Java Server and 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

HTML HTTP Web Server Database CGI bin Browser Process CGI Pros and Cons • 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

HTML HTTP Web Server Database Servlet Engine Browser Servlets Application Business Log. Server and Servlet Interaction

Demo and Servlet Life Cycle Servlet Engine Init() doGet () HttpResponse Service () PrintWriter doPost () HttpRequest Do… () Destroy() Application Server link to Utopia 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

HTTP Algorithm Tomcat PANDA Servlets JDBC Project Group Assignment Servlets in Action 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

Java Server and Servlet