| Java
Server Pages FAQ : |
 |
| What
is JavaServer Pages technology? |
|
| JavaServer Pages (JSP) technology
provides a simplified, fast way to create
web pages that display dynamically-generated
content. The JSP specification, developed
through an industry-wide initiative led by
Sun Microsystems, defines the interaction
between the server and the JSP page, and describes
the format and syntax of the page. |
|
| How
does the JavaServer Pages technology work?
|
|
JSP pages use XML tags and scriptlets
written in the Java programming language to
encapsulate the logic that generates the content
for the page. It passes any formatting (HTML
or XML) tags directly back to the response
page. In this way, JSP pages separate the
page logic from its design and display.
JSP technology is part of the Java technology
family. JSP pages are compiled into servlets
and may call JavaBeans components (beans)
or Enterprise JavaBeans components (enterprise
beans) to perform processing on the server.
As such, JSP technology is a key component
in a highly scalable architecture for web-based
applications. |
|
| JSP pages are not restricted
to any specific platform or web server. The
JSP specification represents a broad spectrum
of industry input. |
|
| What
is a servlet? |
|
A servlet is a program written
in the Java programming language that runs
on the server, as opposed to the browser (applets).
Detailed information can be found at http://java.sun.com/products/servlet.
Why do I need JSP technology if I already
have servlets? |
|
| JSP pages are compiled into
servlets, so theoretically you could write
servlets to support your web-based applications.
However, JSP technology was designed to simplify
the process of creating pages by separating
web presentation from web content. In many
applications, the response sent to the client
is a combination of template data and dynamically-generated
data. In this situation, it is much easier
to work with JSP pages than to do everything
with servlets. |
|
| How
does the JSP specification relate to the Java
2 Platform, Enterprise Edition? |
|
| The JSP 2.0 specification is
an important part of the Java 2 Platform,
Enterprise Edition 1.4. Using JSP and Enterprise
JavaBeans technologies together is a great
way to implement distributed enterprise applications
with web-based front ends. |
|
| Which
web servers support JSP technology? |
|
| There are a number of JSP technology
implementations for different web servers.
The latest information on officially-announced
support can be found at http://java.sun.com/products/jsp/industry.html.
|
|
| Is
Sun providing a reference implementation for
the JSP specification? |
|
| The J2EE SDK is a reference
implementation of the JavaTM 2 Platform, Enterprise
Edition. Sun adapts and integrates the Tomcat
JSP and Java Servlet implementation into the
J2EE SDK. The J2EE SDK can be used as a development
environment for applications prior to their
deployment and distribution. |
|
| Tomcat a free, open-source implementation
of Java Servlet and JavaServer Pages technologies
developed under the Jakarta project at the
Apache Software Foundation, can be downloaded
from http://jakarta.apache.org/.
Tomcat is available for commercial use under
the ASF license from the Apache web site in
both binary and source versions. An implementation
of JSP technology is part of the J2EE SDK.
|
|
| How
is JSP technology different from other products?
|
|
| JSP technology is the result
of industry collaboration and is designed
to be an open, industry-standard method supporting
numerous servers, browsers and tools. JSP
technology speeds development with reusable
components and tags, instead of relying heavily
on scripting within the page itself. All JSP
implementations support a Java programming
language-based scripting language, which provides
inherent scalability and support for complex
operations. |
|
| Where
do I get more information on JSP technology?
|
|
| The first place to check for
information on JSP technology is http://java.sun.com/products/jsp/.
This site includes numerous resources, as
well as pointers to mailing lists and discussion
groups for JSP technology-related topics.
|
|
| What
is a JSP page? |
|
| A JSP page is a page created
by the web developer that includes JSP technology-specific
and custom tags, in combination with other
static (HTML or XML) tags. A JSP page has
the extension .jsp or .jspx; this signals
to the web server that the JSP engine will
process elements on this page. Using the web.xml
deployment descriptor, additional extensions
can be associated with the JSP engine. The
exact format of a JSP page is described in
the JSP specification.. |
|
| How
do JSP pages work? |
|
| A JSP engine interprets tags,
and generates the content required - for example,
by calling a bean, accessing a database with
the JDBC API or including a file. It then
sends the results back in the form of an HTML
(or XML) page to the browser. The logic that
generates the content is encapsulated in tags
and beans processed on the server. |
|
| Does
JSP technology require the use of other Java
platform APIs? |
|
| JSP pages are typically compiled
into Java platform servlet classes. As a result,
JSP pages require a Java virtual machine that
supports the Java platform servlet specification.
|
|
| How
is a JSP page invoked and compiled? |
|
| Pages built using JSP technology
are typically implemented using a translation
phase that is performed once, the first time
the page is called. The page is compiled into
a Java Servlet class and remains in server
memory, so subsequent calls to the page have
very fast response times. |
|
| Can
I create XML pages using JSP technology? |
|
| Yes, the JSP specification does
support creation of XML documents. For simple
XML generation, the XML tags may be included
as static template portions of the JSP page.
Dynamic generation of XML tags occurs through
bean components or custom tags that generate
XML output. See the white paper Developing
XML Solutions with JavaServer Pages Technology
(PDF) for details. |
|
| Can
I generate and manipulate JSP pages using
XML tools? |
|
| The JSP 2.0 specification describes
a mapping between JSP pages and XML documents.
The mapping enables the creation and manipulation
of JSP pages using XML tools. |
|
| How
do I use JavaBeans components (beans) from
a JSP page? |
|
| The JSP specification includes
standard tags for bean use and manipulation.
The useBean tag creates an instance of a specific
JavaBeans class. If the instance already exists,
it is retrieved. Otherwise, it is created.
The setProperty and getProperty tags let you
manipulate properties of the given object.
These tags are described in more detail in
the JSP specification and tutorial. |
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