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通过实例解析Python RPC实现原理及方法

作者：cxc1357　　发布时间：2022-06-19 00:50:38　

标签：Python,RPC,实现

单线程同步

使用socket传输数据
使用json序列化消息体
struct将消息编码为二进制字节串，进行网络传输

消息协议

// 输入
{
in: "ping",
params: "ireader 0"
}

// 输出
{
out: "pong",
result: "ireader 0"
}

客户端 client.py

# coding: utf-8
# client.py

import json
import time
import struct
import socket

def rpc(sock, in_, params):
response = json.dumps({"in": in_, "params": params}) # 请求消息体
length_prefix = struct.pack("I", len(response)) # 请求长度前缀
sock.sendall(length_prefix)
sock.sendall(response)
length_prefix = sock.recv(4) # 响应长度前缀
length, = struct.unpack("I", length_prefix)
body = sock.recv(length) # 响应消息体
response = json.loads(body)
return response["out"], response["result"] # 返回响应类型和结果

if __name__ == '__main__':
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("localhost", 8080))
for i in range(10): # 连续发送10个rpc请求
out, result = rpc(s, "ping", "ireader ％d" ％ i)
print out, result
time.sleep(1) # 休眠1s，便于观察
s.close() # 关闭连接

服务端 blocking_single.py

# coding: utf8
# blocking_single.py

import json
import struct
import socket

def handle_conn(conn, addr, handlers):
print addr, "comes"
while True: # 循环读写
length_prefix = conn.recv(4) # 请求长度前缀
if not length_prefix: # 连接关闭了
print addr, "bye"
conn.close()
break # 退出循环，处理下一个连接
length, = struct.unpack("I", length_prefix)
body = conn.recv(length) # 请求消息体
request = json.loads(body)
in_ = request['in']
params = request['params']
print in_, params
handler = handlers[in_] # 查找请求处理器
handler(conn, params) # 处理请求

def loop(sock, handlers):
while True:
conn, addr = sock.accept() # 接收连接
handle_conn(conn, addr, handlers) # 处理连接

def ping(conn, params):
send_result(conn, "pong", params)

def send_result(conn, out, result):
response = json.dumps({"out": out, "result": result}) # 响应消息体
length_prefix = struct.pack("I", len(response)) # 响应长度前缀
conn.sendall(length_prefix)
conn.sendall(response)

if __name__ == '__main__':
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # 创建一个TCP套接字
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) # 打开reuse addr选项
sock.bind(("localhost", 8080)) # 绑定端口
sock.listen(1) # 监听客户端连接
handlers = { # 注册请求处理器
"ping": ping
}
loop(sock, handlers) # 进入服务循环