An 15 minute introduction to web applications and writing them in Perl with CGI.pm and mod_perl v1 and v2

1. WEB APPS WITH PERL
HTTP 101
HENDRIK VAN BELLEGHEM
HENDRIK.VANBELLEGHEM@GMAIL.COM

2. UNDERSTANDING HTTP
ONE PAGE, MANY PACKETS

3. UNDERSTANDING HTTP
DOCUMENT REQUEST

4. UNDERSTANDING HTTP
RESPONSE STATUS

5. UNDERSTANDING HTTP
REQUEST DOMAIN

6. UNDERSTANDING HTTP
RESPONSE SIZE

7. UNDERSTANDING HTTP
RESPONSE TIME

8. UNDERSTANDING HTTP

9. UNDERSTANDING HTTP
BROWSER SENDS

10. UNDERSTANDING HTTP
WEBSERVER RESPONDS

11. DIY
CGI SCRIPT - HELLO WORLD
#!/usr/bin/perl
print quot;Content-type: text/htmlnnquot;;
print quot;Hello Worldquot;;

12. DIY

13. DIY
CGI SCRIPT - INTERACTION
#!/usr/bin/perl
print quot;Content-type: text/htmlnnquot;;
@pairs = split(/&/, $ENV{'QUERY_STRING'});
foreach $pair (@pairs)
{ ($name, $value) = split(/=/, $pair);
$value =~ tr/+/ /;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack(quot;Cquot;, hex($1))/eg;
$value =~ s/n/ /g;
$request{$name} = $value;
}
print quot;Hello quot;,$request{'name'};

14. DIY

15. DIY
CGI SCRIPT - INTERACTION
#!/usr/bin/perl
MY EYES!!!!
print quot;Content-type: text/htmlnnquot;;
@pairs = split(/&/, $ENV{'QUERY_STRING'});
foreach $pair (@pairs)
{ ($name, $value) = split(/=/, $pair);
$value =~ tr/+/ /;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack(quot;Cquot;, hex($1))/eg;
$value =~ s/n/ /g;
$request{$name} = $value;
}
THE HORROR!!!!
print quot;Hello quot;,$request{'name'};

16. CGI.PM
CGI SCRIPT - HELLO WORLD
#!/usr/bin/perl
use CGI qw(header);
print header;
print “Hello world”;

17. CGI.PM
CGI SCRIPT - INTERACTION
#!/usr/bin/perl
use CGI qw(header param);
print header;
my $name = param(‘name’);
print “Hello $name”;

18. CGI.PM
TRANSPARENT POST & GET
FILE UPLOADS
QUICK COOKIES
HTML GENERATION (NOT MY FAVORITE)
FUNCTION SETS: :CGI = PARAM , HEADER, ...
DROP-IN DEVELOPMENT

19. MOD_PERL
PERL AS AN APACHE MODULE
INTERACT WITH EVERY STEP OF APACHE REQUEST CYCLE
PERSISTENT COPY OF PERL IN MEMORY
NO DROP-IN DEVELOPMENT
EXCEPT FOR APACHE::RELOAD

20. MOD_PERL 1
16 CYCLES IN MOD_PERL 1
CONTENT HANDLER: PERLHANDLER
LOG HANDLER: PERLLOGHANDLER
AUTHENTICATION HANDLER

21. MOD_PERL 2
21 CYCLES IN MOD_PERL 2
CONTENT HANDLER: PERLRESPONSEHANDLER
LOG HANDLER: PERLLOGHANDLER
AUTHENTICATION HANDLER

22. MOD_PERL 1
CONTENT HANDLER - HELLO WORLD
package Apache::HelloWorld;
use Apache::Constants qw(:common); # Export OK
sub handler
# mod_perl uses handler method unless specified otherwise
{ print quot;Content-type: text/plainnnquot;; # MY EYES!!
print quot;Hello Worldnquot;;
return OK; # read as HTTP status 200
}
1;
PerlModule Apache::HelloWorld
<Location /HelloWorld>
SetHandler perl-script
PerlHandler Apache::HelloWorld
</Location>
http://localhost/HelloWorld/

