code: protected function getActionFromWsdl($wsdlFilePath, $messageName)
      {
          $wsdlId = $this->getWsdlIdFor($messageName);
  
          return WsdlAnalyser::exaluateXpathQueryOnWsdl(
              $wsdlId,
              $wsdlFilePath,
              sprintf(self::XPATH_OPERATION_ACTION, $messageName)
          );
      }
docs: Get the SOAPAction for a given message from the WSDL contents.
  
  @param string $wsdlFilePath
  @param string $messageName
  @return string|null