如何在 Express 到 C++ 程序中通过 TCP 套接字编写 JSON 文件

Question

这与问题About server-client architecture in express.js有关

我目前正在编写程序的客户端部分，它应该在 express.jsvar 中

var request = require('request'),
    express = require('express'),
    path    = require('path');

const net = require('net');

var app = express();

// for Express 4.16 above use this instead of
// using body-Parser: app.use(bodyParser.json())
app.use(express.json());


// configuration setting
const PORT1 = 5000;
const port2 = 5001;
const PORT3 = 1337;
const HOST = '127.0.0.1';

app.set('port', (process.env.PORT || PORT1));

var client = new net.Socket();
var id = 0;

// start a tcp connection to connect to server
client.connect(PORT3, HOST, function() {
    console.log('SEND PORT CONNECTED TO: ' + HOST + ':' + PORT3);
});

// using Github for testing web hook
app.post('/getGithub', function(req, res) 
{
    // tester code
    //var data = "20a980dc00b413dc3d0000a3";
    //var data = "e36ace0044ed3d0cc3810000";
    var data = req.body;
    console.log(data);
        
    client.write('Hello, server! Love, Client.' + id + " ");
    client.write(data);
    res.json(data);

});

// http server location
var server = app.listen(app.get('port'), function() {
    var host   = server.address().address
    var portid = server.address().port

    console.log('App listening at http://%s:%s', host, portid)
    console.log("App listening on port " + app.get('port'));
});

// error handler
app.use(function (err, req, res, next) {
    res.status(400).send(err.message)
});

我有一些问题

1. 如何将 JSON 对象写入我的服务器应用程序 (C++)。我知道 JSON.stringify(obj) 会返回字符串并且可以被覆盖？
2. 如何在另一端编写我的 C++ 程序？我已经编写了一些 C++ 程序，但是在使用另一个 express 程序时似乎出现了一些问题，这似乎还可以。当我运行 C++ 程序时，express 中的客户端程序不断给我 ECONNECT 拒绝

我的 C++ 程序

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <jsoncpp/json/json.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

int main()
{
    /* all previous code until
    printf("Reading from client\n"); */

   int listenfd = 0, connfd = 0;    //related with the server
   int MAX_SIZE = 158;
   struct sockaddr_in serv_addr;

   //json_object * jobj;
   char buf[MAX_SIZE], i;

   memset(&buf, '0', sizeof(buf));
   listenfd = socket(AF_INET, SOCK_STREAM, 0);

   serv_addr.sin_family = AF_INET;
   serv_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
   serv_addr.sin_port = htons(1337); 

   bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
   printf("binding\n");

   listen(listenfd, 5);
   printf("listening\n");
   connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);

   printf("Reading from client\n");
    ssize_t r;

    for (;;)
    {
        r = read(connfd, buf, MAX_SIZE);

        if (r == -1)
        {
            perror("read");
            return EXIT_FAILURE;
        }
        if (r == 0)
            break;

        printf("READ: %s\n", buf);
    }

    return EXIT_SUCCESS;
}

错误是：

Error: connect ECONNREFUSED 127.0.0.1:1337
    at Object._errnoException (util.js:1022:11)
    at _exceptionWithHostPort (util.js:1044:20)
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1198:14)

Answer 1

不管 languaje 是服务器：一旦你发送一个 Json 字符串，它就独立于服务器：你可以有一个 java 程序、一个 C++ 程序，甚至是一个 Apache/PHP 程序（在最后一种情况下，通过 HTTP 调用、使用库或添加标头）。

首先你需要你的 json 数据

var obj = { name: "John", age: 30, city: "New York" };
var myJSONData = JSON.stringify(obj);

然后，你应该做一个原始套接字连接：

var net = require('net');
var HOST = '127.0.0.1';
var PORT = 1337;

// (a) =========
var client = new net.Socket();
client.connect(PORT, HOST, function() {

    console.log('CONNECTED TO: ' + HOST + ':' + PORT);
    // Write a message to the socket as soon as the client is connected, the server will receive it as message from the client
    client.write(myJSONData );

});
client.destroy();