I'm trying to create a simple Node.js server that receives files from clients via UDP. The problem I'm having is that every time I try to transmit a large file (anything over 100kb), the server doesn't seem to respond. So far I've been successful at transmitting files up to 50kb.
Is there any way to resolve this issue?
Client Code:
var PORT = 33333;
var HOST = 'localhost';
var dgram = require('dgram');
var log = require('sys').log;
var client = dgram.createSocket('udp4');
var fs = require("fs");
fs.readFile('C:\\test.pdf', function (err,data) {
if (err) {
return console.log(err);
}
client.send(data, 0, data.length, PORT, HOST, function(err, bytes) {
if (err)
throw err;
log('UDP file sent to ' + HOST +':'+ PORT);
log('File sise: ' + data.length);
});
});
Server Code:
var PORT = 33333;
var HOST = 'localhost';
var dgram = require('dgram');
var server = dgram.createSocket('udp4');
var fs = require("fs");
var log = require('sys').log;
var wstream = fs.createWriteStream('test.pdf');
wstream.on('finish', function () {
console.log('file has been written');
});
server.on('message', function (message, remote) {
wstream.write(message);
wstream.end();
});
server.bind(PORT, HOST);
From the dgram docs:
The Payload Length field is 16 bits wide, which means that a normal payload cannot be larger than 64K octets including internet header and data (65,507 bytes = 65,535 − 8 bytes UDP header − 20 bytes IP header); this is generally true for loopback interfaces, but such long datagrams are impractical for most hosts and networks.
You can't send datagrams of more than 65,507 bytes. That's a hard limit on UDP. It sounds like you should be using a higher-level protocol for these files.
Related
I believe this is a simple question: I have a websocket server (index.js) that opens a serial port when the browser (index.html) is loaded. I have a scale connected via USB (COM3). From the browser I want to send commands to the scale and receive data back to the browser. My node version is v7.7.4 and npm version is 4.1.2. I have also NPM installed serialport and ws.
index.js
var SerialPort = require('serialport');// include the library
//var SerialPort = serialport.SerialPort; // make a local instance of it
var WebSocketServer = require('ws').Server;
var SERVER_PORT = 8080; // port number for the webSocket server
var wss = new WebSocketServer({port: SERVER_PORT}); // the webSocket server
var connections = new Array; // list of connections to the server
wss.on('connection', handleConnection);
// get port name from the command line:
portName = process.argv[2];
var myPort = new SerialPort(portName, {
baudRate: 9600,
// look for return and newline at the end of each data packet:
parser: SerialPort.parsers.readline("\n")
});
myPort.on('open', showPortOpen);
myPort.on('data', sendSerialData);
myPort.on('close', showPortClose);
myPort.on('error', showError);
// This function broadcasts messages to all webSocket clients
function broadcast(data) {
for (myConnection in connections) { // iterate over the array of connections
connections[myConnection].send(data); // send the data to each connection
}
}
function sendToSerial(data) {
myPort.write(" From: index.js:sendToSerial "+data);
console.log("sendToSerial (index.js): " + data);
// if there are webSocket connections, send the serial data
// to all of them:
if (connections.length > 0) {
broadcast(data);
}}
function handleConnection(client) {
console.log("New Connection"); // you have a new client
connections.push(client); // add this client to the connections array
client.on('message', sendToSerial); // when a client sends a message,
client.on('close', function() { // when a client closes its connection
console.log("connection closed"); // print it out
var position = connections.indexOf(client); // get the client's position in the array
connections.splice(position, 1); // and delete it from the array
});
}
function showPortOpen() {
console.log(portName+' port open. Data rate: ' + myPort.options.baudRate);
}
function sendSerialData(data) {
myPort.write(" From: index.js:sendSerialData "+data);
myPort.write("sendSerialData "+data);
console.log("sendSerialData "+data);
}
function showPortClose() {
console.log('port closed.');
}
function showError(error) {
console.log('Serial port error: ' + error);
}
and index.html
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.4.8/p5.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.4.8/addons/p5.dom.js"></script>
<script type="text/javascript">
var text; // variable for the text div you'll create
var socket = new WebSocket("ws://localhost:8080");
function setup() {
// The socket connection needs two event listeners:
socket.onopen = openSocket;
socket.onmessage = showData;
// make a new div and position it at 10, 10:
text = createDiv("xxSensor reading:");
text.position(10,10);
}
function openSocket() {
text.html("Socket open");
socket.send("Hello websocket server - from index.html");
}
function showData(result) {
// when the server returns, show the result in the div:
text.html("Sensor reading: " + result.data);
xPos = int(result.data); // convert result to an integer
text.position(xPos, 10); // position the text
}
I have tried SERVER_PORT = 8081 with the same results.
I am able to see info from index.html in the cmd "node index.js COM3" but the command myPort.write does not get to the index.html browser.
