EIC code displayed by LXR master/​include/​google/​protobuf/​service.h	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2025-01-31 10:12:26

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
 // Author: kenton@google.com (Kenton Varda)
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 //
 // DEPRECATED:  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.
 //
 //
 // When you use the protocol compiler to compile a service definition, it
 // generates two classes:  An abstract interface for the service (with
 // methods matching the service definition) and a "stub" implementation.
 // A stub is just a type-safe wrapper around an RpcChannel which emulates a
 // local implementation of the service.
 //
 // For example, the service definition:
 //   service MyService {
 //     rpc Foo(MyRequest) returns(MyResponse);
 //   }
 // will generate abstract interface "MyService" and class "MyService::Stub".
 // You could implement a MyService as follows:
 //   class MyServiceImpl : public MyService {
 //    public:
 //     MyServiceImpl() {}
 //     ~MyServiceImpl() {}
 //
 //     // implements MyService ---------------------------------------
 //
 //     void Foo(google::protobuf::RpcController* controller,
 //              const MyRequest* request,
 //              MyResponse* response,
 //              Closure* done) {
 //       // ... read request and fill in response ...
 //       done->Run();
 //     }
 //   };
 // You would then register an instance of MyServiceImpl with your RPC server
 // implementation.  (How to do that depends on the implementation.)
 //
 // To call a remote MyServiceImpl, first you need an RpcChannel connected to it.
 // How to construct a channel depends, again, on your RPC implementation.
 // Here we use a hypothetical "MyRpcChannel" as an example:
 //   MyRpcChannel channel("rpc:hostname:1234/myservice");
 //   MyRpcController controller;
 //   MyServiceImpl::Stub stub(&channel);
 //   FooRequest request;
 //   FooResponse response;
 //
 //   // ... fill in request ...
 //
 //   stub.Foo(&controller, request, &response, NewCallback(HandleResponse));
 //
 // On Thread-Safety:
 //
 // Different RPC implementations may make different guarantees about what
 // threads they may run callbacks on, and what threads the application is
 // allowed to use to call the RPC system.  Portable software should be ready
 // for callbacks to be called on any thread, but should not try to call the
 // RPC system from any thread except for the ones on which it received the
 // callbacks.  Realistically, though, simple software will probably want to
 // use a single-threaded RPC system while high-end software will want to
 // use multiple threads.  RPC implementations should provide multiple
 // choices.
 
 #ifndef GOOGLE_PROTOBUF_SERVICE_H__
 #define GOOGLE_PROTOBUF_SERVICE_H__
 
 #include <string>
 
 #include "google/protobuf/stubs/callback.h"
 #include "google/protobuf/stubs/common.h"
 #include "google/protobuf/port.h"
 
 #ifdef SWIG
 #error "You cannot SWIG proto headers"
 #endif
 
 // Must be included last.
 #include "google/protobuf/port_def.inc"
 
 namespace google {
 namespace protobuf {
 
 // Defined in this file.
 class Service;
 class RpcController;
 class RpcChannel;
 
 // Defined in other files.
 class Descriptor;         // descriptor.h
 class ServiceDescriptor;  // descriptor.h
 class MethodDescriptor;   // descriptor.h
 class Message;            // message.h
 
 // Abstract base interface for protocol-buffer-based RPC services.  Services
 // themselves are abstract interfaces (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 Reflection).
 class PROTOBUF_EXPORT Service {
  public:
   inline Service() {}
   Service(const Service&) = delete;
   Service& operator=(const Service&) = delete;
   virtual ~Service();
 
   // When constructing a stub, you may pass STUB_OWNS_CHANNEL as the second
   // parameter to the constructor to tell it to delete its RpcChannel when
   // destroyed.
   enum ChannelOwnership { STUB_OWNS_CHANNEL, STUB_DOESNT_OWN_CHANNEL };
 
   // Get the ServiceDescriptor describing this service and its methods.
   virtual const ServiceDescriptor* GetDescriptor() = 0;
 
