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c#amazon-web-servicesapiamazon-advertising-api

amazon product advertising api - item lookup request working example


would anyone have a working example of an amazon ITEMLOOKUP ?>

i have the following code but it does not seem to work:

string ISBN = "0393326381";
            string ASIN = "";

            if (!(string.IsNullOrEmpty(ISBN) && string.IsNullOrEmpty(ASIN)))
            {
                AWSECommerceServicePortTypeChannel service = new AWSECommerceServicePortTypeChannel();
                ItemLookup lookup = new ItemLookup();
                ItemLookupRequest request = new ItemLookupRequest();

                lookup.AssociateTag = secretKey;
                lookup.AWSAccessKeyId = accessKeyId;
                if (string.IsNullOrEmpty(ASIN))
                {
                    request.IdType = ItemLookupRequestIdType.ISBN;
                    request.ItemId = new string[] { ISBN.Replace("-", "") };
                }
                else
                {
                    request.IdType = ItemLookupRequestIdType.ASIN;
                    request.ItemId = new string[] { ASIN };
                }
                request.ResponseGroup = new string[] { "OfferSummary" };

                lookup.Request = new ItemLookupRequest[] { request };
                response = service.ItemLookup(lookup);

                if (response.Items.Length > 0 && response.Items[0].Item.Length > 0)
                {
                    Item item = response.Items[0].Item[0];
                    if (item.MediumImage == null)
                    {
                        //bookImageHyperlink.Visible = false;
                    }
                    else
                    {
                        //bookImageHyperlink.ImageUrl = item.MediumImage.URL;
                    }
                    //bookImageHyperlink.NavigateUrl = item.DetailPageURL;
                    //bookTitleHyperlink.Text = item.ItemAttributes.Title;
                    //bookTitleHyperlink.NavigateUrl = item.DetailPageURL;
                    if (item.OfferSummary.LowestNewPrice == null)
                    {
                        if (item.OfferSummary.LowestUsedPrice == null)
                        {
                            //priceHyperlink.Visible = false;
                        }
                        else
                        {
                            //priceHyperlink.Text = string.Format("Buy used {0}", item.OfferSummary.LowestUsedPrice.FormattedPrice);
                            //priceHyperlink.NavigateUrl = item.DetailPageURL;
                        }
                    }
                    else
                    {
                        //priceHyperlink.Text = string.Format("Buy new {0}", item.OfferSummary.LowestNewPrice.FormattedPrice);
                        //priceHyperlink.NavigateUrl = item.DetailPageURL;
                    }
                    if (item.ItemAttributes.Author != null)
                    {
                        //authorLabel.Text = string.Format("By {0}", string.Join(", ", item.ItemAttributes.Author));
                    }
                    else
                    {
                        //authorLabel.Text = string.Format("By {0}", string.Join(", ", item.ItemAttributes.Creator.Select(c => c.Value).ToArray()));
                    }
                    /*
                    ItemLink link = item.ItemLinks.Where(i => i.Description.Contains("Wishlist")).FirstOrDefault();
                    if (link == null)
                    {
                        //wishListHyperlink.Visible = false;
                    }
                    else
                    {
                        //wishListHyperlink.NavigateUrl = link.URL;
                    }
                     * */
                }
            }

        }

the problem is with this:

thisshould be defined differently but i do not know how AWSECommerceServicePortTypeChannel service = new AWSECommerceServicePortTypeChannel();


Solution

  • Say, that code looks awful familiar. You're missing the Endpoint signing piece from when they switched over to requiring that you add message signing. You need to add a behavior on your client. Here's the change to your code above:

    if (!(string.IsNullOrEmpty(ISBN) && string.IsNullOrEmpty(ASIN)))
    {
        AWSECommerceServicePortTypeClient client = new AWSECommerceServicePortTypeClient();
        client.ChannelFactory.Endpoint.Behaviors.Add(
            new Amazon.AmazonSigningEndpointBehavior(
                accessKeyId,
                secretKey);
    
        ItemLookup lookup = new ItemLookup();
        ItemLookupRequest request = new ItemLookupRequest();
        lookup.AssociateTag = accessKeyId;
        lookup.AWSAccessKeyId = secretKey;
    //... etc.
    

    And here's the Endpoint (I can't take credit for this, I wish I could remember who should):

    namespace Amazon
    {
        public class AmazonSigningEndpointBehavior : IEndpointBehavior {
            private string    accessKeyId    = "";
            private string    secretKey    = "";
    
            public AmazonSigningEndpointBehavior(string accessKeyId, string secretKey) {
                this.accessKeyId    = accessKeyId;
                this.secretKey        = secretKey;
            }
    
            public void ApplyClientBehavior(ServiceEndpoint serviceEndpoint, ClientRuntime clientRuntime) {
                clientRuntime.MessageInspectors.Add(new AmazonSigningMessageInspector(accessKeyId, secretKey));
            }
    
            public void ApplyDispatchBehavior(ServiceEndpoint serviceEndpoint, EndpointDispatcher endpointDispatcher) { return; }
            public void Validate(ServiceEndpoint serviceEndpoint) { return; }
            public void AddBindingParameters(ServiceEndpoint serviceEndpoint, BindingParameterCollection bindingParameters) { return; }
        }
    }
    

    Oh. And you'll need the MessageInspector for that to work.

    namespace Amazon
    {
        public class AmazonSigningMessageInspector : IClientMessageInspector {
            private string    accessKeyId    = "";
            private string    secretKey    = "";
    
            public AmazonSigningMessageInspector(string accessKeyId, string secretKey) {
                this.accessKeyId    = accessKeyId;
                this.secretKey        = secretKey;
            }
    
            public object BeforeSendRequest(ref Message request, IClientChannel channel) {
                // prepare the data to sign
                string        operation        = Regex.Match(request.Headers.Action, "[^/]+$").ToString();
                DateTime    now                = DateTime.UtcNow;
                string        timestamp        = now.ToString("yyyy-MM-ddTHH:mm:ssZ");
                string        signMe            = operation + timestamp;
                byte[]        bytesToSign        = Encoding.UTF8.GetBytes(signMe);
    
                // sign the data
                byte[]        secretKeyBytes    = Encoding.UTF8.GetBytes(secretKey);
                HMAC        hmacSha256        = new HMACSHA256(secretKeyBytes);
                byte[]        hashBytes        = hmacSha256.ComputeHash(bytesToSign);
                string        signature        = Convert.ToBase64String(hashBytes);
    
                // add the signature information to the request headers
                request.Headers.Add(new AmazonHeader("AWSAccessKeyId", accessKeyId));
                request.Headers.Add(new AmazonHeader("Timestamp", timestamp));
                request.Headers.Add(new AmazonHeader("Signature", signature));
    
                return null;
            }
    
            public void AfterReceiveReply(ref Message reply, object correlationState) { }
        }
    }
    

    And finally, the Header:

    namespace Amazon
    {
        public class AmazonHeader : MessageHeader
        {
            private string name;
            private string value;
    
            public AmazonHeader(string name, string value)
            {
                this.name = name;
                this.value = value;
            }
    
            public override string Name { get { return name; } }
            public override string Namespace { get { return "http://security.amazonaws.com/doc/2007-01-01/"; } }
    
            protected override void OnWriteHeaderContents(XmlDictionaryWriter xmlDictionaryWriter, MessageVersion messageVersion)
            {
                xmlDictionaryWriter.WriteString(value);
            }
        }
    }
    

    Yes, they made it complicated when they started requiring message signing...