SlideShare a Scribd company logo
1 of 126
www.oeclib.in
Submitted By:
Odisha Electronics Control Library
Seminar
On
Common Gateway Interface
CGI
Objective
 After the completion of this training,
participants will able to understand about
perl scripting and cgi programming aspects.
 Topics Covered:
 Introduction of CGI
The Definition
Web Browsing
Architecture of CGI
How does CGI works
Preparing CGI for work
2
Cont…
 Introduction to Perl
 The CGI.pm Module
 Pattern Matching
 Arrays
 Dealing With Files In PERL
 Basic HTML
 What is cgi-lib.pl?
 Communicating with databases
 Sending mail with Perl – CGI Scripts
3
Dynamic Web
4
 When the Web first started, there were only static
HTML pages.
 The internet had been around for some time already,
but it was only after the introduction of HTML.
 A lot has happened since then.
 We would like to place the birth of the dynamic web to
when CGI, Common Gateway Interface, was first
introduced in 1993.
 CGI was a way to let a website run scripts (usually Perl
scripts back then) on the web server and display the
output.
Cont…
5
CGI (Common Gateway Interface)
 A standard protocol for interfacing external
application software with an information server,
usually a web server.
 It is basically a set of rules used to describe
the way in which a web server communicates
with other software housed on the same
machine, and then how that software talks
back to the web server.
 What is returned from the CGI program is
based on what was requested, and this
information can be accessed and returned to
the user in many different ways.
6
Definition of CGI
 The Common Gateway Interface, or CGI, is a set of
standards that define how information is exchanged
between the web server and a custom script.
 CGI is a standard interface that sits between the web
browser and the web server.
 When the browser makes a request of the server, all
of the request details flow into the server through the
input interface of the CGI.
 When the server responds with its output, the
information flows back out through the output
interface of the CGI.
7
Cont…
 CGI programs can be written in any language.
 Perl is a very common language for CGI
programming as it is largely platform independent
and the language’s features make it very easy to write
powerful applications.
 However, some CGI programs are written in C, shell
script, or other languages.
 It is important to remember that CGI is not a
language in itself.
8
Some Things to Remember About CGI
9
 CGI is not the program itself.
 CGI is simply the interface between the Web page or
browser and the Web server that runs the program.
 You must have CGI access to run programs on your
Web page.
 Any program or script that will run on your Web
server, can be used as a CGI program.
 Most people use Perl to write their CGI scripts, but
other languages include C and C++, Tcl, and UNIX
shell scripts.
Uses of CGI Scripts
10
 CGI scripts are used to resolve form data, put that data
in to databases, send the data out as an email message,
respond to the form entry with email or another Web
page, and much more.
 CGI scripts also are used for behind the scenes
interaction with Web readers.
 They can set and read cookies, get and tabulate
information such as browser and operating system,
calculate hit counts, and monitor Web traffic.
Why Use CGI?
11
 Many of the uses of CGI can be duplicated by newer
technology such as JavaScript and ActiveX.
 The primary benefit to using CGI rather than browser based
scripting is that you can be sure that all of your readers (with
very few exceptions) will be able to use the program.
 Java, JavaScript, and ActiveX can all be turned off within the
browser, and many browsers simply don't support them.
 Also, it is becoming more common for company firewalls to
disallow these technologies to work in their system (often for
security or bandwidth reasons).
 Because CGI scripts are run on the external Web server, they
are not limited by browser or firewall limitations.
Why Not Use CGI?
12
 The biggest drawback to CGI Scripts is that they can put a lot
of load on a Web server.
 The Web browser will time out (usually after around 5
minutes), but often the server will continue to run the
program until a system administrator comes in and shuts off
the faulty script.
 The browser based scripting tools mentioned above have the
advantage of running off the reader's computer.
 They use the processor locally rather than on the Web server
itself, and so are less intense on the Web server.
Comparing Server-Side Web Languages
13
 Php - Probably currently most popular! But not a general purpose language.
 Perl - Older than Php. More difficult to use, but general purpose. Good
for general Unix system admin tasks.
 ASP.NET - Microsoft’s server-side language; commercial; platform
dependent.
 Python - Object oriented multi-purpose scripting language. Really good
for server-side tasks! But not that well known.
 Java Servlets - Java server-side programming, requires Apache Tomcat
engine or similar.
 JSP - Sun’s version of Java server-side programming.
Java Scripts And Other Web Technologies…
14
 Scripts come in many different formats such as JavaScript,
VBScript, ActiveX, Active Server Pages (ASP), Java Applets,
JavaBeans, CGI and others.
 JavaScript can do some things, however they have
limitations and can only work on the client-side.
 In other words, the scripts are interpreted and run in
the browser of the user.
 CGI scripts, on the other hand, will directly interact with
the server, where your whole web site resides, simply they
are server-side.
 Since it works from your server you can take control over
the scripts which are running by using other
server files (for example the sendmail program of Unix).
Cont…
15
 JavaScripts don't access any of your other files, (for
example you cannot access a database which is in your
server).
 JavaScripts are simply inserted into your HTML pages,
which can be run by the browser.
 Netscape browsers don't support VBScripts and ActiveX, so
are not usually used by the typical web user.
 Another technology like ASP can be used instead of CGI but
only in a Windows-NT server as UNIX servers do not
support them.
 Java applets can also be used, however speed can be a
problem so many users prefer CGI scripts.
Web Browsing
 To understand the concept of CGI, lets see what
happens when we click a hyper link to browse a
particular web page or URL.
 Your browser contacts the HTTP web server and demand for
the URL ie. filename.
 Web Server will parse the URL and will look for the filename in
if it finds that file then sends back to the browser otherwise
sends an error message indicating that you have requested a
wrong file.
 Web browser takes response from web server and displays
either the received file or error message.
16
CGI Architecture Diagram
17
How does CGI work?
CGI
1. HTTP
request
2. Call CGI
3. CGI
program’s
response
4. HTTP
response
User
Web
Browser
(on client)
Application
(on server)
Server
18
Introduction to CGI
(continued)
 CGI programs work as follows:
 STEP 1 (On the client side): Get Information from the user
(using HTML forms,, Java Applet, …,etc).
 STEP 2 (On the server side): Process the data, connect to
DATABASE, search for PATTERNS, …,etc.
 STEP 3 (On the server side): Send the result of computation
back to the client.
19
Preparing CGI for work
 The steps involved in preparing a CGI program
for work.
1. Contact your Web host to find out where you should
put your CGI programs on the server. Usually it will
be a directory on the server named “cgi-bin”.
2. Set up the access permission of directory “cgi-bin”
using the following UNIX command:
chmod 755 cgi-bin/
3. Set up the access permission of the CGI program
using the following UNIX command:
chmod 755 cgi-program
4. Test your CGI program from the server command
line to make sure it works perfectly before
publishing it.
20
History of Perl
 Perl was introduced in 1987
 reason for its creation was that Mr. Wall was
unhappy by the functionality that sed, C, awk and the
Bourne Shell offered him. He looked for a language
that will combine all of their best features, while
having as
few disadvantages
of its own.
21
Cont… A brief history of Perl
 Perl became especially popular as a language for
writing server-side scripts for web-servers.
 But that's not the only use of perl, as it is
commonly used for system administration tasks,
managing database data, as well as writing GUI
applications.
22
 written by Larry Wall
 A GNU product FREE, Open
Source software
 Interpreted and not compiled!
 Originally designed for UNIX®, but
is portable to other O/S
 stable, cross platform programming
language
Introduction
23
What does Perl stand for?
 ‘Perl’ isn’t really an acronym
 2 favorite expansion:
-- Practical Extraction Report Language
-- Pathologically Eclectic Rubbish Lister
 It's not PERL or P.E.R.L.
 'Perl' refers to the language
 'perl' to the interpreter that runs the programs
written in Perl
24
What is Perl and why is it so great?
 Perl is a stable, cross platform programming language.
 Perl stands for Practical Extraction and Report
Language.
 Perl is a general purpose computer language ideally
suited to handling words and text.
 The quote of Perl gurus, “It makes the easy things easy,
and the difficult things possible.”
 Perl's strengths is that there are usually many ways of
accomplishing any particular bit of programming.
 This strength inspires Perl programmers to quote the
motto "TIMTOWTDI" (pronounced "timtoady") - the
acronym of "There Is More Than One Way To Do It."
25
Perl Features
 Perl takes the best features from other languages,
such as C, awk, sed, sh, and BASIC, among others.
 Perls database integration interface (DBI) supports
third-party databases including Oracle, MySQL
and others.
 works with HTML, XML, and other mark-up
languages.
26
Cont… Perl Features
 supports Unicode.
 supports both procedural and OO programming.
 extensible.
 The Perl interpreter can be embedded into other
systems.
27
Perl & the Web
 Perl is the most popular web programming
language due to its text manipulation capabilities
and rapid development cycle.
 Perl is widely known as "the duct-tape of the
Internet".
 Perl's CGI.pm module, part of Perl's standard
distribution, makes handling HTML forms simple.
 Perl can handle encrypted Web data, including e-
commerce transactions.
28
Cont… Perl and the Web
 Perl can be embedded into web servers to speed up
processing by as much as 2000%.
 mod_perl allows the Apache web server to embed a
Perl interpreter.
 Perl's DBI package makes web-database integration
easy.
mod_perl is an optional module for the Apache HTTP server. It
embeds a Perl interpreter into the Apache server, so that dynamic
content produced by Perl scripts can be served in response to incoming
requests, without the significant overhead of re-launching the Perl
interpreter for each request.
29
What is needed to run Perl CGI programs?
 There are several things you need in order to
create and run Perl CGI programs.
 a web server
 web server configuration which gives you
permission to run CGI
 a Perl interpreter
 appropriate Perl modules, such as CGI.pm
 a shell account is extremely useful but not
essential
30
Setting up Perl/CGI
 First, you need to get Perl if you do not already have
it installed.
 Go
to http://www.activestate.com/Products/ActivePerl/
Download.html and download the latest release for
Windows.
 Next, you need a Web server.
 http://httpd.apache.org/download.cgi
 Scroll down to locate Win32 Binary without
crypto (no mod_ssl) (MSI Installer).
http://www.webdevelopersnotes.com/how-do-i/install-apache-windows-7.php
31
First CGI Program
 #!C:Perlbinperl.exe
 use CGI;
 print "Content-Type: text/htmlnn";
 print "<HTML>n";
 print "<HEAD>n";
 print "<TITLE>Hello World</TITLE>n";
 print "</HEAD>n";
 print "<BODY>n";
 print "<H4>Hello World</H4>n";
 print "<P>n";
 print "Your IP Address is $ENV{REMOTE_ADDR}.n";
 print "<P>";
 print "<H5>Have a nice day</H5>n";
 print "</BODY>n";
 print "</HTML>n";
32
Explanation
 The first line of your program should look like this:
 #!C:Perlbinperl -wT
 The first part of this line, #!, indicates that this is a script. The next
part, C:Perlbinperl.exe, is the location (or path) of the Perl
interpreter.
 The final part contains optional flags for the Perl interpreter.
Warnings are enabled by the -w flag. Special user input taint
checking is enabled by the -T flag. Taint mode tells Perl to keep track
of data that comes from the user and avoid doing anything insecure
with it.
 print "Content-type: text/htmlnn";
 This is a content-type header that tells the receiving web browser
what sort of data it is about to receive — in this case, an HTML
document. If you forget to include it, or if you print something else
before printing this header, you'll get an "Internal Server Error"
when you try to access the CGI program.
33
Introduction to PERL
 To run PERL programs:
 On UNIX, type the command from UNIX shell:
perl perl_prog.pl
 On Windows, type the command from DOS prompt:
perl perl_prog.pl
 PERL is a case-sensitive language just like C
or Java.
 “#”sign is used for comments in PERL
 Example:
#!/usr/bin/perl
# This program is to . . .
34
Programming Standards
 The following coding standards should be followed:
 Start the program with a header comment giving info about
the PERL path, programmer, copyrights, last modified date,
and description.
 Example:
#!/usr/bin/perl
######################################
# Girish Srivastava
# Copyrights © 2001
# All rights reserved.
#
# Last modified 9/16/2001
# This program is to . . .
######################################
35
Programming Standards
(Continued)
 Use three-line-comment style. Example:
#
# Incrementing variable $count.
#
$count++;
 Use meaningful names for variables or
subroutines. Capitalize every word except the first
one. Example:
$myBuffer=1;
sub printThankYouMessage(){
…}
36
PERL Data Types
 PERL has three built-in data types: scalars, arrays of
scalars, and associative arrays of scalars, known as
"hashes".
 Scalar Variables
 A scalar may contain one single value in any of three
different flavors: a number, a string, or a reference.
 Scalar values are always named with '$‘ at the beginning,
even when referring to a scalar that is part of an array or a
hash. Examples:
$day #A simple scalar value "day"
$day[28] #the 29th element of @day
$day{'Feb'} #The 'Feb' value from %day
37
PERL Data Type
(Continued)
 Array Variables
 An array is basically a way to store a whole bunch of scalar
values under one name.
 An array name begins with an "@" symbol. Examples:
@arrayName = ("element1", "element2");
@browser = ("NS", "IE", "Opera");
@one_two_thre = (1, 2, 3);
 To access a single element is an array, use a $+array
name+[ + index+]. Array indexing starts form zero.
Examples:
$arrayName[0] # the first element of the
# array
$browser[1] # This will return ‘IE’.
38
PERL Data Type
(Continued)
 Associative Arrays “Hashes”
 Associative arrays are created with a set of key/value
pairs. A key is a text string of your choice that will
help you remember the value later.
 A hash name begins with % sign. Examples:
%hashName = ('key1', 'value1', 'key2',
'value2');
%ourFriends = ('best', 'Don', 'good', 'Robert',
'worst', 'Joe');
 To access an element, use $+hash name+{+key+}.
Examples:
$hashName{‘key1’} #This will return value1
$ourFriends{'good'} #This will return
#‘Robert’
39
Example
 #!C:Perlbinperl.exe
 my $text = 'cool guy';
 my $string = "some $text";
 print $string; # prints literally “some cool guy”;
Arrays
#!C:Perlbinperl -w
#DEFINE SOME ARRAYS
@days = ("Monday", "Tuesday", "Wednesday");
@months = ("April", "May", "June");
#PRINT MY ARRAYS TO THE BROWSER
print @days;
print @months;
Hashes
#!C:Perlbinperl -w
#DEFINE SOME HASHES
%hashName = ('key1', 'value1', 'key2', 'value2');
%ourFriends = ('best', 'Don', 'good', 'Robert', 'worst',
'Joe');
#PRINT MY HASHES TO THE BROWSER
print $hashName{'key1'};
print $ourFriends{'good'};
40
Operators
 PERL uses:
 Arithmetic operations: +, -, *, /, %,**.
 Relational operations: <, >, <=, >=, ==.
 String Operations: eq, ne, lt, gt, le, ge.
 Assignment Operators: =, +=, -+, *=, /=, .=.
 Increment/decrement operators: ++, --.
 Boolean operations: &&, ||, !.
 Quotation marks:
 ”” character string with variable interpolation.
 ’’ character string without variable interpolation.
41
#!C:Perlbinperl.exe
$one = 1;
$two = 2;
$three = 3;
$four = 4;
$abcd = "abcd";
$pqrs = "pqrs";
$xyz = "xyz";
# concantenate the two strings and print
print $abcd . " another stringn";
# repeat the string abcd three times
print $abcd x $three . "n";
# add the data in variables one and two.
The numerical value is converted to string
and concantenated with n
print $one + $two . "n";
print $three % $two . "n";
# modulo - returns the remainder of three
divided by two
print $three ** $two . "n";
# exponentiation - three raised to power
two
print $one++ . "n";
# post increment
print ++$one . "n";
# pre increment
print $one-- . "n";
# post decrement
print --$one . "n";
# pre decrement
$one += $two;
# $one = $one + $two
$one -= $two;
# $one = $one - $two
Control Structures
 Control structures include conditional statements,
such as if/elsif/else blocks, as well as loops
like foreach, for and while.
 if ($varname > 23) { # do stuff here if the condition is true }
 if ($varname > 23) {
 print "$varname is greater than 23";
 } elsif ($varname == 23) {
 print "$varname is 23";
 } else {
 print "$varname is less than 23"; }
42
#!C:Perlbinperl.exe
my $number = 95;
if($number eq 92)
{
print 'Number is ninety-five!';
}
else
{
print 'Number is not ninety-five';
}
Unless
 unless is similar to if. Let's say you wanted to execute code
only if a certain condition were false. You could do
something like this:
 if ($varname != 23) { # code to execute if $varname is not 23 }
 The same test can be done using unless:
 unless ($varname == 23) { # code to execute if $varname is not 23 }
 There is no "elseunless", but you can use an else clause:
 unless ($varname == 23) {
 # code to execute if $varname is not 23 }
 else {
 # code to execute if $varname IS 23
 }
43
Looping
 Loops allow you to repeat code for as long as a condition is met. Perl
has several loop control structures: foreach, for, while and until.
 Foreach Loops
 foreach iterates through a list of values:
 foreach my $i (@arrayname) {
 # code here
 }
 This loops through each element of @arrayname, setting $i to the
current array element for each pass through the loop. You may omit the
loop variable $i:
 foreach (@arrayname) {
 # $_ is the current array element
 }
 This sets the special Perl variable $_ to each array element. $_ does not
need to be declared (it's part of the Perl language) and its scope
localized to the loop itself.
44
Cont…
 For Loops
 Perl also supports C-style for loops:
 for ($i = 1; $i < 23; $i++) {
 # code here
 }
 While Loops
 A while loop executes as long as particular condition is true:
 while (condition) {
 # code to run as long as condition is true
 }
 Until Loops
 until is the reverse of while. It executes as long as a particular condition is
NOT true:
 until (condition) {
 # code to run as long as condition is not true
 }
45
#!C:Perlbinperl.exe
@array = ("value1", "value2", 1, 2, 3, 4);
foreach my $value (@array)
{
print $value;
}
#!C:Perlbinperl.exe
$integer = 0;
while($integer < 50)
{
print $integer;
$integer++;
}
Until
#!C:Perlbinperl.exe
$firstVar = 10;
until ($firstVar > 12)
{
print("inside: firstVar = $firstVarn");
$firstVar++;
}
print("outside: firstVar = $firstVarn");
This program displays:
inside: firstVar = 10
inside: firstVar = 11
inside: firstVar = 12
outside: firstVar = 13
Exercise
46
1. Create a program using PERL, which gives the output
as per the following figure:
*
* *
* * *
* * * *
* * * * *
Breaking from Loops
 There are several ways to break from a loop. To stop the current loop
iteration (and move on to the next one), use the next command:
 foreach my $i (1..20) {
 if ($i == 13) {
 next;
 }
 print "$in";
 }
 This example prints the numbers from 1 to 20, except for the number 13.
When it reaches 13, it skips to the next iteration of the loop.
 To break out of a loop entirely, use the last command:
 foreach my $i (1..20) {
 if ($i == 13) {
 last;
 }
 print "$in"; }
 This example prints the numbers from 1 to 12, then terminates the loop
when it reaches 13.
47
Cont…
 next and last only effect the innermost loop structure, so if you have
something like this:
 foreach my $i (@list1) {
 foreach my $j (@list2) {
 if ($i == 5 && $j == 23) {
 last; }
 } # this is where that last sends you
 }
 The last command only terminates the innermost loop. If you want to
break out of the outer loop, you need to use loop labels:
 OUTER: foreach my $i (@list1) {
 INNER: foreach my $j (@list2) {
 if ($i == 5 && $j == 23) {
 last OUTER; }
 }
 } # this is where that last sends you
 The loop label is a string that appears before the loop command (foreach,
for, or while). In this example we used OUTER as the label for the outer
foreach loop and INNER for the inner loop label.
48
The CGI.pm Module
 Perl offers a powerful feature to programmers: add-on
modules.
 These are collections of pre-written code that you can
use to do all kinds of tasks.
 Some modules are included as part of the Perl
distribution; these are called standard library
modules and don't have to be installed. If you have
Perl, you already have the standard library modules.
49
Cont…
 Let's see how to use a module in your CGI program. First
you have to actually include the module via the use
command. This goes after the #!C:Perlbinperl.exe line
and before any other code:
 use CGI qw(:standard);
 Note :we're not doing use CGI.pm but rather use CGI.
The .pm is implied in the use statement.
The qw(:standard) part of this line indicates that we're
importing the "standard" set of functions from CGI.pm.
 Now you can call the various module functions by typing
the function name followed by any arguments:
 functionname(arguments)
50
Cont…
 A function is a piece of code that performs a specific
task; it may also be called a subroutine or a method.
 Functions may accept optional arguments (also
called parameters), which are values (strings,
numbers, and other variables) passed into the function
for it to use.
 The CGI.pm module has many functions; for now we'll
start by using these three:
 header;
 start_html;
 end_html;
51
Cont…
 The header function prints out the "Content-type"
header. With no arguments, the type is assumed to be
"text/html".
 start_html prints out the <html>, <head>, <title> and
<body> tags. It also accepts optional arguments. If you
call start_html with only a single string argument, it's
assumed to be the page title. For example:
 print start_html("Hello World");
 will print out the following*:
 <html>
 <head> <title>Hello World</title>
 <head>
 <body>
52
Cont…
 The end_html function prints out the closing HTML
tags:
 </body>
 </html>
 #!C:Perlbinperl.exe
 use CGI qw(:standard);
 print header;
 print start_html("Hello World");
 print "<h2>Hello, world!</h2>n";
 print end_html;
53
Basic HTML
 HyperText Markup Language
 HTML is the language used to prepare hypertext
document.
 Web browsers are used to view HTML documents
and display data to users
54
HTML Document
<html>
<head><title>Test Page</title></head>
<body>
<b>Hello, world</b>
</body>
</html>
Document Structure
- Head
- Body
55
HTML Tags
 HTML tags are commands, they tell the browser how
to display the text.
 There are opening and closing versions for many tags
opening tag: <HTML>
