Java Server/Servlet

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Transcript Java Server/Servlet 

Java Server and Servlet
CS616 Team 9
Kim Doyle, Susan Kroha,
Arunima Palchowdhury, Wei Xu
Java Server and Servlet
• History
• What is a Java Server/Servlet
• Architecture
• Pros and Cons
• Existing Java Servers
• Conclusion
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
•Insecure
•Platform dependent
HTTP
HTML
•Inefficient
Web Server
CGI bin
Browser
Process
Database
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
HTTP
HTML
Web Server
Servlet Engine
Database
Browser
Servlets
Application
Business Log.
Demo and Servlet Life Cycle
Init()
Service ()
Servlet Engine
doGet ()
HttpResponse
doPost ()
Do… () HttpRequest
Destroy()
Application Server
link to Utopia
link to Laptop
PrintWriter
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
Project Group Assignment
Servlets in Action
HTTP
Algorithm
Tomcat
PANDA
Servlets
JDBC
link to Utopia
Link to Laptop
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
Java Servers or Engines
• WebSphere from IBM
• WebLogic from BEA
• 9i Application Server from Oracle
• Jrun from Allaire
• iPlanet from Sun
• Tomcat from Apache
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