Programming Jabber

Reviewing the hlv Script Step by Step

The script starts with the declarations of the libraries we’re going to use, along with some constants:

use Tk;
use Net::Jabber qw(Client);
use strict;

use constant SERVER   => 'gnu.pipetree.com';
use constant PORT     => 5222;
use constant USER     => 'dj';
use constant PASSWORD => 'secret';
use constant RESOURCE => 'hlv';

use constant BROWSER  => '/usr/bin/konqueror';

The hlv script will connect to Jabber as a client, so we need to specify that in the use statement to have the appropriate Net::Jabber modules loaded. We’re going to be connecting to the Jabber server at gnu.pipetree.com, although, as we said, the RSS news agent might live somewhere else. It just so happens that in this scenario, there’s a reference to the component in gnu.pipetree.com’s JSM <browse/> section, so we can carry out registration conversations with it (using JIM, for example).

If the Fetch button is clicked when an item in the list is selected (see Figure 9-10), we want to jump to the story by launching a web browser. The constant BROWSER used here refers to the browser—in this case, Konqueror, the browser of choice for KDE users—on the local machine.

my @headlines;
my @list;

We declare two arrays: @headlines, which we’ll use to hold the items as they arrive contained in the headline <message/> elements on the XML stream, and @list, to hold the URLs that relate to those items in @headlines.

After connecting to and authenticating with the Jabber server, we set up the callback ...