First of all you need to register for a free Shopping.com developer account.

Then you can start building the API request URL:

http://publisher.api.shopping.com/publisher/3.0/rest/GeneralSearch?
	apiKey=%apikey%&
	trackingId=%trackingid%&
	subTrackingId=%subTrackingId%&
	categoryId=%categoryId%&
	keyword=%keyword%&
	pageNumber=%pageNumber%&
	numItems=%numItems%&
	hybridSortType=%hybridSortType%
	hybridSortOrder=%hybridSortOrder%

Now let’s see what the individual parameters mean:

• GeneralSearch: we need the operation GeneralSearch for our keyword-based search.
• apiKey: you get this API key in your Shopping.com developer account.
• trackingId: you need to request a tracking ID from Shopping.com to earn some money with your traffic.
• subTrackingId: choose any additional code here you want to use as optional tracking (e. g. for special campaigns).
• categoryId: the category you want to search in (leave empty to search in all categories).
• keyword: your search keywords. Make sure you use utf8_decode if the keywords are in UTF-8.
• pageNumber: for the first request you set this to 1 and increase it in previous requests if you need more items.
• numItems: here you can choose how many items (maximal 100) are returned per request.
• hybridSortType: choose if you want the result to be sorted by relevance or price.
• hybridSortOrder: choose if you want the result to be sorted ascending or descending.

That’s all: we just need to pass this URL again to the small function we used already in the eBay Finding API and the Amazon Product Advertising API examples and receive the XML response data:

/**
 * Returns the SimpleXML object.
 *
 * @param string $url The URL to receive the XML document.
 * @return string The SimpleXML object.
 *
 */
function getXml($url) {
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, $url);
	curl_setopt($ch, CURLOPT_HEADER, false);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLOPT_TIMEOUT, 3);
	$result = curl_exec($ch);
	curl_close($ch);

	return simplexml_load_string($result);
}

As you can see the Shopping.com API is very easy to handle as it is also the smallest of these three APIs.

Did you use the Shopping.com API yourself already?
Do you know other interesting online shopping APIs?

Again we need to start with a sign up for a free Amazon Web Services account. To make money with your Amazon traffic you also need to register for the Amazon affiliate program.

Now we can start to build the request URL for the Amazon Product Advertising API:

http://ecs.amazonaws.com/onca/xml?
	AWSAccessKeyId=%awsAccessKeyId%&
	AssociateTag=%associateTag%&
	ItemPage=%itemPage%&
	Keywords=%keywords%&
	Operation=%operation%&
	ResponseGroup=%responseGroup%&
	SearchIndex=%categoryId%&
	Service=AWSECommerceService&
	Timestamp=%timestamp%&
	Signature=%signature%

Let’s see what the individual parameters mean:

• ecs.amazonaws.com: based on the country you want to target, you have to use a specific endpoint. It is ecs.amazonaws.com for USA.
• AWSAccessKeyId: you get this access key in your Amazon Web Services account.
• ItemPage: for the first request you set this to 1 and increase it in previous requests if you need more items. Each response has up to 10 items (you cannot change that).
• Keywords: your search keywords. Make sure you use rawurlencode here.
• Operation: the name of the operation of the Amazon Product Advertising API you want to call. For the keyword search we choose ItemSearch.
• ResponseGroup: based on the level of detail you need in the response, choose a useful response group. For item searches I choose Medium most of the time.
• SearchIndex: a search index is a kind of first level category. If you want to search in everything, just choose All.
• Service: just use AWSECommerceService here.
• Timestamp:a timestamp generated in PHP like this:

  rawurlencode(gmdate('Y-m-d\TH:i:s\Z'))

• Signature: that’s the funniest part: please see below how to generate this signature.

To be able to send a valid API request, you have to calculate the signature as following:

$request = "GET\necs.amazonaws.com\n/onca/xml\n";
$request .= "AWSAccessKeyId=%awsAccessKeyId%&AssociateTag=%associateTag%&ItemPage=%itemPage%&Keywords=%keywords%&Operation=%operation%&ResponseGroup=%responseGroup%&SearchIndex=%categoryId%&Service=AWSECommerceService&Timestamp=%timestamp%";
$signature = rawurlencode(base64_encode(hash_hmac('sha256', $request, %secretKey%, true)));

You get the needed %secretKey% in your Amazon Web Services account, too.

