Using PHP to develop SCA and SDO_PHP tutorial

Initiated by the Open Service-Oriented Architecture Alliance (OSOA), Component-Oriented Architecture (SCA) and Service Data Objects (SDO) have become the latest methods for developing service-oriented architecture. At the beginning, these developments were only concentrated in some common development environments, such as Java and C++. Currently, SCA and SDO have begun to enter some other platforms. Here we will explain how to include some SOA technologies on PHP.

First let’s see what SDO can provide you. In a typical PHP application, half of the data comes from a relational database, but what if the application later not only gets the data from here, but also gets the data from an ordinary text file or a Web service? This issue is complicated because each data source requires its own way of obtaining it.

In this case, SDO in PHP provides a transparent way to handle the data source. Rather than processing each data source individually, it provides a unified way to access data objects. This process is completed through the Data Access Service (DAS), which is an intermediary method on the SDO architecture. Let's look at an SDO request in PHP.

＜?php<br>$providers = $company-＞shippingByGround;<br>foreach ($providers as $name =＞ $value) {<br>　echo "$name: $valuen";<br>}<br>?＞

Note how the last request handles unknown data sources. You don’t know where the data here is extracted from. You just use PHP’s SDO format to make one. While the lookup details are done by DAS, PHP currently supports obtaining data sources from XML and relational databases.

SDO cares about data, while SCA uses more general classes and components to achieve the same transparency. Does accessing existing business logic from any PHP class force developers to design around a specific set of assumptions? Is the logic already in another native PHP class? Does it exist on the network? Is it written in PHP?

When the scenarios mentioned above are satisfactory in their respective requirements, then each needs to be handled in a different way.

Using the SCA method, it doesn’t matter where the logic is stored, let alone what language is used to implement it. Then you will definitely say: "Isn't this similar to an ordinary Web Service? It's no different!" Then let's take an example to see what is included in the PHP SCA component.

<p>＜?php</p><p>include "SCA/SCA.php";</p><p>/**<br>* Calculate a shipment price for a given customer using a specific provider<br>*<br>* @service<br>*/<br>class ShipmentQuote {</p><p>　/**<br>　* The customer discount fee service to use.<br>　*<br>　* @reference<br>　* @binding.php ../DiscountFeeRate/DiscountFeeRate.php<br>　*/<br>　public $discountFee;</p><p>　/**<br>　* The shipping service to use.<br>　*<br>　* @reference<br>　* @binding.wsdl ../Shipper/ShipperQuote.wsdl<br>　*/<br>　public $shipper;</p><p>　/**<br>　* Get a quote for a given customer using a specific provider<br>　*<br>　* @param string $shipping The shipping company <br>　* @param string $customer The customer requiring shipment, in order to obtain discount rate<br>　* @return float The quote for a given customer using a certain shipping provider. <br>　*/<br>　function getQuote($shippingCo, $customer)<br>　{<br>$rateShip = $this-＞shipper-＞getShippingPrice($shippingCo);<br>$rate = $this-＞discountFee-＞getDiscountRate($customer);<br>return $rate * $rateShip;<br>　}<br>}<br>?＞</p>

The most critical part of the above is the statement part containing @, each of them provides a specific SCA behavior. The top-level @service identifier indicates that a class is exposed as a service. In this example, the final getQuote function will be the only operation exposed by the service, marked using @param and @return.

The execution or deployment of this final service - which will be delegated to a PHP SCA runtime - will bring us to an access point for creating a WSDL contract, just like you can in a web service As seen. Besides the simplicity of this way of deploying services, the real advantages of the SCA model will become more apparent when you examine the getQuote code.

Notice the two statements $this-getShippingPrice($shippingCo) and $this->discountFee->getDiscountRate($customer), which are based on the previous applications in the class. Each application is supported by its supporting service lock (specified by @reference and @binding flags). In the $discountFee use case, this will be a PHP class, and in the shipper use case, this will be a standard WSDL based Serve.

Although PHP’s simplicity and support from a large user base make it a good choice for building web applications, its capabilities are limited in many scenarios of enterprise applications. Now, by adding SCA and SDO, it provides With strong support from PHP and previous technologies, it, like other mainstream languages, can participate in the service-oriented trend.

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