Introduction Servlets and JSP Celsina Bignoli

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) –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 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 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

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 A JSP is converted into a Servlet

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(“ ”); out.println(“Today is: “); Date d = new Date(); out.println(“ ” + DateFormat.getInstance().format(d)+ “ ”); out.println(“ ”); } embedded HTML

JSP Example Static: HTML/XML elements Dynamic: scriptlets Additional: special JSP elements Example.jsp <% Date d=new Date(); String today = DateFormat.getInstance().format(d); %> Today is: HTML Scriptlet JSP tag

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 is a specification, not a product –competing implementations integral part of J2EE –access all features of the Java language

How to get Started Install JDK 5.0 Download Apache Tomcat 5.5 from: Use a regular editor or an IDE that supports JSP development –Eclipse –JBuilder –JCreator –Oracle JDeveloper –NetBeans –Macromedia DreamWeaver