closing tag: </HTML>
56
HTML Tags (continued)
 <HTML></HTML> For identifying a text document as an HTML
document
 <HEAD></HEAD> For creating the head section of page
 <BODY></BODY> For enclosing the main section of page
 <B></B> For displaying text in boldface
 <I></I> For displaying text in italics
 <OL></OL> For creating ordered lists
 <A></A> For creating links
 <FORM></FORM> For creating fill-in forms
 <P> For creating a new paragraph
 <BR> For creating a line break
 <INPUT> For creating form elements
57
HTML Tags (continued)
The affected text is contained within the tags
 <B>Hello</B> ------- Hello
 <I>Bye!</I> ---------- Bye
 Ordered list
<OL>
<LI>Apple</LI>
<LI>Banana</LI>
<LI>Orange</LI>
</OL>
1. Apple
2. Banana
3. Orange
58
HTML Form
 <FORM> and </FORM> mark the beginning and
the end of a form
 Form establishes the relationship between the
form page and the script that will process the
current form data
 HTML forms are the user interface that provides
input to your CGI scripts
- Collecting data
- Accepting commands
59
HTML Form (continued)
<HTML><HEAD>
<TITLE>My first html page</TITLE></HEAD>
<BODY>
<FORM method=post action=“aftersubmit.cgi”>
Name: <INPUT type=text name=“uname"><BR>
Password: <INPUT type=password
name=“upwd"><BR>
<INPUT type=submit>
<INPUT type=reset>
</FORM>
</BODY></HTML>
60
The <FORM> Tag
 <FORM method=post action=“aftersubmit.cgi”>
Tag attributes specify the properties for the element
 Method determines how the form data is sent to the
script
- GET-- delivers form data by appending it to
the URL of the script
- POST-- sends the data as a body of text
 action
specifies the address of the script that is going to
process the current form data
61
The <INPUT> Tags
 INPUT
- is an element of the form
- creates a wide variety of interface widgets
 <INPUT type=text name=“uname">
 Attribute “type”— the appearance and features
<INPUT type=text>-------text field
<INPUT type=submit>-----submit button
<INPUT type=reset>------reset button
<INPUT type=password>---password field
<INPUT type=hidden>-----hidden field
62
The <INPUT> Tag (continued)
 INPUT attribute "name"
identifies each user interface element
<input type=text name=“uname">
<input type=password name=“upwd">
 INPUT attribute "value"
contains associated information that is also sent to
the script.
<input type=text name=“uname">
<input type=text name=“uadd">
<input type=text name=“ucity“
value=“Edmonton”>
63
Form Submission
<FORM method=post action = “aftersubmit.cgi”>
 The browser assembles the form data (name and
password) into a series of name/value pairs
 The browser delivers data to the server and then
the script
“aftersubmit.cgi”
 The script “aftersubmit.cgi” can retrieve the
element value by using its name (uname and
upwd)
64
Forms: Checkbox
 Checkboxes allow the viewer to select one or more options on a form. If
you assign each checkbox field a different name, you can print them the
same way you'd print any form field using param('fieldname').
 Here is the HTML code for a set of checkboxes:
 <b>Pick a Color:</b><br>
 <form action="colors.cgi" method="POST">
 <input type="checkbox" name="red" value=1> Red<br>
 <input type="checkbox" name="green" value=1> Green<br>
 <input type="checkbox" name="blue" value=1> Blue<br>
 <input type="checkbox" name="gold" value=1> Gold<br>
 <input type="submit"> </form>
 This example lets the visitor pick as many options as they want — or none,
if they prefer. Since this example uses a different field name for each
checkbox, you can test it using param:
 my @colors = ("red","green","blue","gold");
 foreach my $color (@colors) {
 if (param($color)) {
 print "You picked $color.n"; } }
65
Cont…
 Since we set the value of each checkbox to 1 (a true value), we didn't need
to actually see if param($color) was equal to anything — if the box is
checked, its true. If it's not checked, then param($color) is undefined and
therefore not true.
 The other way you could code this form is to set each checkbox name to
the same name, and use a different value for each checkbox:
 <b>Pick a Color:</b><br>
 <form action="colors.cgi" method="POST">
 <input type="checkbox" name="color" value="red"> Red<br>
 <input type="checkbox" name="color" value="green"> Green<br>
 <input type="checkbox" name="color" value="blue"> Blue<br>
 <input type="checkbox" name="color" value="gold"> Gold<br>
 <input type="submit"> </form>
66
Cont…
 param('color') returns a list of the selected
checkboxes, which you can then store in an array.
Here is how you'd use it in your CGI program:
 my @colors = param('color');
 foreach my $color (@colors)
 {
 print "You picked $color.<br>n";
 }
67
Radiobutton
 <b>Pick a Color:</b><br>
 <form action="colors.cgi" method="POST">
 <input type="radio" name="color" value="red"> Red<br>
 <input type="radio" name="color" value="green"> Green<br>
 <input type="radio" name="color" value="blue"> Blue<br>
 <input type="radio" name="color" value="gold"> Gold<br>
 <input type="submit"> </form>
 Cgi code:
 Since the viewer can only choose one item from a set
of radio buttons, param('color') will be the color that
was picked:
 my $color = param('color');
 print "You picked $color.<br>n";
68
Basic Setup
 That's the basic set up for a CGI form, but what
happens after the user presses Submit? Consider, for
example, this simple form:
 Name:
E-mail:
 SUBMIT
 Here's the chain of events when the user hits
"Submit":
69
Cont…
70
Cont…
 When the user presses Submit, the browser sends the form data
to the web server.
 The web server launches the CGI program which was written to
process this form.
 The CGI program does whatever it does with the data. The
program might consult a database, perform calculations on the
data, use the data to add the user to a mailing list, whatever the
programmer wants it to do. Whatever else the program does, it
generates a web page using HTML so the user can see the results
of submitting the form.
 The CGI program passes the HTML back to the web server.
 The web server passes the HTML back to the browser.
 So there are three pieces to the CGI process: the form
on your web page, the web server, and the CGI
program.
71
Exercise
72
Exercise
73
 Create an html form having multiple radio buttons
showing different different colors. If you select any of
the radio button and press submit, then it will call
appropriate cgi page and the background color of
that page will be same as the color which you have
selected from the list.
Pattern Matching
 Almost every script you write in Perl will have some
kind of pattern matching operation .
 Patterns are subject to an additional level of
interpretation as a regular expression. This is done
as a second pass, after variables are interpolated.
 To use pattern matching in Perl, first we figure out
what we want to find, we write a regular expression
to find it, and then we stick that pattern in a
situation where the result of finding.
74
Cont…
 The Binding Operator
 When you do a pattern match, you need three things:
 the text you are searching through
 the pattern you are looking for
 a way of linking the pattern with the searched text
 As a simple example, let's say you want to see whether a string
variable has the value of "success". Here's how you could write
the problem in Perl:
 $word = "success";
 if ( $word =~ m/success/ ) {
 print "Found successn";
 } else {
 print "Did not find successn"; }
75
Cont…
 There are two things to note here.
 First, the "=~" construct, called the binding operator, is what
binds the string being searched with the pattern that specifies
the search. The binding operator links these two together and
causes the search to take place.
 Next, the "m/success/" construct is the matching
operator, m//, in action. The "m" stands for
matching to make it easy to remember. The slash
characters here are the "delimiters". They
surround the specified pattern. In m/success/, the
matching operator is looking for a match of the
letter sequence: success.
 Generally, the value of the matching statement returns 1 if
there was a match, and 0 if there wasn't.
76
Regular Expressions
 Regular expressions are very powerful tools for matching,
searching, and replacing text.
 All pattern matching in Perl is based on this concept of
regular expressions.
 Regular expressions form a standard way of expressing
almost any text pattern unambiguously.
 Special Characters
 Some special characters or combinations of characters have a
special meaning and do not represent themselves.
 This is what give regular expressions their power.
 For example, the lowly period does not stand for a period in a
match. Instead, it stands for any character.
77
Cont…
 The pattern /b.g/ would match "bag", "big", "bug",
etc, as well as any other sequence: "b2g", "b&g",
"b]g" and so on.
 Matching simply means "found somewhere,
anywhere, within the searched string".
 You can use special characters to specify the position
where the search pattern must be located.
 A ^ character stands for the beginning of the searched string, so:
 /^success/ would match "success" but not "unsuccessful".
 A $ character stands for the end of the searched string, so:
 /success$/ would match "unsuccess" but not "successful".
 Using both ^ and $ together nails the pattern down at both ends, so:
 /^success$/ will only match the exact string "success".
78
Cont…
 Other special characters include:
  - a form of a "quote" character
| - alternation, used for "or'ing"
() - grouping matched elements
[] - character class
 The first character, "", is used in combination with
special letters to take away their special meaning.
E.g.:
 . will match a period
$ will match a dollar sign
^ will match a caret
 will match a backslash
 and so on.
79
Cont…
 Repetition Characters
 The expressions above show you how to match
certain characters, but they don't allow you to
control how many matches should be made at once.
Matching repetition is controlled by a few other
special characters:
 + means 1 or more matches
* means 0 or more matches
? means 0 or 1 matches
{n} exactly n matches
{m,n} m to n matches
80
"Hello world!" to be changed to "Hello mom!"
instead.
 $mystring =~ s/world/mom/;
 print $mystring;
 Prints "Hello mom!". The substitution operator s/// replaces the pattern
between the s/ and the middle /, with the pattern between the
middle / and last /. In this case, "world" is replaced with the word "mom".
 Now change "Hello mom!" to say "Goodby mom!".
 $mystring =~ s/hello/Goodbye/;
 print $mystring;
 This does not substitute, and prints "Hello mom!" as before. By default,
the search is case sensitive. As before, use the pattern
modifier i immediately after the trailing / to make the search case-
insensitive.
 Okay, ignoring case, change "Hello mom!" to say "Goodby
mom!".
 $mystring =~ s/hello/Goodbye/i;
 print $mystring;
 Prints "Goodby mom!".
81
Process form with regular expression: first name
and last name
82
 <html>
<head>
<title>form page</title>
</head>
<body>
<p>here's my test form</p>
<form method = "post" action = "/cgi-bin/RegExpExample.cgi">
<p>First name:
<input name = "firstName" type = "text" size = "20"></p>
<p>Last name:
<input name = "lastName" type = "text" size = "20"></p>
<p>Phone number:
<input name = "phone" type = "text" size = "20"></p>
<p>Date (MM/DD/YY):
<input name = "date" type = "text" size = "20"></p>
<p>Time (HH:MM:SS):
<input name = "time" type = "text" size = "20"></p>
<input type = "submit" value = "submit">
<input type = "reset" value = "reset">
</form>
</body>
</html>
Cont…
83
 #!C:Perlbinperl.exe
 use strict;
 use warnings;
 use CGI ':standard';
 my $firstName = param( "firstName" );
 my $lastName = param( "lastName" );
 my $phone = param( "phone" );
 my $date = param( "date" );
 my $time = param( "time" );
 print header();
 print start_html( -title => "form page" );
 if ( $firstName =~ /^w+$/ ) {
 print "<p>Hello there Lu$firstName.</p>";
 }
 if ( $lastName =~ /^w+$/ ) {
 print "<p>Hello there Mr./Ms. Lu$lastName.</p>";
 }
 print end_html();
Arrays
 An array stores an ordered list of values. While a
scalar variable can only store one value, an array can
store many. Perl array names are prefixed with an
@-sign. Here is an example:
 my @colors = ("red","green","blue");
 Each individual item (or element) of an array may be
referred to by its index number. Array indices start
with 0, so to access the first element of the array
@colors, you use $colors[0].
 when you're referring to a single element of an array,
you prefix the name with $ instead of @. The $-sign
again indicates that it's a single (scalar) value; the @-
sign means you're talking about the entire array.
84
Cont…
 If you want to loop through an array, printing out all
of the values, you could print each element one at a
time:
 my @colors = ("red","green","blue");
 print "$colors[0]n"; # prints "red"
 print "$colors[1]n"; # prints "green"
 print "$colors[2]n"; # prints "blue"
 A much easier way to do this is to use a foreach loop:
 my @colors = ("red","green","blue");
 foreach my $i (@colors)
 {
 print "$in";}
85
Finding the Length of Arrays
 If you want to find out how many elements are in a
given array, you can use the scalar function:
 my @people = ("Howard", "Sara", "Ken", "Josh");
 my $linelen = scalar(@people);
 print "There are $linelen people in line.n";
 Sorting Arrays
 You can do an alphabetical (ASCII) sort on an array
of strings using the sort function:
 my @colors = ("cyan", "magenta", "yellow", "black");
 my @colors2 = sort(@colors);
86
Dealing With HTML Components in perl-cgi
87
 We can create html form component like: textbox, textarea,
buttons, etc, in CGI.
 use strict;
use warnings;
use CGI;
my $cgi=new CGI;
print $cgi->header(),$cgi-
>start_html("Simple Examples");
print $cgi->center("Centered Text");
print $cgi->p("A Paragraph");
print $cgi->br();
print $cgi->b("Bold"),$cgi->i("Italic");
print $cgi->p("A Paragraph",$cgi->sup("A superscript"));
print $cgi->end_html();
Form Example
88
 use CGI;
$co = new CGI;
print $co->header,
$co->start_html(-title=>'CGI Example'),
$co->center($co->h1('Welcome to CGI!')),
$co->start_form(),
$co->textarea
(
-name=>'textarea',
-rows=>10,
-columns=>60
),
$co->end_form(),
$co->end_html;
#!C:Perlbinperl
use CGI ':standard';
print header();
print "Form Elements", br(), br(), br();
print start_form;
print "A Text Box: &nbsp; &nbsp; &nbsp; ", textfield('surname', 'Default', 50), br();
print "A Select Box: &nbsp; &nbsp; &nbsp; ", popup_menu('SelectBox', ['Perl', 'Web',
'Development']);
print p, "Text Area: &nbsp; &nbsp; &nbsp;", textarea('comments', 'Default Text', 10,
50);
print p, "CheckBoxes: ", checkbox_group('check1', ['one', 'two', 'three']);
print p, "Radio Buttons: ", radio_group('radio1', ['a', 'b', 'c']);
print p, submit();
print end_form;
if (param())
{
print "The surname you entered was: ",em(param('surname')),
p, "The Selections are: ",em(join(", ",param('SelectBox'))),
p, "The comments box contains: ",em(param('comments')),
p, "you selected checkbox: ",em(param('check1')),
p, "you selected radio: ",em(param('radio1'));
}
Dealing With Files In PERL
 Reading Files:
 STEP 1: Open the file for reading:
open(DFH, “data.txt") || die (“Can’t Open
file”);
 STEP 2: Read the data from the file:
@rawData = <DFH>;
 STEP 3: Close the file:
close(DFH);
89
Dealing With Files In PERL
(Continued)
 Writing to files:
 STEP 1: Open the file for writing:
open(DFH, “>data.txt") || die (“Cannot Open
file”);
 STEP 2: Write data to the file:
print DFH “New Data”;
 STEP 3: Close the file:
close(DFH);
90
Dealing With Files In PERL
(Continued)
 Appending Files:
 STEP 1: Open the file for appending:
open(DFH, “>>data.txt") || die (“Cannot Open
file”);
 STEP 2: Write data at the end of the file:
print DFH “Another data line”;
 STEP 3: Close the file:
close(DFH);
91
Reading Data File
 When you build large web application, you will
need to store data and retrieve it later
 Text files are the simplest way to maintain data
92
Reading And Writing Data File (script)
#!C:Perlbinperl.exe
open(SRC, “file.txt”) || die “Could not open source
file.n”;
open(DST, “>newfile.txt”);
while ( $line = <SRC> )
{
print DST $line;
}
close SRC;
close DST;
93
File Handle
 The file handles are just the things we use when we
are dealing with files.
 A file handle is associated with a file by the open
statement.
open (FILE, $filename)
 All the interaction with a file is done by the file
handle.
@filecontent = <FILE> -- get the whole file
$filecontent = <FILE> ---- get the first line
94
Writing Data File
#!C:Perlbinperl.exe
use CGI;
$q=new CGI;
print "Content-type: text/htmlnn";
my $name=$q->param("name");
my $outputfile="users.txt";
if (open (OUTPUT, ">>$outputfile")) # open a file
{
print OUTPUT "$namen"; # write the user name to
the file
print "<HTML><BODY>Thank you!
$name</BODY></HTML>";
}
95
<html>
<head>
</head>
<body>
<form action="/cgi-bin/FileRead_Html.cgi"
method="post">
<input type="text" name="name">
<input type="submit" name="submit" value="Go">
</form>
</body>
</html>
Writing Data File (continued)
 Opening a file for writing
- For overwriting
open (OUTPUT, ">>$outputfile")
- For appending
open (OUTPUT, ">$outputfile")
 Without “>>” and “>”, the file is opened for reading
open (OUTPUT, "$outputfile")
 Creating the output file and making it writable
touch users.txt
chmod a+w users.txt
96
Exercise
97
 Create a login page using perl-cgi script, read the user name
and password from existing .txt file. After pressing the
submit button it should show the Message of successful or
unsuccessful login.
 Write a Perl script that will take as input a file called
“foo.txt”, produce as output a file called “bar.txt”; lines in
input will be copied to output, except for the following
transformations:
 any line with the string “IgNore” in it will not go to output
 any line with the string “#” in it will have that character and all
characters after it, to end of line, removed
 any string “*DATE*” will be replaced by the current date in output
•We have a file containing lines in different formats.
We want to pick out the lines which start with a digit and
end in a period.
Debugging
 Default response of the server:
"Internal Server Error" --- not useful
 Better ways:
In the script
use CGI::Carp qw(fatalsToBrowser);
In the UNIX shell (check the syntax)
perl -cw scriptname.cgi
98
see the error in your browser
instead of the error logs
If you want to do a similar thing with Perl warnings as well,
use this instead:
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
Debugging (continued)
 use CGI::Carp qw(fatalsToBrowser);
99
What is cgi-lib.pl?
 Cgi-lib is a CGI parsing library written by Steven Brenner.
 The cgi-lib.pl library that was become the first standard perl library to
help parse and deal with CGI Web based interfaces.
 The cgi-lib.pl library makes CGI scripting in Perl easy enough for anyone to
process forms and create dynamic Web content. The library has the
following features:
 Extremely simple to learn and easy to use
 Designed for operation under Perl5 and Perl4
 Very efficient
 Compatibility with all CGI interactions
 Compatible with Perl5 security features such as taint, warnings, (command
line options -Tw) and use strict;
 Debugging facilities
100
Cont…
 The cgi-lib.pl Perl library simply consists of handy, easy-to-
use Perl functions. The library is more than simply a means
of processing CGI input. The library includes subroutines to:
 Read and parse CGI input -- a value(s) for a given name can
be easily found.
 Conveniently format CGI output.
 Conveniently return Headers and Bottoms of standard CGI output.
 Conveniently return URLs.
 Conveniently return CGI Error Codes.
 Print in HTML format all name/value pairs input.
 Print in HTML format Environment variables.
 The cgi-lib.pl input routines can accept all and process all
methods of input (e.g. GET and POST methods). You do not
have to worry about which mechanism has been adopted.
101
A Sample Form Response CGI Perl Script
 In this subsection we will develop a minimal.pl CGI routine that accepts
input form our minimal form and sends back HTML that echoes the input
data.
 We will use the cgi-lib.pl to
 Parse the input from the form.
 Format the HTML output.
 We will need to learn some more basic Perl:
 How to include and call Perl libraries.
 How to call Perl subroutines
 The first thing our Perl script will need to do is to include the Perl library
file cgi-lib.pl.
 The Perl command require will load in any external Perl file. It is easier and
sometimes essential that all library files exist in the same folder or directory
as the main Perl script calling the library.
 Therefore make sure that all Perl files required for a Perl program do exist
at the same folder or directory level.
102
Cont…
 Thus to include our cgi-lib.pl file we need the Perl command:
 require "cgi-lib.pl";
 Having included the library we can call on its many useful subroutines.
 The &ReadParse() subroutine reads either GET or POST input and
conveniently stores the name/value pairs in a Perl array.
 Thus a Perl call of the form:
 &ReadParse(*input);
 will store the input in an array input.
 & is used to indicate a Perl subroutine call.
 Next we will need to extract out the relevant value of a given name.
 In our current example there is only one input field and we are therefore
only interested in the value associated with the myfield name.
 To get this value you simply do: $input{'myfield'}
 Thus to print out the value typed we could do something like:
 print "You typed: " . $input{'myfield'} . "n";
103
http://stein.cshl.org/WWW/CGI/cgi-lib_porting.html
A first minimal Perl script
 minimalExample.html
 <html>
 <head><title>Sample Example</title></head>
 <body bgcolor="white"><form method="post"
 action="/cgi-bin/minimal.cgi">
 Please enter your name:<br>
 <input type="text" name="myfield" size="35"><br>
 <input type="submit" value="Send">
 <input type="reset" value="Reset">
 </form>
 </body>
 </html>
Minimal.cgi
#!C:Perlbinperl
# This is the minimalist form script
# to demonstrate the use of
# the cgi-lib.pl library
require "cgi-lib.pl";
# Read in all the variables set by the form
&ReadParse(*input);
print "Content-Type: text/htmlnn";
print "<html> <head>n";
print "<title>Sample Input</title>n";
print "</head>n";
print "<body>n";
print "You typed: " . $input{'myfield'} . "n";
print "</body> </html>n";
104
A second minimal Perl script
 some more cgi-lib.pl subroutines:
 Nearly every CGI output has:
 exactly the same header output.
 similar HTML head information
 similar HTML ending
 Fortunately subroutines exist to save us typing this same
information all the time.
 The &PrintHeader subroutine returns the string:
 Content-Type: text/htmlnn
 Thus we can use print in conjunction to produce our CGI header
output via:
 print &PrintHeader;
105
Cont..
 The &HtmlTop subroutine accepts a single string
argument, MY TITLE say, and return an HTML Head and Body
(opening only) with the argument as the HTML
page TITLE and H1 Header. I.e.
 <html>
 <head>
 <title>MY TITLE</title>
 </head>
 <body>
 <h1>MY TITLE</h1>
 which is rather useful.
 The &HtmlBot subroutine is the compliment of &HtmlTop and
returns:
 </body>
 </html>
106
Cont…
 Thus we can use these functions and we only need to provide the main HTML
body ourselves.
 Thus we develop a better minimal.cgi program as follows
 #!C:Perlbinperl
 # minimal.cgi
 # This is the minimalist form script
 # to demonstrate the use of
 # the cgi-lib.pl library
 require "cgi-lib.pl";
 # Read in all the variables set by the form
 &ReadParse(*input);
 # Print the header + html top
 print &PrintHeader;
 print &HtmlTop ("Minimal Input");