   // Call a method of the service specified by MethodDescriptor.  This is
   // normally implemented as a simple switch() that calls the standard
   // definitions of the service's methods.
   //
   // Preconditions:
   // * method->service() == GetDescriptor()
   // * request and response are of the exact same classes as the objects
   //   returned by GetRequestPrototype(method) and
   //   GetResponsePrototype(method).
   // * After the call has started, the request must not be modified and the
   //   response must not be accessed at all until "done" is called.
   // * "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.  Server-side Service
   //   implementations are expected to accept whatever type of RpcController
   //   the server-side RPC implementation uses.
   //
   // 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.
   // * If the RPC succeeded, "response" contains the response returned by
   //   the server.
   // * If the RPC failed, "response"'s contents are undefined.  The
   //   RpcController can be queried to determine if an error occurred and
   //   possibly to get more information about the error.
   virtual void CallMethod(const MethodDescriptor* method,
                           RpcController* controller, const Message* request,
                           Message* response, Closure* done) = 0;
 
   // CallMethod() requires that the request and response passed in are of a
   // particular subclass of Message.  GetRequestPrototype() and
   // GetResponsePrototype() get the default instances of these required types.
   // You can then call Message::New() on these instances to construct mutable
   // objects which you can then pass to CallMethod().
   //
   // Example:
   //   const MethodDescriptor* method =
   //     service->GetDescriptor()->FindMethodByName("Foo");
   //   Message* request  = stub->GetRequestPrototype (method)->New();
   //   Message* response = stub->GetResponsePrototype(method)->New();
   //   request->ParseFromString(input);
   //   service->CallMethod(method, *request, response, callback);
   virtual const Message& GetRequestPrototype(
       const MethodDescriptor* method) const = 0;
   virtual const Message& GetResponsePrototype(
       const MethodDescriptor* method) const = 0;
 };
 
 // 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).
 class PROTOBUF_EXPORT RpcController {
  public:
   inline RpcController() {}
   RpcController(const RpcController&) = delete;
   RpcController& operator=(const RpcController&) = delete;
   virtual ~RpcController();
 
   // Client-side methods ---------------------------------------------
   // These calls may be made from the client side only.  Their results
   // are undefined on the server side (may crash).
 
   // Resets the RpcController to its initial state so that it may be reused in
   // a new call.  Must not be called while an RPC is in progress.
   virtual void Reset() = 0;
 
   // 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.
   virtual bool Failed() const = 0;
 
   // If Failed() is true, returns a human-readable description of the error.
   virtual std::string ErrorText() const = 0;
 
   // 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.
   virtual void StartCancel() = 0;
 
   // Server-side methods ---------------------------------------------
   // These calls may be made from the server side only.  Their results
   // are undefined on the client side (may crash).
 
   // 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().
   virtual void SetFailed(const std::string& reason) = 0;
 
   // 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.
   virtual bool IsCanceled() const = 0;
 
   // 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.
   virtual void NotifyOnCancel(Closure* callback) = 0;
 };
 
 // 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 call an RpcChannel directly, but instead construct a stub Service
 // wrapping it.  Example:
 //   RpcChannel* channel = new MyRpcChannel("remotehost.example.com:1234");
 //   MyService* service = new MyService::Stub(channel);
 //   service->MyMethod(request, &response, callback);
 class PROTOBUF_EXPORT RpcChannel {
  public:
   inline RpcChannel() {}
   RpcChannel(const RpcChannel&) = delete;
   RpcChannel& operator=(const RpcChannel&) = delete;
   virtual ~RpcChannel();
 
   // 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 and response objects
   // need not be of any specific class as long as their descriptors are
   // method->input_type() and method->output_type().
   virtual void CallMethod(const MethodDescriptor* method,
                           RpcController* controller, const Message* request,
                           Message* response, Closure* done) = 0;
 };
 
 }  // namespace protobuf
 }  // namespace google
 
 #include "google/protobuf/port_undef.inc"
 
 #endif  // GOOGLE_PROTOBUF_SERVICE_H__

This page was automatically generated by the 2.3.7 LXR engine. The LXR team