Hack 93 Cache Amazon Images Locally

Caching product images locally can save your users several trips to the Amazon server and speed up your applications.

The easiest way to save an image locally is to visit the product detail page, right-click on the image, and choose "Save Picture As . . . ". Of course, "easy" is relative. If you have to do this for hundreds of products, suddenly it's the hard way.

Luckily, every programming environment has methods for retrieving an image from a remote server and saving it as a local file.

93.1 The Code

Each of these examples takes an ASIN, builds the proper URL [Hack #5], grabs the image, and saves it locally as [ASIN].jpg.

Perl

This uses the getstore( ) function of LWP::Simple to request and save the file. $rp is the return code, and to shore this function up you could take additional action if it's equal to 404.

use LWP::Simple;
$Asin = "0596004478";
$rp = getstore(
      "http://images.amazon.com/images/P/$Asin.01.MZZZZZZZ.jpg",[RETURN]
      "$Asin.jpg");

VBScript

Writing binary files like images isn't quite as straightforward with VBScript, so you have to turn to some unusual components. The ServerXMLHTTP component makes the request, which is written to an ADODB stream. The ADODB component has the ability to write binary files.

strASIN = "0596004478"
strURL = "http://images.amazon.com/images/P/" & strASIN & _
         ".01.MZZZZZZZ.jpg"
strFile = strASIN & ".jpg"

'Get the Image
Set xmlhttp = CreateObject("Msxml2.SERVERXMLHTTP")
xmlhttp.Open "GET", strURL, false
xmlhttp.Send(Now)

'Create a Stream
Set adodbStream = CreateObject("ADODB.Stream")
    
'Open the stream
adodbStream.Open 
adodbStream.Type = 1 'adTypeBinary
adodbStream.Write xmlhttp.responseBody
adodbStream.SaveToFile strFile, 2 'adSaveCreateOverWrite
adodbStream.Close

Set adodbStream = Nothing
Set xmlhttp = Nothing

This code will run as a WSH file. Simply add Server. before the CreateObject commands to use this code in an ASP file.

PHP

The key to this PHP code is setting the fopen( ) function to read and write binary files. Note the rb (read binary) and wb (write binary) options.

$asin = "0596004478";
$url = "http://images.amazon.com/images/P/".$asin.".01.MZZZZZZZ.jpg";
$filedata = "";
$remoteimage = fopen($url, 'rb');
if ($remoteimage) {
    while(!feof($remoteimage)) {
           $filedata.= fread($remoteimage,1024);
    }
}
fclose($remoteimage);
$localimage = fopen($asin.".jpg", 'wb');
fwrite($localimage,$filedata);
fclose($localimage);

Python

As with PHP, be sure to set the file open command to wb (write binary) so it can save the file properly.

import urllib
asin = "0596004478"
url = 'http://images.amazon.com/images/P/' + asin + ".01.MZZZZZZZ.jpg"
filedata = urllib.urlopen(url).read(  )
f = open(asin + '.jpg', 'wb')
f.write(filedata)
f.close(  )

Amazon's license asks that you update any information you've cached from its servers every 24 hours. Check the Last Saved property of your local copy of the file before running any of these snippets; if it's longer than 24 hours, rerun the code to stay in compliance. (See http://www.amazon.com/gp/aws/license_agree.html.)