通过stdio的服务器客户端连接

Question

There is a client and a server that communicates through stdio. I think I am basically confused about the stdin and stdout. I have some questions about the stdio.

1. Does the server read the request from stdin or stdout where the client writes to?
2. Does the server write response to stdin or stdout where the client can read?

Below is the code snippet of connection part on server side.

case "stdio":
    log.Println("server: reading on stdin, writing on stdout")
    <-jsonrpc2.NewConn(context.Background(), jsonrpc2.NewBufferedStream(stdrwc{}, jsonrpc2.VSCodeObjectCodec{}), handler, connOpt...).DisconnectNotify()
    log.Println("connection closed")
    return nil


type stdrwc struct{}

func (stdrwc) Read(p []byte) (int, error) {
    return os.Stdin.Read(p)
}

func (stdrwc) Write(p []byte) (int, error) {
    return os.Stdout.Write(p)
}

func (stdrwc) Close() error {
    if err := os.Stdin.Close(); err != nil {
        return err
    }
    return os.Stdout.Close()
}

Answer 1

It's hard to say what this program is doing (as there's just a portion of it). Looks like you have an implementation of ReadWriteCloser that reads from stdin and writes to stdout (and a portion of a switch statement).

Generally any program can read from stdin and write to stdout (and stderr). You can link stdout of one program to stdin of other program with a pipe (e.g. client | server), but that's unidirectional. In your case, it sounds like you want client's stdin to go to server's stdout and vice versa. In local development, Unix sockets are usually used for that, but you might be able to create a named pipe (with mkfifo) like shown here.

Also, it might be easier to start with a super simple toy program, that doesn't include jsonrpc2 and any other packages.

I hope that helps!