Introduction to JSP

JSP is a Sun Microsystems specification that enables you to produce dynamic Web-based applications. WebLogic Server's implementation of the Sun specification employs the Model-View-Controller design pattern (see Chapter 16, "JavaBeans and Model-View-Controller (MVC) Architecture"). This design pattern allows multiple presentation views and varied data update mechanisms with no effect on core application logic. This is accomplished by separating content development from presentation development, which enables Java developers to add JSP code to predeveloped presentation pages (HTML, DHTML, WML, XML) and enables presentation developers to modify Web page appearance without altering dynamic content.

WebLogic Server's implementation of JSP can be coded using either JSP-specific XML-like shorthand tags or actual XML equivalent tags. The application logic with the JSP container (the host for JSP infrastructure) resides on the WebLogic server. The client (usually a Web browser) requests a JSP page (an HTML page with embedded JSP tags), and the JSP page is transitioned into a Java file, which is a servlet class (the compiled JSP page equivalent). This servlet class is executed to service client requests.

The JSP 1.2 specification is an extension of the JavaSoft Servlet 2.3 specification. For detailed information about these specifications, refer to the JavaSoft documentation site at http://java.sun.com/products. WebLogic Server's implementation of JSP 1.2 includes support for defining custom JSP tag extensions among other embellishments to JSP 1.1. Detailed information on WebLogic Server's implementation of JSP can be found at http://edocs.beasys.com/wls/docs81/jsp.

The new JSP 2.0 specification is an extension to the JavaSoft Servlet 2.4 specification. JSP 2.0 greatly improves JSP functionality over JSP 1.2 by mandating the use of Java 1.4, adopting a simple expression language (EL) that allows writing scriptless JSP pages, including an EL API, adopting syntax that creates custom actions (packaged within .tag files), and adopting a new simple invocation protocol that's used to implement the .tag files. BEA WebLogic Server 8.1 does not support JSP 2.0.