23. MOD_PERL 1
CONTENT HANDLER - HELLO WORLD REVISED
package Apache::HelloWorld;
use Apache::Constants qw(:common); # Export OK
sub handler
# mod_perl uses handler method unless specified otherwise
{ my $r = shift;
# 1st argument is instance of Apache's Request object
$r->send_http_header('text/plain');
# Send HTTP header (similar to CGI's header)
$r->print(quot;Hello Worldnquot;);
return OK; # read as HTTP status 200
}
1;
PerlModule Apache::HelloWorld
<Location /HelloWorld>
SetHandler perl-script
PerlHandler Apache::HelloWorld
</Location>
http://localhost/HelloWorld/

24. MOD_PERL 1
CONTENT HANDLER - HELLO BOB!
package Apache::HelloBob
use Apache::Constants qw(:common); # Export OK
sub handler
# mod_perl uses handler method unless specified otherwise
{ my $r = shift;
# 1st argument is instance of Apache's Request object
my %query_string = $r->args; # GET data
my %post_data = $r->content; # POST data
my $name = $query_string{'name'};
$r->send_http_header('text/plain');
# Send HTTP header (similar to CGI's header)
$r->print(quot;Hello $namenquot;);
return OK; # read as HTTP status 200
}
1;
http://localhost/HelloBob?name=Bob

25. APACHE::REQUEST (A::R)
INHERITS FROM APACHE CLASS
MIMICS CGI.PM METHODS
SUPPORTS FILE UPLOADS
SUPPORTS COOKIES - APACHE::COOKIE / APACHE2::COOKIE
AVAILABLE FOR MOD_PERL V1 & V2

26. MOD_PERL 1
CONTENT HANDLER - HELLO BOB WITH A::R
package Apache::HelloWorld;
use Apache::Constants qw(:common); # Export OK
use Apache::Request (); # isa Apache
sub handler
# mod_perl uses handler method unless specified otherwise
{ my $r = shift;
my $apr = Apache::Request->new($r);
# Pass Apaches Request object to A::R
$apr->send_http_header('text/plain');
my $name = $apr->param(‘name’);
# Send HTTP header (similar to CGI's header)
$apr->print(quot;Hello $namenquot;);
return OK; # read as HTTP status 200
}
1;
http://localhost/HelloWorld?name=Bob

27. MOD_PERL 2
CONTENT HANDLER - HELLO WORLD
package Apache2::HelloWorld;
use Apache2::Const qw(:common); # Export OK
sub handler
# mod_perl2 uses handler method unless specified otherwise
{ print quot;Content-type: text/plainnnquot;; # MY EYES!!
print quot;Hello Worldnquot;;
return OK; # read as HTTP status 200
}
1;
PerlModule Apache2::HelloWorld
<Location /HelloWorld>
SetHandler perl-script
PerlResponseHandler Apache2::HelloWorld
</Location>
http://localhost/HelloWorld/

28. MOD_PERL 2
CONTENT HANDLER - HELLO WORLD REVISED
package Apache2::HelloWorld;
use Apache2::Const qw(:common); # Export OK
sub handler
# mod_perl2 uses handler method unless specified otherwise
{ my $r = shift;
# 1st argument is instance of Apache's Request object
$r->content_type('text/plain');
# Send HTTP header (similar to CGI's header)
$r->print(quot;Hello Worldnquot;);
return OK; # read as HTTP status 200
}
1;
PerlModule Apache2::HelloWorld
<Location /HelloWorld>
SetHandler perl-script
PerlResponseHandler Apache2::HelloWorld
</Location>
http://localhost/HelloWorld/

29. MOD_PERL 2
CONTENT HANDLER - HELLO BOB WITH A2::R
package Apache2::HelloBob;
use Apache2::Const qw(:common); # Export OK
use Apache2::Request (); # isa Apache
sub handler
# mod_perl uses handler method unless specified otherwise
{ my $r = shift;
my $apr = Apache2::Request->new($r);
# Pass Apaches Request object to A2::R
$apr->send_http_header('text/plain');
my $name = $apr->param(‘name’);
# Send HTTP header (similar to CGI's header)
$apr->print(quot;Hello $namenquot;);
return OK; # read as HTTP status 200
}
1;
http://localhost/HelloWorld?name=Bob