#! perl -slw
use strict;
use LWP::Simple;
use XML::Simple;
use Data::Dump qw[ pp ];
use constant ACCESS_ID => 'XXXXXXXX'; ## Your access key here.

my $isbn = $ARGV[ 0 ] or die 'Need an ISBN number';
die "'$isbn' doesn't look like a valid ISBN"
    unless $isbn =~ m[^\d{10}$];

my $uri = sprintf 
    "http://isbndb.com/api/books.xml?access_key=%s&index1=isbn&value1=%s",
    ACCESS_ID, $isbn;

my $xml = get $uri or die "Request failed";
my $info = XMLin $xml;

pp $info;