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Diffstat (limited to 'python/google/protobuf/service.py')
-rwxr-xr-x | python/google/protobuf/service.py | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/python/google/protobuf/service.py b/python/google/protobuf/service.py new file mode 100755 index 00000000..461031b7 --- /dev/null +++ b/python/google/protobuf/service.py @@ -0,0 +1,194 @@ +# Protocol Buffers - Google's data interchange format +# Copyright 2008 Google Inc. +# http://code.google.com/p/protobuf/ +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +"""Declares the RPC service interfaces. + +This module declares the abstract interfaces underlying proto2 RPC +services. These are intented to be independent of any particular RPC +implementation, so that proto2 services can be used on top of a variety +of implementations. +""" + +__author__ = 'petar@google.com (Petar Petrov)' + + +class Service(object): + + """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). + """ + + def GetDescriptor(self): + """Retrieves this service's descriptor.""" + raise NotImplementedError + + def CallMethod(self, method_descriptor, rpc_controller, + request, done): + """Calls a method of the service specified by method_descriptor. + + Preconditions: + * 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. + + Postconditions: + * "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. + """ + raise NotImplementedError + + def GetRequestClass(self, method_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. + + Example: + method = service.GetDescriptor().FindMethodByName("Foo") + request = stub.GetRequestClass(method)() + request.ParseFromString(input) + service.CallMethod(method, request, callback) + """ + raise NotImplementedError + + def GetResponseClass(self, method_descriptor): + """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. + """ + raise NotImplementedError + + +class RpcController(object): + + """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: + + Example: + RpcChannel channel = rpcImpl.Channel("remotehost.example.com:1234") + RpcController controller = rpcImpl.Controller() + MyService service = MyService_Stub(channel) + service.MyMethod(controller, request, callback) + """ + + # Client-side methods below + + def Reset(self): + """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. + """ + raise NotImplementedError + + def Failed(self): + """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. + """ + raise NotImplementedError + + def ErrorText(self): + """If Failed is true, returns a human-readable description of the error.""" + raise NotImplementedError + + def StartCancel(self): + """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. + """ + raise NotImplementedError + + # Server-side methods below + + def SetFailed(self, reason): + """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(). + """ + raise NotImplementedError + + def IsCanceled(self): + """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. + """ + raise NotImplementedError + + def NotifyOnCancel(self, 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. + """ + raise NotImplementedError + + +class RpcChannel(object): + + """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). + """ + + def CallMethod(self, 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. + """ + raise NotImplementedError |