gRPC|gRPC 在 Python中的应用 gRPC在Python中的应用

python -m grpc_tools.protoc --proto_path=. --python_out=. --grpc_python_out=. hello.proto
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
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) {}
}
【gRPC|gRPC 在 Python中的应用】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
1
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.proto import 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 grpc
import grpchello_pb2 as grpchello__pb2
class gRPCStub(object):
# missing associated documentation comment in .proto file
pass
def 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
pass
def 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 * 24
class 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_pb2 import * ## 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':