 print "You typed: " . $input{'myfield'} . "n";
 print &HtmlBot;
107
Installing and Using MySQL
 In order to successfully connect to a MySQL database with Perl, you will
first need to ensure that the MySQL drivers are installed on your system.
 DBI (DataBase Interface) and DBD:MySQL (DataBase Driver for MySQL).
 First, we need to start the Perl Package Manager. Click on your start menu
and select the Run...option. In the pop-up window, type cmd and hit
enter.
 This will bring up the Windows command line.
 If you did the default install of ActiveState's ActivePerl, you should be able
to type ppm at the prompt to start the Perl Package Manager.
 First comes the DBI (DataBase Interface) which can be installed by
typing install DBI.
 Finally we install the MySQL driver for the DBI. This is done by
typing install DBD-mysql.
108
Cont…
 When you are able to do some basic administration tasks, let's create a
database called mydb in mysql.
 And in that database, we will create a simple table called ofuser and
populate it with some data.
 Here is the SQL you'll need to create the table and fill in a few records, just
connect to your MySQL database and run them.
 CREATE DATABASE mydb;
 USE mydb;
 CREATE TABLE ofuser ( id int(10) unsigned NOT NULL
auto_increment, name varchar(128) NOT NULL default '', phone
varchar(128) NOT NULL default '', PRIMARY KEY (id) );
 INSERT INTO ofuser VALUES (1, 'Some Person', '555');
 INSERT INTO ofuser VALUES (2, 'Another Person', '222');
109
Cont…
 Now that we have a database to connect to, let's look at how we access the
information from our Perl programs. The following is a simple script that
connects to the database and runs a short bit of SQL to retrieve all the
samples.
 #!C:Perlbinperl.exe
 use strict;
 use CGI::Carp qw(fatalsToBrowser);
 use CGI qw(:standard);
 use DBI;
 my $dbh;
 my $user = "root";
 my $password = "admin";
 print header,
 start_html;
 $dbh = DBI->connect("dbi:mysql:database=mydb;host=localhost:3306;", $user, $password);
 my $sth = $dbh->prepare('select * from ofuser');
 $sth->execute;
 print "<ul>";
 while (my @row = $sth->fetchrow_array) {
 print "<li>@rowt";
 }
 print "</ul>";
 print end_html;
The first thing we need to do is
let the Perl interpreter know
that we intend to use the Perl
DBI function library, by
including it in our program
with the use function.
Next we'll need to create a
connection to the database
itself. For this part of the script,
your mydb database will need
to be running.
Finally we use
the fetchrow_array function
to fetch each row of the results
from the MySQL database and
print them one to a line.
110
Exercise
111
 Create an html login form, try to authenticate it via
mysql database and if authentication is valid then it
should go to welcome page displaying your user name
and your details.
Using Cookies in CGI
 HTTP protocol is a stateless protocol.
 But for a commercial website it is required to
maintain session information among different pages.
 For example one user registration ends after
completing many pages.
 But how to maintain user's session information
across all the web pages.
112
Cont…
 In many situations, using cookies is the
most efficient method of remembering
and tracking preferences, purchases,
commissions, and other information
required for better visitor experience or
site statistics.
113
Cont…
 How It Works
 Your server sends some data to the visitor's browser in the
form of a cookie.
 The browser may accept the cookie.
 If it does, it is stored as a plain text record on the visitor's
hard drive.
 Now, when the visitor arrives at another page on your site,
the cookie is available for retrieval.
 Once retrieved, your server knows/remembers what was
stored.
114
Cont…
 Cookies are a plain text data record of 5
variable-length fields:
 Expires : The date the cookie will expire. If this is blank, the cookie will
expire when the visitor quits the browser.
 Domain : The domain name of your site.
 Path : The path to the directory or web page that set the cookie. This
may be blank if you want to retrieve the cookie from any directory or
page.
 Secure : If this field contains the word "secure" then the cookie may
only be retrieved with a secure server. If this field is blank, no such
restriction exists.
 Name=Value : Cookies are set and retrviewed in the form of key and
value pairs.
115
Example
 Setting up Cookies
 This is very easy to send cookies to browser. These cookies will be sent along
with HTTP Header. Assuming you want to set UserID and Password as cookies.
So it will be done as follows:
 #!C:Perlbinperl.exe
 use strict;
 use CGI qw(:standard);
 use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
 print "Set-Cookie:UserID=XYZ;n";
 print "Set-Cookie:Password=XYZ123;n";
 print "Set-Cookie:Expires=Tuesday, 25-Dec-2012 23:12:40 GMT n";
 print "Content-type:text/htmlrnrn";
 From this example you must have understood how to
set cookies. We use Set-Cookie HTTP header to set
cookies.
#!C:Perlbinperl.exe
use strict;
use CGI qw/:standard/;
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
my $cookie = cookie(
-name=>'CGI-PERL-COOKIE-EXAMPLE',
value=>'cookie.linuxconfig.org',
-expires=>'+1y');
print header (-cookie=>$cookie),
start_html('CGI Cookie with Exipire Date'),
p("Cookie had been saved !n"),
end_html;
exit;
The following code uses same principles of creating a cookies however on
larger scale. When creating a cookies we need to keep in mind that there
is a limitation of maximum 20 cookies per domain. Use a following code
to create multiple cookies simultaneously. The code first creates a scalar
variable to hold a cookies definitions and then we print a header with
both cookies in form of array.
#!C:Perlbinperl.exe
use strict;
use CGI qw/:standard/;
my $cookie1 = cookie(-
name=>'cookie_one',value=>'value1',expires=>'+1d');
my $cookie2 = cookie(-
name=>'cookie_two',value=>'value2',expires=>'+10y');
print header (-cookie=>[$cookie1,$cookie2]),
start_html('CGI Multiple Cookie Example'),
p("Cookies received!n"),
end_html;
exit;
116
Retrieving Cookies
 This is very easy to retrieve all the set cookies. Cookies are stored in CGI environment
variable HTTP_COOKIE and they will have following form.
 key1=value1;key2=value2;key3=value3....
 Here is an example of how to retrieving cookies.
 #!C:Perlbinperl.exe
 use strict;
 use CGI qw(:standard);
 use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
 my $cookie;my $key;my $val;my $user_id;my $password;
 print "Content-type:text/htmlrnrn";
 my $rcvd_cookies = $ENV{'HTTP_COOKIE'};
 my @cookies = split /;/, $rcvd_cookies;
 foreach $cookie ( @cookies ){
 ($key, $val) = split(/=/, $cookie); # splits on the first =.
 $key =~ s/^s+//;
 $val =~ s/^s+//;
 $key =~ s/s+$//;
 $val =~ s/s+$//;
 if( $key eq "UserID" ){
 $user_id = $val;
 }elsif($key eq "Password"){
 $password = $val;
 }
 }
 print "User ID = $user_idn";
 print "Password = $passwordn";
#!C:Perlbinperl.exe
use strict;
use CGI qw/:standard/;
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
my $retrieve_cookie = cookie('CGI-PERL-COOKIE-EXAMPLE');
print header,
start_html,
p("Cookie value is $retrieve_cookien"),
end_html;
exit;
Similarly the code below retrieves multiple cookies at once:
#!C:Perlbinperl.exe
use strict;
use CGI qw/:standard/;
my $retrieve_cookie1 = cookie('cookie_one');
my $retrieve_cookie2 = cookie('cookie_two');
print header,
start_html,
p("COOKIE_ONE Value: $retrieve_cookie1 n"),
p("COOKIE_TWO Value: $retrieve_cookie2 n"),
end_html;
exit;
117
What is sendmail?
 Sendmail is the most popular Unix-based
implementation of the Simple Mail Transfer Protocol
(SMTP) for transmitting e-mail.
 When a sendmail server receives e-mail, it attempts to
deliver the mail to the intended recipient.
 However, because it does not provide a mailbox facility
and for other reasons, other software such as a POP3
or Internet Message Access Protocol server are also
needed.
 Most Internet service providers (ISPs) provide both an
SMTP server (such as sendmail) and a POP or IMAP
server.
118
How does sendmail for windows work?
 In perl or php or asp scripts we can write a code to
send mail to mail recepients.
 We direct data to program sendmail.exe who sends
email to person or persons that our script sends.
 So all we need is to send header and email-msg to
sendmail.exe program and that is it.
119
Installation of sendmail.exe
 All of scripts are in cgi-bin folder (for example
c:Inetpubwwwroottestdomain.comhttpdoc
scgi-bin). "Cgi-bin" folder must have execute
permissions.
120
Cont…
 Download sendmail.zip
 http://velikan.net/sendmail-for-windows-iis/sendmail.zip
 Now upload sendmail.zip to your cgi-bin folder end
extract contents.
 Next step is to edit sendmail.ini file. You only need
to set your domain and if you do not have your own
smtp server installed on your server you can write
smtp mail server of your internet service provider.
121
Cont…
That is it. You have successfully installed
sendmail.exe program for windows - now only thing
for you is to use it...
122
Example
 #!C:Perlbinperl.exe
 use CGI qw(:standard);
 use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
 use strict;
 print "Content-type: text/htmlnn";
 my $title='Perl Mail demo';
 my $to='girish092.ch@gmail.com';
 my $from= 'girish092.ch@gmail.com';
 my $subject='YOUR SUBJECT';
 open(MAIL, "|sendmail/sendmail.exe -t");
 ## Mail Header
 print MAIL "To: $ton";
 print MAIL "From: $fromn";
 print MAIL "Subject: $subjectnn";
 ## Mail Body
 print MAIL "This is a test message from CGI-Perl! You can write your
 mail body text heren";
 close(MAIL);
 print "<html><head><title>$title</title>
 </head>n<body>nn";
 ## HTML content let use know we sent an email
 print "<h1>$title</h1>n";
 print "<p>A message has been sent from $from to $to";
 print "nn</body></html>";
123
In UNIX
124
 #!/usr/bin/perl
 print "Content-type: text/htmlnn";
 $title='Perl Mail demo';
 $to='MAIL ADDRESS TO SEND TO';
 $from= 'webmaster@YOURDOMAIN.COM';
 $subject='YOUR SUBJECT';
 open(MAIL, "|/usr/sbin/sendmail -t");
 ## Mail Header
 print MAIL "To: $ton";
 print MAIL "From: $fromn";
 print MAIL "Subject: $subjectnn";
 ## Mail Body
 print MAIL "This is a test message ! You can write your mail body text heren";
 close(MAIL);
 print "<html><head><title>$title</title> </head>n<body>nn";
 ## HTML content let use know we sent an email
 print "<h1>$title</h1>n";
 print "<p>A message has been sent from $from to $to";
 print "nn</body></html>";
References
 www.google.com
 www.wikipedia.org
 www.oeclib.in
125
126

