Magento WSI SOAP v2 API Custom Webservice Returns Empty Response

Question

Problem: I succesfully call my webservice, but I get an empty response in return.

Situation:

• I created a new Module structure and files following this tutorial: Magento: Extending the API (v2)
  • MyNamespace
    • MyModule
      • Helper
        • Data.php
      • Model
        • MyModel
          • Api
            • V2.php
        • etc
          • api.xml
          • config.xml
          • wsdl.xml
          • wsi.xml

Also added the module config in: app/etc/modules/MyNamespace_MyModule.xml

• I debug the call with XDebug, and effectively stops at the breakpoint inside the webservice function
• The webservice is supposed to return a simple string: "Hello World"
• Testing with SoapUI all I get is an empty response with content length 0.

What can be wrong or missing!? Any help is appreciated.

EDIT:

I've managed to debug the call and realized that when it reaches class Zend_Soap_Server on line 832:

$soap->handle($request);

It doesn't execute any further! I don't know why.

Answer 1

The wsdl.xml had a small mis-configuration in the following line:

<binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>

It should be:

<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>