try:

            self._func = self._find_method()

        except AttributeError, e:

            return jsonrpc_error(message=str(e))

        # now that we have a method, add self._req_params to

        # self.kargs and dispatch control to WGIController

        argspec = inspect.getargspec(self._func)

        arglist = argspec[0][1:]

        defaults = map(type, argspec[3] or [])

        default_empty = types.NotImplementedType

        # kw arguments required by this method

        func_kwargs = dict(izip_longest(reversed(arglist), reversed(defaults),

                                        fillvalue=default_empty))

        # this is little trick to inject logged in user for

        # perms decorators to work they expect the controller class to have

        # rhodecode_user attribute set

        self.rhodecode_user = auth_u

        # This attribute will need to be first param of a method that uses

        # api_key, which is translated to instance of user at that name

        USER_SESSION_ATTR = 'apiuser'

        if USER_SESSION_ATTR not in arglist:

            return jsonrpc_error(message='This method [%s] does not support '

                                 'authentication (missing %s param)' %

                                 (self._func.__name__, USER_SESSION_ATTR))

        # get our arglist and check if we provided them as args

        for arg, default in func_kwargs.iteritems():

            if arg == USER_SESSION_ATTR:

                # USER_SESSION_ATTR is something translated from api key and

                # this is checked before so we don't need validate it

                continue

            # skip the required param check if it's default value is

            # NotImplementedType (default_empty)

            if (default == default_empty and arg not in self._request_params):

                return jsonrpc_error(

                    message=(

                        'Missing non optional `%s` arg in JSON DATA' % arg

                    )

                )

        self._rpc_args = {USER_SESSION_ATTR: u}

        self._rpc_args.update(self._request_params)

        self._rpc_args['action'] = self._req_method

        self._rpc_args['environ'] = environ

        self._rpc_args['start_response'] = start_response

        status = []

        headers = []

        exc_info = []

        def change_content(new_status, new_headers, new_exc_info=None):

            status.append(new_status)

            headers.extend(new_headers)

            exc_info.append(new_exc_info)

        output = WSGIController.__call__(self, environ, change_content)

        output = list(output)

        headers.append(('Content-Length', str(len(output[0]))))

        replace_header(headers, 'Content-Type', 'application/json')

        start_response(status[0], headers, exc_info[0])

        return output

    def _dispatch_call(self):

        """

        Implement dispatch interface specified by WSGIController

        """

        try:

            raw_response = self._inspect_call(self._func)

            if isinstance(raw_response, HTTPError):

                self._error = str(raw_response)

        except JSONRPCError, e:

            self._error = str(e)

        except Exception, e:

            log.error('Encountered unhandled exception: %s' \

                      % traceback.format_exc())

            json_exc = JSONRPCError('Internal server error')

            self._error = str(json_exc)

        if self._error is not None:

            raw_response = None

        response = dict(id=self._req_id, result=raw_response,

                        error=self._error)

        try:

            return json.dumps(response)

        except TypeError, e:

            log.debug('Error encoding response: %s', e)

    def _find_method(self):

        """

        Return method named by `self._req_method` in controller if able

        """

        log.debug('Trying to find JSON-RPC method: %s', self._req_method)

        if self._req_method.startswith('_'):

            raise AttributeError("Method not allowed")

        try:

            func = getattr(self, self._req_method, None)

        except UnicodeEncodeError:

            raise AttributeError("Problem decoding unicode in requested "

                                 "method name.")

        if isinstance(func, types.MethodType):

            return func

        else:

            raise AttributeError("No such method: %s" % self._req_method)