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

Overview and Architecture
NonStop Servlets for JavaServer Pages (NSJSP) System Administrator’s Guide—525644-002
1-5
The Web Application
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.
The Web Application
The web application is a collection of servlets, HTML pages, images, JSPs, a
deployment descriptor, and other configuration files that together represent all the
resources necessary to host a complete application on a J2EE-compliant webserver.
Figure 1-2. JSP Data Flows
VST902.vsd
Client Browser iTP WebServer
JSP Page
Java Servlet
Component
First Time Use
Subsequent Use
Compilation