epwzf20

08 $this->em = $this->_helper->EntityManager();

09$this->_helper->layout()->disableLayout();

10Zend_Controller_Front::getInstance()

11->setParam('noViewRenderer', true);

12}

13

14public function usernameAction()

15{

16

17// Retrieve the provided username

18$username = $this->_request->getParam('username');

20// Does an account associated with username already exist?

21$account = $this->em->getRepository('Entities\Account')

24// If $account is null, the username is available

25if (is_null($account))

26{

27echo json_encode("TRUE");

28} else {

29echo json_encode("FALSE");

30}

31

32 }

33

34 }

Let's review the code:

•Lines 06-12 define the controller's init method. In this method we'll disable both the layout and view renderer, because the controller should not render anything other than the returned JSONformatted data.

•Lines 14-32 define the username action. This is pretty standard stuff by this point in the book, involving using Doctrine to determine whether the provided username already exists. If it doesn't, TRUE is returned to the caller, otherwise FALSE is returned.

Keep in mind that you shouldn't rely solely upon JavaScript-based features for important validation tasks such as verifying username availability; a malicious user could disable JavaScript and wreak a bit of havoc by introducing duplicate usernames into the system. To be safe, you should also carry out similar validation procedures on the server-side.

Test Your Knowledge

Test your understanding of the concepts introduced in this chapter by answering the following questions. You can find the answers in the back of the book.

•Why should you link to the jQuery library via Google's content distribution network rather than store a version locally?

•What role does jQuery's $.getJSON method play in creating the Ajax-driven feature discussed earlier in this chapter?

Chapter 10. Integrating Web

Services

Data is the lifeblood of today's economy, with companies like Google, Microsoft, and Amazon.com spending billions of dollars amassing, organizing, parsing, and analyzing astoundingly large sums of information about their products, services, users, and the world at large. So it may seem counterintuitive that all of the aforementioned companies and many others make this data available for others for free.

By exposing this data through an application programming interface (API) known as a web service, their goal is to provide savvy developers with a practical way to present this data to others. Additional exposure will hopefully lead to increased interest in that company's offerings, with increased revenues to follow. A great example of this strategy is evident in Amazon.com's Product Advertising API. Via the Product Advertising API, Amazon exposes information about almost every product in what is undoubtedly the largest shopping catalog on the planet, including the product title, manufacturer, price, description, images, sales rank, and much more. You're free to use this information to create new and interesting online services, provided you follow the API's terms of service, which among other requirements demands that any product information retrieved from the API is linked back to the product's primary Amazon product description page.

Other web services such as the Google Maps API and Twitter API, expose both data and useful features which allow you to interact with the service itself. For instance, the Google Maps API provides you with not only the ability to render a map centered over any pair of coordinates, but also the opportunity to plot markers, routes, and create other interesting location-based services. Likewise, the Twitter API not only gives you the ability to search the ever-growing mountain of tweets, but also the ability to update your own account with new updates.

The Zend Framework offers a particularly powerful set of web services-related components which connect to popular APIs including those offered by Amazon.com, eBay, Flickr, Google, Microsoft, Twitter, Yahoo, and others. In this chapter I'll introduce you to Zend_Service_Amazon (the gateway to the Product Advertising API), a Zend Framework component which figures prominently into GameNomad, and also show you how easy it is to integrate the Google Maps API into your Zend Framework application despite the current lack of a Zend Framework Google Maps API component.

associates/ and click the Sign Up Now button. You'll be asked to sign in to your existing Amazon.com account, and provide contact information, your company name or website, and the website URL where you'll be invoking the service. You'll also be asked to read and agree to the AWS Customer Agreement. Please read this agreement carefully, because there are some stipulations which can most definitely affect your ability to use this information within certain applications. Once done, Amazon will confirm the creation of your account. Click on the Manage Your Account link to retrieve your keys. From here click on the Access Identifiers link. You'll be presented with two identifiers, your Access Key ID and your Secret Access Key. Copy these keys into your application.ini file, along with your associate ID:

;------------------------

; Amazon ;------------------------

amazon.product_advertising.public.key = "12345678ABCDEFGHIJK" amazon.product_advertising.public.private.key = "KJIHGFESECRET876" amazon.product_advertising.country = "US"

amazon.associate_id = "gamenomad-20"

We'll use these keys to connect to Amazon using the Zend_Service_Amazon component, introduced in the next step.

