三种方式实现RPC调用

一：RabbitMQ实现RPC调用

客户端：

import pika
import uuid

class FibonacciRpcClient(object):

    def __init__(self):

        self.credentials = pika.PlainCredentials("admin", "admin")
        self.connection = pika.BlockingConnection(pika.ConnectionParameters('10.0.0.200', credentials=self.credentials))
        self.channel = self.connection.channel()

        result = self.channel.queue_declare(queue='', exclusive=True)
        self.callback_queue = result.method.queue

        self.channel.basic_consume(
            queue=self.callback_queue,
            on_message_callback=self.on_response,
            auto_ack=True)

    def on_response(self, ch, method, props, body):
        if self.corr_id == props.correlation_id:
            self.response = body

    def call(self, n):
        self.response = None
        self.corr_id = str(uuid.uuid4())
        self.channel.basic_publish(
            exchange='',
            routing_key='rpc_queue',
            properties=pika.BasicProperties(
                reply_to=self.callback_queue,
                correlation_id=self.corr_id,
            ),
            body=str(n))
        while self.response is None:
            self.connection.process_data_events()
        return int(self.response)

fibonacci_rpc = FibonacciRpcClient()

print(" [x] Requesting fib(30)")
response = fibonacci_rpc.call(10)  # 外界看上去，就像调用本地的call()函数一样
print(" [.] Got %r" % response)

服务端：

import pika

credentials = pika.PlainCredentials("admin", "admin")
connection = pika.BlockingConnection(pika.ConnectionParameters('10.0.0.200', credentials=credentials))
channel = connection.channel()

channel.queue_declare(queue='rpc_queue')

def fib(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fib(n - 1) + fib(n - 2)

def on_request(ch, method, props, body):
    n = int(body)

    print(" [.] fib(%s)" % n)
    response = fib(n)

    ch.basic_publish(exchange='',
                     routing_key=props.reply_to,
                     properties=pika.BasicProperties(correlation_id=props.correlation_id),
                     body=str(response))
    ch.basic_ack(delivery_tag=method.delivery_tag)

channel.basic_qos(prefetch_count=1)
channel.basic_consume(queue='rpc_queue', on_message_callback=on_request)

print(" [x] Awaiting RPC requests")
channel.start_consuming()

二、python中的rpc框架

SimpleXMLRPCServer

python自带的SimpleXMLRPCServer，数据包大，速度慢。

使用

只需要在服务端定义一个类，类内定义需要被调用的变量及方法，

客户端通过连接服务端，然后直接调用该类即可

服务端

from xmlrpc.server import SimpleXMLRPCServer
class RPCServer(object):

    def __init__(self):
        super(RPCServer, self).__init__()
        print(self)
        self.send_data = {'server:'+str(i): i for i in range(100)}
        self.recv_data = None

    def getObj(self):
        print('get data')
        return self.send_data

    def sendObj(self, data):
        print('send data')
        self.recv_data = data
        print(self.recv_data)
# SimpleXMLRPCServer
server = SimpleXMLRPCServer(('localhost',4242), allow_none=True)
server.register_introspection_functions()
server.register_instance(RPCServer())
server.serve_forever()

客户端

import time
from xmlrpc.client import ServerProxy

# SimpleXMLRPCServer
def xmlrpc_client():
    print('xmlrpc client')
    c = ServerProxy('http://localhost:4242')
    data = {'client:'+str(i): i for i in range(100)}
    start = time.clock()  # python3.8后不支持clock(),改用perf_counter()
    for i in range(50):
        a=c.getObj()
        print(a)
    for i in range(50):
        c.sendObj(data)
    print('xmlrpc total time %s' % (time.clock() - start))  # python3.8后不支持clock(),改用perf_counter()

if __name__ == '__main__':
    xmlrpc_client()

ZeroRPC实现RPC

第三方的ZeroRPC（底层使用ZeroMQ和MessagePack），速度快，响应时间短，并发高。除此外第三方的还有grpc（谷歌推出，支持跨语言）

使用

只需要在服务端定义一个类，类内定义需要被调用的变量及方法，

客户端通过连接服务端，然后直接调用该类即可

服务端

import zerorpc

class RPCServer(object):

    def __init__(self):
        super(RPCServer, self).__init__()
        print(self)
        self.send_data = {'server:'+str(i): i for i in range(100)}
        self.recv_data = None

    def getObj(self):
        print('get data')
        return self.send_data

    def sendObj(self, data):
        print('send data')
        self.recv_data = data
        print(self.recv_data)
# zerorpc
s = zerorpc.Server(RPCServer())
s.bind('tcp://0.0.0.0:4243')
s.run()

客户端

import zerorpc
import time
# zerorpc
def zerorpc_client():
    print('zerorpc client')
    c = zerorpc.Client()
    c.connect('tcp://127.0.0.1:4243')
    data = {'client:'+str(i): i for i in range(100)}
    start = time.clock()
    for i in range(500):
        a=c.getObj()
        print(a)
    for i in range(500):
        c.sendObj(data)

    print('total time %s' % (time.clock() - start))

if __name__ == '__main__':
    zerorpc_client()

SimpleXMLRPCServer 和 ZeroRPC比较：

利用远程调用同样的方法，执行500次，ZeroRPC耗时大幅度的小于SimpleXMLRPCServer，所以，推荐使用ZeroRPC