Node.js：一个接一个地处理对 HTTP 服务器的 2 个请求

Question

Upon POST to http server, the server has to:

1. send TCP message to external agent
2. receive TCP reply from external agent
3. send response to client

But my client sends 2 POSTs almost on the same time. How can I make sure that the 2 POST requests will be handled one after another ?

 function sendReq (body, res) { var byteArr=[]; len = body.length; //get pure data without {,} data = body.substr (1,len-2); //convert to array arr = data.split (','); for (let i = 0; i < arr.length; i++) { num = parseInt (arr[i]); var numArr = num2arr (num); byteArr = byteArr.concat (numArr); } res.writeHead (200,{ 'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*'}); if (arr[1]==28) { var body = Buffer.alloc (392); res.write (body); } if (arr[1]==11) { var body = Buffer.alloc (28); res.write (body); } res.end (); } var http=require ('http'); http.createServer (function(req,res) { data=''; req.on ('data', chunk => { console.log (`Data chunk: ${chunk}`); data += chunk; sendReq (data,res); }); }).listen (8000);

Thank you, Zvika

Answer 1

This code works:

 const Net = require('net'); var http=require ('http'); var events=require ('events'); var eventEmitter = new events.EventEmitter(); var reqQueue =[]; var resQueue =[]; // Create a new TCP client. const client = new Net.Socket(); /************************************************************************/ /* This callback will be fired upon TCP message sent from server /************************************************************************/ client.on('data',function(chunk){ //console.log (chunk); //pull response object from queue var res = resQueue.shift (); //add response header res.writeHead (200,{ 'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*'}); //write response body res.write (chunk); res.end (); }); /************************************************************************/ /* Convert number (eg 0xCAFE2DAD to 4 bytes) /************************************************************************/ function num2arr(n) { // Mask off 8 bytes at a time then shift them into place return [ (n & 0xFF) >>> 0, (n & 0xFF00) >>> 8, (n & 0xFF0000) >>> 16, (n & 0xFF000000) >>> 24, ]; } /************************************************************************/ /* Connect to TCP server /************************************************************************/ function tcpConnect () { // Send a connection request to the server. client.connect({ host:'localhost', port:5100 }); client.on('connect',function(){ console.log('Client: connection established with server'); }); } /************************************************************************/ /* Convert HTTP request to TCP raw data request /************************************************************************/ function sendReq (body) { let byteArr=[]; let len = body.length; //get pure data without {,} let data = body.substr (1,len-2); //console.log (data); //convert to array let arr = data.split (','); for (let i = 0; i < arr.length; i++) { let num = parseInt (arr[i]); let numArr = num2arr (num); byteArr = byteArr.concat (numArr); } client.write (Buffer.from(byteArr)); } /************************************************************************/ /* Event callback fired upon HTTP request /************************************************************************/ var eventHandler = function (){ //console.log ('event fired'); //console.log (resQueue.length); //pull request from queue var chunk = reqQueue.shift(); sendReq (chunk); } /************************************************************************/ eventEmitter.on ('httpReq', eventHandler); tcpConnect (); /************************************************************************/ /* Launch HTTP server /************************************************************************/ http.createServer (function(req,res) { let data=''; req.on ('data', chunk => { //console.log (`Data chunk: ${chunk}`); data += chunk; //push response to queue resQueue.push (res); //push request to queue reqQueue.push (data); //fire event eventEmitter.emit ('httpReq'); }); }).listen (8000);

This code crashes if the external TCP server is closed. In this case, the HTTP server should try to reconnect forever. Is this the right way ?

Evert - Thank you very much ! Zvika