iTP Secure WebServer System Administrator's Guide (iTPWebSvr 6.0+)

Using NonStop Servlets for JavaServer Pages
(NSJSP)
iTP Secure WebServer System Administrator’s Guide—523346-002
9-7
JavaServer Pages
JavaServer Pages
JavaServer Pages, a presentation layer technology that sits on top of the Java servlets
model, simplifies the creation and management of dynamic HTML. The technology
takes a component-based rather than page-based approach to development. With
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 faster and easier 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 with 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 precompiled as Java bytecode, thus 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 9-2, JSP Data Flows.
Further information on JSP can be found at JavaServer Pages on page 9-35.
Figure 9-2. JSP Data Flows
VST902.vsd
Client Browser iTP WebServer
JSP Page
Java Servl et
Component
First Time Use
Subsequent Use
Compilation