More Related Content

What's hot

Introduction to Compiler Construction
Introduction to Compiler Construction Introduction to Compiler Construction
Introduction to Compiler Construction Sarmad Ali
 
Introduction to Software Engineering
Introduction to Software EngineeringIntroduction to Software Engineering
Introduction to Software EngineeringSaqib Raza
 
4 evolution-of-programming-languages
4 evolution-of-programming-languages4 evolution-of-programming-languages
4 evolution-of-programming-languagesRohit Shrivastava
 
Threads (operating System)
Threads (operating System)Threads (operating System)
Threads (operating System)Prakhar Maurya
 
Unit II - 2 - Operating System - Threads
Unit II - 2 - Operating System - ThreadsUnit II - 2 - Operating System - Threads
Unit II - 2 - Operating System - Threadscscarcas
 
Introduction to JavaScript
Introduction to JavaScriptIntroduction to JavaScript
Introduction to JavaScriptAndres Baravalle
 
Integrated Development Environments (IDE)
Integrated Development Environments (IDE) Integrated Development Environments (IDE)
Integrated Development Environments (IDE) SeanPereira2
 
Parsing in Compiler Design
Parsing in Compiler DesignParsing in Compiler Design
Parsing in Compiler DesignAkhil Kaushik
 
Formal Methods lecture 01
Formal Methods lecture 01Formal Methods lecture 01
Formal Methods lecture 01Sidra Ashraf
 
Analysis modeling & scenario based modeling
Analysis modeling &  scenario based modeling Analysis modeling &  scenario based modeling
Analysis modeling & scenario based modeling Benazir Fathima
 
CS8651 Internet Programming - Basics of HTML, HTML5, CSS
CS8651   Internet Programming - Basics of HTML, HTML5, CSSCS8651   Internet Programming - Basics of HTML, HTML5, CSS
CS8651 Internet Programming - Basics of HTML, HTML5, CSSVigneshkumar Ponnusamy
 
Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...
Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...
Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...ssuser65bfce
 
Multithreading
MultithreadingMultithreading
MultithreadingA B Shinde
 

What's hot (20)

Introduction to Compiler Construction
Introduction to Compiler Construction Introduction to Compiler Construction
Introduction to Compiler Construction
 
Introduction to Software Engineering
Introduction to Software EngineeringIntroduction to Software Engineering
Introduction to Software Engineering
 
4 evolution-of-programming-languages
4 evolution-of-programming-languages4 evolution-of-programming-languages
4 evolution-of-programming-languages
 
Sending emails through PHP
Sending emails through PHPSending emails through PHP
Sending emails through PHP
 
Phases of Compiler
Phases of CompilerPhases of Compiler
Phases of Compiler
 
Php Presentation
Php PresentationPhp Presentation
Php Presentation
 
Threads (operating System)
Threads (operating System)Threads (operating System)
Threads (operating System)
 
Unit II - 2 - Operating System - Threads
Unit II - 2 - Operating System - ThreadsUnit II - 2 - Operating System - Threads
Unit II - 2 - Operating System - Threads
 
Unix ppt
Unix pptUnix ppt
Unix ppt
 
Introduction to JavaScript
Introduction to JavaScriptIntroduction to JavaScript
Introduction to JavaScript
 
Integrated Development Environments (IDE)
Integrated Development Environments (IDE) Integrated Development Environments (IDE)
Integrated Development Environments (IDE)
 
Coding standard
Coding standardCoding standard
Coding standard
 
Parsing in Compiler Design
Parsing in Compiler DesignParsing in Compiler Design
Parsing in Compiler Design
 
Formal Methods lecture 01
Formal Methods lecture 01Formal Methods lecture 01
Formal Methods lecture 01
 
Analysis modeling & scenario based modeling
Analysis modeling &  scenario based modeling Analysis modeling &  scenario based modeling
Analysis modeling & scenario based modeling
 
CS8651 Internet Programming - Basics of HTML, HTML5, CSS
CS8651   Internet Programming - Basics of HTML, HTML5, CSSCS8651   Internet Programming - Basics of HTML, HTML5, CSS
CS8651 Internet Programming - Basics of HTML, HTML5, CSS
 
Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...
Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...
Assembly Language for x86 Processors 7th Edition Chapter 2 : x86 Processor Ar...
 
Multithreading
MultithreadingMultithreading
Multithreading
 
Web application architecture
Web application architectureWeb application architecture
Web application architecture
 
Debugging
DebuggingDebugging
Debugging
 

Similar to Common Gateway Interface ppt

SERVER SIDE SCRIPTING
SERVER SIDE SCRIPTINGSERVER SIDE SCRIPTING
SERVER SIDE SCRIPTINGProf Ansari
 
Programming Server side with Sevlet
 Programming Server side with Sevlet  Programming Server side with Sevlet
Programming Server side with Sevlet backdoor
 
Server side programming
Server side programming Server side programming
Server side programming javed ahmed
 
Docs Python Org Howto Webservers Html
Docs Python Org Howto Webservers HtmlDocs Python Org Howto Webservers Html
Docs Python Org Howto Webservers HtmlAkramWaseem
 
IRJET- Mail Server Communication:PHP
IRJET-  	  Mail Server Communication:PHPIRJET-  	  Mail Server Communication:PHP
IRJET- Mail Server Communication:PHPIRJET Journal
 
Perl web programming
Perl web programmingPerl web programming
Perl web programmingJohnny Pork
 
Web II - 01 - Introduction to server-side development
Web II - 01 - Introduction to server-side developmentWeb II - 01 - Introduction to server-side development
Web II - 01 - Introduction to server-side developmentRandy Connolly
 
Unit - 1: ASP.NET Basic
Unit - 1:  ASP.NET BasicUnit - 1:  ASP.NET Basic
Unit - 1: ASP.NET BasicKALIDHASANR
 
Fundamental of-web design-trends-20142
Fundamental of-web design-trends-20142Fundamental of-web design-trends-20142
Fundamental of-web design-trends-20142Ly Nguyen Bui
 
Class 17-18 Introduction to Perl.pdf bbbbbb
Class 17-18 Introduction to Perl.pdf bbbbbbClass 17-18 Introduction to Perl.pdf bbbbbb
Class 17-18 Introduction to Perl.pdf bbbbbb21h51a0581
 
Selenium Training in Amritsar
Selenium Training in AmritsarSelenium Training in Amritsar
Selenium Training in AmritsarE2MATRIX
 

Similar to Common Gateway Interface ppt (20)

Cgi
CgiCgi
Cgi
 
SERVER SIDE SCRIPTING
SERVER SIDE SCRIPTINGSERVER SIDE SCRIPTING
SERVER SIDE SCRIPTING
 
Ecom 1
Ecom 1Ecom 1
Ecom 1
 
Programming Server side with Sevlet
 Programming Server side with Sevlet  Programming Server side with Sevlet
Programming Server side with Sevlet
 
Chapter 1
Chapter 1Chapter 1
Chapter 1
 
Server side programming
Server side programming Server side programming
Server side programming
 
Docs Python Org Howto Webservers Html
Docs Python Org Howto Webservers HtmlDocs Python Org Howto Webservers Html
Docs Python Org Howto Webservers Html
 
Mohit Jaiswal
Mohit JaiswalMohit Jaiswal
Mohit Jaiswal
 
IRJET- Mail Server Communication:PHP
IRJET-  	  Mail Server Communication:PHPIRJET-  	  Mail Server Communication:PHP
IRJET- Mail Server Communication:PHP
 
Perl web programming
Perl web programmingPerl web programming
Perl web programming
 
Lamp Zend Security
Lamp Zend SecurityLamp Zend Security
Lamp Zend Security
 
Web II - 01 - Introduction to server-side development
Web II - 01 - Introduction to server-side developmentWeb II - 01 - Introduction to server-side development
Web II - 01 - Introduction to server-side development
 
Learn ASP
Learn ASPLearn ASP
Learn ASP
 
Unit - 1: ASP.NET Basic
Unit - 1:  ASP.NET BasicUnit - 1:  ASP.NET Basic
Unit - 1: ASP.NET Basic
 
Fundamental of-web design-trends-20142
Fundamental of-web design-trends-20142Fundamental of-web design-trends-20142
Fundamental of-web design-trends-20142
 
Asp
AspAsp
Asp
 
Rutgers - Active Server Pages
Rutgers - Active Server PagesRutgers - Active Server Pages
Rutgers - Active Server Pages
 
Class 17-18 Introduction to Perl.pdf bbbbbb
Class 17-18 Introduction to Perl.pdf bbbbbbClass 17-18 Introduction to Perl.pdf bbbbbb
Class 17-18 Introduction to Perl.pdf bbbbbb
 
6. The grid-COMPUTING OGSA and WSRF
6. The grid-COMPUTING OGSA and WSRF6. The grid-COMPUTING OGSA and WSRF
6. The grid-COMPUTING OGSA and WSRF
 
