• First – need to know the various “java” related terms:
J2EE, J2SE, JDK, JRE, JSP,JSTL, Java
Servlets,Tomcat, Apache etc…..

• Sun Microsystems supply the Java 2 Enterprise Edition
(J2EE) platform, enabling developers to develop java based enterprise applications
• J2EE is a standard set of technologies and APIs
• (note: J2SE is the standard edition of the java platform but is not geared at large enterprise environments with distributed systems)
• J2EE includes the following components:
Java
Server
Pages
JDBC
Servlets
JNDI
Java beans
Java
Messaging

• Since J2EE is a specification, vendors create products that support the J2EE specifcation e.g. Apache, IBM
WebSphere, BEA Weblogic.
• From a web perspective, the J2EE applications that are particularly relevant are:
Java Server Pages
Java servlets
Can be used on its own or with beans/servlets to create a web application
Can be used on its own or with JSP/beans to create a web application
Java Beans
More complex web applications may use all 3

• The (JDK) Java Development Kit is the collective name for the various development components supplied in the J2EE (or J2SE).
• The Java Runtime Environment (JRE) is consists of the components required to run a java application

• Java Server Pages – A technology for developing web pages that include dynamic content
• Created by SUN microsystems
• ‘Equivalent’ of Microsoft’s Active Server Pages technology
• Pages have a file extension of .JSP
• JSPs enable web developers to enhance HTML code by adding special JSP elements that are processed by the server
• Will use JSP v2.0

•JSP pages are pre-compiled  Fast
•Part of the Sun’s J2EE  Can be used with other types of java technologies, such as servlets  flexible
•JSP is a specification  multiple vendors support it  commercially stable/not ‘fly by night’ technology
•Easy to develop: HTML can be easily maintained with JSP.
Relatively minimal programming skills required.
•JSP page code is not visible on client – only generated
HTML is visible

To develop and run JSP pages, need:
Not automatically included with all web servers
- Java Developer Kit (JDK which is part of J2EE) or higher
AND a Web server that contains a JSP Container
-JSP Containers are not automatically included with all Web servers
-Examples of web servers that contain a JSP container are
Apache Tomcat and Blazix.

JSP Container
-The JSP Container intercepts all client request for JSP pages
-First time a JSP page is requested, the Container converts the page into a java program called a Servlet and compiles - Translation phase
-For all follow-on request, the Container processes each request by invoking the appropriate servlet and then generating the response  Request processing phase
Q: What happens if the JSP page is changed?

First time through,
JSP is translated to a servlet
After, container goes directly to the servlet in the request processing phase
If JSP page is changed, servlet is recompiled

•Apache project have a sub project called Jakarta
(see http://jakarta.apache.org/index2.html)
•Jakarta project produces
- Tomcat web server (nicknamed Catalina)
- Tomcat webserver incorporates JSP container
(nicknamed Jasper)

JSP technology developing rapidly
 New version contain major new capabilities
 Always note the JSP container version you are working with, and check functionality supported (on apache website)
This course using
Apache Tomcat Version 5
JSP 2
JSLT 1.1
Servlet 2.4

Using apache Tomcat…
Create your web application directory
Create the subset WEB-INF directory (won’t run without this)
Put JSP page into web application directory
Call from the browser http://localhost:8080/webapp/somename.jsp

In the background –
Tomcat will retrieve the JSP page from the web server
If it’s the first time JSP page has been called/run or if page has changed, Tomcat will compile the JSP page (into a servlet) - .java and .class placed in /work directory.
 subsequent calls to page will be faster as no compile needed
JSP page will be presented back to the user

• Prints out message to user when JSP is loaded..
• Tomcat demo..

<html>
<%@ page import="java.util.Date" %>
<head>
<title>JSP DATE EXAMPLE</title>
</head>
<body bgcolor=#ffffff>
<h1>JSP DATE</h1>
<h2>
The current date is <%= new Date() %> .
</h2>
</body>
</html>
Prints out the current date

Always always always ensure that code is:
INDENTED COMMENTED CONTAINS AN ID BLOCK
1) Indented - to reflect level of the code
<html>
<head>ajsdlkfjads etc
2) Well commented. Comments in JSP appear as
<%-- calculate the sum of x and z here --%>
Comments in HTML appear as <!--this is a comment -->
HTML comments will be visible by view source in browser,
JSP comments won’t.

3) Titled with an ID block:
At the top of each JSP page, should have an ID block explaining who write the script, date, script name, description and any revisions. Can use either JSP or HTML comments (depending on whether users should be able to see the ID block)
<%--
*********************************************
*** Script name: addition.jsp ***
*** Author: Keith Morneau ***
*** Date: July 7th 2006 ***
*** Desciption: whatever it does.. ***
*** Revisions: ***
*** August 8th 2006: added subroutine ***
************************************************
--%> etc