Creating Web Services

To create your own Web service, you first need a WSDL description. This is a rather unpleasant task, so the best thing is to take the WSDL description of a Web service that does the same (or at least whose methods have a similar signature). By the way, this is how the WSDL description in Listing 18.1 was developed, too. If you have a look at the description, you see the URL of the Web service:

 <soap:address location='http://localhost/php/guid-server.php'/> 

Change this according to your setup.

After this is done, the service itself can be written. As you may have guessed, the sample Web service will create a GUID, a Globally Unique Identifier with a prefix provided as a parameter. As you might know, PHP offers this functionality in the uniqid() function. In reality, this Web service is a wrapper for uniqid(), but for this sample this is good enough. Following is the code for the getGuid() function:

 function getGuid($prefix) {   return uniqid($prefix); } 

Now you have only three more stepsor lines of codeto do:

1.	Create a SOAP Server, providing the WSDL description.
2.	Add the getGuid() function to the server.
3.	Let the server handle the rest.

These three commands do the trick:

 $soap = new SoapServer("guid.wsdl"); $soap->addFunction("getGuid"); $soap->handle(); 

Listing 18.2 contains the complete code for this example, including disabling the WSDL cache.

Listing 18.2. The SOAP Server for the getGuid() Method

 <?php   ini_set('soap.wsdl_cache_enabled', 'Off');   function getGuid($prefix) {     return uniqid($prefix);   }   $soap = new SoapServer('guid.wsdl');   $soap->addFunction('getGuid');   $soap->handle(); ?>