Develop Reference

Rest API based TCP client using Node js

I have tried to create TCP Client with rest api using nodejs and also used net module to establish tcp connection to send/receive data. The main idea is to use this restAPI from browser to load test TCP Connections.
Here in my case there are 2 steps involved while load testing TCP.
1) send initial TCP request which has token for authentication.
2) then send other TCP request to send some data.
The issue is when i try to send 2nd TCP request after authentication. Getting response as invalid session.
Please suggest if i can send TCP request for authentication and using same session/connection while making subsequent requests.
I am new to node js. My Apologize if I have not provided enough details or done some thing invalid.
Initially I have used Packet Sender application and enabled persistent TCP Connection option in it. It worked well as expected but this is for single user and cant use this tool for load testing. Here in this tool with persistent TCP enabled I can see the local port is fixed and not changing upon sending multiple requests but with my node js code i can see the local port is getting changed upon every new request.
I have also used TCP Sampler in Jmeter with reuse Connection option but not working when i send 2nd request after authentication.
var Net = require('net');
var express = require("express");
var bodyParser = require('body-parser');
var app = express();
app.use(bodyParser.json());
app.post('/api/push', function (req, res) {
var reqBody = req.body.reqBody;
var req = JSON.stringify(reqBody);
const client = new Net.Socket({
allowHalfOpen: true
});
client.connect({
port: req.body.port,
host: req.body.host
}, function () {
client.write(req);
});
client.on('data', function (chunk) {
res.write(chunk.toString());
//Tried to use client connection information, but didnt worked not sure if i missed something.
console.log(JSON.stringify(client));
// Tried commenting below client.end but no luck.
client.end();
});
client.on('end', function () {
res.end();
});
client.on('error', function (err) {
console.log("Error: " + err.message);
res.write(err.message);
client.end();
});
});
app.listen(1234, () => {
console.log("Server running on port 1234");
});
1) send restAPI with TCP server host/port and request body for authentication.
2) send another restAPI to use same TCP connection and send data. but it failed for mere

Inspect the behavior and get the cookies details and preserve the same in HTTP cookie manager to reuse the same session for the second request. Just adding http cookie manager also might work. Please check,

How to handle tcp/ip raw requests and http requests on the same server

I am working on a gps tracking system and have built a server on node js.
This is how the file looks like for reference.
const net = require('net');
const lora_packet = require('lora-packet');
const dataParser = require('./dataParser');
const clients = [];
net.createServer(function(socket) {
socket.name = socket.remoteAddress + ":" + socket.remotePort;
clients.push(socket);
socket.on('data', function(data) {
console.log("Buffer sent by terminal : ");
console.log(data);
const packet = lora_packet.fromWire(data, 'hex');
const str = packet._packet.PHYPayload.toString('hex');
dataParser.parse_data(str, socket);
});
socket.on('end', function() {
clients.splice(clients.indexOf(socket), 1);
//broadcast(socket.name + "has left the cartel.\n");
});
function broadcast(message, sender) {
clients.forEach(function(client) {
if (client === sender) client.write(message + "\nsent\n");
return;
client.write(message);
});
process.stdout.write(message);
}
}).listen(8080);
console.log("cartel is running on the port 8080\n");
This server file handles only requests from the hardware and processes raw tcp/ip requests.
I want the server to handle http requests also and want to incorporate routing feature in the server too for client side applicarions for browser.
1) Is there any way that http requests can also be handled by the same server or should I open another port and deploy an express node js app on that?
2) If I use the same 8080 port for http, how can the routing be achieved?
3) If I use different ports for http and raw tcp/ip, what would be the best way for communication between the two server. The communication between tcp/ip server and http server should happen via socket(sending data dynamically).
From http server using socket, data has to be sent dynamically to browser to update live location
So is the flow right?
Hardware (<---->)TCP/IP server(<--->)Http server(<--->)Browser
If more information is needed to solve the query, I'll provide with that!
Thank you

It's very complicated to try to speak multiple protocols on the same port. It requires some sort of scheme at the beginning of each connection to sample the incoming data and identify which protocol it is and then shunt that connection off to the right code to handle that protocol. I wouldn't suggest it.
It is way, way easier to just open a second server on a different port for an Express server to field your http requests. Very simple. You can do it right in the same app. Because both servers can be in the same app, you can just directly read from one connection and write to the other. There's no need for interprocess communication.
Is there any way that http requests can also be handled by the same server or should I open another port and deploy an express node js app on that?
Open another port. No need to write another app unless you have a specific reason to use two processes. You can put both the plain TCP server and the Express server in the same node.js app.
If I use the same 8080 port for http, how can the routing be achieved?
It's not easy. Not suggest to use the same port for multiple protocols.
If I use different ports for http and raw tcp/ip, what would be the best way for communication between the two server. The communication between tcp/ip server and http server should happen via socket(sending data dynamically).
You can put both servers in the same node.js app and then you can just read/write directly from one to the other with the same code. No need for interprocess communication.
From http server using socket, data has to be sent dynamically to browser to update live location
Sending data dynamically to a browser usually means you want the browser to hold something like a webSocket or socket.io connection to your server so you can then send data to the browser at any time over the existing connection. Otherwise, you would have to "wait" for the browser to request data and then respond with the data when it asks.

