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Net-Amazon-0.14
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/ Net::Amazon

NAME

Net::Amazon - Framework for accessing amazon.com via SOAP and XML/HTTP

SYNOPSIS

use Net::Amazon;

my $ua = Net::Amazon->new(token => 'YOUR_AMZN_TOKEN');

  # Get a request object
my $response = $ua->search(asin => '0201360683');

if($response->is_success()) {
    print $response->as_string(), "\n";
} else {
    print "Error: ", $response->message(), "\n";
}

ABSTRACT

Net::Amazon provides an object-oriented interface to amazon.com's
SOAP and XML/HTTP interfaces. This way it's possible to create applications
using Amazon's vast amount of data via a functional interface, without
having to worry about the underlying communication mechanism.

DESCRIPTION

Net::Amazon works very much like LWP: First you define a useragent like

my $ua = Net::Amazon->new(
    token     => 'YOUR_AMZN_TOKEN',
    max_pages => 3,
);

which you pass your personal amazon developer's token (can be obtained from http://amazon.com/soap) and (optionally) the maximum number of result pages the agent is going to request from Amazon in case all results don't fit on a single page (typically holding 20 items).

According to the different search methods on Amazon, there's a bunch of different request types in Net::Amazon. The user agent's convenience method search() triggers different request objects, depending on which parameters you pass to it:

$ua->search(asin => "0201360683")

The asin parameter has Net::Amazon search for an item with the specified ASIN. Returns at most one result.

$ua->search(artist => "Rolling Stones")

The artist parameter has the user agent search for items created by the specified artist. Can return many results.

$ua->search(keyword => "perl xml", mode => "books")

Search by keyword, mandatory parameters keyword and mode. Can return many results.

$ua->search(wishlist => "1XL5DWOUFMFVJ")

Search for all items in a specified wishlist. Can return many results.

$ua->search(upc => "075596278324", mode => "music")

Music search by UPC (product barcode), mandatory parameter upc. mode has to be set to music. Returns at most one result.

$ua->search(similar => "0201360683")

Search for all items similar to the one represented by the ASIN provided. Can return many results.

The user agent's search method returns a response object, which can be checked for success or failure:

if($resp->is_success()) {
    print $resp->as_string();
} else {
    print "Error: ", $resp->message(), "\n";
}

In case the request succeeds, the response contains one or more Amazon 'properties', as it calls the products found. All matches can be retrieved from the Response object using it's properties() method.

Response objects always have the methods is_success(), is_error(), message(), as_string() and properties() available.

properties() returns one or more Net::Amazon::Property objects of type Net::Amazon::Property (or one of its subclasses like Net::Amazon::Property::Book, Net::Amazon::Property::Music or Net::Amazon::Property::DVD), each of which features accessors named after the attributes of the product found in Amazon's database:

for ($resp->properties) {
   print $_->Asin(), " ",
         $_->OurPrice(), "\n";
}

Also the specialized classes Net::Amazon::Property::Book and Net::Amazon::Property::Music feature convenience methods like authors() (returning the list of authors of a book) or album() for CDs, returning the album title.

Customer reviews: Every property features a review_set() method which returns a Net::Amazon::Attribute::ReviewSet object, which in turn offers a list of Net::Amazon::Attribute::Review objects. Check the respective man pages for details on what's available.

Requests behind the scenes

Net::Amazon's search() method is just a convenient way to create different kinds of request objects behind the scenes and trigger them to send requests to Amazon.

Depending on the parameters fed to the search method, Net::Amazon will determine the kind of search requested and create one of the following request objects:

Net::Amazon::Request::ASIN

Search by ASIN, mandatory parameter asin. Returns at most one result.

Net::Amazon::Request::Artist

Music search by Artist, mandatory parameter artist. Can return many results.

Net::Amazon::Request::Keyword

Keyword search, mandatory parameters keyword and mode. Can return many results.

