the EL. The JSP 2.0 specification also adds a mechanism by which page authors can write actions using the JSP technology directly. This greatly increases the ease with which action abstractions can be created. - Web access layer for N-tier enterprise application architecture(s). JavaServer Pages technology is an integral part of J2EE. The J2EE platform brings Java technology to enterprise computing. You can now develop powerful middle-tier server applications that include a web site using JavaServer Pages technology as a front end to Enterprise JavaBeans components in a J2EE compliant environment.
|
|
