From SOAP to REST
07/31/2012 Leave a comment
Let me start by saying that the examples below are provided in order to illustrate a point before making inquires. Do not assume anything you see below constitutes good design or implementation.
We currently have a SOAP based API to allow customers to perform a few basic things with our system instead of manually doing them via our user portal. I’ve extended a lot of the Zend_Soap_* classes in order to customize a good amount of the functionality. In the end, it works pretty much like this:
A proxy class contains all of the methods. The Zend_Soap_AutoDiscover and Zend_Soap_Wsdl classes parse the docblocks in order to build the WSDL. The Zend_Soap_Server is told which class to use as the proxy, as well as an array of class mappings, to allow proper translation between the types defined in the WSDL and the PHP classes.
Here is a simplified implementation. I’ve left out all the enhancements I’ve made to the core Zend_Soap functionality, as I don’t think it’s needed
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<?php class My_Soap_Proxy { /** * Creates a new record. * @param My_Soap_Type_Request $request * @return My_Soap_Type_Response */ public function CreateRecord($request){ //stuff return $response; } /** * Gets a record. * @param int $id * @return My_Soap_Type_Record */ public function GetRecord($id){ $record = new My_Soap_Type_Record($id); return $record; } } /* Omitting comments from remainder of classes for brevity */ class My_Soap_Type_Request { public $name; public $age; } class My_Soap_Type_Response { public $id; } class My_Soap_Type_Record { public $id; public $name; public $age; public function __construct($id){ //get the record } } |
The WSDL would define three complex types, Request, Response, Record. It would also define two methods, CreateRecord and GetRecord. The SOAP libraries take care of all of the magic to make sure the WSDL is properly defined, that a client that sends a CreateRecord call gets routed to My_Soap_Proxy::CreateRecord, and that the method gets an instance of My_Soap_Type_Request. The WSDL is available at http://my.url.com/webservices/index.php?wsdl, and the endpoint itself is just http://my.url.com/webservices/index.php. That script is also pretty simple:
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<?php //do some configuration related to defining the proxy, class maps, etc $server = new My_Soap_Server($config); //My_Soap_Server extends Zend_Soap_Server $server->handle(); |
So, here is where my question about REST comes into play.
Is there any reason that, with possibly a few modifications, the proxy and type classes above can’t be used by a RESTful web service? You would have a single endpoint script, similar to the SOAP endpoint, that handles the requests, http://my.url.com/rest/endpoint.php, and single rewrite rule, /rest/(.*) -> /rest/endpoint.php, is all that is needed to send all the requests to that script.
The script itself would invoke the REST “server” class which would then be in charge of properly translating the provided data into an instance of the proper type class, passing that to the proper method in the proxy class, and then translating the response back into the proper format before sending it to the client.
I only have a very basic understanding of RESTful web services, so while that above seems obvious to me, it is very possible I am missing something. One reason I question such a solution, is that I constantly hear people talking about why RESTful web services are great, and SOAP web services are evil. While I agree that RESTful web services are much easier to understand and interface with, when a customer wants to know why their system’s SOAP based API can’t interface with your system, the fact you think SOAP is evil is not going to be a good answer.
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