Net::Amazon::Request::UPC

Music search by UPC (product barcode), mandatory parameter upc. mode has to be set to music. Returns at most one result.

Check the respective man pages for details on these request objects. Request objects are typically created like this (with a Keyword query as an example):

my $req = Net::Amazon::Request::Keyword->new(
    keyword   => 'perl',
    mode      => 'books',
);

and are handed over to the user agent like that:

  # Response is of type Net::Amazon::Response::ASIN
my $resp = $ua->request($req);

The convenient search() method just does these two steps in one.

METHODS

$ua = Net::Amazon->new(token => $token, ...)

Create a new Net::Amazon useragent. $token is the value of the mandatory Amazon developer's token, which can be obtained from http://amazon.com/soap.

Additional optional parameters:

max_pages => $max_pages

sets how many result pages the module is supposed to fetch back from Amazon, which only sends back 10 results per page.

affiliate_id => $affiliate_id

your Amazon affiliate ID, if you have one. It defaults to webservices-20 which is currently (as of 06/2003) required by Amazon.

$resp = $ua->request($request)

Sends a request to the Amazon web service. $request is of a Net::Amazon::Request::* type and $response will be of the corresponding Net::Amazon::Response::* type.

Accessing foreign Amazon Catalogs

As of this writing (07/2003), Amazon also offers its web service for the UK, Germany, and Japan. Just pass in

locale => 'uk'
locale => 'de'
locale => 'jp'

respectively to Net::Amazon's constructor new() and instead of returning results sent by the US mothership, it will query the particular country's catalog and show prices in (gack!) local currencies.

EXAMPLE

Here's a full-fledged example doing a artist search:

use Net::Amazon;
use Net::Amazon::Request::Artist;
use Data::Dumper;

die "usage: $0 artist\n(use Zwan as an example)\n"
    unless defined $ARGV[0];

my $ua = Net::Amazon->new(
    token       => 'YOUR_AMZN_TOKEN',
);

my $req = Net::Amazon::Request::Artist->new(
    artist  => $ARGV[0],
);

   # Response is of type Net::Amazon::Artist::Response
my $resp = $ua->request($req);

if($resp->is_success()) {
    print $resp->as_string, "\n";
} else {
    print $resp->message(), "\n";
}

And here's one displaying someone's wishlist:

use Net::Amazon;
use Net::Amazon::Request::Wishlist;

die "usage: $0 wishlist_id\n" .
    "(use 1XL5DWOUFMFVJ as an example)\n" unless $ARGV[0];

my $ua = Net::Amazon->new(
    token       => 'YOUR_AMZN_TOKEN',
);

my $req = Net::Amazon::Request::Wishlist->new(
    id  => $ARGV[0]
);

   # Response is of type Net::Amazon::ASIN::Response
my $resp = $ua->request($req);

if($resp->is_success()) {
    print $resp->as_string, "\n";
} else {
    print $resp->message(), "\n";
}

CACHING

Responses returned by Amazon's web service can be cached locally. Net::Amazon's new method accepts a reference to a Cache object. Cache (or one of its companions like Cache::Memory, Cache::File, etc.) can be downloaded from CPAN, please check their documentation for details. In fact, any other type of cache implementation will do as well, see the requirements below.

Here's an example utilizing a file cache which causes Net::Amazon to cache responses for 30 minutes:

use File::Cache;

my $cache = Cache::File->new( 
    cache_root        => '/tmp/mycache',
    default_expires   => '30 min',
);

my $ua = Net::Amazon->new(
    token       => 'YOUR_AMZN_TOKEN',
    cache       => $cache,
);

Net::Amazon uses positive caching only, errors won't be cached. Erroneous requests will be sent to Amazon every time. Positive cache entries are keyed by the full URL used internally by requests submitted to Amazon.

