use 5.008;
use strict;
use warnings;
use utf8;

use CGI;
use LWP::Simple;
use XML::LibXML;

use constant {
  URL_TEMPLATE => 'http://ax.itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=%s&mt=8',
  APPLE_ITEMS_NS => 'http://www.apple.com/itms/'
};

# Create CGI context, XML parser object and XPath context
my $cgi = CGI->new();

my $libxml = XML::LibXML->new();

my $xpath = XML::LibXML::XPathContext->new();
$xpath->registerNs(itms => APPLE_ITEMS_NS);

# Get application ID from query parameters or use default
my $appid = $cgi->param('appid') || '321234472';

# Format URL using template and application ID, load content and parse XML
my $document = $libxml->parse_string(get(sprintf(URL_TEMPLATE, $appid)));

# Extract all <b>-tags from the XML data
my @bs = $xpath->findnodes('//itms:b', $document);

# Print HTTP header and the text contained in the extracted tags
print $cgi->header(-type => 'text/plain', -charset => 'utf-8');
print $_->textContent . "\n" foreach (@bs);