Selenium Training in Amritsar
Selenium Training in AmritsarSelenium Training in Amritsar
Selenium Training in Amritsar
 

More from OECLIB Odisha Electronics Control Library

More from OECLIB Odisha Electronics Control Library (20)

5G technology-ppt
5G technology-ppt5G technology-ppt
5G technology-ppt
 
Futex ppt
Futex  pptFutex  ppt
Futex ppt
 
Distributed Computing ppt
Distributed Computing pptDistributed Computing ppt
Distributed Computing ppt
 
Autonomic Computing PPT
Autonomic Computing PPTAutonomic Computing PPT
Autonomic Computing PPT
 
Asynchronous Chips ppt
Asynchronous Chips pptAsynchronous Chips ppt
Asynchronous Chips ppt
 
Artificial Eye PPT
Artificial Eye PPTArtificial Eye PPT
Artificial Eye PPT
 
Agent Oriented Programming PPT
Agent Oriented Programming PPTAgent Oriented Programming PPT
Agent Oriented Programming PPT
 
Wireless application protocol ppt
Wireless application protocol  pptWireless application protocol  ppt
Wireless application protocol ppt
 
Wireless Communication ppt
Wireless Communication pptWireless Communication ppt
Wireless Communication ppt
 
4G Wireless Systems ppt
4G Wireless Systems ppt4G Wireless Systems ppt
4G Wireless Systems ppt
 
Steganography ppt
Steganography pptSteganography ppt
Steganography ppt
 
Sixth sense technology ppt
Sixth sense technology pptSixth sense technology ppt
Sixth sense technology ppt
 
Soa ppt
Soa pptSoa ppt
Soa ppt
 
Software developement life cycle ppt
Software developement life cycle pptSoftware developement life cycle ppt
Software developement life cycle ppt
 
Voice-over-Internet Protocol (VoIP) ppt
Voice-over-Internet Protocol (VoIP) pptVoice-over-Internet Protocol (VoIP) ppt
Voice-over-Internet Protocol (VoIP) ppt
 
ZIGBEE TECHNOLOGY ppt
ZIGBEE TECHNOLOGY pptZIGBEE TECHNOLOGY ppt
ZIGBEE TECHNOLOGY ppt
 
Wimax ppt
Wimax pptWimax ppt
Wimax ppt
 
Wibree ppt
Wibree pptWibree ppt
Wibree ppt
 
Wearable Computing
Wearable ComputingWearable Computing
Wearable Computing
 
Virtual Private Networks (VPN) ppt
Virtual Private Networks (VPN) pptVirtual Private Networks (VPN) ppt
Virtual Private Networks (VPN) ppt
 

Recently uploaded

VIP Kolkata Call Girl Kestopur 👉 8250192130 Available With Room
VIP Kolkata Call Girl Kestopur 👉 8250192130  Available With RoomVIP Kolkata Call Girl Kestopur 👉 8250192130  Available With Room
VIP Kolkata Call Girl Kestopur 👉 8250192130 Available With Roomdivyansh0kumar0
 
Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)
Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)
Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)Dana Luther
 
Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作
Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作
Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作ys8omjxb
 
Call Girls Near The Suryaa Hotel New Delhi 9873777170
Call Girls Near The Suryaa Hotel New Delhi 9873777170Call Girls Near The Suryaa Hotel New Delhi 9873777170
Call Girls Near The Suryaa Hotel New Delhi 9873777170Sonam Pathan
 
Git and Github workshop GDSC MLRITM
Git and Github  workshop GDSC MLRITMGit and Github  workshop GDSC MLRITM
Git and Github workshop GDSC MLRITMgdsc13
 
Call Girls South Delhi Delhi reach out to us at ☎ 9711199012
Call Girls South Delhi Delhi reach out to us at ☎ 9711199012Call Girls South Delhi Delhi reach out to us at ☎ 9711199012
Call Girls South Delhi Delhi reach out to us at ☎ 9711199012rehmti665
 
VIP Call Girls Kolkata Ananya 🤌 8250192130 🚀 Vip Call Girls Kolkata
VIP Call Girls Kolkata Ananya 🤌  8250192130 🚀 Vip Call Girls KolkataVIP Call Girls Kolkata Ananya 🤌  8250192130 🚀 Vip Call Girls Kolkata
VIP Call Girls Kolkata Ananya 🤌 8250192130 🚀 Vip Call Girls Kolkataanamikaraghav4
 
定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一
定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一
定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一Fs
 
Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170
Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170
Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170Sonam Pathan
 
VIP Kolkata Call Girl Alambazar 👉 8250192130 Available With Room
VIP Kolkata Call Girl Alambazar 👉 8250192130  Available With RoomVIP Kolkata Call Girl Alambazar 👉 8250192130  Available With Room
VIP Kolkata Call Girl Alambazar 👉 8250192130 Available With Roomdivyansh0kumar0
 
定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一
定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一
定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一Fs
 
PHP-based rendering of TYPO3 Documentation
PHP-based rendering of TYPO3 DocumentationPHP-based rendering of TYPO3 Documentation
PHP-based rendering of TYPO3 DocumentationLinaWolf1
 
A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)
A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)
A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)Christopher H Felton
 
Font Performance - NYC WebPerf Meetup April '24
Font Performance - NYC WebPerf Meetup April '24Font Performance - NYC WebPerf Meetup April '24
Font Performance - NYC WebPerf Meetup April '24Paul Calvano
 
Call Girls Service Adil Nagar 7001305949 Need escorts Service Pooja Vip
Call Girls Service Adil Nagar 7001305949 Need escorts Service Pooja VipCall Girls Service Adil Nagar 7001305949 Need escorts Service Pooja Vip
Call Girls Service Adil Nagar 7001305949 Need escorts Service Pooja VipCall Girls Lucknow
 
办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一
办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一
办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一z xss
 
Blepharitis inflammation of eyelid symptoms cause everything included along w...
Blepharitis inflammation of eyelid symptoms cause everything included along w...Blepharitis inflammation of eyelid symptoms cause everything included along w...
Blepharitis inflammation of eyelid symptoms cause everything included along w...Excelmac1
 

Recently uploaded (20)

VIP Kolkata Call Girl Kestopur 👉 8250192130 Available With Room
VIP Kolkata Call Girl Kestopur 👉 8250192130  Available With RoomVIP Kolkata Call Girl Kestopur 👉 8250192130  Available With Room
VIP Kolkata Call Girl Kestopur 👉 8250192130 Available With Room
 
Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)
Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)
Packaging the Monolith - PHP Tek 2024 (Breaking it down one bite at a time)
 
Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作
Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作
Potsdam FH学位证,波茨坦应用技术大学毕业证书1:1制作
 
Call Girls Near The Suryaa Hotel New Delhi 9873777170
Call Girls Near The Suryaa Hotel New Delhi 9873777170Call Girls Near The Suryaa Hotel New Delhi 9873777170
Call Girls Near The Suryaa Hotel New Delhi 9873777170
 
Git and Github workshop GDSC MLRITM
Git and Github  workshop GDSC MLRITMGit and Github  workshop GDSC MLRITM
Git and Github workshop GDSC MLRITM
 
Call Girls South Delhi Delhi reach out to us at ☎ 9711199012
Call Girls South Delhi Delhi reach out to us at ☎ 9711199012Call Girls South Delhi Delhi reach out to us at ☎ 9711199012
Call Girls South Delhi Delhi reach out to us at ☎ 9711199012
 
VIP Call Girls Kolkata Ananya 🤌 8250192130 🚀 Vip Call Girls Kolkata
VIP Call Girls Kolkata Ananya 🤌  8250192130 🚀 Vip Call Girls KolkataVIP Call Girls Kolkata Ananya 🤌  8250192130 🚀 Vip Call Girls Kolkata
VIP Call Girls Kolkata Ananya 🤌 8250192130 🚀 Vip Call Girls Kolkata
 
定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一
定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一
定制(Lincoln毕业证书)新西兰林肯大学毕业证成绩单原版一比一
 
young call girls in Uttam Nagar🔝 9953056974 🔝 Delhi escort Service
young call girls in Uttam Nagar🔝 9953056974 🔝 Delhi escort Serviceyoung call girls in Uttam Nagar🔝 9953056974 🔝 Delhi escort Service
young call girls in Uttam Nagar🔝 9953056974 🔝 Delhi escort Service
 
Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170
Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170
Call Girls In The Ocean Pearl Retreat Hotel New Delhi 9873777170
 
Hot Sexy call girls in Rk Puram 🔝 9953056974 🔝 Delhi escort Service
Hot Sexy call girls in  Rk Puram 🔝 9953056974 🔝 Delhi escort ServiceHot Sexy call girls in  Rk Puram 🔝 9953056974 🔝 Delhi escort Service
Hot Sexy call girls in Rk Puram 🔝 9953056974 🔝 Delhi escort Service
 
VIP Kolkata Call Girl Alambazar 👉 8250192130 Available With Room
VIP Kolkata Call Girl Alambazar 👉 8250192130  Available With RoomVIP Kolkata Call Girl Alambazar 👉 8250192130  Available With Room
VIP Kolkata Call Girl Alambazar 👉 8250192130 Available With Room
 
定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一
定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一
定制(AUT毕业证书)新西兰奥克兰理工大学毕业证成绩单原版一比一
 
PHP-based rendering of TYPO3 Documentation
PHP-based rendering of TYPO3 DocumentationPHP-based rendering of TYPO3 Documentation
PHP-based rendering of TYPO3 Documentation
 
A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)
A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)
A Good Girl's Guide to Murder (A Good Girl's Guide to Murder, #1)
 
Font Performance - NYC WebPerf Meetup April '24
Font Performance - NYC WebPerf Meetup April '24Font Performance - NYC WebPerf Meetup April '24
Font Performance - NYC WebPerf Meetup April '24
 
Call Girls Service Adil Nagar 7001305949 Need escorts Service Pooja Vip
Call Girls Service Adil Nagar 7001305949 Need escorts Service Pooja VipCall Girls Service Adil Nagar 7001305949 Need escorts Service Pooja Vip
Call Girls Service Adil Nagar 7001305949 Need escorts Service Pooja Vip
 
Model Call Girl in Jamuna Vihar Delhi reach out to us at 🔝9953056974🔝
Model Call Girl in  Jamuna Vihar Delhi reach out to us at 🔝9953056974🔝Model Call Girl in  Jamuna Vihar Delhi reach out to us at 🔝9953056974🔝
Model Call Girl in Jamuna Vihar Delhi reach out to us at 🔝9953056974🔝
 
办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一
办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一
办理(UofR毕业证书)罗切斯特大学毕业证成绩单原版一比一
 
Blepharitis inflammation of eyelid symptoms cause everything included along w...
Blepharitis inflammation of eyelid symptoms cause everything included along w...Blepharitis inflammation of eyelid symptoms cause everything included along w...
Blepharitis inflammation of eyelid symptoms cause everything included along w...
 

