grpc|在python中使用grpc和protobuf python|protobuf

简介在python中使用grpc和protobuf，比java和c#中使用要简单一些。只需要先安装grpcio包，然后就可以应用了。
安装使用pip安装grpcio依赖包；

$ pip install grpcio Collecting grpcio Downloading grpcio-1.7.0-cp27-cp27m-macosx_10_10_intel.whl (1.5MB) 100% |████████████████████████████████| 1.5MB 18kB/s Requirement already satisfied: enum34>=1.0.4 in /Users/David/anaconda2/lib/python2.7/site-packages (from grpcio) Requirement already satisfied: futures>=2.2.0 in /Users/David/anaconda2/lib/python2.7/site-packages (from grpcio) Requirement already satisfied: six>=1.5.2 in /Users/David/anaconda2/lib/python2.7/site-packages (from grpcio) Collecting protobuf>=3.3.0 (from grpcio) Downloading protobuf-3.5.0-py2.py3-none-any.whl (388kB) 100% |████████████████████████████████| 389kB 32kB/s Requirement already satisfied: setuptools in /Users/David/anaconda2/lib/python2.7/site-packages (from protobuf>=3.3.0->grpcio) Installing collected packages: protobuf, grpcio Successfully installed grpcio-1.7.0 protobuf-3.5.0

安装时，自动地安装了protobuf工具包。
定义protobuf 【grpc|在python中使用grpc和protobuf】下面定义一个简单的protobuf文件，在其中声明一个grpc服务。
创建一个proto目录，并在其中创建grpchello.proto文件，如下内容。

syntax = "proto3"; package grpcDemo; message HelloRequest { string name = 1; }message HelloReply { string message = 1; }service gRPC { rpc SayHello (HelloRequest) returns (HelloReply) {} }

Note：
- 其实这个protobuf定义文件，在我们的java、c#版本示例中使用了，而且各版本的服务和客户端可以正常通行调用。
编译protobuf 使用protobuf的编译器，为我们生成python版本的Message定义和服务的架手脚。

python -m grpc_tools.protoc -I./proto --python_out=. --grpc_python_out=. grpchello.proto

在当前目录下，生成2个文件：
- grpchello_pb2.py
- grpchello_pb2_grpc.py
可以看看这2个文件：
首先消息定义文件：

# Generated by the protocol buffer compiler.DO NOT EDIT! # source: grpchello.protoimport sys _b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1')) from google.protobuf import descriptor as _descriptor from google.protobuf import message as _message from google.protobuf import reflection as _reflection from google.protobuf import symbol_database as _symbol_database from google.protobuf import descriptor_pb2 # @@protoc_insertion_point(imports)_sym_db = _symbol_database.Default()DESCRIPTOR = _descriptor.FileDescriptor( name='grpchello.proto', package='grpcDemo', syntax='proto3', serialized_pb=_b('\n\x0fgrpchello.proto\x12\x08grpcDemo\"\x1c\n\x0cHelloRequest\x12\x0c\n\x04name\x18\x01 \x01(\t\"\x1d\n\nHelloReply\x12\x0f\n\x07message\x18\x01 \x01(\t2B\n\x04gRPC\x12:\n\x08SayHello\x12\x16.grpcDemo.HelloRequest\x1a\x14.grpcDemo.HelloReply\"\x00\x62\x06proto3') )_HELLOREQUEST = _descriptor.Descriptor( name='HelloRequest', full_name='grpcDemo.HelloRequest', filename=None, file=DESCRIPTOR, containing_type=None, fields=[ _descriptor.FieldDescriptor( name='name', full_name='grpcDemo.HelloRequest.name', index=0, number=1, type=9, cpp_type=9, label=1, has_default_value=https://www.it610.com/article/False, default_value=_b("").decode('utf-8'), message_type=None, enum_type=None, containing_type=None, is_extension=False, extension_scope=None, options=None), ], extensions=[ ], nested_types=[], enum_types=[ ], options=None, is_extendable=False, syntax='proto3', extension_ranges=[], oneofs=[ ], serialized_start=29, serialized_end=57, )_HELLOREPLY = _descriptor.Descriptor( name='HelloReply', full_name='grpcDemo.HelloReply', filename=None, file=DESCRIPTOR, containing_type=None, fields=[ _descriptor.FieldDescriptor( name='message', full_name='grpcDemo.HelloReply.message', index=0, number=1, type=9, cpp_type=9, label=1, has_default_value=https://www.it610.com/article/False, default_value=_b("").decode('utf-8'), message_type=None, enum_type=None, containing_type=None, is_extension=False, extension_scope=None, options=None), ], extensions=[ ], nested_types=[], enum_types=[ ], options=None, is_extendable=False, syntax='proto3', extension_ranges=[], oneofs=[ ], serialized_start=59, serialized_end=88, )DESCRIPTOR.message_types_by_name['HelloRequest'] = _HELLOREQUEST DESCRIPTOR.message_types_by_name['HelloReply'] = _HELLOREPLY _sym_db.RegisterFileDescriptor(DESCRIPTOR)HelloRequest = _reflection.GeneratedProtocolMessageType('HelloRequest', (_message.Message,), dict( DESCRIPTOR = _HELLOREQUEST, __module__ = 'grpchello_pb2' # @@protoc_insertion_point(class_scope:grpcDemo.HelloRequest) )) _sym_db.RegisterMessage(HelloRequest)HelloReply = _reflection.GeneratedProtocolMessageType('HelloReply', (_message.Message,), dict( DESCRIPTOR = _HELLOREPLY, __module__ = 'grpchello_pb2' # @@protoc_insertion_point(class_scope:grpcDemo.HelloReply) )) _sym_db.RegisterMessage(HelloReply)_GRPC = _descriptor.ServiceDescriptor( name='gRPC', full_name='grpcDemo.gRPC', file=DESCRIPTOR, index=0, options=None, serialized_start=90, serialized_end=156, methods=[ _descriptor.MethodDescriptor( name='SayHello', full_name='grpcDemo.gRPC.SayHello', index=0, containing_service=None, input_type=_HELLOREQUEST, output_type=_HELLOREPLY, options=None, ), ]) _sym_db.RegisterServiceDescriptor(_GRPC)DESCRIPTOR.services_by_name['gRPC'] = _GRPC# @@protoc_insertion_point(module_scope)

