Preprocesses a request.

def preprocessRequest(self, service_request, *args, **kwargs):
        """
        Preprocesses a request.
        """
        processor = self.getPreprocessor(service_request)

        if processor is None:
            return

        args = (service_request,) + args

        if hasattr(processor, '_pyamf_expose_request'):
            http_request = kwargs.get('http_request', None)
            args = (http_request,) + args

        return processor(*args)