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Introduction Servlets and JSP. Celsina Bignoli bignolic@smccd.net. Dynamic web pages. Content may change based on identity of the user user’s browser type information provided by the user selections made by the user. CGI. CGI (Common Gateway Inteface)

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Introduction Servlets and JSP

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Introduction servlets and jsp

Introduction Servlets and JSP

Celsina Bignoli

bignolic@smccd.net


Dynamic web pages

Dynamic web pages

  • Content may change based on

    • identity of the user

    • user’s browser type

    • information provided by the user

    • selections made by the user


Introduction servlets and jsp

CGI

  • CGI (Common Gateway Inteface)

    • outlines how a web server communicates with a program.

    • Typically written in Pearl (or C)

  • CGI scripting is not efficient

    • for every request the web server has to create a new process load an interpreter run the program and dispose of the process once done.


Cgi improvements

CGI improvements

  • Fast-CGI

    • runs program in a external process or pool of processes

  • mod_perl, NSAPI, ISAPI

    • run server-side programs in the same process as the web server

    • available only on some web servers


Servlets

Servlets

  • Server side Java programs

  • Solve scalability issue

    • serlvets are run on threads of execution not separate processes

  • Solve portability issue

    • runs on every platform that supports Java

    • supported by all most popular web servers

  • Issue

    • html tags are embedded in java programs within out.print() statements


Introduction servlets and jsp

JSP

  • server-side technology

  • separate dynamic content from static content of a page

    • Java scriptlets embedded into html-like page

  • Separate the work of

    • java programmers

    • page authors


Jsp relationship to servlets

JSP relationship to Servlets

A JSP is converted into a Servlet


Servlet example

Servlet Example

import java.text.*;

import java.util.*;

import

public class DateServlet extends HttpServlet{

public void doGet(HTTPServletRequest request,

HttpServletResponse response)

throws ServletException, IOException

{

response.setContentType(“text/html’);

PrintWriter out = response.getWriter();

out.println(“<html>”);

out.println(“<head><title><Date Example</title></head>”);

out.println(“<body>”);

out.println(“Today is: “);

Date d = new Date();

out.println(“<em>” + DateFormat.getInstance().format(d)+ “</em>”);

out.println(“<body>”);

out.println(“</html>”);

}

}

embedded HTML


Jsp example

<%

Date d=new Date();

String today = DateFormat.getInstance().format(d);

%>

JSP Example

JSP tag

<%@ page import=“java.text.*’, java.util.*”%>

<html>

HTML

<head><title><Date Example</title></head>

<body>

Scriptlet

Today is:

<em><%=today%></em>

</body>

</html>

Example.jsp

  • Static: HTML/XML elements

  • Dynamic: scriptlets

  • Additional: special JSP elements


Jsp alternatives

JSP alternatives

  • Active Server Pages

    • allows you to add VBScript or JScript code to the page

    • primarily a solution for te Windows platform

  • PHP

    • open source web-scripting language.

    • extensive set of predifined functions to access databases, LDAP directories, mail servers etc…

    • widely supported

  • ColdFusion

    • ColdFusion Markup Language(CFML) accessing databases, files, mail servers etc…

    • custom elements can be developed in C++ or Java


Jsp unique features

JSP Unique Features

  • JSP is a specification, not a product

    • competing implementations

  • integral part of J2EE

    • access all features of the Java language


How to get started

How to get Started

  • Install JDK 5.0

  • Download Apache Tomcat 5.5 from:

    www.apache.org

  • Use a regular editor or an IDE that supports JSP development

    • Eclipse

    • JBuilder

    • JCreator

    • Oracle JDeveloper

    • NetBeans

    • Macromedia DreamWeaver


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