RPC概念学习笔记-图灵课堂

什么是RPC？

Remote procedure call -远程过程调用对应的本地过程调用，即本地方法调用
它本身不是一个特定的协议，而是一种调用方式。
TCP 粘包

什么是粘包:TCP面向字节流，没有内容分割符，可以同时从缓存区读取两条消息。发送两条消息 1:这是李东 2:**亚**健康终结者。接收端可接收1:这是李东**亚** 2:健康终结者。如果没有正确阅读字节
如何解决：通过分隔符号或定义消息长度等.
直接使用TCP需要定义信息边界和格式来解决这个通用问题，因此一般应用程序不会直接在TCP上建立自己的应用层协议.
演示demo

服务端

public class ServerDemo {    public static void main(String[] args) throws IOException {        // Create a server socket on port 1234        ServerSocket serverSocket = new ServerSocket(1234);        // Wait for a client to connect        Socket clientSocket = serverSocket.accept();        // Create input and output streams for the client socket        BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);        // Read input from the client and send a response        String inputLine = "";        char[] buffer = new char[5];        int bytesRead;        while ((bytesRead = in.read(buffer)) != -1) {            inputLine = new String(buffer, 0, bytesRead);            System.out.println("received "+ inputLine);            out.println("Server received: " + inputLine);        }        // Close the streams and sockets        out.close();        in.close();        clientSocket.close();        serverSocket.close();    }}

客户端

public class ClientDemo {    public static void main(String[] args) throws IOException {        // Create a socket to connect to the server on port 1234        Socket socket = new Socket("localhost", 1234);                // Create input and output streams for the socket        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);                // Send a message to the server        out.printf(“这是李东”);        out.printf(“亚健康终结者”);//        out.println("Hello, server!");        // Read the server's response        String inputLine;        while ((inputLine = in.readLine()) != null) {            System.out.println("get response = "+inputLine);        }        // Close the streams and socket        out.close();        in.close();        socket.close();    }}

使用RPC框架

IDL : Interface Definition Language

Proto

syntax = “proto3”;option java_multiple_files = true;option java_package = "io.grpc.examples.helloworld";option java_outer_classname = "HelloWorldProto";option objc_class_prefix = "HLW";package helloworld;// The greeting service definition.service Greeter {  // Sends a greeting  rpc SayHello (HelloRequest) returns (HelloReply) {}}// The request message containing the user's name.message HelloRequest {  string name = 1;}// The response message containing the greetingsmessage HelloReply {  string message = 1;}

AIDL
RPC和HTTP的区别

RPC是一种比HTTP早出现的思想
HTTP是一种协议

RPC的使用场景是什么？

HTTP 浏览器->服务器
RPC 客户端->服务器
服务端内部集群RPC
AndroidRPC
常见的RPC框架和实现模式

Dubbo 基于TCP，性能更好，可定制
gRPC 基于HTTP，兼容性更好.
RPC的优势

调用本地方法就像调用本地方法一样

gPRC

channel = ManagedChannelBuilder.forAddress(host, port).usePlaintext().build();GreeterGrpc.GreeterBlockingStub stub = GreeterGrpc.newBlockingStub(channel);HelloRequest request = HelloRequest.newBuilder().setName(message).build();HelloReply reply = stub.sayHello(request);return reply.getMessage();

Android上的RPC

val clipboard: ClipboardManager =            getContext().getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager           val clip = ClipData.newPlainText("label", "text")          clipboard.setPrimaryClip(clip)

使用IDL定义方法-在编译过程中可以检测到类型错误
总结

应该说，RPC和HTTP不应该是同一概念层次的东西
RPC是一种基于HTTP的调用方式，TCP,UDP.常见的RPC应该算是一个框架，包括服务发现、注册等功能

参考

Build client-server applications with gRPC

RPC概念学习笔记

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