Tuesday, September 20, 2011

Webservice in SOAP using PHP

What is SOAP?

SOAP, the Simple Object Access Protocol, is the powerhouse of web services. It’s a highly adaptable, object-oriented protocol that exists in over 80 implementations on every popular platform, including AppleScript, JavaScript, and Cocoa. It provides a flexible communication layer between applications, regardless of platform and location. As long as they both speak SOAP, a PHP-based web application can ask a C++ database application on another continent to look up the price of a book and have the answer right away. Another Internet Developer article shows how to use SOAP with AppleScript and Perl.

How SOAP works?

A SOAP transaction begins with an application making a call to a remote procedure. The SOAP client script then encodes the procedure request as an XML payload and sends it over the transport protocol to a server script. The server parses the request and passes it to a local method, which returns a response. The response is encoded as XML by the server and returned as a response to the client, which parses the response and passes the result to the original function.

SOAP versionings?

There are a number of different implementations of SOAP under PHP. It’s a shifting landscape: new ones appear, and old ones aren’t maintained or simply vanish. As of this writing, the most viable PHP implementation of SOAP seems to be Dietrich Ayala’s SOAPx4, also known as NuSOAP. This implementation is the most commonly used and appears to be the most fully developed and actively maintained, and it shows every sign of continuing to be a robust and popular solution. It’s not complete—a number of features, including full documentation, are still in the works—but it’s still a highly viable and easy-to-use SOAP solution.

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