Common Gateway Interface ppt

  • 1. www.oeclib.in Submitted By: Odisha Electronics Control Library Seminar On Common Gateway Interface CGI
  • 2. Objective  After the completion of this training, participants will able to understand about perl scripting and cgi programming aspects.  Topics Covered:  Introduction of CGI The Definition Web Browsing Architecture of CGI How does CGI works Preparing CGI for work 2
  • 3. Cont…  Introduction to Perl  The CGI.pm Module  Pattern Matching  Arrays  Dealing With Files In PERL  Basic HTML  What is cgi-lib.pl?  Communicating with databases  Sending mail with Perl – CGI Scripts 3
  • 4. Dynamic Web 4  When the Web first started, there were only static HTML pages.  The internet had been around for some time already, but it was only after the introduction of HTML.  A lot has happened since then.  We would like to place the birth of the dynamic web to when CGI, Common Gateway Interface, was first introduced in 1993.  CGI was a way to let a website run scripts (usually Perl scripts back then) on the web server and display the output.
  • 6. CGI (Common Gateway Interface)  A standard protocol for interfacing external application software with an information server, usually a web server.  It is basically a set of rules used to describe the way in which a web server communicates with other software housed on the same machine, and then how that software talks back to the web server.  What is returned from the CGI program is based on what was requested, and this information can be accessed and returned to the user in many different ways. 6
  • 7. Definition of CGI  The Common Gateway Interface, or CGI, is a set of standards that define how information is exchanged between the web server and a custom script.  CGI is a standard interface that sits between the web browser and the web server.  When the browser makes a request of the server, all of the request details flow into the server through the input interface of the CGI.  When the server responds with its output, the information flows back out through the output interface of the CGI. 7
  • 8. Cont…  CGI programs can be written in any language.  Perl is a very common language for CGI programming as it is largely platform independent and the language’s features make it very easy to write powerful applications.  However, some CGI programs are written in C, shell script, or other languages.  It is important to remember that CGI is not a language in itself. 8
  • 9. Some Things to Remember About CGI 9  CGI is not the program itself.  CGI is simply the interface between the Web page or browser and the Web server that runs the program.  You must have CGI access to run programs on your Web page.  Any program or script that will run on your Web server, can be used as a CGI program.  Most people use Perl to write their CGI scripts, but other languages include C and C++, Tcl, and UNIX shell scripts.
  • 10. Uses of CGI Scripts 10  CGI scripts are used to resolve form data, put that data in to databases, send the data out as an email message, respond to the form entry with email or another Web page, and much more.  CGI scripts also are used for behind the scenes interaction with Web readers.  They can set and read cookies, get and tabulate information such as browser and operating system, calculate hit counts, and monitor Web traffic.
  • 11. Why Use CGI? 11  Many of the uses of CGI can be duplicated by newer technology such as JavaScript and ActiveX.  The primary benefit to using CGI rather than browser based scripting is that you can be sure that all of your readers (with very few exceptions) will be able to use the program.  Java, JavaScript, and ActiveX can all be turned off within the browser, and many browsers simply don't support them.  Also, it is becoming more common for company firewalls to disallow these technologies to work in their system (often for security or bandwidth reasons).  Because CGI scripts are run on the external Web server, they are not limited by browser or firewall limitations.
  • 12. Why Not Use CGI? 12  The biggest drawback to CGI Scripts is that they can put a lot of load on a Web server.  The Web browser will time out (usually after around 5 minutes), but often the server will continue to run the program until a system administrator comes in and shuts off the faulty script.  The browser based scripting tools mentioned above have the advantage of running off the reader's computer.  They use the processor locally rather than on the Web server itself, and so are less intense on the Web server.
  • 13. Comparing Server-Side Web Languages 13  Php - Probably currently most popular! But not a general purpose language.  Perl - Older than Php. More difficult to use, but general purpose. Good for general Unix system admin tasks.  ASP.NET - Microsoft’s server-side language; commercial; platform dependent.  Python - Object oriented multi-purpose scripting language. Really good for server-side tasks! But not that well known.  Java Servlets - Java server-side programming, requires Apache Tomcat engine or similar.  JSP - Sun’s version of Java server-side programming.
  • 14. Java Scripts And Other Web Technologies… 14  Scripts come in many different formats such as JavaScript, VBScript, ActiveX, Active Server Pages (ASP), Java Applets, JavaBeans, CGI and others.  JavaScript can do some things, however they have limitations and can only work on the client-side.  In other words, the scripts are interpreted and run in the browser of the user.  CGI scripts, on the other hand, will directly interact with the server, where your whole web site resides, simply they are server-side.  Since it works from your server you can take control over the scripts which are running by using other server files (for example the sendmail program of Unix).
  • 15. Cont… 15  JavaScripts don't access any of your other files, (for example you cannot access a database which is in your server).  JavaScripts are simply inserted into your HTML pages, which can be run by the browser.  Netscape browsers don't support VBScripts and ActiveX, so are not usually used by the typical web user.  Another technology like ASP can be used instead of CGI but only in a Windows-NT server as UNIX servers do not support them.  Java applets can also be used, however speed can be a problem so many users prefer CGI scripts.
  • 16. Web Browsing  To understand the concept of CGI, lets see what happens when we click a hyper link to browse a particular web page or URL.  Your browser contacts the HTTP web server and demand for the URL ie. filename.  Web Server will parse the URL and will look for the filename in if it finds that file then sends back to the browser otherwise sends an error message indicating that you have requested a wrong file.  Web browser takes response from web server and displays either the received file or error message. 16
  • 18. How does CGI work? CGI 1. HTTP request 2. Call CGI 3. CGI program’s response 4. HTTP response User Web Browser (on client) Application (on server) Server 18
  • 19. Introduction to CGI (continued)  CGI programs work as follows:  STEP 1 (On the client side): Get Information from the user (using HTML forms,, Java Applet, …,etc).  STEP 2 (On the server side): Process the data, connect to DATABASE, search for PATTERNS, …,etc.  STEP 3 (On the server side): Send the result of computation back to the client. 19
  • 20. Preparing CGI for work  The steps involved in preparing a CGI program for work. 1. Contact your Web host to find out where you should put your CGI programs on the server. Usually it will be a directory on the server named “cgi-bin”. 2. Set up the access permission of directory “cgi-bin” using the following UNIX command: chmod 755 cgi-bin/ 3. Set up the access permission of the CGI program using the following UNIX command: chmod 755 cgi-program 4. Test your CGI program from the server command line to make sure it works perfectly before publishing it. 20
  • 21. History of Perl  Perl was introduced in 1987  reason for its creation was that Mr. Wall was unhappy by the functionality that sed, C, awk and the Bourne Shell offered him. He looked for a language that will combine all of their best features, while having as few disadvantages of its own. 21
  • 22. Cont… A brief history of Perl  Perl became especially popular as a language for writing server-side scripts for web-servers.  But that's not the only use of perl, as it is commonly used for system administration tasks, managing database data, as well as writing GUI applications. 22
  • 23.  written by Larry Wall  A GNU product FREE, Open Source software  Interpreted and not compiled!  Originally designed for UNIX®, but is portable to other O/S  stable, cross platform programming language Introduction 23
  • 24. What does Perl stand for?  ‘Perl’ isn’t really an acronym  2 favorite expansion: -- Practical Extraction Report Language -- Pathologically Eclectic Rubbish Lister  It's not PERL or P.E.R.L.  'Perl' refers to the language  'perl' to the interpreter that runs the programs written in Perl 24
  • 25. What is Perl and why is it so great?  Perl is a stable, cross platform programming language.  Perl stands for Practical Extraction and Report Language.  Perl is a general purpose computer language ideally suited to handling words and text.  The quote of Perl gurus, “It makes the easy things easy, and the difficult things possible.”  Perl's strengths is that there are usually many ways of accomplishing any particular bit of programming.  This strength inspires Perl programmers to quote the motto "TIMTOWTDI" (pronounced "timtoady") - the acronym of "There Is More Than One Way To Do It." 25
  • 26. Perl Features  Perl takes the best features from other languages, such as C, awk, sed, sh, and BASIC, among others.  Perls database integration interface (DBI) supports third-party databases including Oracle, MySQL and others.  works with HTML, XML, and other mark-up languages. 26
  • 27. Cont… Perl Features  supports Unicode.  supports both procedural and OO programming.  extensible.  The Perl interpreter can be embedded into other systems. 27
  • 28. Perl & the Web  Perl is the most popular web programming language due to its text manipulation capabilities and rapid development cycle.  Perl is widely known as "the duct-tape of the Internet".  Perl's CGI.pm module, part of Perl's standard distribution, makes handling HTML forms simple.  Perl can handle encrypted Web data, including e- commerce transactions. 28
  • 29. Cont… Perl and the Web  Perl can be embedded into web servers to speed up processing by as much as 2000%.  mod_perl allows the Apache web server to embed a Perl interpreter.  Perl's DBI package makes web-database integration easy. mod_perl is an optional module for the Apache HTTP server. It embeds a Perl interpreter into the Apache server, so that dynamic content produced by Perl scripts can be served in response to incoming requests, without the significant overhead of re-launching the Perl interpreter for each request. 29
  • 30. What is needed to run Perl CGI programs?  There are several things you need in order to create and run Perl CGI programs.  a web server  web server configuration which gives you permission to run CGI  a Perl interpreter  appropriate Perl modules, such as CGI.pm  a shell account is extremely useful but not essential 30
  • 31. Setting up Perl/CGI  First, you need to get Perl if you do not already have it installed.  Go to http://www.activestate.com/Products/ActivePerl/ Download.html and download the latest release for Windows.  Next, you need a Web server.  http://httpd.apache.org/download.cgi  Scroll down to locate Win32 Binary without crypto (no mod_ssl) (MSI Installer). http://www.webdevelopersnotes.com/how-do-i/install-apache-windows-7.php 31
  • 32. First CGI Program  #!C:Perlbinperl.exe  use CGI;  print "Content-Type: text/htmlnn";  print "<HTML>n";  print "<HEAD>n";  print "<TITLE>Hello World</TITLE>n";  print "</HEAD>n";  print "<BODY>n";  print "<H4>Hello World</H4>n";  print "<P>n";  print "Your IP Address is $ENV{REMOTE_ADDR}.n";  print "<P>";  print "<H5>Have a nice day</H5>n";  print "</BODY>n";  print "</HTML>n"; 32
  • 33. Explanation  The first line of your program should look like this:  #!C:Perlbinperl -wT  The first part of this line, #!, indicates that this is a script. The next part, C:Perlbinperl.exe, is the location (or path) of the Perl interpreter.  The final part contains optional flags for the Perl interpreter. Warnings are enabled by the -w flag. Special user input taint checking is enabled by the -T flag. Taint mode tells Perl to keep track of data that comes from the user and avoid doing anything insecure with it.  print "Content-type: text/htmlnn";  This is a content-type header that tells the receiving web browser what sort of data it is about to receive — in this case, an HTML document. If you forget to include it, or if you print something else before printing this header, you'll get an "Internal Server Error" when you try to access the CGI program. 33
  • 34. Introduction to PERL  To run PERL programs:  On UNIX, type the command from UNIX shell: perl perl_prog.pl  On Windows, type the command from DOS prompt: perl perl_prog.pl  PERL is a case-sensitive language just like C or Java.  “#”sign is used for comments in PERL  Example: #!/usr/bin/perl # This program is to . . . 34
  • 35. Programming Standards  The following coding standards should be followed:  Start the program with a header comment giving info about the PERL path, programmer, copyrights, last modified date, and description.  Example: #!/usr/bin/perl ###################################### # Girish Srivastava # Copyrights © 2001 # All rights reserved. # # Last modified 9/16/2001 # This program is to . . . ###################################### 35
  • 36. Programming Standards (Continued)  Use three-line-comment style. Example: # # Incrementing variable $count. # $count++;  Use meaningful names for variables or subroutines. Capitalize every word except the first one. Example: $myBuffer=1; sub printThankYouMessage(){ …} 36
  • 37. PERL Data Types  PERL has three built-in data types: scalars, arrays of scalars, and associative arrays of scalars, known as "hashes".  Scalar Variables  A scalar may contain one single value in any of three different flavors: a number, a string, or a reference.  Scalar values are always named with '$‘ at the beginning, even when referring to a scalar that is part of an array or a hash. Examples: $day #A simple scalar value "day" $day[28] #the 29th element of @day $day{'Feb'} #The 'Feb' value from %day 37
  • 38. PERL Data Type (Continued)  Array Variables  An array is basically a way to store a whole bunch of scalar values under one name.  An array name begins with an "@" symbol. Examples: @arrayName = ("element1", "element2"); @browser = ("NS", "IE", "Opera"); @one_two_thre = (1, 2, 3);  To access a single element is an array, use a $+array name+[ + index+]. Array indexing starts form zero. Examples: $arrayName[0] # the first element of the # array $browser[1] # This will return ‘IE’. 38
  • 39. PERL Data Type (Continued)  Associative Arrays “Hashes”  Associative arrays are created with a set of key/value pairs. A key is a text string of your choice that will help you remember the value later.  A hash name begins with % sign. Examples: %hashName = ('key1', 'value1', 'key2', 'value2'); %ourFriends = ('best', 'Don', 'good', 'Robert', 'worst', 'Joe');  To access an element, use $+hash name+{+key+}. Examples: $hashName{‘key1’} #This will return value1 $ourFriends{'good'} #This will return #‘Robert’ 39
  • 40. Example  #!C:Perlbinperl.exe  my $text = 'cool guy';  my $string = "some $text";  print $string; # prints literally “some cool guy”; Arrays #!C:Perlbinperl -w #DEFINE SOME ARRAYS @days = ("Monday", "Tuesday", "Wednesday"); @months = ("April", "May", "June"); #PRINT MY ARRAYS TO THE BROWSER print @days; print @months; Hashes #!C:Perlbinperl -w #DEFINE SOME HASHES %hashName = ('key1', 'value1', 'key2', 'value2'); %ourFriends = ('best', 'Don', 'good', 'Robert', 'worst', 'Joe'); #PRINT MY HASHES TO THE BROWSER print $hashName{'key1'}; print $ourFriends{'good'}; 40
  • 41. Operators  PERL uses:  Arithmetic operations: +, -, *, /, %,**.  Relational operations: <, >, <=, >=, ==.  String Operations: eq, ne, lt, gt, le, ge.  Assignment Operators: =, +=, -+, *=, /=, .=.  Increment/decrement operators: ++, --.  Boolean operations: &&, ||, !.  Quotation marks:  ”” character string with variable interpolation.  ’’ character string without variable interpolation. 41 #!C:Perlbinperl.exe $one = 1; $two = 2; $three = 3; $four = 4; $abcd = "abcd"; $pqrs = "pqrs"; $xyz = "xyz"; # concantenate the two strings and print print $abcd . " another stringn"; # repeat the string abcd three times print $abcd x $three . "n"; # add the data in variables one and two. The numerical value is converted to string and concantenated with n print $one + $two . "n"; print $three % $two . "n"; # modulo - returns the remainder of three divided by two print $three ** $two . "n"; # exponentiation - three raised to power two print $one++ . "n"; # post increment print ++$one . "n"; # pre increment print $one-- . "n"; # post decrement print --$one . "n"; # pre decrement $one += $two; # $one = $one + $two $one -= $two; # $one = $one - $two
  • 42. Control Structures  Control structures include conditional statements, such as if/elsif/else blocks, as well as loops like foreach, for and while.  if ($varname > 23) { # do stuff here if the condition is true }  if ($varname > 23) {  print "$varname is greater than 23";  } elsif ($varname == 23) {  print "$varname is 23";  } else {  print "$varname is less than 23"; } 42 #!C:Perlbinperl.exe my $number = 95; if($number eq 92) { print 'Number is ninety-five!'; } else { print 'Number is not ninety-five'; }
  • 43. Unless  unless is similar to if. Let's say you wanted to execute code only if a certain condition were false. You could do something like this:  if ($varname != 23) { # code to execute if $varname is not 23 }  The same test can be done using unless:  unless ($varname == 23) { # code to execute if $varname is not 23 }  There is no "elseunless", but you can use an else clause:  unless ($varname == 23) {  # code to execute if $varname is not 23 }  else {  # code to execute if $varname IS 23  } 43
  • 44. Looping  Loops allow you to repeat code for as long as a condition is met. Perl has several loop control structures: foreach, for, while and until.  Foreach Loops  foreach iterates through a list of values:  foreach my $i (@arrayname) {  # code here  }  This loops through each element of @arrayname, setting $i to the current array element for each pass through the loop. You may omit the loop variable $i:  foreach (@arrayname) {  # $_ is the current array element  }  This sets the special Perl variable $_ to each array element. $_ does not need to be declared (it's part of the Perl language) and its scope localized to the loop itself. 44