Retrieving a Single Video Game

Amazon.com has long used a custom product identification standard known as the Amazon Standard Identification Number, or ASIN. These 10-digit alphanumerical strings uniquely identify every product in the Amazon.com catalog. Of course, you need to know what the product's ASIN is in order to perform such a query, so how do you find it? The easiest way is to either locate it within the product's URL, or scroll down the product's page where it will be identified alongside other information such as the current Amazon sales rank and manufacturer name. For instance, the ASIN for Halo 3 on the Xbox 360 is B000FRU0NU. With that in hand, we can use the Zend_Services_Amazon component to query Amazon. Use the following code snippet to retrieve the product details associated with the ASIN B000FRU0NU:

Although I'd venture a guess this code is self-explanatory, let's nonetheless expand upon some of its key points:

•Lines 01-06 retrieve the assigned Product Advertising API public and private keys, and the country setting. I'm based in the United States and so have set this to "US", however if you were in the United Kingdom you'd presumably want to use the product catalog associated with http:// www.amazon.co.uk and so you'll set your country code to UK. See the Product Advertising API manual for a complete list of available codes.

•Lines 08-09 instantiates the Zend_Service_Amazon component class, readying it for subsequent authentication and product retrieval.

•Line 11 searches the catalog for a product identified by the ASIN B000FRU0NU. As you'll see later in this chapter, we can also perform open-ended searches using criteria such as product title and manufacturer.

•Lines 13-15 output the returned product's title, manufacturer, and product group. You can think of the product group as an organizational attribute, like a category. Amazon has many such product groups, among them Books, Video Games, and Sporting Goods.

Executing this code returns the following output:

Title: Halo 3

Publisher: Microsoft

Category: Video Games

Setting the Response Group

To maximize efficiency both in terms of bandwidth usage and parsing of the returned object, Amazon empowers you to specify the degree of product detail you'd like returned. When it comes to querying for general product information, typically you'll choose from one of three levels:

•Small: The Small group (set by default) contains only the most fundamental product attributes, including the ASIN, creator (author or manufacturer, for instance), manufacturer, product group (book, video game, or sporting goods, for instance), title, and Amazon.com product URL.

Let's start by creating the action, which will contact the web service and retrieve the desired game. Assume the URL is a custom route of the format http://www.gamenomad.com/games/B000FRU0NU. This code contains nothing you haven't already encountered:

public function showAction()

{

// Retrieve the ASIN

$asin = $this->_request->getParam('asin');

// Query AWS

$amazonPublicKey = Zend_Registry::get('config') ->amazon->product_advertising->public->key;

$amazonPrivateKey = Zend_Registry::get('config') ->amazon->product_advertising->private->key;

$amazonCountry = Zend_Registry::get('config')->amazon->country;

$amazon =

new Zend_Service_Amazon($amazonPublicKey, $amazonCountry, $amazonPrivateKey);

$this->view->item =

$amazon->itemLookup('B000FRU0NU', array('ResponseGroup' => 'Medium'));

}

Once the query has been returned, all that's left to do is populate the data into the view, as is demonstrated here:

<h1><?= $this->item->Title; ?></h1>

<img src="<?= $this->item->MediumImage->url; ?>" /> <b>Publisher</b>: <?= $this->item->Manufacturer; ?><br /> <b>Release Date</b>:

<?= $this->ReleaseDate($this->item->ReleaseDate)); ?><br /> <b>Amazon.com Price</b>: <?= $this->item->FormattedPrice; ?><br /> <b>Latest Amazon.com Sales Rank</b>:

<?= $this->SalesRank($this->item->SalesRank); ?><br />

Like the controller, we're really just connecting the dots regarding what's been learned here and in other chapters. Perhaps the only worthy note is that a few custom view helpers are used in order to format the publication date and sales rank. Within these view helpers native PHP functions such as strtotime(), date() and number_format() are used in order to convert the returned values into more desirable formats.

Of course, because GameNomad is a live website, the Product Advertising API isn't actually queried every time a video game's profile page is retrieved. Much of this data is cached locally, and