1. 1 The Internet Programming Language Design and Implementation (4th Edition) by T. Pratt and M. Zelkowitz Prentice Hall, 2001 Section 12.2.2-12.2.4

2. 2 HTML FORMS A method for passing information between a user at a Web browser and a Web server. This information is passed to a program on the server system. This is the Common Gateway Interface (CGI) file. Web servers typically have a specific cgi-bin directory containing these CGI programs. HTML forms are used: <form method=“type” action= “location of cgi script to execute”> text Perl often used as language for such scripts

3. 3 CGI script example

4. 4 HTML for form cgi-test This is a sample page to read two data items from the web page: First name= Last name= Parameters passed as arguments xfirst and xlast

5. 5 Perl - CGI script #!/usr/bin/perl print “Content-Type: text/html\n\n”; print “ \n”; print “ Sample PERL script \n”; print “ \n”; print “ Query_string is $ENV{'QUERY_STRING'}\n”; foreach ( split( /&/, $ENV{'QUERY_STRING'}) ) { ( $key, $val ) = split( /=/, $_, 2 ); $tmp{$key} = $val; } print “ First name is $tmp{'xfirst'} \n”; print “ Last name is $tmp{'xlast'} \n”; print “ \n” Perl program first reads parameters as xfirst&zlast from $ENV (environment) into QUERY_STRING Output of Perl is the syntax of an HTML page that is displayed

6. 6 Java applets Issue: Many different protocols Solution: Send program to read protocol as part of HTML (Role for Java) Moves processing needs from HTML server to HTML cllient Do more processing on client side of web import java.awt.*; /* applet library */ public class hello extends java.applet.Applet public void paint(Graphics x) {x.drawString(“Hello World”, 100, 100);} Displayed by: