PHP's SOAP extension is an implementation of the SOAP protocol for PHP. Written in C, it provides a performance advantage over the PEAR::SOAP implementation, which is written in PHP.
In the following sections, you will learn how to expose a PHP/Oracle application as a web service with the help of PHP's SOAP extension.
As mentioned, SOAP is a messaging protocol. What this means is that SOAP clients and SOAP servers interact by sending SOAP messages to each other.
Note
A SOAP message is a SOAP-formatted XML document used to transport information between SOAP-based interfaces. For more information on SOAP, you can refer to the W3C SOAP Recommendation documents. Links to the latest versions of these documents can be found at http://www.w3.org/TR/soap/.
The following figure illustrates the general structure of a SOAP message.
As you can see in the figure, an XML document representing a SOAP message...