NonStop Servlets for JavaServer Pages (NSJSP) 5.0 System Administrator's Guide

Overview and Architecture

NonStop Servlets for JavaServer Pages (NSJSP) System Administrator’s Guide—525644-003

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JavaServer Pages (JSP)

JavaServer Pages (JSP), a presentation-layer technology that sits on top of the Java

servlets model, simplifies the creation and management of dynamic HTML. JSP uses a

component-based rather than a page-based approach to development. In page-based

design, the web page combines the presentation material usually created by designers

with the business logic usually created by programmers.

By separating the user interface from content generation, JSP allows page designers

to change the page layout without altering the underlying programmable dynamic

content. Furthermore, the programmable content, or business logic, can be written in

the form of reusable components such as Java Beans. This separation of the page

logic from its display and the support for a reusable component-based design makes

JSP a fast and easy way to build web-based applications.

JavaServer Pages use XML-like tags and scriptlets written in the Java programming

language to encapsulate the logic that generates the content for the page. Additionally,

the application logic can reside in server-based resources, Java Beans, that the page

accesses by using these tags and scriptlets. All formatting (HTML or XML) tags are

passed directly back to the response page. The underlying JSP engine (actually a

specialized servlet itself) transforms JSP tags, scriptlets, and HTML into Java code

which is organized as a Java servlet. This servlet is compiled as Java bytecode, so the

page does not need to be interpreted every time it is requested. The code is

recompiled automatically if the page is changed. A high-level view of JSP is shown in

Figure 1-2, JSP Data Flows, on page 1-5.

Figure 1-1. A J2EE Web Container With Two Applications

VST901.vsd

WEB CONTAINER

APPLICATION # 2

JAVA

SERVLETS

DEPLOYMENT

DESCRIPTOR

JAVA

CLASSES

JSP

PAGES

APPLICATION # 1

JAVA

SERVLETS

DEPLOYMENT

DESCRIPTOR

JAVA

CLASSES

JSP

PAGES