When you’ve done everything correctly, you can pass the resulting request URL to this small function that we used already for the eBay Finding API request and receive the XML document response of the API:

/**
 * Returns the SimpleXML object.
 *
 * @param string $url The URL to receive the XML document.
 * @return string The SimpleXML object.
 *
 */
function getXml($url) {
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, $url);
	curl_setopt($ch, CURLOPT_HEADER, false);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLOPT_TIMEOUT, 3);
	$result = curl_exec($ch);
	curl_close($ch);

	return simplexml_load_string($result);
}

Unfortunately I have to say that I think the Amazon Product Advertising API is really confusing and badly documented. Especially if you need to work with these search indices and categories (so-called nodes) that’s not very funny at all. And there are even things that are not bad, but just wrong documented in the Amazon Product Advertising API documentation.

What’s your opinion about the Amazon Product Advertising API?

In the following I want to show how to get eBay items from the eBay Finding API based on a keyword search.

First of all you need to join the free eBay developers program to get your application ID. If you additionally want to earn some money with your eBay traffic – and probably that’s the reason why you want to integrate eBay items in your website – you also need to apply to the eBay partner network.

After you have been registered in the eBay developers program and partner network, you can use following URL in your request to query for eBay items:

http://svcs.ebay.com/services/search/FindingService/v1?
	OPERATION-NAME=%operationName%&
	SERVICE-VERSION=%serviceVersion%&
	GLOBAL-ID=%globalId%&
	SECURITY-APPNAME=%appId%&
	RESPONSE-DATA-FORMAT=%responseDataFormat%&
	REST-PAYLOAD&
	affiliate.networkId=%networkId%&
	affiliate.trackingId=%trackingId%&
	affiliate.customId=%customId%&
	paginationInput.entriesPerPage=%entriesPerPage%&
	paginationInput.pageNumber=%pageNumber%&
	keywords=%keywords%

Now let’s see what the individual parameters mean:

• OPERATION-NAME: the name of the operation of the eBay Finding API you want to call. For the keyword search we choose findItemsByKeywords.
• SERVICE-VERSION: the API version you’re using (the current one is 1.0.0 right now).
• GLOBAL-ID: here you need to include the ID of the eBay site you’re using.
• SECURITY-APPNAME: the application ID you got from the eBay developers program website.
• RESPONSE-DATA-FORMAT: you can choose here how the data should be returned. I use XML, but you also could choose JSON or NV (name-value pair).
• REST-PAYLOAD: just specify this without a value after the standard headers above.
• affiliate.networkId: you get this ID from the eBay partner network.
• affiliate.trackingId: you get this ID from the eBay partner network.
• affiliate.customId: choose any additional code here you want to use as optional tracking (e. g. for special campaigns).
• paginationInput.entriesPerPage: here you can choose how many items (maximal 100) are returned per request.
• paginationInput.pageNumber: for the first request you set this to 1 and increase it in previous requests if you need more items.
• keywords: last but not least you include your search keywords here. Make sure you use utf8_decode if the keywords are in UTF-8.

Finally we just need to receive our XML data. Therefore I use this simple function to get the data from the URL and load the XML document:

/**
 * Returns the SimpleXML object.
 *
 * @param string $url The URL to receive the XML document.
 * @return string The SimpleXML object.
 *
 */
function getXml($url) {
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, $url);
	curl_setopt($ch, CURLOPT_HEADER, false);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLOPT_TIMEOUT, 3);
	$result = curl_exec($ch);
	curl_close($ch);

	return simplexml_load_string($result);
}

Of course, there is very much more you can do with the eBay APIs. For example I also needed to get items by category as well as the most watched items. That’s also pretty easy. If you need more, you can even do the whole buying process directly through the eBay APIs: this way the user does not need to leave your website at all to buy an item.

Finally I want to say that in fact the eBay APIs are very big and complex APIs, but the documentation is quite good, too. There are much worse examples of big APIs (see also my post about the Amazon Product Advertising API).

Did you use the eBay APIs yourself already?