Programming Jabber

Module declarations and variable definitions

We start out by using the Jabber::Connection library, which is defined as follows:

use strict;
use Jabber::Connection;
use Jabber::NodeFactory;
use Jabber::NS qw(:all);
use MLDBM 'DB_File';
use LWP::Simple;
use XML::RSS;

The Jabber::Connection library consists of the following three modules:

Jabber::Connection

This module is used to manage the connection to the server and parses and dispatches incoming elements.

Jabber::NodeFactory

This module allows us to manipulate elements, which are generically called nodes.

Jabber::NS

The last module provides us with a list of constants that reflect namespaces and other common strings used in Jabber server, client, and component programming.

Next we need a way of storing the registration information between invocations of the component script, and for that we’ll use the Multi-Level Database Manager module, MLDBM. MLDBM is a useful wrapper that can be placed around the DB_File module. DB_File provides access to Berlekey Database (Berkeley DB, at http://www.sleepycat.com) facilities using the tie() function. While you can’t store references (i.e., complex data structures) via DB_File, you can with the MLDBM wrapper.

We will use the LWP::Simple module to grab the RSS sources by URL and the XML::RSS module to parse those sources once retrieved:

my $NAME = 'RSS News Agent'; my $ID = 'rss.qmacro.dyndns.org'; my $VERSION = '0.1'; my $reg_file = 'registrations'; my %reg; my %cache; my %sources = ...