Chapter 1: JSP Overview

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Chapter 1JSP Overview
Reference Beginning JSP
2
Objectives

• To learn
• Relative advantages of using JSP
• Vendors and platforms supporting JSP
• Steps in servlet development
• Why use JSP
• Apache Tomcat 5.5

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A Brief History of the Java Platform

• 1995 Version 1.0 (Sun Microsystems)
• 1997 Version 1.1
• 1998 Java 2 platform
• 1999 J2SE, J2EE, and J2ME
• 2001 Version 1.3 of J2SE
• 2002 Version 1.4 of J2SE
• 2002 Version 1.3 of J2EE (JSP 1.2)
• 2004 Version 1.4 of J2EE (JSP 2.0)

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The Three Editions of the Java 2 Platform

• The Java 2 platform comes in three versions
• Java 2 Standard Edition (J2SE)
• Java 2 Enterprise Edition (J2EE)
• Java 2 Micro Edition (J2ME)

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JSP is a part of J2EE

• J2EE
• A set of integrated Java APIs that enable
  client-server Web applications
• Originally defined by Sun Microsystems
• Java Community Process now includes many software
  vendors including IBM, BEA, etc.
• J2EE is not the same as J2SE
• J2EE has many versions
• J2EE 1.2
• J2EE 1.3
• J2EE 1.4 (used in this course)
• JSP 2.0, Servlet 2.4

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Products (Web containers) that support JSP
2.0/Servlet 2.4

• Apache Tomcat 5.5
• used in this course
• JBoss 4.0
• Sun Application Server 8.1
• IBM WebSphere 6.0
• BEA Weblogic 9.0
• Etc.

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Reasons for Using J2EE

• Hardware Independence
• Works with different hardware and software
  platforms
• http//java.sun.com/j2ee/compatibility.html
• Code Separation
• Layered architecture, MVC
• Compatibility
• different versions of APIs work together
• Scalability
• Pluggable components multiple servers
• Tool Independence
• Multiple vendors to choose from

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Web ApplicationUsing Servlets and JSPs

• JSP Model 2 (MVC Pattern)

Servlets
HTML/Web Browser
HTTP Request
JavaBeans
HTTP Response
JSPs
Client
J2EE Server (Tomcat 5.5)
Database (MySQL)
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J2EE Architecture
Source Sun Microsystems
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Key J2EE APIs

• Component Technologies
• Servlets
• Java Server Pages (JSP)
• Enterprise Java Beans (EJB)
• Standard Services
• Java Database Connectivity (JDBC API)
• Java Naming and Directory Interface (JNDI)
• Java Transaction API (JTA)
• Other Services
• HTTP, HTTPS, RMI-IIOP, JMS, JavaMail

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JSP Example

• lt_at_ taglib prefix"tags" tagdir"/WEB-INF/tags"
  gt lthtmlgt
• ltheadgt
• lttitlegtJSP 2.0 Examples - Hello World Using a Tag
  Filelt/titlegt
• lt/headgt
• ltbodygt
• lth1gtJSP 2.0 Examples - Hello World Using a Tag
  Filelt/h1gt lthrgt
• ltpgt lttagshelloWorld/gt.lt/pgt
• lt/bodygt
• lt/htmlgt

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Dynamic Web Pages with JSP

• JSP is a server-side scripting language that
  produces Web pages that can be viewed with any
  browser
• You can mix regular HTML tags with JSP script in
  the same JSP page
• The JSP scripts, if any, are interpreted by the
  application server
• The content generated by the execution of JSP
  code is mixed with HTML code and the whole
  content is sent to the client browser

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JSP versus HTML

• JSP can perform the following tasks
• Connect to and manipulate a database.
• Create pages that can display things which will
  be of interest to a particular user.
• Collect data from users and return information to
  a visitor based on the data collected.
• Modify the content of a Web page, by updating a
  text file or the contents of a database rather
  than the HTML code itself.
• Access file systems via the Internet so that you
  can read, write, and update files.
• Utilize extensive Java Applications Programming
  Interface.

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CGI, ASP, and ASP.NET

• CGI
• Compiled, runs fast
• Difficult to modify and update
• Not convenient to connect to database
• ASP
• Mix ASP script with HTML
• Using Active control and DLL
• ASP script itself needs to be interpreted every
  time it is requested
• ASP.NET
• Overcome all drawbacks discussed above
• Drawback only supported on Windows platform

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Servlets

• Servlets are small Java programs that run on a
  Web server in response to client requests
• Servlets generate dynamic content that is sent
  back to client
• Servlets are compiled and represented as .class
  files
• Servlets are loaded either on demand or by the
  server at start-up
• When a servlet is requested from client, a method
  or function is called in response to the request

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Steps in Servlet Development

• Write / edit Java servlet code
• repeated use of PrintWriter.println() to generate
  HTML output (e.g., out.println(lttitlegtJSP
  2.0lt/titlegt)
• Compile servlet
• Deploy to servlet container (e.g., Tomcat 5.5)
• Test via browser and server
• If tests not ok, repeat the above steps
• Major Drawback Need to modify Java code every
  time a change is needed in the presentation code.

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Why Use JSP

• JSP is built on top of servlets, so it has all
  the advantages of servlets
• JSP is compiled into its corresponding servlet
  when it is requested the first time
• The servlet stays in memory, speeding response
  times
• Extensive use of Java API (Applications
  Programming Interface) for networking, database
  access, distributed objects, and others like it
• Powerful, reusable and portable to other
  operating systems and Web servers

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Steps in JSP Development

• Write / edit JSP page
• Java code embedded in HTML
• Deploy to JSP engine (servlet container )
• e.g., Tomcat 5.5
• Test via browser and server
• If tests not ok, repeat the above steps
• Advantage No need to manually compile the JSP
  page.

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Apache Tomcat 5.5

• Open-source (free)
• Very popular servlet container and JSP engine
• Runs on many platforms including Windows and
  Linux
• Implemented the latest servlet and JSP
  specifications (servlet 2.4 and JSP 2.0)
• Supported by the popular Java/J2EE IDE such as
  Eclipse/IBM WSAD, JBuilder, NetBeans, JDeveloper
• Easy to deploy and administer using Tomcat Manager

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Next Steps

• Do
• Lab 1 Start/ stop Tomcat 5.5
• Lab 2 NetBeans 5.5 with bundled Tomcat 5.5.
• Optional
• Try It Out Chapter 1 (optional)
• Read J2EE Overview http//java.sun.com/j2ee/1.4/d
  ocs/tutorial/doc/Overview.htmlwp80172