Hack 95 Create an Amazon AIM Bot

Chat with some Perl code to get book prices via AOL Instant Messenger.

AOL Instant Messenger isn't the most likely place you'll need Amazon book data, but that doesn't mean the applications aren't fun to connect. With Perl and the Net::AIM module, you can have your own chattering book-bot requesting Amazon information for you.

95.1 What You Need

First you'll need the Net::AIM library, which provides all the functions for logging into AIM and sending or receiving messages. You can find it at activestate.com (http://aspn.activestate.com/ASPN/CodeDoc/Net-AIM/AIM.html). To get a jumpstart on coding, check out the tutorials at Wired Bots (http://www.wiredbots.com/tutorial.html). They have some fully functional sample bots and lots of example code for working with Net::AIM.

You'll also need an AIM screen name and password for your new virtual assistant, along with a screen name for yourself if you don't have one; sign up at http://www.aim.com.

95.2 The Code

Create a file called asin_bot.pl and include the following code. The code that communicates with Amazon is based on a previous hack ([Hack #80]), though the AWS request is made inside the on_im subroutine, when a message comes in. Instead of printing out to the console, it saves the results in a variable, $detail, and sends it as an instant message back to the person sending the message.

#!/usr/bin/perl
# asin_bot.pl
#
# An AIM bot that given an ASIN will
# return the product title and price.
# Usage: perl asin_bot.pl

use warnings;
use strict;
use Net::AIM;
use LWP::Simple;
use XML::Simple;

# fill in your relevants.
my $aim_un = 'insert AIM username';
my $aim_pw = 'insert AIM password';
my $dev_key = 'insert developer token';
my $af_code = 'insert affiliate tag';

# create an AIM connection
# and return it for usage.
my $aim = new Net::AIM;
$aim->newconn(Screenname=>$aim_un,Password=>$aim_pw)
                or die "Cannot connect to AIM.";
my $conn = $aim->getconn();

# Set up a handler for messages.
$conn->set_handler('im_in', on_im);
$conn->set_handler('error', on_error);
print "Logged on to AIM!\n\n";
$aim->start;

# incoming.
sub on_im {

    my ($aim, $evt, $from, $to) = @_;
    my $args = $evt->args();
    ($from, my $friend, my $msg) = @$args;

    # cheaply remote html.
    $msg =~ s/<(.|\n)+?>//g;

    # if this isn't an ASIN sized string, 
    # send back an error message stating such.
    $aim->send_im($from, "I only accept ASINs.") unless length($msg) eq 10;

    # create our final URL.
    my $url = "http://xml.amazon.com/onca/xml3?t=$af_code". 
              "&dev-t=$dev_key&type=lite&f=xml&".
              "AsinSearch=$msg";

    my $content = get($url);
    my $response = XMLin($content);
    my $detail = $response->{Details}->{ProductName}||"no title";
    $detail   .= " $response->{Details}->{OurPrice}";
    $aim->send_im($from, $detail);
}

# oops!
sub on_error {
    my ($self, $evt) = @_;
    my ($error, @stuff) = @{$evt->args()};

    # Translate error number into English.
    # then filter and print to STDERR.
    my $errstr = $evt->trans($error);
    $errstr =~ s/\$(\d+)/$stuff[$1]/ge;
    print "ERROR: $errstr\n";
}

Notice that inside the on_im subroutine, the script checks to make sure the incoming message is exactly 10 characters, the length of an ASIN. Otherwise it sends back the message, "I only accept ASINs." It's a good idea to set up rules like this for any kind of queries you allow. Bots should always send a message about success or failure.

95.3 Running the Hack

Start up AOL Instant Messenger and add the virtual screen name you gave your bot to your buddy list. When you run asin_bot.pl, you should see the bot appear among your online buddies. Send a message consisting of only an ASIN, and you should get the book title and Amazon price back. This conversation is shown in Figure 6-9.