Amazon Product Advertising API through Java/SOAP

Question

I have been playing with Amazon's Product Advertising API, and I cannot get a request to go through and give me data. I have been working off of this: http://docs.amazonwebservices.com/AWSECommerceService/2011-08-01/GSG/ and this: Amazon Product Advertising API signed request with Java

Here is my code.. I generated the SOAP bindings using this: http://docs.amazonwebservices.com/AWSECommerceService/2011-08-01/GSG/YourDevelopmentEnvironment.html#Java

On the Classpath, I only have: commons-codec.1.5.jar

import com.ECS.client.jax.AWSECommerceService;
import com.ECS.client.jax.AWSECommerceServicePortType;
import com.ECS.client.jax.Item;
import com.ECS.client.jax.ItemLookup;
import com.ECS.client.jax.ItemLookupRequest;
import com.ECS.client.jax.ItemLookupResponse;
import com.ECS.client.jax.ItemSearchResponse;
import com.ECS.client.jax.Items;

public class Client {

    public static void main(String[] args) {

        String secretKey = <my-secret-key>;
        String awsKey = <my-aws-key>;

        System.out.println("API Test started");

        AWSECommerceService service = new AWSECommerceService();
        service.setHandlerResolver(new AwsHandlerResolver(
                secretKey)); // important
        AWSECommerceServicePortType port = service.getAWSECommerceServicePort();

        // Get the operation object:
        com.ECS.client.jax.ItemSearchRequest itemRequest = new com.ECS.client.jax.ItemSearchRequest();

        // Fill in the request object:
        itemRequest.setSearchIndex("Books");
        itemRequest.setKeywords("Star Wars");
        // itemRequest.setVersion("2011-08-01");
        com.ECS.client.jax.ItemSearch ItemElement = new com.ECS.client.jax.ItemSearch();
        ItemElement.setAWSAccessKeyId(awsKey);
        ItemElement.getRequest().add(itemRequest);

        // Call the Web service operation and store the response
        // in the response object:
        com.ECS.client.jax.ItemSearchResponse response = port
                .itemSearch(ItemElement);

        String r = response.toString();
        System.out.println("response: " + r);

        for (Items itemList : response.getItems()) {
            System.out.println(itemList);
            for (Item item : itemList.getItem()) {
                System.out.println(item);
            }
        }

        System.out.println("API Test stopped");

    }
}

Here is what I get back.. I was hoping to see some Star Wars books available on Amazon dumped out to my console :-/:

API Test started
response: com.ECS.client.jax.ItemSearchResponse@7a6769ea
com.ECS.client.jax.Items@1b5ac06e
API Test stopped

What am I doing wrong (Note that no "item" in the second for loop is being printed out, because its empty)? How can I troubleshoot this or get relevant error information?

Answer 1

I don't use the SOAP API but your Bounty requirements didn't state that it had to use SOAP only that you wanted to call Amazon and get results. So, I'll post this working example using the REST API which will at least fulfill your stated requirements:

I would like some working example code that hits the amazon server and returns results

You'll need to download the following to fulfill the signature requirements:

http://associates-amazon.s3.amazonaws.com/signed-requests/samples/amazon-product-advt-api-sample-java-query.zip

Unzip it and grab the com.amazon.advertising.api.sample.SignedRequestsHelper.java file and put it directly into your project. This code is used to sign the request.

You'll also need to download Apache Commons Codec 1.3 from the following and add it to your classpath i.e. add it to your project's library. Note that this is the only version of Codec that will work with the above class (SignedRequestsHelper)

http://archive.apache.org/dist/commons/codec/binaries/commons-codec-1.3.zip

Now you can copy and paste the following making sure to replace your.pkg.here with the proper package name and replace the SECRET and the KEY properties:

package your.pkg.here;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;

public class Main {

    private static final String SECRET_KEY = "<YOUR_SECRET_KEY>";
    private static final String AWS_KEY = "<YOUR_KEY>";

    public static void main(String[] args) {
        SignedRequestsHelper helper = SignedRequestsHelper.getInstance("ecs.amazonaws.com", AWS_KEY, SECRET_KEY);

