Some time back I wrote a post on C# API for Amazon Product Advertising Web Service. If you are one of amazon associates who is using their web service to advertise their products to earn some money, then you must be getting emails with following message from Amazon.com.

There is nothing to worry about this. It is a very simple change that you will need to make on your end. Amazon has given two options to digitally sign the requests. Either encrypt all requests with HMAC-SHA encryption or use X509Certificate. If you don't have X509Certificate, don't worry about it. Amazon.com is creating one for you if you ask it to. I found this option to use X509Certificate to be the easiest to comply with Amazon.com policy. Here are the steps you will need to use.

• Login into your AWS account.
• Click on Access Identifiers link on Your Account page.
• At the end of the page you will find section for X509.Certificate. Click on Create New option to create your certificate.
• Make sure that you follow the instructions and save the private key and certificate file as the process asks you to.

Now time to make code change. It is simple. Just add one line to your implementation and you are all set.

m_obAmazonService.ClientCertificates.Add(X509Certificate.CreateFromCertFile(X509CertFile));

X509CertFile is full path to where this file is stored. If you are using the API in web application, make sure you specify fully qualified path and your application has read permissions on this file as well. You can this in action here - Winazon.Net

In my previous post WCF Error I discussed adding app.config to your application to get Amazon.com web service client to work. I also mentioned in that post that you can provide Binding and EndPoint parameters programatically to send search request to Amazon.com web service. Here is the sample code that demonstrates how you can do that.

using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.ServiceModel.Channels;
using AmazonClient.AmazonData;
namespace AmazonClient
{
  class Program
  {
    static void Main(string[] args)
    {
       System.ServiceModel.BasicHttpBinding httpBinding = new BasicHttpBinding();
       httpBinding.Name = "AWSECommerceServiceBinding";
       BasicHttpSecurity security = httpBinding.Security;
       security.Mode = BasicHttpSecurityMode.None;
       EndpointAddress addr = 
         new EndpointAddress("http://soap.amazon.com/onca/soap?Service=AWSECommerceService");
       AWSECommerceServicePortTypeClient client = 
        new AWSECommerceServicePortTypeClient(httpBinding,  addr);
            
       try
       {
         ItemSearch srch = new ItemSearch();
         srch.AssociateTag = "xxxxxxx";
         srch.AWSAccessKeyId = "xxxxxx";
         ItemSearchRequest req = new ItemSearchRequest();
         req.Keywords = "silverlight";
         req.SearchIndex = "Books";
         srch.Request = new ItemSearchRequest[1]{req};
         ItemSearchResponse resp = client.ItemSearch(srch);
         if (null != resp)
         {
           Console.WriteLine("It works!");
         }
       }
       catch(Exception ex)
       {
         Console.WriteLine(ex.Message);
       }
    }
   }
}