AmazonClient.cs

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Web;
using System.Net;
using System.Net.Http;
using amazon_rest;
using System.Xml;

public class AmazonECSWrapper : IBookSearch
{
    public Book[] getBooks(string keywords)
    {
        String amazonAccessKey = "AKIAI35H25WR6DBFXD4Q";
        String amazonSecretKey = "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";
        String destination = "ecs.amazonaws.de";
        String associateID = "amazon015d-20";

        // Creating the Request-String
        SignedRequestHelper requestHelper = new SignedRequestHelper(amazonAccessKey, amazonSecretKey, destination, associateID);
        String amazonQueryString = "Service=AWSECommerceService"
                                    + "&Version=2011-08-01"
                                    + "&Operation=ItemSearch"
                                    + "&SearchIndex=Books"
                                    + "&ResponseGroup=Large"
                                    + "&Keywords=" + keywords;

        String signedAmazonQueryString = requestHelper.Sign(amazonQueryString);

        // Send Request to Amazon webservice and get the result in XML
        WebClient webClient = new WebClient();
        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.Load(webClient.OpenRead(signedAmazonQueryString));

        ArrayList bookList = new ArrayList();

        // Iterate over items
        foreach(XmlElement itemXmlElem in xmlDoc.SelectNodes("/ItemSearchResponse/Items")) {
            String bildURL = "";
            String author = "";
            String isbn = "";
            String titel = "";
            double preis = 0;
            String erscheinungsDatum = "";

            XmlNode bildURLNode = itemXmlElem.GetElementsByTagName("SmallImage/URL")[0];
            if (bildURLNode != null)
                bildURL = bildURLNode.Value;

            XmlNode authorNode = itemXmlElem.GetElementsByTagName("ItemAttributes/Author")[0];
            if (authorNode != null)
                author = authorNode.Value;

            XmlNode isbnNode = itemXmlElem.GetElementsByTagName("ItemAttributes/ISBN")[0];
            if (isbnNode != null)
                isbn = isbnNode.Value;

            XmlNode titelNode = itemXmlElem.GetElementsByTagName("ItemAttributes/Title")[0];
            if (titelNode != null)
                titel = titelNode.Value;

            XmlNode preisNode = itemXmlElem.GetElementsByTagName("ItemAttributes/Price")[0];
            if (preisNode != null)
                preis = Double.Parse(preisNode.Value);

            XmlNode erscheinungsDatumNode = itemXmlElem.GetElementsByTagName("ItemAttributes/PublicationDate")[0];
            if (erscheinungsDatumNode != null)
                erscheinungsDatum = erscheinungsDatumNode.Value;

            bookList.Add(new Book(isbn, titel, preis, author, bildURL, erscheinungsDatum));
        }

        return (Book[])bookList.ToArray(typeof(Book));
    }
}