tives. A good way to go about creating a system configuration is by defining what you need in a Perl module and call it Constants.pm and include it in the base class you are using to build framework. An example might look something like:

#!/usr/bin/perl

package Website::Constants;

use constant DOMAIN => ‘www.mydomain.com’; use constant CONTENT => ‘/home/httpd/mydomain/content’; use constant TEMPLATE_

Introduction

There are many application frameworks around for various programming languages to simplify the development of web applications, sometimes though there comes a time when the ready-made solutions don’t cover what you need to do or don’t do what you need in an intuitive way. An application framework is often referred to as middle-ware or back-end system. The goal is to take the heavy work away from the front-end that serves up to pages, abstract it, and push it down the stack of the operating environment. Common things included to make live easier in developing a web site front-end are handling of database interaction, templating for content and output files, communicating with remote servers, configuration of web site, and handling email. In this article I aim to outline how you can create this functionality through an object-orientated mod_perl approach.

The front-end should make use of separate objects for each page/functional unit of the web site and should inherit from the base class, for our purposes we will call this Base.pm.

Base class, Configuration & Control flow

A global configuration for your website can be used to store common attributes to the web environment, this would include paths and URL locations of content, data, images, etc. You could also include paths to email program or SMTP host used for sending email. Locations of template files you will use for content should also be specified in a configuration file. Other attributes such as domain name, database details such as name, user and password, location of apache http auth password files and general purpose apache configuration directives. A good way to go about creating a system configuration is by defining what you need in a Perl module and call it Constants.pm and include it in the base class you are using to build framework. An example might look something like:

#!/usr/bin/perl

package Website::Constants;

use constant DOMAIN => ‘www.mydomain.com’; use constant CONTENT => ‘/home/httpd/mydomain/content’; use constant TEMPLATE_P

away from the front-end that serves up to pages, abstract it, and push it down the stack of the operating environment. Common things included to make live easier in developing a web site front-end are handling of database interaction, templating for content and output files, communicating with remote servers, configuration of web site, and handling email. In this article I aim to outline how you can create this functionality through an object-orientated mod_perl approach.

The front-end should make use of separate objects for each page/functional unit of the web site and should inherit from the base class, for our purposes we will call this Base.pm.

Base class, Configuration & Control flow

A global configuration for your website can be used to store common attributes to the web environment, this would include paths and URL locations of content, data, images, etc. You could also include paths to email program or SMTP host used for sending email. Locations of template files you will use for content should also be specified in a configuration file. Other attributes such as domain name, database details such as name, user and password, location of apache http auth password files and general purpose apache configuration directives. A good way to go about creating a system configuration is by defining what you need in a Perl module and call it Constants.pm and include it in the base class you are using to build framework. An example might look something like:

#!/usr/bin/perl

package Website::Constants;

use constant DOMAIN => ‘www.mydomain.com’; use constant CONTENT => ‘/home/httpd/mydomain/content’; use constant TEMPLATE_

lity through an object-orientated mod_perl approach.

The front-end should make use of separate objects for each page/functional unit of the web site and should inherit from the base class, for our purposes we will call this Base.pm.

Base class, Configuration & Control flow

A global configuration for your website can be used to store common attributes to the web environment, this would include paths and URL locations of content, data, images, etc. You could also include paths to email program or SMTP host used for sending email. Locations of template files you will use for content should also be specified in a configuration file. Other attributes such as domain name, database details such as name, user and password, location of apache http auth password files and general purpose apache configuration directives. A good way to go about creating a system configuration is by defining what you need in a Perl module and call it Constants.pm and include it in the base class you are using to build framework. An example might look something like:

#!/usr/bin/perl

package Website::Constants;

use constant DOMAIN => ‘www.mydomain.com’; use constant CONTENT => ‘/home/httpd/mydomain/content’; use constant TEMPLATE_

clude paths and URL locations of content, data, images, etc. You could also include paths to email program or SMTP host used for sending email. Locations of template files you will use for content should also be specified in a configuration file. Other attributes such as domain name, database details such as name, user and password, location of apache http auth password files and general purpose apache configuration directives. A good way to go about creating a system configuration is by defining what you need in a Perl module and call it Constants.pm and include it in the base class you are using to build framework. An example might look something like:

#!/usr/bin/perl

package Website::Constants;

use constant DOMAIN => ‘www.mydomain.com’; use constant CONTENT => ‘/home/httpd/mydomain/content’; use constant TEMPLATE_

tives. A good way to go about creating a system configuration is by defining what you need in a Perl module and call it Constants.pm and include it in the base class you are using to build framework. An example might look something like:

#!/usr/bin/perl

package Website::Constants;

use constant DOMAIN => ‘www.mydomain.com’; use constant CONTENT => ‘/home/httpd/mydomain/content’; use constant TEMPLATE_PATH => ‘/home/httpd/mydomain/templates’

Control flow can be managed by a starter script which accepts what module to use along with its regular CGI parameters. This file should include any global options and/or variables, in our case here we initial a random number with srand to seed random functions and declare our database handle as $dbh.

Note the use of the hash to store object/page modules, using a lookup in this method prevents a nefarious user from inserting malicious code to be executed.

Starter script example:

#!/usr/bin/perl

use CGI; use CGI::Carp qw(fatalsToBrowser);

use lib '/srv/www/www.internationaljobsolutions.com/perl';

use Website::Base;

srand;

use vars qw($dbh);

my $q = new CGI;

my $actions = {

'Login' => 'Login',

'Search' => 'Search',

'ProductList' => ‘ProductList’,

'ProductDetail' => 'ProductDetail',

‘InternalError’ => ‘InternalError’,

…. };

my $action = 'Website::Actions::' . ($actions->{$q->param('action')} ||

'InternalError');

eval "use $action";

if ( $@ ) {

#…eval failed, do error handling here }

# execute object and return page $action->new();

Base.pm should contain the bulk of the required methods, any extensions to this should be created as subclasses. Here is an example object constructor for Base.pm which connects us to a database and logs an error if it fails. Every major action such as database interactions, reading parameters, template handling should produce debug error logs.

sub new {

my $self = [];

bless($self);

my $db_name = Website::Constants::DB_NAME;

my