// 语法版本声明，必须放在非注释的第一行
// Syntax version declaration. Must be placed on the first line of non-commentary.
syntax = "proto3";

// 包名定义, Python中使用时可以省略不写(PS:我还要再Go中使用,所以留在这里了)
// Package name definition, which can be omitted in Python. (PS: I'll use it again in Go, so stay here)
package demo;

/*
`message`是用来定义传输的数据的格式的, 等号后面的是字段编号
消息定义中的每个字段都有唯一的编号
总体格式类似于Python中定义一个类或者Golang中定义一个结构体
*/
/*
`message` is used to define the structure of the data to be transmitted, After the equal sign is the field number.
Each field in the message definition has a unique number.
The overall format is similar to defining a class in Python or a structure in Golang.
*/
message Request {
    int64 client_id = 1;
    string request_data = 2;
}

message Response {
    int64 server_id = 1;
    string response_data = 2;
}

// service是用来给GRPC服务定义方法的, 格式固定, 类似于Golang中定义一个接口
// `service` is used to define methods for GRPC services in a fixed format, similar to defining an interface in Golang
service GRPCDemo {
    // 简单模式
    // unary-unary
    rpc SimpleMethod (Request) returns (Response);

    // 客户端流模式（在一次调用中, 客户端可以多次向服务器传输数据, 但是服务器只能返回一次响应）
    // stream-unary (In a single call, the client can transfer data to the server several times,
    // but the server can only return a response once.)
    rpc ClientStreamingMethod (stream Request) returns (Response);

    // 服务端流模式（在一次调用中, 客户端只能一次向服务器传输数据, 但是服务器可以多次返回响应）
    // unary-stream (In a single call, the client can only transmit data to the server at one time,
    // but the server can return the response many times.)
    rpc ServerStreamingMethod (Request) returns (stream Response);

    // 双向流模式 (在一次调用中, 客户端和服务器都可以向对方多次收发数据)
    // stream-stream (In a single call, both client and server can send and receive data
    // to each other multiple times.)
    rpc BidirectionalStreamingMethod (stream Request) returns (stream Response);
}