Caching isn't limited to the Cache class. Any cache object which adheres to the following interface can be used:

    # Set a cache value
$cache->set($key, $value);

    # Return a cached value, 'undef' if it doesn't exist
$cache->get($key);

DEBUGGING

If something's going wrong and you want more verbosity, just bump up Net::Amazon's logging level. Net::Amazon comes with Log::Log4perl statements embedded, which are disabled by default. However, if you initialize Log::Log4perl, e.g. like

use Net::Amazon;
use Log::Log4perl qw(:easy);

Log::Log4perl->easy_init($DEBUG);
my Net::Amazon->new();
# ...

you'll see what's going on behind the scenes, what URLs the module is requesting from Amazon and so forth. Log::Log4perl allows all kinds of fancy stuff, like writing to a file or enabling verbosity in certain parts only -- check http://log4perl.sourceforge.net for details.

LIVE TESTING

Results returned by Amazon can be incomplete or simply wrong at times, due to their "best effort" design of the service. This is why the test suite that comes with this module has been changed to perform its test cases against canned data. If you want to perform the tests against the live Amazon servers instead, just set the environment variable

NET_AMAZON_LIVE_TESTS=1

WHY ISN'T THERE SUPPORT FOR METHOD XYZ?

Because nobody wrote it yet. If Net::Amazon doesn't yet support a method advertised on Amazon's web service, you could help us out. Net::Amazon has been designed to be expanded over time, usually it only takes a couple of lines to support a new method, the rest is done via inheritance within Net::Amazon.

Here's the basic plot:

  • Get Net::Amazon from CVS. Use

    cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/Net-Amazon login
cvs -z3 -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/Net-Amazon co Net-Amazon

  • Write a new Net::Amazon::Request::XYZ package, start with this template

    ######################################
package Net::Amazon::Request::XYZ;
######################################
use base qw(Net::Amazon::Request);

######################################
sub new {
######################################
    my($class, %options) = @_;

    if(!exists $options{XYZ_option}) {
        die "Mandatory parameter 'XYZ_option' not defined";
    }

    my $self = $class->SUPER::new(%options);

    bless $self, $class;   # reconsecrate
}

    and add documentation. Then, create a new Net::Amazon::Response::XYZ module:

    ##############################
package Net::Amazon::Response;
##############################
use base qw(Net::Amazon::Response);

use Net::Amazon::Property;

##############################
sub new {
##############################
    my($class, %options) = @_;

    my $self = $class->SUPER::new(%options);

    bless $self, $class;   # reconsecrate
}

    and also add documentation to it. Then, add the line

    use Net::Amazon::Request::XYZ;

    to Net/Amazon.pm.

And that's it! Check out the different Net::Amazon::Request::* and Net::Amazon::Response modules in the distribution if you need to adapt your new module to fulfil any special needs, like a different Amazon URL or a different way to handle the as_string() method. Also, post and problems you might encounter to the mailing list, we're gonna help you out.

INSTALLATION

Net::Amazon depends on Log::Log4perl, which can be pulled from CPAN by simply saying

perl -MCPAN -eshell 'install Log::Log4perl'

Also, it needs XML::Simple 2.x, which can be obtained in a similar way.

Once all dependencies have been resolved, Net::Amazon installs with the typical sequence

perl Makefile.PL
make
make test
make install

Make sure you're connected to the Internet while running make test because it will actually contact amazon.com and run a couple of live tests.

The module's distribution tarball and documentation are available at

http://perlmeister.com/devel/#amzn

and on CPAN.

SEE ALSO

CONTACT

The Net::Amazon project's home page is hosted on

http://net-amazon.sourceforge.net

where you can find documentation, news and the latest development and stable releases for download. If you have questions about how to use Net::Amazon, want to report a bug or just participate in its development, please send a message to the mailing list amazon-net-devel@lists.sourceforge.net

AUTHOR

Mike Schilli, <na@perlmeister.com> (Please contact me via the mailing list: net-amazon-devel@lists.sourceforge.net )

COPYRIGHT AND LICENSE

Copyright 2003 by Mike Schilli <na@perlmeister.com>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.