  • 45. Cont…  For Loops  Perl also supports C-style for loops:  for ($i = 1; $i < 23; $i++) {  # code here  }  While Loops  A while loop executes as long as particular condition is true:  while (condition) {  # code to run as long as condition is true  }  Until Loops  until is the reverse of while. It executes as long as a particular condition is NOT true:  until (condition) {  # code to run as long as condition is not true  } 45 #!C:Perlbinperl.exe @array = ("value1", "value2", 1, 2, 3, 4); foreach my $value (@array) { print $value; } #!C:Perlbinperl.exe $integer = 0; while($integer < 50) { print $integer; $integer++; } Until #!C:Perlbinperl.exe $firstVar = 10; until ($firstVar > 12) { print("inside: firstVar = $firstVarn"); $firstVar++; } print("outside: firstVar = $firstVarn"); This program displays: inside: firstVar = 10 inside: firstVar = 11 inside: firstVar = 12 outside: firstVar = 13
  • 46. Exercise 46 1. Create a program using PERL, which gives the output as per the following figure: * * * * * * * * * * * * * * *
  • 47. Breaking from Loops  There are several ways to break from a loop. To stop the current loop iteration (and move on to the next one), use the next command:  foreach my $i (1..20) {  if ($i == 13) {  next;  }  print "$in";  }  This example prints the numbers from 1 to 20, except for the number 13. When it reaches 13, it skips to the next iteration of the loop.  To break out of a loop entirely, use the last command:  foreach my $i (1..20) {  if ($i == 13) {  last;  }  print "$in"; }  This example prints the numbers from 1 to 12, then terminates the loop when it reaches 13. 47
  • 48. Cont…  next and last only effect the innermost loop structure, so if you have something like this:  foreach my $i (@list1) {  foreach my $j (@list2) {  if ($i == 5 && $j == 23) {  last; }  } # this is where that last sends you  }  The last command only terminates the innermost loop. If you want to break out of the outer loop, you need to use loop labels:  OUTER: foreach my $i (@list1) {  INNER: foreach my $j (@list2) {  if ($i == 5 && $j == 23) {  last OUTER; }  }  } # this is where that last sends you  The loop label is a string that appears before the loop command (foreach, for, or while). In this example we used OUTER as the label for the outer foreach loop and INNER for the inner loop label. 48
  • 49. The CGI.pm Module  Perl offers a powerful feature to programmers: add-on modules.  These are collections of pre-written code that you can use to do all kinds of tasks.  Some modules are included as part of the Perl distribution; these are called standard library modules and don't have to be installed. If you have Perl, you already have the standard library modules. 49
  • 50. Cont…  Let's see how to use a module in your CGI program. First you have to actually include the module via the use command. This goes after the #!C:Perlbinperl.exe line and before any other code:  use CGI qw(:standard);  Note :we're not doing use CGI.pm but rather use CGI. The .pm is implied in the use statement. The qw(:standard) part of this line indicates that we're importing the "standard" set of functions from CGI.pm.  Now you can call the various module functions by typing the function name followed by any arguments:  functionname(arguments) 50
  • 51. Cont…  A function is a piece of code that performs a specific task; it may also be called a subroutine or a method.  Functions may accept optional arguments (also called parameters), which are values (strings, numbers, and other variables) passed into the function for it to use.  The CGI.pm module has many functions; for now we'll start by using these three:  header;  start_html;  end_html; 51
  • 52. Cont…  The header function prints out the "Content-type" header. With no arguments, the type is assumed to be "text/html".  start_html prints out the <html>, <head>, <title> and <body> tags. It also accepts optional arguments. If you call start_html with only a single string argument, it's assumed to be the page title. For example:  print start_html("Hello World");  will print out the following*:  <html>  <head> <title>Hello World</title>  <head>  <body> 52
  • 53. Cont…  The end_html function prints out the closing HTML tags:  </body>  </html>  #!C:Perlbinperl.exe  use CGI qw(:standard);  print header;  print start_html("Hello World");  print "<h2>Hello, world!</h2>n";  print end_html; 53
  • 54. Basic HTML  HyperText Markup Language  HTML is the language used to prepare hypertext document.  Web browsers are used to view HTML documents and display data to users 54
  • 55. HTML Document <html> <head><title>Test Page</title></head> <body> <b>Hello, world</b> </body> </html> Document Structure - Head - Body 55
  • 56. HTML Tags  HTML tags are commands, they tell the browser how to display the text.  There are opening and closing versions for many tags opening tag: <HTML> closing tag: </HTML> 56
  • 57. HTML Tags (continued)  <HTML></HTML> For identifying a text document as an HTML document  <HEAD></HEAD> For creating the head section of page  <BODY></BODY> For enclosing the main section of page  <B></B> For displaying text in boldface  <I></I> For displaying text in italics  <OL></OL> For creating ordered lists  <A></A> For creating links  <FORM></FORM> For creating fill-in forms  <P> For creating a new paragraph  <BR> For creating a line break  <INPUT> For creating form elements 57
  • 58. HTML Tags (continued) The affected text is contained within the tags  <B>Hello</B> ------- Hello  <I>Bye!</I> ---------- Bye  Ordered list <OL> <LI>Apple</LI> <LI>Banana</LI> <LI>Orange</LI> </OL> 1. Apple 2. Banana 3. Orange 58
  • 59. HTML Form  <FORM> and </FORM> mark the beginning and the end of a form  Form establishes the relationship between the form page and the script that will process the current form data  HTML forms are the user interface that provides input to your CGI scripts - Collecting data - Accepting commands 59
  • 60. HTML Form (continued) <HTML><HEAD> <TITLE>My first html page</TITLE></HEAD> <BODY> <FORM method=post action=“aftersubmit.cgi”> Name: <INPUT type=text name=“uname"><BR> Password: <INPUT type=password name=“upwd"><BR> <INPUT type=submit> <INPUT type=reset> </FORM> </BODY></HTML> 60
  • 61. The <FORM> Tag  <FORM method=post action=“aftersubmit.cgi”> Tag attributes specify the properties for the element  Method determines how the form data is sent to the script - GET-- delivers form data by appending it to the URL of the script - POST-- sends the data as a body of text  action specifies the address of the script that is going to process the current form data 61
  • 62. The <INPUT> Tags  INPUT - is an element of the form - creates a wide variety of interface widgets  <INPUT type=text name=“uname">  Attribute “type”— the appearance and features <INPUT type=text>-------text field <INPUT type=submit>-----submit button <INPUT type=reset>------reset button <INPUT type=password>---password field <INPUT type=hidden>-----hidden field 62
  • 63. The <INPUT> Tag (continued)  INPUT attribute "name" identifies each user interface element <input type=text name=“uname"> <input type=password name=“upwd">  INPUT attribute "value" contains associated information that is also sent to the script. <input type=text name=“uname"> <input type=text name=“uadd"> <input type=text name=“ucity“ value=“Edmonton”> 63
  • 64. Form Submission <FORM method=post action = “aftersubmit.cgi”>  The browser assembles the form data (name and password) into a series of name/value pairs  The browser delivers data to the server and then the script “aftersubmit.cgi”  The script “aftersubmit.cgi” can retrieve the element value by using its name (uname and upwd) 64
  • 65. Forms: Checkbox  Checkboxes allow the viewer to select one or more options on a form. If you assign each checkbox field a different name, you can print them the same way you'd print any form field using param('fieldname').  Here is the HTML code for a set of checkboxes:  <b>Pick a Color:</b><br>  <form action="colors.cgi" method="POST">  <input type="checkbox" name="red" value=1> Red<br>  <input type="checkbox" name="green" value=1> Green<br>  <input type="checkbox" name="blue" value=1> Blue<br>  <input type="checkbox" name="gold" value=1> Gold<br>  <input type="submit"> </form>  This example lets the visitor pick as many options as they want — or none, if they prefer. Since this example uses a different field name for each checkbox, you can test it using param:  my @colors = ("red","green","blue","gold");  foreach my $color (@colors) {  if (param($color)) {  print "You picked $color.n"; } } 65
  • 66. Cont…  Since we set the value of each checkbox to 1 (a true value), we didn't need to actually see if param($color) was equal to anything — if the box is checked, its true. If it's not checked, then param($color) is undefined and therefore not true.  The other way you could code this form is to set each checkbox name to the same name, and use a different value for each checkbox:  <b>Pick a Color:</b><br>  <form action="colors.cgi" method="POST">  <input type="checkbox" name="color" value="red"> Red<br>  <input type="checkbox" name="color" value="green"> Green<br>  <input type="checkbox" name="color" value="blue"> Blue<br>  <input type="checkbox" name="color" value="gold"> Gold<br>  <input type="submit"> </form> 66
  • 67. Cont…  param('color') returns a list of the selected checkboxes, which you can then store in an array. Here is how you'd use it in your CGI program:  my @colors = param('color');  foreach my $color (@colors)  {  print "You picked $color.<br>n";  } 67
  • 68. Radiobutton  <b>Pick a Color:</b><br>  <form action="colors.cgi" method="POST">  <input type="radio" name="color" value="red"> Red<br>  <input type="radio" name="color" value="green"> Green<br>  <input type="radio" name="color" value="blue"> Blue<br>  <input type="radio" name="color" value="gold"> Gold<br>  <input type="submit"> </form>  Cgi code:  Since the viewer can only choose one item from a set of radio buttons, param('color') will be the color that was picked:  my $color = param('color');  print "You picked $color.<br>n"; 68
  • 69. Basic Setup  That's the basic set up for a CGI form, but what happens after the user presses Submit? Consider, for example, this simple form:  Name: E-mail:  SUBMIT  Here's the chain of events when the user hits "Submit": 69
  • 71. Cont…  When the user presses Submit, the browser sends the form data to the web server.  The web server launches the CGI program which was written to process this form.  The CGI program does whatever it does with the data. The program might consult a database, perform calculations on the data, use the data to add the user to a mailing list, whatever the programmer wants it to do. Whatever else the program does, it generates a web page using HTML so the user can see the results of submitting the form.  The CGI program passes the HTML back to the web server.  The web server passes the HTML back to the browser.  So there are three pieces to the CGI process: the form on your web page, the web server, and the CGI program. 71
  • 73. Exercise 73  Create an html form having multiple radio buttons showing different different colors. If you select any of the radio button and press submit, then it will call appropriate cgi page and the background color of that page will be same as the color which you have selected from the list.
  • 74. Pattern Matching  Almost every script you write in Perl will have some kind of pattern matching operation .  Patterns are subject to an additional level of interpretation as a regular expression. This is done as a second pass, after variables are interpolated.  To use pattern matching in Perl, first we figure out what we want to find, we write a regular expression to find it, and then we stick that pattern in a situation where the result of finding. 74
  • 75. Cont…  The Binding Operator  When you do a pattern match, you need three things:  the text you are searching through  the pattern you are looking for  a way of linking the pattern with the searched text  As a simple example, let's say you want to see whether a string variable has the value of "success". Here's how you could write the problem in Perl:  $word = "success";  if ( $word =~ m/success/ ) {  print "Found successn";  } else {  print "Did not find successn"; } 75
  • 76. Cont…  There are two things to note here.  First, the "=~" construct, called the binding operator, is what binds the string being searched with the pattern that specifies the search. The binding operator links these two together and causes the search to take place.  Next, the "m/success/" construct is the matching operator, m//, in action. The "m" stands for matching to make it easy to remember. The slash characters here are the "delimiters". They surround the specified pattern. In m/success/, the matching operator is looking for a match of the letter sequence: success.  Generally, the value of the matching statement returns 1 if there was a match, and 0 if there wasn't. 76
  • 77. Regular Expressions  Regular expressions are very powerful tools for matching, searching, and replacing text.  All pattern matching in Perl is based on this concept of regular expressions.  Regular expressions form a standard way of expressing almost any text pattern unambiguously.  Special Characters  Some special characters or combinations of characters have a special meaning and do not represent themselves.  This is what give regular expressions their power.  For example, the lowly period does not stand for a period in a match. Instead, it stands for any character. 77
  • 78. Cont…  The pattern /b.g/ would match "bag", "big", "bug", etc, as well as any other sequence: "b2g", "b&g", "b]g" and so on.  Matching simply means "found somewhere, anywhere, within the searched string".  You can use special characters to specify the position where the search pattern must be located.  A ^ character stands for the beginning of the searched string, so:  /^success/ would match "success" but not "unsuccessful".  A $ character stands for the end of the searched string, so:  /success$/ would match "unsuccess" but not "successful".  Using both ^ and $ together nails the pattern down at both ends, so:  /^success$/ will only match the exact string "success". 78
  • 79. Cont…  Other special characters include:  - a form of a "quote" character | - alternation, used for "or'ing" () - grouping matched elements [] - character class  The first character, "", is used in combination with special letters to take away their special meaning. E.g.:  . will match a period $ will match a dollar sign ^ will match a caret will match a backslash  and so on. 79
  • 80. Cont…  Repetition Characters  The expressions above show you how to match certain characters, but they don't allow you to control how many matches should be made at once. Matching repetition is controlled by a few other special characters:  + means 1 or more matches * means 0 or more matches ? means 0 or 1 matches {n} exactly n matches {m,n} m to n matches 80
  • 81. "Hello world!" to be changed to "Hello mom!" instead.  $mystring =~ s/world/mom/;  print $mystring;  Prints "Hello mom!". The substitution operator s/// replaces the pattern between the s/ and the middle /, with the pattern between the middle / and last /. In this case, "world" is replaced with the word "mom".  Now change "Hello mom!" to say "Goodby mom!".  $mystring =~ s/hello/Goodbye/;  print $mystring;  This does not substitute, and prints "Hello mom!" as before. By default, the search is case sensitive. As before, use the pattern modifier i immediately after the trailing / to make the search case- insensitive.  Okay, ignoring case, change "Hello mom!" to say "Goodby mom!".  $mystring =~ s/hello/Goodbye/i;  print $mystring;  Prints "Goodby mom!". 81
  • 82. Process form with regular expression: first name and last name 82  <html> <head> <title>form page</title> </head> <body> <p>here's my test form</p> <form method = "post" action = "/cgi-bin/RegExpExample.cgi"> <p>First name: <input name = "firstName" type = "text" size = "20"></p> <p>Last name: <input name = "lastName" type = "text" size = "20"></p> <p>Phone number: <input name = "phone" type = "text" size = "20"></p> <p>Date (MM/DD/YY): <input name = "date" type = "text" size = "20"></p> <p>Time (HH:MM:SS): <input name = "time" type = "text" size = "20"></p> <input type = "submit" value = "submit"> <input type = "reset" value = "reset"> </form> </body> </html>
  • 83. Cont… 83  #!C:Perlbinperl.exe  use strict;  use warnings;  use CGI ':standard';  my $firstName = param( "firstName" );  my $lastName = param( "lastName" );  my $phone = param( "phone" );  my $date = param( "date" );  my $time = param( "time" );  print header();  print start_html( -title => "form page" );  if ( $firstName =~ /^w+$/ ) {  print "<p>Hello there Lu$firstName.</p>";  }  if ( $lastName =~ /^w+$/ ) {  print "<p>Hello there Mr./Ms. Lu$lastName.</p>";  }  print end_html();
  • 84. Arrays  An array stores an ordered list of values. While a scalar variable can only store one value, an array can store many. Perl array names are prefixed with an @-sign. Here is an example:  my @colors = ("red","green","blue");  Each individual item (or element) of an array may be referred to by its index number. Array indices start with 0, so to access the first element of the array @colors, you use $colors[0].  when you're referring to a single element of an array, you prefix the name with $ instead of @. The $-sign again indicates that it's a single (scalar) value; the @- sign means you're talking about the entire array. 84
  • 85. Cont…  If you want to loop through an array, printing out all of the values, you could print each element one at a time:  my @colors = ("red","green","blue");  print "$colors[0]n"; # prints "red"  print "$colors[1]n"; # prints "green"  print "$colors[2]n"; # prints "blue"  A much easier way to do this is to use a foreach loop:  my @colors = ("red","green","blue");  foreach my $i (@colors)  {  print "$in";} 85
  • 86. Finding the Length of Arrays  If you want to find out how many elements are in a given array, you can use the scalar function:  my @people = ("Howard", "Sara", "Ken", "Josh");  my $linelen = scalar(@people);  print "There are $linelen people in line.n";  Sorting Arrays  You can do an alphabetical (ASCII) sort on an array of strings using the sort function:  my @colors = ("cyan", "magenta", "yellow", "black");  my @colors2 = sort(@colors); 86
  • 87. Dealing With HTML Components in perl-cgi 87  We can create html form component like: textbox, textarea, buttons, etc, in CGI.  use strict; use warnings; use CGI; my $cgi=new CGI; print $cgi->header(),$cgi- >start_html("Simple Examples"); print $cgi->center("Centered Text"); print $cgi->p("A Paragraph"); print $cgi->br(); print $cgi->b("Bold"),$cgi->i("Italic"); print $cgi->p("A Paragraph",$cgi->sup("A superscript")); print $cgi->end_html();
  • 88. Form Example 88  use CGI; $co = new CGI; print $co->header, $co->start_html(-title=>'CGI Example'), $co->center($co->h1('Welcome to CGI!')), $co->start_form(), $co->textarea ( -name=>'textarea', -rows=>10, -columns=>60 ), $co->end_form(), $co->end_html; #!C:Perlbinperl use CGI ':standard'; print header(); print "Form Elements", br(), br(), br(); print start_form; print "A Text Box: &nbsp; &nbsp; &nbsp; ", textfield('surname', 'Default', 50), br(); print "A Select Box: &nbsp; &nbsp; &nbsp; ", popup_menu('SelectBox', ['Perl', 'Web', 'Development']); print p, "Text Area: &nbsp; &nbsp; &nbsp;", textarea('comments', 'Default Text', 10, 50); print p, "CheckBoxes: ", checkbox_group('check1', ['one', 'two', 'three']); print p, "Radio Buttons: ", radio_group('radio1', ['a', 'b', 'c']); print p, submit(); print end_form; if (param()) { print "The surname you entered was: ",em(param('surname')), p, "The Selections are: ",em(join(", ",param('SelectBox'))), p, "The comments box contains: ",em(param('comments')), p, "you selected checkbox: ",em(param('check1')), p, "you selected radio: ",em(param('radio1')); }