I get:
C:\Users\pmfoo\nodeSerialExample>node index.js COM3
COM3 port open. Data rate: 9600
New Connection
sendToSerial (index.js): Hello websocket server - from index.html
sendSerialData 277.5 g
sendSerialData
where 277.5 g is the output from the scale on COM3.
and in the browser:
Sensor reading: Hello websocket server - from index.html
I followed Tom Igoe's tutorial https://itp.nyu.edu/physcomp/labs/labs-serial-communication/lab-serial-communication-with-node-js/ with only partial results. I cannot write from index.js to index.html nor can I send a command via index.js to the scale. This scale command ("ON" or "OFF" or "PSN") is seen by index.js. Can anyone help me solve these 2 communication problems?
I am trying to build a Node.js App to Monitor some Raspberry Pi's.
Since those Raspberries don’t have a static IP, they send an UDP Broadcast every 5 seconds.
I'm able to catch that Broadcast with Node.js, but I'm failing to trigger a new function to notify the Node.js Clients.
I tried WebSockets, ServerSendEvents and Socket.io.
I'm able to use Example Code and they work just fine.
But I'm not Experienced enough to build a function which will send data to the clients.
Node.js App:
// ==============================================================================================================
// ===== Dependencies ===========================================================================================
// ==============================================================================================================
var dgram = require('dgram');
var http = require('http');
var url = require("url");
var path = require("path");
var fs = require("fs");
// ==============================================================================================================
// ===== HTTP Serv ==============================================================================================
// ==============================================================================================================
var server = http.createServer(function(request, response) {
var uri = url.parse(request.url).pathname, filename = path.join(process.cwd(), uri);
var contentTypesByExtension = {
'.html': "text/html",
'.css': "text/css",
'.js': "text/javascript",
'.svg': "image/svg+xml"
};
fs.exists(filename, function(exists) {
if(!exists) {
response.writeHead(404, {"Content-Type": "text/plain"});
response.write("404 Not Found\n");
response.end();
return;
}
if (fs.statSync(filename).isDirectory()) filename += '/index.html';
fs.readFile(filename, "binary", function(err, file) {
if(err) {
response.writeHead(500, {"Content-Type": "text/plain"});
response.write(err + "\n");
response.end();
return;
}
var headers = {};
var contentType = contentTypesByExtension[path.extname(filename)];
if (contentType) headers["Content-Type"] = contentType;
response.writeHead(200, headers);
response.write(file, "binary");
response.end();
});
});
});
// ==============================================================================================================
// ===== HeartBeat Broadcast ====================================================================================
// ==============================================================================================================
var bcast = dgram.createSocket('udp4');
bcast.on('message', function (message) {
console.log("Triggered: UDP Broadcast");
// If UDP Broadcast is received, send message/data to client.
});
bcast.bind(5452, "0.0.0.0");
// ==============================================================================================================
// ===== Start Server ===========================================================================================
// ==============================================================================================================
server.listen(80);
console.log("Static file server running/\nCTRL + C to shutdown");
EDIT:
I think I did not explain myself accurate enough.
I do not want to send a UDP message back.
This UDP Broadcast should fire an (Node.js) event, which should update the html and display the raspberry pi (whom send the UDP Package) as online.
EDIT:
In documentation from official page of nodejs (DOCUMENTATION):
var socket = require('socket.io')(http);
var bcast = dgram.createSocket('udp4');
bcast.bind(5452, "0.0.0.0");
bcast.on('message', function (message, remote) {
////if message is an Object pushed into Buffer////
message = message.toString('utf8');
socket.emit("HTML_Update", message);
//////////////////////////////////Solution for unedited question//////////////////////////
// var msgBuffer = Buffer.from(message.toString(); //creating a buffer //
// bcast.send(msgBuffer, 0, msgBuffer.length, remote.port, remote.address, (err) => { //
// bcast.close(); //
// }); //sending message to remote.address:remote.port (like localhost:23456) //
// //
// **build a function which will send data to the clients** //
//////////////////////////////////Solution for unedited question//////////////////////////
});
"If message is an Object pushed into Buffer" - lets say that one of the RPI turned on and started sending UDP message, what should the message pass to server so server can pass it to display: mac address only because if it sends something You can be sure its on, if it does not send its off simple as that. Also to show that change on client You should initialize TCP sockets on server to pass info to servers web page to update content on html with jquery.
Now here is the HTML java script part (I personally make main.js file and write all java script into it and use import it as src into html). Using jquery in main.js:
$(document).ready(function() {
var time = new Date();
var rpi = {
"list" : ["mac1", "mac2", "mac3"],
"time" : [time.getTime(), time.getTime(), time.getTime()],
"label" : ["label_ID1", "label_ID2", "label_ID3"]};
var socket = io.connect('http://your_server_address:80');
setInterval( function(){
for (var i = 0; i <= 2; i++){
if((rpi.time[i] + 10000) < time.getTime()){
$(rpi.label[i]).text("RPI " + rpi.list[i] + " is DOWN");
}
}
}, 5000);
socket.on("HTML_Update", function(data){
for (var i = 0; i<=2; i++) {
if (data.toString().equals(rpi.list[i])) {
$(rpi.label[i]).text("RPI: "+ rpi.list[i] + " is UP");
rpi.time[i] = time.getTime();
}
}
});
}
If You put text label in html to show if specific rpi is up or down this part of code works in this scheme:
Multiple RPI + Server - RPI sends UDP data with mac to server. Server device is used to receive data and show it on any device as web page and change data if RPI is UP/DOWN.
