Back to the Good Ol' Days

Yes, it's 5 a.m., and I'm still up.

But success!

C:\Perl>perl MyFindBook.pl 0385504209
ISBN: 0385504209
Author: Dan Brown
Title: The Da Vinci Code
Binding: Hardcover
Number of Pages: 454
Publication Date: 2003-03-18
Publisher: Doubleday

A program that takes an ISBN and returns book details!
Only command line at the moment though, nothing fancy.
Major bitch setting up XML parsing in Perl.
But Amazon Web Services is cool!

[Code]
#!/usr/bin/perl -w

use strict;
use LWP::Simple qw /get/;
use XML::XPath;

# Defining parts of the REST request URL. These are parts of the URL

that are independent of the Operation being performed
my $BaseURL = "http://aws-beta.amazon.com";
my $Path = "/onca/xml";
my $Service = "AWSProductData";
my $SubscriptionId = "[INSERT YOUR SUBSCRIPTION ID]";

my $xp; # XPath object for parsing the xml response

main();

sub main {
# reading from the command line
my $asin = shift @ARGV or die "Usage: pricing_tool.pl \n";

if (@ARGV > 0) {
$BaseURL = shift @ARGV;
}

# Make the request
my $response = lookup_Asin($asin);

# Construct the XPath object
$xp = XML::XPath->new(xml => $response);

# Die if there is an error
die_if_error();


my $isbn =

$xp->findvalue("/ItemLookupResponse/Items/Item/ItemAttributes/ISBN");
print "ISBN: $isbn\n";

my $author =

$xp->findvalue("/ItemLookupResponse/Items/Item/ItemAttributes/Author")

;
print "Author: $author\n";

my $title =

$xp->findvalue("/ItemLookupResponse/Items/Item/ItemAttributes/Title");
print "Title: $title\n";

my $binding =

$xp->findvalue("/ItemLookupResponse/Items/Item/ItemAttributes/Binding"

);
print "Binding: $binding\n";

my $pages =

$xp->findvalue("/ItemLookupResponse/Items/Item/ItemAttributes/NumberOf

Pages");
print "Number of Pages: $pages\n";

my $date =

$xp->findvalue("/ItemLookupResponse/Items/Item/ItemAttributes/Publicat

ionDate");
print "Publication Date: $date\n";

my $publisher =

$xp->findvalue("/ItemLookupResponse/Items/Item/ItemAttributes/Publishe

r");
print "Publisher: $publisher\n";

}

# Function takes an ASIN as an argument and performs an ItemLookup on

it.
# It then returns a string containing the XML response received
sub lookup_Asin {
my $asin = shift; # shifts one element of default array @_.

Arguments passed are stored in @_.
my $Operation = "ItemLookup";
my $ResponseGroup = "Medium";

# Create the REST request to AWS
my $Request = "$BaseURL" . "$Path?" . "Service=$Service" .

"&Operation=$Operation" .
"&SubscriptionId=$SubscriptionId" . "&ItemId=$asin" .

"&ResponseGroup=$ResponseGroup";

# Use LWP to make an HTTP request to AWS
my $response = get($Request);
die "Attempt to make request failed!\n" unless defined($response);

return $response;
}


# Function checks if there is an error returned from the request.
# If there is an error then it outputs a message and dies
sub die_if_error {
if($xp->find("//Error")) {
print "Error recieved while making request:\n",
"Error Code: ", $xp->findvalue("//Error/Code"),
"\nError Message: ", $xp->findvalue("//Error/Message"),

"\n\n";

die;
}
}