DEPRECATED: Declares the RPC service interfaces.

This module declares the abstract interfaces underlying proto2 RPC services. These are intended to be independent of any particular RPC implementation, so that proto2 services can be used on top of a variety of implementations. Starting with version 2.3.0, RPC implementations should not try to build on these, but should instead provide code generator plugins which generate code specific to the particular RPC implementation. This way the generated code can be more appropriate for the implementation in use and can avoid unnecessary layers of indirection.

class google.protobuf.service.RpcChannel

Abstract interface for an RPC channel.

An RpcChannel represents a communication line to a service which can be used to call that service’s methods. The service may be running on another machine. Normally, you should not use an RpcChannel directly, but instead construct a stub {@link Service} wrapping it. Example:


RpcChannel channel = rpcImpl.Channel(“”) RpcController controller = rpcImpl.Controller() MyService service = MyService_Stub(channel) service.MyMethod(controller, request, callback)

CallMethod(method_descriptor, rpc_controller, request, response_class, done)

Calls the method identified by the descriptor.

Call the given method of the remote service. The signature of this procedure looks the same as Service.CallMethod(), but the requirements are less strict in one important way: the request object doesn’t have to be of any specific class as long as its descriptor is method.input_type.

class google.protobuf.service.RpcController

An RpcController mediates a single method call.

The primary purpose of the controller is to provide a way to manipulate settings specific to the RPC implementation and to find out about RPC-level errors. The methods provided by the RpcController interface are intended to be a “least common denominator” set of features which we expect all implementations to support. Specific implementations may provide more advanced features (e.g. deadline propagation).


If Failed is true, returns a human-readable description of the error.


Returns true if the call failed.

After a call has finished, returns true if the call failed. The possible reasons for failure depend on the RPC implementation. Failed() must not be called before a call has finished. If Failed() returns true, the contents of the response message are undefined.


Checks if the client cancelled the RPC.

If true, indicates that the client canceled the RPC, so the server may as well give up on replying to it. The server should still call the final “done” callback.


Sets a callback to invoke on cancel.

Asks that the given callback be called when the RPC is canceled. The callback will always be called exactly once. If the RPC completes without being canceled, the callback will be called after completion. If the RPC has already been canceled when NotifyOnCancel() is called, the callback will be called immediately.

NotifyOnCancel() must be called no more than once per request.


Resets the RpcController to its initial state.

After the RpcController has been reset, it may be reused in a new call. Must not be called while an RPC is in progress.


Sets a failure reason.

Causes Failed() to return true on the client side. “reason” will be incorporated into the message returned by ErrorText(). If you find you need to return machine-readable information about failures, you should incorporate it into your response protocol buffer and should NOT call SetFailed().


Initiate cancellation.

Advises the RPC system that the caller desires that the RPC call be canceled. The RPC system may cancel it immediately, may wait awhile and then cancel it, or may not even cancel the call at all. If the call is canceled, the “done” callback will still be called and the RpcController will indicate that the call failed at that time.

exception google.protobuf.service.RpcException

Exception raised on failed blocking RPC method call.


Exception.with_traceback(tb) – set self.__traceback__ to tb and return self.

class google.protobuf.service.Service

Abstract base interface for protocol-buffer-based RPC services.

Services themselves are abstract classes (implemented either by servers or as stubs), but they subclass this base interface. The methods of this interface can be used to call the methods of the service without knowing its exact type at compile time (analogous to the Message interface).

CallMethod(method_descriptor, rpc_controller, request, done)

Calls a method of the service specified by method_descriptor.

If “done” is None then the call is blocking and the response message will be returned directly. Otherwise the call is asynchronous and “done” will later be called with the response value.

In the blocking case, RpcException will be raised on error.


  • method_descriptor.service == GetDescriptor

  • request is of the exact same classes as returned by GetRequestClass(method).

  • After the call has started, the request must not be modified.

  • “rpc_controller” is of the correct type for the RPC implementation being used by this Service. For stubs, the “correct type” depends on the RpcChannel which the stub is using.


  • “done” will be called when the method is complete. This may be before CallMethod() returns or it may be at some point in the future.

  • If the RPC failed, the response value passed to “done” will be None. Further details about the failure can be found by querying the RpcController.


Retrieves this service’s descriptor.


Returns the class of the request message for the specified method.

CallMethod() requires that the request is of a particular subclass of Message. GetRequestClass() gets the default instance of this required type.


method = service.GetDescriptor().FindMethodByName(“Foo”) request = stub.GetRequestClass(method)() request.ParseFromString(input) service.CallMethod(method, request, callback)


Returns the class of the response message for the specified method.

This method isn’t really needed, as the RpcChannel’s CallMethod constructs the response protocol message. It’s provided anyway in case it is useful for the caller to know the response type in advance.