  • 89. Dealing With Files In PERL  Reading Files:  STEP 1: Open the file for reading: open(DFH, “data.txt") || die (“Can’t Open file”);  STEP 2: Read the data from the file: @rawData = <DFH>;  STEP 3: Close the file: close(DFH); 89
  • 90. Dealing With Files In PERL (Continued)  Writing to files:  STEP 1: Open the file for writing: open(DFH, “>data.txt") || die (“Cannot Open file”);  STEP 2: Write data to the file: print DFH “New Data”;  STEP 3: Close the file: close(DFH); 90
  • 91. Dealing With Files In PERL (Continued)  Appending Files:  STEP 1: Open the file for appending: open(DFH, “>>data.txt") || die (“Cannot Open file”);  STEP 2: Write data at the end of the file: print DFH “Another data line”;  STEP 3: Close the file: close(DFH); 91
  • 92. Reading Data File  When you build large web application, you will need to store data and retrieve it later  Text files are the simplest way to maintain data 92
  • 93. Reading And Writing Data File (script) #!C:Perlbinperl.exe open(SRC, “file.txt”) || die “Could not open source file.n”; open(DST, “>newfile.txt”); while ( $line = <SRC> ) { print DST $line; } close SRC; close DST; 93
  • 94. File Handle  The file handles are just the things we use when we are dealing with files.  A file handle is associated with a file by the open statement. open (FILE, $filename)  All the interaction with a file is done by the file handle. @filecontent = <FILE> -- get the whole file $filecontent = <FILE> ---- get the first line 94
  • 95. Writing Data File #!C:Perlbinperl.exe use CGI; $q=new CGI; print "Content-type: text/htmlnn"; my $name=$q->param("name"); my $outputfile="users.txt"; if (open (OUTPUT, ">>$outputfile")) # open a file { print OUTPUT "$namen"; # write the user name to the file print "<HTML><BODY>Thank you! $name</BODY></HTML>"; } 95 <html> <head> </head> <body> <form action="/cgi-bin/FileRead_Html.cgi" method="post"> <input type="text" name="name"> <input type="submit" name="submit" value="Go"> </form> </body> </html>
  • 96. Writing Data File (continued)  Opening a file for writing - For overwriting open (OUTPUT, ">>$outputfile") - For appending open (OUTPUT, ">$outputfile")  Without “>>” and “>”, the file is opened for reading open (OUTPUT, "$outputfile")  Creating the output file and making it writable touch users.txt chmod a+w users.txt 96
  • 97. Exercise 97  Create a login page using perl-cgi script, read the user name and password from existing .txt file. After pressing the submit button it should show the Message of successful or unsuccessful login.  Write a Perl script that will take as input a file called “foo.txt”, produce as output a file called “bar.txt”; lines in input will be copied to output, except for the following transformations:  any line with the string “IgNore” in it will not go to output  any line with the string “#” in it will have that character and all characters after it, to end of line, removed  any string “*DATE*” will be replaced by the current date in output •We have a file containing lines in different formats. We want to pick out the lines which start with a digit and end in a period.
  • 98. Debugging  Default response of the server: "Internal Server Error" --- not useful  Better ways: In the script use CGI::Carp qw(fatalsToBrowser); In the UNIX shell (check the syntax) perl -cw scriptname.cgi 98 see the error in your browser instead of the error logs If you want to do a similar thing with Perl warnings as well, use this instead: use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
  • 99. Debugging (continued)  use CGI::Carp qw(fatalsToBrowser); 99
  • 100. What is cgi-lib.pl?  Cgi-lib is a CGI parsing library written by Steven Brenner.  The cgi-lib.pl library that was become the first standard perl library to help parse and deal with CGI Web based interfaces.  The cgi-lib.pl library makes CGI scripting in Perl easy enough for anyone to process forms and create dynamic Web content. The library has the following features:  Extremely simple to learn and easy to use  Designed for operation under Perl5 and Perl4  Very efficient  Compatibility with all CGI interactions  Compatible with Perl5 security features such as taint, warnings, (command line options -Tw) and use strict;  Debugging facilities 100
  • 101. Cont…  The cgi-lib.pl Perl library simply consists of handy, easy-to- use Perl functions. The library is more than simply a means of processing CGI input. The library includes subroutines to:  Read and parse CGI input -- a value(s) for a given name can be easily found.  Conveniently format CGI output.  Conveniently return Headers and Bottoms of standard CGI output.  Conveniently return URLs.  Conveniently return CGI Error Codes.  Print in HTML format all name/value pairs input.  Print in HTML format Environment variables.  The cgi-lib.pl input routines can accept all and process all methods of input (e.g. GET and POST methods). You do not have to worry about which mechanism has been adopted. 101
  • 102. A Sample Form Response CGI Perl Script  In this subsection we will develop a minimal.pl CGI routine that accepts input form our minimal form and sends back HTML that echoes the input data.  We will use the cgi-lib.pl to  Parse the input from the form.  Format the HTML output.  We will need to learn some more basic Perl:  How to include and call Perl libraries.  How to call Perl subroutines  The first thing our Perl script will need to do is to include the Perl library file cgi-lib.pl.  The Perl command require will load in any external Perl file. It is easier and sometimes essential that all library files exist in the same folder or directory as the main Perl script calling the library.  Therefore make sure that all Perl files required for a Perl program do exist at the same folder or directory level. 102
  • 103. Cont…  Thus to include our cgi-lib.pl file we need the Perl command:  require "cgi-lib.pl";  Having included the library we can call on its many useful subroutines.  The &ReadParse() subroutine reads either GET or POST input and conveniently stores the name/value pairs in a Perl array.  Thus a Perl call of the form:  &ReadParse(*input);  will store the input in an array input.  & is used to indicate a Perl subroutine call.  Next we will need to extract out the relevant value of a given name.  In our current example there is only one input field and we are therefore only interested in the value associated with the myfield name.  To get this value you simply do: $input{'myfield'}  Thus to print out the value typed we could do something like:  print "You typed: " . $input{'myfield'} . "n"; 103 http://stein.cshl.org/WWW/CGI/cgi-lib_porting.html
  • 104. A first minimal Perl script  minimalExample.html  <html>  <head><title>Sample Example</title></head>  <body bgcolor="white"><form method="post"  action="/cgi-bin/minimal.cgi">  Please enter your name:<br>  <input type="text" name="myfield" size="35"><br>  <input type="submit" value="Send">  <input type="reset" value="Reset">  </form>  </body>  </html> Minimal.cgi #!C:Perlbinperl # This is the minimalist form script # to demonstrate the use of # the cgi-lib.pl library require "cgi-lib.pl"; # Read in all the variables set by the form &ReadParse(*input); print "Content-Type: text/htmlnn"; print "<html> <head>n"; print "<title>Sample Input</title>n"; print "</head>n"; print "<body>n"; print "You typed: " . $input{'myfield'} . "n"; print "</body> </html>n"; 104
  • 105. A second minimal Perl script  some more cgi-lib.pl subroutines:  Nearly every CGI output has:  exactly the same header output.  similar HTML head information  similar HTML ending  Fortunately subroutines exist to save us typing this same information all the time.  The &PrintHeader subroutine returns the string:  Content-Type: text/htmlnn  Thus we can use print in conjunction to produce our CGI header output via:  print &PrintHeader; 105
  • 106. Cont..  The &HtmlTop subroutine accepts a single string argument, MY TITLE say, and return an HTML Head and Body (opening only) with the argument as the HTML page TITLE and H1 Header. I.e.  <html>  <head>  <title>MY TITLE</title>  </head>  <body>  <h1>MY TITLE</h1>  which is rather useful.  The &HtmlBot subroutine is the compliment of &HtmlTop and returns:  </body>  </html> 106
  • 107. Cont…  Thus we can use these functions and we only need to provide the main HTML body ourselves.  Thus we develop a better minimal.cgi program as follows  #!C:Perlbinperl  # minimal.cgi  # This is the minimalist form script  # to demonstrate the use of  # the cgi-lib.pl library  require "cgi-lib.pl";  # Read in all the variables set by the form  &ReadParse(*input);  # Print the header + html top  print &PrintHeader;  print &HtmlTop ("Minimal Input");   print "You typed: " . $input{'myfield'} . "n";  print &HtmlBot; 107
  • 108. Installing and Using MySQL  In order to successfully connect to a MySQL database with Perl, you will first need to ensure that the MySQL drivers are installed on your system.  DBI (DataBase Interface) and DBD:MySQL (DataBase Driver for MySQL).  First, we need to start the Perl Package Manager. Click on your start menu and select the Run...option. In the pop-up window, type cmd and hit enter.  This will bring up the Windows command line.  If you did the default install of ActiveState's ActivePerl, you should be able to type ppm at the prompt to start the Perl Package Manager.  First comes the DBI (DataBase Interface) which can be installed by typing install DBI.  Finally we install the MySQL driver for the DBI. This is done by typing install DBD-mysql. 108
  • 109. Cont…  When you are able to do some basic administration tasks, let's create a database called mydb in mysql.  And in that database, we will create a simple table called ofuser and populate it with some data.  Here is the SQL you'll need to create the table and fill in a few records, just connect to your MySQL database and run them.  CREATE DATABASE mydb;  USE mydb;  CREATE TABLE ofuser ( id int(10) unsigned NOT NULL auto_increment, name varchar(128) NOT NULL default '', phone varchar(128) NOT NULL default '', PRIMARY KEY (id) );  INSERT INTO ofuser VALUES (1, 'Some Person', '555');  INSERT INTO ofuser VALUES (2, 'Another Person', '222'); 109
  • 110. Cont…  Now that we have a database to connect to, let's look at how we access the information from our Perl programs. The following is a simple script that connects to the database and runs a short bit of SQL to retrieve all the samples.  #!C:Perlbinperl.exe  use strict;  use CGI::Carp qw(fatalsToBrowser);  use CGI qw(:standard);  use DBI;  my $dbh;  my $user = "root";  my $password = "admin";  print header,  start_html;  $dbh = DBI->connect("dbi:mysql:database=mydb;host=localhost:3306;", $user, $password);  my $sth = $dbh->prepare('select * from ofuser');  $sth->execute;  print "<ul>";  while (my @row = $sth->fetchrow_array) {  print "<li>@rowt";  }  print "</ul>";  print end_html; The first thing we need to do is let the Perl interpreter know that we intend to use the Perl DBI function library, by including it in our program with the use function. Next we'll need to create a connection to the database itself. For this part of the script, your mydb database will need to be running. Finally we use the fetchrow_array function to fetch each row of the results from the MySQL database and print them one to a line. 110
  • 111. Exercise 111  Create an html login form, try to authenticate it via mysql database and if authentication is valid then it should go to welcome page displaying your user name and your details.
  • 112. Using Cookies in CGI  HTTP protocol is a stateless protocol.  But for a commercial website it is required to maintain session information among different pages.  For example one user registration ends after completing many pages.  But how to maintain user's session information across all the web pages. 112
  • 113. Cont…  In many situations, using cookies is the most efficient method of remembering and tracking preferences, purchases, commissions, and other information required for better visitor experience or site statistics. 113
  • 114. Cont…  How It Works  Your server sends some data to the visitor's browser in the form of a cookie.  The browser may accept the cookie.  If it does, it is stored as a plain text record on the visitor's hard drive.  Now, when the visitor arrives at another page on your site, the cookie is available for retrieval.  Once retrieved, your server knows/remembers what was stored. 114
  • 115. Cont…  Cookies are a plain text data record of 5 variable-length fields:  Expires : The date the cookie will expire. If this is blank, the cookie will expire when the visitor quits the browser.  Domain : The domain name of your site.  Path : The path to the directory or web page that set the cookie. This may be blank if you want to retrieve the cookie from any directory or page.  Secure : If this field contains the word "secure" then the cookie may only be retrieved with a secure server. If this field is blank, no such restriction exists.  Name=Value : Cookies are set and retrviewed in the form of key and value pairs. 115
  • 116. Example  Setting up Cookies  This is very easy to send cookies to browser. These cookies will be sent along with HTTP Header. Assuming you want to set UserID and Password as cookies. So it will be done as follows:  #!C:Perlbinperl.exe  use strict;  use CGI qw(:standard);  use CGI::Carp qw(warningsToBrowser fatalsToBrowser);  print "Set-Cookie:UserID=XYZ;n";  print "Set-Cookie:Password=XYZ123;n";  print "Set-Cookie:Expires=Tuesday, 25-Dec-2012 23:12:40 GMT n";  print "Content-type:text/htmlrnrn";  From this example you must have understood how to set cookies. We use Set-Cookie HTTP header to set cookies. #!C:Perlbinperl.exe use strict; use CGI qw/:standard/; use CGI::Carp qw(warningsToBrowser fatalsToBrowser); my $cookie = cookie( -name=>'CGI-PERL-COOKIE-EXAMPLE', value=>'cookie.linuxconfig.org', -expires=>'+1y'); print header (-cookie=>$cookie), start_html('CGI Cookie with Exipire Date'), p("Cookie had been saved !n"), end_html; exit; The following code uses same principles of creating a cookies however on larger scale. When creating a cookies we need to keep in mind that there is a limitation of maximum 20 cookies per domain. Use a following code to create multiple cookies simultaneously. The code first creates a scalar variable to hold a cookies definitions and then we print a header with both cookies in form of array. #!C:Perlbinperl.exe use strict; use CGI qw/:standard/; my $cookie1 = cookie(- name=>'cookie_one',value=>'value1',expires=>'+1d'); my $cookie2 = cookie(- name=>'cookie_two',value=>'value2',expires=>'+10y'); print header (-cookie=>[$cookie1,$cookie2]), start_html('CGI Multiple Cookie Example'), p("Cookies received!n"), end_html; exit; 116
  • 117. Retrieving Cookies  This is very easy to retrieve all the set cookies. Cookies are stored in CGI environment variable HTTP_COOKIE and they will have following form.  key1=value1;key2=value2;key3=value3....  Here is an example of how to retrieving cookies.  #!C:Perlbinperl.exe  use strict;  use CGI qw(:standard);  use CGI::Carp qw(warningsToBrowser fatalsToBrowser);  my $cookie;my $key;my $val;my $user_id;my $password;  print "Content-type:text/htmlrnrn";  my $rcvd_cookies = $ENV{'HTTP_COOKIE'};  my @cookies = split /;/, $rcvd_cookies;  foreach $cookie ( @cookies ){  ($key, $val) = split(/=/, $cookie); # splits on the first =.  $key =~ s/^s+//;  $val =~ s/^s+//;  $key =~ s/s+$//;  $val =~ s/s+$//;  if( $key eq "UserID" ){  $user_id = $val;  }elsif($key eq "Password"){  $password = $val;  }  }  print "User ID = $user_idn";  print "Password = $passwordn"; #!C:Perlbinperl.exe use strict; use CGI qw/:standard/; use CGI::Carp qw(warningsToBrowser fatalsToBrowser); my $retrieve_cookie = cookie('CGI-PERL-COOKIE-EXAMPLE'); print header, start_html, p("Cookie value is $retrieve_cookien"), end_html; exit; Similarly the code below retrieves multiple cookies at once: #!C:Perlbinperl.exe use strict; use CGI qw/:standard/; my $retrieve_cookie1 = cookie('cookie_one'); my $retrieve_cookie2 = cookie('cookie_two'); print header, start_html, p("COOKIE_ONE Value: $retrieve_cookie1 n"), p("COOKIE_TWO Value: $retrieve_cookie2 n"), end_html; exit; 117
  • 118. What is sendmail?  Sendmail is the most popular Unix-based implementation of the Simple Mail Transfer Protocol (SMTP) for transmitting e-mail.  When a sendmail server receives e-mail, it attempts to deliver the mail to the intended recipient.  However, because it does not provide a mailbox facility and for other reasons, other software such as a POP3 or Internet Message Access Protocol server are also needed.  Most Internet service providers (ISPs) provide both an SMTP server (such as sendmail) and a POP or IMAP server. 118
  • 119. How does sendmail for windows work?  In perl or php or asp scripts we can write a code to send mail to mail recepients.  We direct data to program sendmail.exe who sends email to person or persons that our script sends.  So all we need is to send header and email-msg to sendmail.exe program and that is it. 119
  • 120. Installation of sendmail.exe  All of scripts are in cgi-bin folder (for example c:Inetpubwwwroottestdomain.comhttpdoc scgi-bin). "Cgi-bin" folder must have execute permissions. 120
  • 121. Cont…  Download sendmail.zip  http://velikan.net/sendmail-for-windows-iis/sendmail.zip  Now upload sendmail.zip to your cgi-bin folder end extract contents.  Next step is to edit sendmail.ini file. You only need to set your domain and if you do not have your own smtp server installed on your server you can write smtp mail server of your internet service provider. 121
  • 122. Cont… That is it. You have successfully installed sendmail.exe program for windows - now only thing for you is to use it... 122
  • 123. Example  #!C:Perlbinperl.exe  use CGI qw(:standard);  use CGI::Carp qw(warningsToBrowser fatalsToBrowser);  use strict;  print "Content-type: text/htmlnn";  my $title='Perl Mail demo';  my $to='girish092.ch@gmail.com';  my $from= 'girish092.ch@gmail.com';  my $subject='YOUR SUBJECT';  open(MAIL, "|sendmail/sendmail.exe -t");  ## Mail Header  print MAIL "To: $ton";  print MAIL "From: $fromn";  print MAIL "Subject: $subjectnn";  ## Mail Body  print MAIL "This is a test message from CGI-Perl! You can write your  mail body text heren";  close(MAIL);  print "<html><head><title>$title</title>  </head>n<body>nn";  ## HTML content let use know we sent an email  print "<h1>$title</h1>n";  print "<p>A message has been sent from $from to $to";  print "nn</body></html>"; 123
  • 124. In UNIX 124  #!/usr/bin/perl  print "Content-type: text/htmlnn";  $title='Perl Mail demo';  $to='MAIL ADDRESS TO SEND TO';  $from= 'webmaster@YOURDOMAIN.COM';  $subject='YOUR SUBJECT';  open(MAIL, "|/usr/sbin/sendmail -t");  ## Mail Header  print MAIL "To: $ton";  print MAIL "From: $fromn";  print MAIL "Subject: $subjectnn";  ## Mail Body  print MAIL "This is a test message ! You can write your mail body text heren";  close(MAIL);  print "<html><head><title>$title</title> </head>n<body>nn";  ## HTML content let use know we sent an email  print "<h1>$title</h1>n";  print "<p>A message has been sent from $from to $to";  print "nn</body></html>";
  • 126. 126