Java Server and Servlet

Java Server and Servlet

CS616 Team 9

Kim Doyle, Susan Kroha,

Arunima Palchowdhury, Wei Xu

• History

• What is a Java Server/Servlet

• Architecture

• Pros and Cons

• Existing Java Servers

• Conclusion

Java Server and Servlet

History

• Web has undergone rapid changes

• E-Commerce Transition from static to dynamic environment Birth of Common Gateway Interface (CGI)

• CGI languages include Perl C, C++ Visual Basic Script

CGI Pros and Cons

Browser

HTTP

Web Server

CGI bin

Process

HTML

Database

•Insecure

•Platform dependent

•Inefficient

CGI vs. Servlet

• Servlet is Sun’s solution for CGI

• Both generate dynamic contents

• Servlet is light

• Servlet is secure

• Servlet is platform independent

• Servlet has better support for reusable component

Java Server Definition

• An instance of Java Virtual Machine

• One Java Server can support multiple concurrent services

• Java Server can start: administrative services HTTP services web proxy services

• Services are configured when server process is initiated

Java Servlet Definition

• Java class that runs in JVM associated with Server

• Java object that conforms to a specific interface defined by the server architecture

• Loaded and invoked by services

• Multithreading

• Extends the functionality of the server

Server and Servlet Interaction

Browser

HTTP

Web Server

Servlet Engine

Servlets

HTML

Database

Application

Business Log.

Demo and Servlet Life Cycle

Application Server

Servlet Engine

Init()

Service ()doGet ()

doPost ()

Destroy()

Do… ()

link to Utopia

HttpResponse

HttpRequest

PrintWriter

link to Laptop

Simple Sample (Hello World)

import java.io.*;import javax.servlet.*;import javax.servlet.http.*; public class HelloWorld extends HttpServlet { public void doGet(HttpServletRequest request,

HttpServletResponse response) throws IOException, ServletException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("<html><head><title>"); out.println("Hello World!</title>"); out.println("</head><body>"); out.println("<h1>Hello World!</h1>"); out.println("</body></html>");

}}

Servlet Functions

• Reads data sent by user

• Looks up information from HTTP request

• Connects to database

• Invokes legacy application

• Executes RMI or CORBA calls

• Executes algorithm

• Formats document

• Sends document back to clients

Servlets

Algorithm

JDBC

PANDA

Project Group Assignment Servlets in Action

Tomcat

HTTP

Link to Laptoplink to Utopia

Servlet with Synchronization…

public class AlgorithmRequest extends HttpServlet {public void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

PrintWriter output; response.setContentType("text/html"); output = response.getWriter();

if(getConnection()){ String SemesterCourse =

request.getParameter("SEMESTERCOURSE"); synchronized (this) { AlgorithmControl ac = new

AlgorithmControl(SemesterCourse); …………………………………………

Servlet Advantanges

• Convenient

• Efficient (light weight thread, memory)

• Inexpensive

• Keep intellectual properties on the server

• Portable

• Powerful

• Secure

Server Advantanges

• Efficient Memory management Light weight

• Platform independent

• Thread-safe

Server Considerations

• Java is slower than C++

• However, Java server uses threads

• WebSphere from IBM

• WebLogic from BEA

• 9i Application Server from Oracle

• Jrun from Allaire

• iPlanet from Sun

• Tomcat from Apache

Java Servers or Engines

Apache and Tomcat

• Industrial strength Web server

• Tomcat is a servlet engine that can be plugged in with Apache

• Apache and Tomcat can be down loaded from http://jakarta.apache.org

• FREE!

Servlet vs. PHP

• PHP also free open source

• PHP consists of tags in HTML document

• Servlet is more widely supported

• Servlet is written in Java with extensive API for: database access distributed objects networking

Servlet vs. ASP

• ASP is a competing technology from Microsoft

• Servlet is portable to other operating systems web servers

• Servlet is more powerful for complex applications

• Better support for reusable components

Conclusion

• Java server and servlet are Economical Portable Powerful Secure

Thank You

Documents

Java Server and Servlet