在看看grpc服务定义

# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT! import grpcimport grpchello_pb2 as grpchello__pb2class gRPCStub(object): # missing associated documentation comment in .proto file passdef __init__(self, channel): """Constructor.Args: channel: A grpc.Channel. """ self.SayHello = channel.unary_unary( '/grpcDemo.gRPC/SayHello', request_serializer=grpchello__pb2.HelloRequest.SerializeToString, response_deserializer=grpchello__pb2.HelloReply.FromString, )class gRPCServicer(object): # missing associated documentation comment in .proto file passdef SayHello(self, request, context): # missing associated documentation comment in .proto file pass context.set_code(grpc.StatusCode.UNIMPLEMENTED) context.set_details('Method not implemented!') raise NotImplementedError('Method not implemented!')def add_gRPCServicer_to_server(servicer, server): rpc_method_handlers = { 'SayHello': grpc.unary_unary_rpc_method_handler( servicer.SayHello, request_deserializer=grpchello__pb2.HelloRequest.FromString, response_serializer=grpchello__pb2.HelloReply.SerializeToString, ), } generic_handler = grpc.method_handlers_generic_handler( 'grpcDemo.gRPC', rpc_method_handlers) server.add_generic_rpc_handlers((generic_handler,))

简单看下：
- 在grpc服务架手脚定义中，定义了gRPCStub，这是给client端使用，调用grpc服务的。
- 定义的服务类gRPCServicer，方法SayHello需要我们在子类中进行实现。定义的add_gRPCServicer_to_server方法，用于把实现的类和grpc API调用注册起来。
这里使用的几个主要方法（类）：
- grpc.server – Creates a Server with which RPCs can be serviced
- grpc.method_handlers_generic_handler – Creates a GenericRpcHandler from RpcMethodHandlers.
- grpc.unary_unary_rpc_method_handler – Creates an RpcMethodHandler for a unary-unary RPC method.
实现服务在我们的实现服务的类中，使用服务方法，并在网络中暴露出来。

# -*- coding: utf-8 -*- import grpc import time from concurrent import futures import grpchello_pb2, grpchello_pb2_grpc_HOST = 'localhost' _PORT = '8188'_ONE_DAY_IN_SECONDS = 60 * 60 * 24class gRPCServicerImpl(grpchello_pb2_grpc.gRPCServicer):def SayHello(self, request, context): print ("called with " + request.name) return grpchello_pb2.HelloReply(message='Hello, %s!' % request.name)def serve(): server = grpc.server(futures.ThreadPoolExecutor(max_workers=10)) grpchello_pb2_grpc.add_gRPCServicer_to_server(gRPCServicerImpl(), server) server.add_insecure_port('[::]:'+_PORT) server.start() try: while True: time.sleep(_ONE_DAY_IN_SECONDS) except KeyboardInterrupt: server.stop(0)if __name__ == '__main__': serve()

这里包括2个实现：
- 1、在grpc的API的实现（服务实现类）gRPCServicerImpl中，实现SayHello方法。
- 2、然后，定义网络服务和端口，把grpc的API注册到网络服务的处理上。这里简单利用了grpc.server类。
使用客户端client 在客户端，调用grpc的服务API。

# -*- coding: utf-8 -*- """The Python implementation of the gRPC client.""" from __future__ import print_function import grpc from grpchello_pb2import *## or import grpchello_pb2 from grpchello_pb2_grpc import * ## No grpcDemo!from grpcDemo import grpchello_pb2, grpchello_pb2_grpc #error!_PORT = '8188'def run(): conn = grpc.insecure_channel(_HOST + ':' + _PORT) client = gRPCStub(channel=conn) response = client.SayHello(HelloRequest(name='David')) print("received: " + response.message)## if __name__ == '__main__':if len(sys.argv)== 2: print (sys.argv[1]) _HOST = sys.argv[1] else: _HOST = 'localhost'# run()

说明：
- 1、 def insecure_channel(target, options=None):
– Creates an insecure Channel to a server.
- 2、客户端使用服务的Stub，调用API。
测试分别启动服务，然后再启动客户端，可以看到调用结果。
也可以启动java、c#版本的grpc服务端、客户端，都能调用成功。