        Map<String, String> params = new HashMap<String, String>();
        params.put("Service", "AWSECommerceService");
        params.put("Version", "2009-03-31");
        params.put("Operation", "ItemLookup");
        params.put("ItemId", "1451648537");
        params.put("ResponseGroup", "Large");

        String url = helper.sign(params);
        try {
            Document response = getResponse(url);
            printResponse(response);
        } catch (Exception ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private static Document getResponse(String url) throws ParserConfigurationException, IOException, SAXException {
        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        Document doc = builder.parse(url);
        return doc;
    }

    private static void printResponse(Document doc) throws TransformerException, FileNotFoundException {
        Transformer trans = TransformerFactory.newInstance().newTransformer();
        Properties props = new Properties();
        props.put(OutputKeys.INDENT, "yes");
        trans.setOutputProperties(props);
        StreamResult res = new StreamResult(new StringWriter());
        DOMSource src = new DOMSource(doc);
        trans.transform(src, res);
        String toString = res.getWriter().toString();
        System.out.println(toString);
    }
}

As you can see this is much simpler to setup and use than the SOAP API. If you don't have a specific requirement for using the SOAP API then I would highly recommend that you use the REST API instead.

One of the drawbacks of using the REST API is that the results aren't unmarshaled into objects for you. This could be remedied by creating the required classes based on the wsdl.

Answer 2

This ended up working (I had to add my associateTag to the request):

public class Client {

    public static void main(String[] args) {

        String secretKey = "<MY_SECRET_KEY>";
        String awsKey = "<MY AWS KEY>";

        System.out.println("API Test started");


        AWSECommerceService service = new AWSECommerceService();
        service.setHandlerResolver(new AwsHandlerResolver(secretKey)); // important
        AWSECommerceServicePortType port = service.getAWSECommerceServicePort();

        // Get the operation object:
        com.ECS.client.jax.ItemSearchRequest itemRequest = new com.ECS.client.jax.ItemSearchRequest();

        // Fill in the request object:
        itemRequest.setSearchIndex("Books");
        itemRequest.setKeywords("Star Wars");
        itemRequest.getResponseGroup().add("Large");
//      itemRequest.getResponseGroup().add("Images");
        // itemRequest.setVersion("2011-08-01");
        com.ECS.client.jax.ItemSearch ItemElement = new com.ECS.client.jax.ItemSearch();
        ItemElement.setAWSAccessKeyId(awsKey);
        ItemElement.setAssociateTag("th0426-20");
        ItemElement.getRequest().add(itemRequest);

        // Call the Web service operation and store the response
        // in the response object:
        com.ECS.client.jax.ItemSearchResponse response = port
                .itemSearch(ItemElement);

        String r = response.toString();
        System.out.println("response: " + r);

        for (Items itemList : response.getItems()) {
            System.out.println(itemList);

            for (Item itemObj : itemList.getItem()) {

                System.out.println(itemObj.getItemAttributes().getTitle()); // Title
                System.out.println(itemObj.getDetailPageURL()); // Amazon URL
            }
        }

        System.out.println("API Test stopped");

    }
}

Answer 3

It looks like the response object does not override toString(), so if it contains some sort of error response, simply printing it will not tell you what the error response is. You'll need to look at the api for what fields are returned in the response object and individually print those. Either you'll get an obvious error message or you'll have to go back to their documentation to try to figure out what is wrong.

Answer 4

You need to call the get methods on the Item object to retrieve its details, e.g.:

for (Item item : itemList.getItem()) {
   System.out.println(item.getItemAttributes().getTitle()); //Title of item
   System.out.println(item.getDetailPageURL()); // Amazon URL
   //etc
}

If there are any errors you can get them by calling getErrors()

if (response.getOperationRequest().getErrors() != null) { 
  System.out.println(response.getOperationRequest().getErrors().getError().get(0).getMessage());
}