Develop Reference

Implementing RabbitMQ in Chrome Kiosk/Extension/Apps and Web Browsers

I'm developing internal applications that require push notifications but we cannot use outside services. I have started to work with RabbitMQ and have it working flawlessly inside of .NET Core. When trying to implement it the same thing with javascript I am not getting the same results.
I developed test clients in C#. I developed a client in javascript. I can make a successful connection but data is not arriving.
In C# I am using:
string e = Console.ReadLine();
Console.WriteLine("Enter a message (blank for test msg)");
string message = Console.ReadLine();
var factory = new ConnectionFactory() { HostName = "10.222.2.160" };
factory.UserName = "Test";
factory.Password = "TestPassword";
factory.VirtualHost = "/";
using (var connection = factory.CreateConnection("TestChannel"))
using (var channel = connection.CreateModel())
{
var body = Encoding.UTF8.GetBytes(message);
channel.BasicPublish(exchange: e,
routingKey: "",
basicProperties: null,
body: body);
Console.WriteLine(" [x] Sent {0}", message);
}
In Javascript:
var wsbroker = "10.222.2.160"; // mqtt websocket enabled broker
var wsport = 15675; // port for above
var client = new Paho.MQTT.Client(wsbroker, wsport, "/ws/",
"test");
client.onConnectionLost = function (responseObject) {
console.log("CONNECTION LOST - " + responseObject.errorMessage);
};
client.onMessageArrived = function (message) {
console.log("RECEIVE ON " + message.destinationName + " PAYLOAD " + message.payloadString);
};
var options = {
userName: "Test",
password: "TestPassword",
timeout: 3,
keepAliveInterval: 30,
onSuccess: function () {
console.log("CONNECTION SUCCESS");
client.subscribe('test', { qos: 1 });
},
onFailure: function (message) {
console.log("CONNECTION FAILURE - " + message.errorMessage);
}
};
if (location.protocol == "https:") {
options.useSSL = true;
}
console.log("CONNECT TO " + wsbroker + ":" + wsport);
client.connect(options);
I need to be able to connect to rabbitmq from javascript (non-node, chrome kiosk application/chrome extension). However, I'm not sure I am "understanding" RabbitMQ. Pointing me in the right direction would help a girl out. Thanks!

You're publishing without a routing key here:
channel.BasicPublish(exchange: e,
routingKey: "",
basicProperties: null,
body: body);
Ensure that the test queue exists, then change routingKey to test in your publisher, and use the exchange named amq.direct.
You should read the RabbitMQ introduction available here to get familiar with how exchanges, queues, routing keys and bindings interact:
https://www.cloudamqp.com/blog/2015-05-18-part1-rabbitmq-for-beginners-what-is-rabbitmq.html
NOTE: the RabbitMQ team monitors the rabbitmq-users mailing list and only sometimes answers questions on StackOverflow.