No need to set up a local server with Node.js?

I see when I want write a Node.js web application on my local machine, I don't need to set-up a local server using WAMP or MAMP. What is node.js really doing behind the scenes? I am providing this code to make a simple hello world web app:
var http = require("http");
http.createServer(function(request,response){
response.writeHead(200, {"content-type":"text/html"});
response.write("hello world");
response.end();
}).listen(8080);
console.log("server is running....");
When loading in my browser URL bar "localhost:8080" it works.
How this is working as and why don't I need a local server when working with Node.js?

You do have a local server... it's your Node.js application.
When you call http.createServer(), it creates an HTTP server. When you call .listen() on that server, it binds to the requested port, and optionally requested address, and listens for connections. When data comes in on those connections, it responds like any other HTTP server.
The HTTP server uses your request/response callback, firing it whenever a valid HTTP request comes in.

Because node comes out of the box with all the libraries you need to run a webserver, the http library that you are using is opening the 8080 port and handling the request with the function you provided
This part:
function(request,response){
response.writeHead(200, {"content-type":"text/html"});
response.write("hello world");
response.end();
}

No, you don't need it. Because node itself can be your webserver, just like in your example. Node is built on V8, which is chrome JavaScript engine .
Take a look a Express js module that gives you lots of features out of the box

Nodejs http server cannot handle, proxy enabled request from Amazon Load balancer

I have a nodeja HTTP server which was woking good until I enabled Proxy at amazon Load balancer (which is on TCP protocol) to get client's IP.
I wonder How TCP server of nodejs works perfectly , but http server cannot
var net = require('net');
var proxy_protocol = require('node-proxy-protocol');
net.createServer(function(socket) {
proxy_protocol.parse(socket, function(error, obj) {
console.log(obj); //returns required client's info
});
});
but, why http server fails to do , if I replace "net" with "http":
This does not work
var net = require('http');
var proxy_protocol = require('node-proxy-protocol');
http.createServer(function(req,res) {
proxy_protocol.parse(req, function(error, obj) {
console.log(obj); //returns nothing
});
});
although I know that HTTP (usually) operates over TCP, so it must work for both.
basically I think, My Http Server is not able to handle TCP request from Load Balancer.
Please let me know where am I going wrong.

My nodejs HTTP server was not handling TCP from Load Balancer, so I switched Load Balancer's Protocol to HTTP.and now my HTTP server works well.

Localhost refuses connection from Javascript

I am making a single web app that takes information from MYSQL database and displays it on screen using AngularJS and NodeJS. I have set up a node.js server that gives out JSON file from a database. It works fine if I connect to it like this: 192.168.1.57:8888 which is my home server ip or remote connecting my server and using localhost:8888. Doing this downloads the JSON file on my computer.
However. If I'm using javascript to get JSON file from the server it gives me this error:
GET http://localhost:8888/ net::ERR_CONNECTION_REFUSED
I have tried connecting to the server with both AngularJS and JQuery and they both give the same error. I've also tried 127.0.0.1 and that doesn't work either. What can I do to fix it or can I do this with a better alternative way?
This is the server code in node.js
var http = require("http");
mysql = require("mysql");
var connection = mysql.createConnection({
user: "test",
password: "test",
database: "test"
});
http.createServer(function (request, response) {
request.on('end', function () {
connection.query('SELECT * FROM feedback;', function (error, rows, fields) {
response.writeHead(200, {
'Content-Type': 'x-application/json'
});
response.end(JSON.stringify(rows));
});
});
}).listen(8888);
this is the client side in angularJS:
(function(){
var app = angular.module('question', [ ]);
app.controller("ServerController", [ '$http', function($http){
$http.get("http://localhost:8888").success(function(data,status,headers,config){
console.log("success");
}).error(function(data,status,headers,config){
console.log("error");
});
} ]);
}
)();

Taking a guess at it, you're running into the Same Origin Policy, which requires that the page making the ajax request be in the same origin as the resource it's requesting (or that the server serving the resource supports CORS and allows the page's origin).
Two different ways this might be hitting you (I can't tell which, the question doesn't give enough information):
If the browser code is running in a page loaded from the file system, not via HTTP, then it's a cross-origin request because the protocols don't match (file: vs. http:).
If the page has not been loaded from localhost:8888, but instead from some other port on localhost, then the origins don't match because the port numbers are different.