I have an image stored at the server end. Whenever client connects to the server, it sends the image through sockets. The received image I am able to display it on canvas, however I am unable to save the received image in the local disk. I am trying to use fs.writeFile(), but maybe I am not sending the right parameters. Any leads to this issue will be helpful. Thank You. [I want implement this as a basic communication client-server].
To optimize it, is there any way can I achieve same operation in a much faster way? Any working code would also he helpful.
//server side js code
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var fs = require('fs'); // required for file serving
http.listen(6969, function(){
console.log('listening on port 6969');
});
// trying to serve the image file from the server
io.on('connection', function(socket){
start = new Date().getTime();
console.log(start);
console.log('a user connected');
fs.readFile(__dirname + '/image.jpg', function(err, buf){
socket.emit('image', { image: true, buffer: buf.toString('base64') });
console.log('image file is transmitted');
});
});
<script>
var socket = io("http://139.25.100.101:6969");
var ctx = document.getElementById('canvas_win').getContext('2d');
var fs = require('fs');
socket.on("image", function(info) {
if (info.image) {
var img = new Image();
img.src = 'data:image/jpeg;base64,' + info.buffer;
ctx.drawImage(img, 0, 0);
var end = new Date().getTime();
document.getElementById("demo").innerHTML = end;
fs.writeFile('logo.jpeg', img.src, 'data:image/jpeg;base64,', function(err){
if (err) throw err
console.log('File saved.')
})
}
});
I am very new to this but I think that for a "communication" between 2 entities, both must be able at some point to act as server, hence thenecessity of a php script on both ends.
Clients usually send requests to be processed by the server, so if you need a p2p communication, the client must download a php script to enable it to act as a server....
Again, I am a newbie so I might be (VERY) wrong
I have the following server:
var pvsio = require("./pvsprocess"),
ws = require("ws"),
util = require("util"),
http = require("http"),
fs = require("fs"),
express = require("express"),
webserver = express(),
procWrapper = require("./processwrapper"),
uploadDir = "/public/uploads",
host = "0.0.0.0",
port = 8082,
workspace = __dirname + "/public",
pvsioProcessMap = {},//each client should get his own process
httpServer = http.createServer(webserver),
baseProjectDir = __dirname + "/public/projects/",
PDFDocument = require ("pdfkit");
var p, clientid = 0, WebSocketServer = ws.Server;
...
var wsServer = new WebSocketServer({server: httpServer});
wsServer.on("connection", function (socket) {
var socketid = clientid++;
var functionMaps = createClientFunctionMaps();
socket.on("message", function (m) {
Is possible send a pdf file to the client inside socket.on("message" .. function ?
I can send message using send(), there is some function to send files?
Thanks
I would just send the pdf in binary.
fs.readFile(something.pdf,function(err,data){
if(err){console.log(err)}
ws.send(data,{binary:true});
}
And at the client side, I would create a blob and an object url from the received binary data. From this onward, you can pretty much do anything, says open the pdf file in a new window/tab.
conn.onmessage = function(e){
pdfBlob = new Blob([e.data],{type:"application/pdf"});
url = webkitURL.createObjectURL(pdfBlob);
window.open(url);
}
Hope this help.
I created an app with NodeJS and I'm using ws module. If I test the app in localhost it works and there isn't any problem to connect websockets. Now I've upload the app to Openshift and when I try to access from the client it returns that is not possible to stablish a connection to the websocket.
If I do a tail in putty to my app I have this message: DEBUG: This type of response MUST NOT have a body. Ignoring data passed to end().
The code that I have in the server is:
#!/bin/env node
//Openshift variables
var ipaddress = process.env.OPENSHIFT_NODEJS_IP || "192.168.69.42";
var port = process.env.OPENSHIFT_NODEJS_PORT || 8080;
//NodeJS require modules
var Enum = require('enum');
var WebSocketServer = require('ws').Server
wss = new WebSocketServer({host:ipaddress, port:port});
var fs = require('fs');
wss.on('connection', function(ws) {
console.log((new Date()) + ' Connection from origin: ' + ws._socket.remoteAddress);
});
console.log((new Date()) + " Server is listening on: " + ipaddress + ':' port);
And in the client:
var ws = new WebSocket("ws://192.168.69.42:8080/");
ws.onopen = function() {
console.log("Connected.");
ws.send("This is the client speaking.");
};
For all WebSocket connections on OpenShift you need to use port 8000 (for Secured sessions it would be 8443). So, your server example works well (I run them after removing the unnecessary line var Enum = require('enum');, you just need to hardcode the port on client to 8000:
var ws = new WebSocket("ws://YourApp-YourName.rhcloud.com:8000");
ws.onopen = function(){
console.log('opened')
}
More information here.
Here is an example on github that works that you can check out: https://github.com/developercorey/openshift-nodejs-http-and-websocket-example