TypeError: serialport.parsers.readline is not a function

I am trying to run this program in Raspberry Pi 3.
I have installed nodejs and ws on my raspberry pi.
Then I installed serial port module.
I am trying to create this project:enter link description here
I have tried to find solutions everywhere but I could not find one.
If any one knows how to solve this problem please help me.
var webSocketUrl = "wss://api.artik.cloud/v1.1/websocket?ack=true";
var device_id = "5bb3ba9304674086bee67fa507a215cf"; //DEVICE ID
var device_token = "36b278345b6d4d11abf764ae213c5c70"; //DEVICE TOKEN
var WebSocket = require('ws');
var isWebSocketReady = false;
var data="";
var ws = null;
var serialport = require("serialport");
var SerialPort = serialport.SerialPort;
var sp = new SerialPort("/dev/ttyACM0", { //for serial communication with arduino
baudrate: 9600,
// The baud rate of uno is 9600
parser: serialport.parsers.readline("\n")
});
/**
* Gets the current time in millis
*/
function getTimeMillis(){
return parseInt(Date.now().toString());
}
/**
* Create a /websocket connection and setup GPIO pin
*/
function start() {
//Create the WebSocket connection
isWebSocketReady = false;
ws = new WebSocket(webSocketUrl);
ws.on('open', function() {
console.log("WebSocket connection is open ....");
register();
});
ws.on('message', function(data) {
//this loop is called whenever the client sends some message
handleRcvMsg(data); //data is send to the function handleRcvMsg()
});
ws.on('close', function() {
console.log("WebSocket connection is closed ....");
});
}
/**
* Sends a register message to /websocket endpoint
*/
//Client will only work when device gets registered from here
function register(){
console.log("Registering device on the WebSocket connection");
try{
var registerMessage = '{"type":"register", "sdid":"'+device_id+'", "Authorization":"bearer '+device_token+'", "cid":"'+getTimeMillis()+'"}';
console.log('Sending register message ' + registerMessage + '\n');
ws.send(registerMessage, {mask: true});
isWebSocketReady = true;
}
catch (e) {
console.error('Failed to register messages. Error in registering message: ' + e.toString());
}
}
//data after receiving is sent here for processing
function handleRcvMsg(msg){
var msgObj = JSON.parse(msg);
if (msgObj.type != "action") return; //Early return;
var actions = msgObj.data.actions;
var actionName = actions[0].name; //assume that there is only one action in actions
console.log("The received action is " + actionName);
}
/**
* Send one message to ARTIK Cloud
*/
//This function is responsible for sending commands to cloud
//function sendStateToArtikCloud(parking,temperature,water){
function sendDataToArtikCloud(pantry){
var result=pantry.split(" ");//data gets split by " " to get the values
try{
ts = ', "ts": '+getTimeMillis();
var data = {
"Garlic": result[1],
"Potato":result[2],
"Temperature":result[3],
"Chilli":result[4],
"Humidity": result[5],
"Ginger":result[6],
"Onion": result[7]
};
var payload = '{"sdid":"'+device_id+'"'+ts+', "data": '+JSON.stringify(data)+', "cid":"'+getTimeMillis()+'"}';
console.log('Sending payload ' + payload + '\n');
ws.send(payload, {mask: true});
} catch (e) {
console.error('Error in sending a message: ' + e.toString() +'\n');
}
}
function exitClosePins() {
console.log('Exit and destroy all pins!');
process.exit();
}
start();
//exectes every second when data is received from arduino (5sec programmed delay from arduino)
sp.on("open", function () {
sp.on('data', function(data) {
console.log("Serial port received data:" + data);
//var result=data.split(" ");//data gets split by " " to get the values
//sendStateToArtikCloud(result[0],result[2],result[1]);//parking,temperature,waterlevel
sendDataToArtikCloud(data);
});
});
process.on('SIGINT', exitClosePins);
I am getting an error on my raspberry pi
enter image description here
Suggest me a solution.

The documentation will tell you that Readline is spelled with a capital R
https://www.npmjs.com/package/serialport#module_serialport--SerialPort.parsers
parser: serialport.parsers.Readline("\n")
~

[TypeError: serialport.parsers.readline is not a function.]
If it has not been resolved yet, try this method.
var serialport = require("serialport")
var SerialPort = serialport.SerialPort;
var sp = new serialport("/dev/ttyACM0"),{
BaudRate: 9600,
parser: new serialport.parsers.Readline("\r\n")
});
I hope your problem is solved.

