man Net::Amazon (3): Framework for accessing amazon.com via REST

SYNOPSIS

use Net::Amazon;
my $ua = Net::Amazon->new(
associate_tag => 'YOUR_AMZN_ASSOCIATE_TAG',
token => 'YOUR_AMZN_TOKEN',
secret_key => 'YOUR_AMZN_SECRET_KEY');
# 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
  REST interface. 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(
      associate_tag => 'YOUR_AMZN_ASSOCIATE_TAG',
      token         => 'YOUR_AMZN_TOKEN',
      secret_key    => 'YOUR_AMZN_SECRET_KEY',
      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). Note that each new page requires a minimum delay of 1 second to comply with Amazon's one-query-per-second policy.

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. If the specified value is an arrayref instead of a single scalar, like in

    $ua->search(asin => ["0201360683", "0596005083"])

then a search for multiple ASINs is performed, returning a list of results.

"$ua->search(actor => "Adam Sandler")"

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

"$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(author => "Robert Jordan")"

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

"$ua->search(browsenode=>"4025", mode=>"books" [, keywords=>"perl"])"

Returns a list of items by category ID (node). For example node ``4025'' is the CGI books category. You can add a keywords parameter to filter the results by that keyword.

"$ua->search(exchange => 'Y04Y3424291Y2398445')"

Returns an item offered by a third-party seller. The item is referenced by the so-called exchange ID.

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

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

DETAILS Net::Amazon is based on Amazon Web Services version 4, and uses WSDL version 2011-08-01.

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 Cache::File;
    my $cache = Cache::File->new( 
        cache_root        => '/tmp/mycache',
        default_expires   => '30 min',
    );
    my $ua = Net::Amazon->new(
        token       => 'YOUR_AMZN_TOKEN',
        secret_key  => 'YOUR_AMZN_SECRET_KEY',
        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);

COMPRESSION

By default "Net::Amazon" will attempt to use HTTP compression if the Compress::Zlib module is available. Pass "compress => 0" to "->new()" to disable this feature.

PROXY SETTINGS

"Net::Amazon" uses "LWP::UserAgent" under the hood to send web requests to Amazon's web site. If you're in an environment where all Web traffic goes through a proxy, there's two ways to configure that.

First, "Net::Amazon" picks up proxy settings from environment variables:

    export http_proxy=http://proxy.my.place:8080

in the surrounding shell or setting

    $ENV{http_proxy} = "http://proxy.my.place:8080";

in your Perl script will route all requests through the specified proxy.

Secondly, you can pass a user agent instance to Net::Amazon's constructor:

    use Net::Amazon;
    use LWP::UserAgent;
    my $ua = LWP::UserAgent->new();
    my $na = Net::Amazon->new(
        ua            => $ua, 
        associate_tag => 'YOUR_AMZN_ASSOCIATE_TAG',
        token         => 'YOUR_AMZN_TOKEN',
        secret_key    => 'YOUR_AMZN_SECRET_KEY',
    );
    # ...

This way, you can configure $ua up front before Net::Amazon will use it.

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

        # (Just hit enter when prompted for a password)
    cvs -d:pserver:[email protected]:/cvsroot/net-amazon login
    cvs -z3 -d:pserver:[email protected]:/cvsroot/net-amazon co Net-Amazon

If this doesn't work, just use the latest distribution from net-amazon.sourceforge.net.

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! Again, don't forget the add documentation part. Modules without documentation are of no use to anybody but yourself.

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.

If possible, provide a test case for your extension. When finished, send a patch to the mailing list at

   [email protected]

and if it works, I'll accept it and will work it into the main distribution. Your name will show up in the contributor's list below (unless you tell me otherwise).

SAMPLE SCRIPTS

There's a number of useful scripts in the distribution's eg/ directory. Take "power" for example, written by Martin Streicher <[email protected]>: I lets you perform a power search using Amazon's query language. To search for all books written by Randal Schwartz about Perl, call this from the command line:

    power 'author: schwartz subject: perl'

Note that you need to quote the query string to pass it as one argument to "power". If a power search returns more results than you want to process at a time, just limit the number of pages, telling "power" which page to start at ("-s") and which one to finish with ("-f"). Here's a search for all books on the subject "computer", limited to the first 10 pages:

    power -s 1 -f 10 'subject: computer'

Check out the script "power" in eg/ for more options.

HOW TO SEND ME PATCHES

If you want me to include your modification or enhancement in the distribution of Net::Amazon, please do the following:

Work off the latest CVS version. Here's the steps to get it:
```
    CVSROOT=:pserver:[email protected]:/cvsroot/net-amazon
    export CVSROOT
    cvs login (just hit Enter)
    cvs co Net-Amazon
```
This will create a new "Net-Amazon" directory with the latest development version of "Net::Amazon" on your local machine.
Apply your changes to this development tree.

Run a diff between the tree and your changes it in this way:

    cd Net-Amazon
    cvs diff -Nau >patch_to_christopher.txt

Email me "patch_to_christopher.txt". If your patch works (and you've included test cases and documentation), I'll apply it on the spot.

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 LWP::UserAgent and 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.

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 [email protected]

The source code has moved from sourceforge.net to github.com. The git URL is

    git://github.com/boumenot/p5-Net-Amazon.git

The hope is that github.com makes collaboration much easier, and git is a much more modern SCM tool.

AUTHOR

Mike Schilli, <[email protected]> (Please contact me via the mailing list: [email protected] )

Maintainers: Christopher Boumenot, <[email protected]>

Contributors (thanks y'all!):

    Andy Grundman <[email protected]>
    Barnaby Claydon <[email protected]>
    Batara Kesuma <[email protected]>
    Bill Fitzpatrick
    Brian <[email protected]>
    Brian Hirt <[email protected]>
    Dan Kreft <[email protected]>
    Dan Sully <[email protected]>
    Dave Cardwell <http://davecardwell.co.uk/>
    Jackie Hamilton <[email protected]>
    Konstantin Gredeskoul <[email protected]>
    Lance Cleveland <[email protected]>
    Martha Greenberg <[email protected]>
    Martin Streicher <[email protected]>
    Mike Evron <[email protected]>
    Padraic Renaghan <[email protected]>
    rayg <[email protected]>
    Robert Graff <[email protected]>
    Robert Rothenberg <[email protected]>
    Steve Rushe <[email protected]>
    Tatsuhiko Miyagawa <[email protected]>
    Tony Bowden <[email protected]>
    Vince Veselosky

COPYRIGHT AND LICENSE

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