1. CGI II: Cookies & Stuff
Web Programming

2. HTTP Cookie Mechanism to store/retrieve information on the HTTP client
Web server sends a “cookie” in HTTP response header
cookie is stored as text file (not executable) on the client’s local drive
cookie is included in subsequent HTTP request headers until expiration
Syntax
HTTP Response
Cookie is created & sent from Web Server to Web Client (e.g., Internet Explorer)
Set-Cookie: NAME=VALUE; expires=DATE; domain=DOMAIN_NAME; path=PATH
e.g. Set-Cookie: user=kiyang; expires=Thursday, 09-Dec-10 11:11:22 GMT; domain= kiyang.kmu.ac.kr; path=/~kiyang/teaching
HTTP Request
Cookie is returned from Web Client to Web Server
Cookie: NAME1=VALUE1; NAME2=VALUE2; ..
e.g. Cookie: user=kiyang;
Web Programming

3. Cookies with CGI.pm Setting Cookies Getting Cookies
$cookie = cookie ( -name => “WP-cookie”, -value => “$cookieID”, -path=> “/teaching/WP/f10’, -expires=>’+24h’); print header (-cookie=>$cookie);
Getting Cookies
$cookie_value = cookie (‘cookie-name’);
 Example: Form Form CGI CGI (sending cookie) CGI (checking cookie)
Web Programming

4. Fetching Web Pages Using LWP::Simple #!/usr/bin/perl use LWP::Simple;
$url=
$body= get($url);
print $body;
Example script
Web Programming

5. Fetching Web Pages Using WWW-Mechanize
use WWW::Mechanize;
$url= "
# Create a mechanize object
my $mech = WWW::Mechanize->new( autocheck => 1 );
# Fetch a page
$mech->get($url);
print $mech->content;
# Fetch a page into a file
$mech->get($url,":content_file"=>"hello.htm");
# Get links
@links= $mech->links(); array of link object
foreach {
my($url,$text,$absurl)= ($link->url(), $link->text, $link->url_abs());
print “$url, $text, $absurl\n”; }
# Find links
$link= $mech->find_link(url_abs_regex=>qr|^
$page= $mech->follow_link(url_abs_regex=>qr|^
@pages= $mech->follow_all_links(url_abs_regex=>qr|^
Mechanized Spider Example: HTML, CGI
S517 Session 13, SLIS-IU

6. CGI Examples Email Webpage Fetch File Upload Simple Search
HTML form
CGI
Webpage Fetch
File Upload
Simple Search
Advanced Search
S517 Session 10, SLIS-IU

7. Reference/Pointer A reference Syntax
a pointer to something (e.g. array, hash)
a variable that refer to other variables
contain a memory address of data
good for
working with large data structures
creating complex data structures
Syntax
to create a reference
$ptr1= \$scalar; $ptr2= $ptr3= \%hash;
$ptr4= [1, 2, 3]; $ptr5= { k1=>v1, k2=>v2}
to get the value
Variable (i.e. scalar, array, hash)
$$ptr1; @$ptr2; %$ptr3;
Element of array/hash
$$ptr2[0]; $$ptr3{0};
$ptr2->[0]; $ptr3->{0};
S517 Session 12, IU-SLIS

8. Multi-dimensional Arrays
Using anonymous arrays
$array = [ [id1,pw1], [id2,pw2], [id3,pw3] ];
for ($i=0; $i<=2; $i++) { for ($j=0; $j<=1; $j++) { print “$array -> [i][j]\n”; }
Using array references
@a1= (id3,pw3);
@array = # array of array pointers
for ($i=0; $i<=2; $i++) {
$ptr= $array[$i];
print
Examples: #1, #2, #3, #4, #5
S517 Session 12, IU-SLIS