Http server with socket-io on node.js doens't running

My http server on node.js using socket-io isn't running. I used npm install socket-io and running server.
This is the server's code.
var static = require('node-static');
var http = require('http');
// Create a node-static server instance
var file = new(static.Server)();
// We use the http moduleÕs createServer function and
// rely on our instance of node-static to serve the files
var app = http.createServer(function (req, res) {
file.serve(req, res);
}).listen(8181);
// Use socket.io JavaScript library for real-time web applications
var io = require('socket.io').listen(app);
// Let's start managing connections...
io.sockets.on('connection', function (socket){
// Handle 'message' messages
socket.on('message', function (message) {
log('S --> got message: ', message);
// channel-only broadcast...
socket.broadcast.emit('message', message);
});
// Handle 'create or join' messages
socket.on('create or join', function (room) {
/*var namespace = '/';
for (var numClients in io.nsps[namespace].adapter.rooms[room]) {
console.log(numClients);
}*/
//var numClients = io.sockets.clients(room).length;
var numClients = io.sockets.adapter.rooms[room]!=undefined ? Object.keys(io.sockets.adapter.rooms[room]).length:0;
log('SERVER: CLIENTS ' + room + ' has ' + numClients + ' client(s)');
log('S --> Room ' + room + ' has ' + numClients + ' client(s)');
log('S --> Request to create or join room', room);
// First client joining...
if (numClients == 0){
socket.join(room);
socket.emit('created', room);
} else if (numClients == 1) {
// Second client joining...
io.sockets.in(room).emit('join', room);
socket.join(room);
socket.emit('joined', room);
log('S: sent JOIN message');
} else { // max two clients
socket.emit('full', room);
}
});
function log(){
var array = [">>> "];
for (var i = 0; i < arguments.length; i++) {
array.push(arguments[i]);
}
socket.emit('log', array);
}
});
While this is client's code connecting to the socket:
var room = getParameterByName('room_name');
alert ("room_name: "+room);
// Connect to signalling server
var socket = io.connect();
// Send 'Create or join' message to singnalling server
if (room !== '') {
console.log('Create or join room', room);
socket.emit('create or join', room);
}
With netstat -a comand I saw what the server's port is active.. but it doesn't send messages.
I've another question: how can server sends messages not in broadcast, but to specified peers connected? I mean: instead of
socket.on('message', function (message) {
log('S --> got message: ', message);
// channel-only broadcast...
socket.broadcast.emit('message', message);
});
How could I do? Thanks!

I've another question: how can server sends messages not in broadcast,
but to specified peers connected?
The second part of your question is that you just do socket.emit() to send to a single socket like this to send back to the same socket that just sent you a message:
socket.on('message', function (message) {
log('S --> got message: ', message);
// channel-only broadcast...
socket.emit('message', "got your message");
});
Or, if you have a socket id value for some other connected client, you can fetch that socket on the server like this:
io.sockets.connected[id].emit(...)

Node.js websocket-server and tcp-server connection

Related to this question Browser with JavaScript TCP Client I asked whether I can connect from a browser to a tcp server. I found out that it won't work so I asked for another solution. '0101' provided me to built up two servers. One tcp server for a c++ application that connects to and one websockets server that receives data from the browser. I have originally built up each one of them, but I don't know how to connect them so I can receive data from the browser in the c++ application.
Here is the websockets-server:
var ClientListe = {};
// Anzahl der Verbundenen Clients
var ClientAnzahl=0;
// Websocket-Server
var WebSocketServer = require('ws').Server
var wss = new WebSocketServer({host: '127.0.0.1',port: 80});
wss.on('connection', function(ws)
{
// Client-Anzahl hochzählen
ClientAnzahl++;
// Client-Verbindung mit in die Client-Liste Aufnehmen
ws['AUTH'] = ClientAnzahl;
ClientListe[ws['AUTH']] = ws;
// Ausgabe
console.log('client '+ClientAnzahl+' verbunden...');
ws.on('message', function(message)
{
console.log('von Client empfangen: ' + message);
for(client in ClientListe)
{
ClientListe[client].send('von Server empfangen: ' + message);
}
});
ws.on('close', function()
{
// Client aus der ClientListe Löschen
delete ClientListe[ws['AUTH']];
// Nachricht der Trennung an die Console ausgeben
console.log('Client '+ ws['AUTH'] +' getrennt.');
});
});
and here is the tcp server:
// Load the TCP Library
net = require('net');
// Keep track of the chat clients
var clients = [];
// Start a TCP Server
net.createServer(function (socket) {
// Identify this client
socket.name = socket.remoteAddress + ":" + socket.remotePort;
// Put this new client in the list
clients.push(socket);
// Send a nice welcome message and announce
socket.write("Welcome " + socket.name + "\n");
broadcast(socket.name + " joined the server\n", socket);
// Handle incoming messages from clients.
socket.on('data', function (data) {
broadcast(socket.name + " message: " + data, socket);
});
// Remove the client from the list when it leaves
socket.on('end', function () {
clients.splice(clients.indexOf(socket), 1);
broadcast(socket.name + " left the server.\n");
});
// Send a message to all clients
function broadcast(message, sender) {
clients.forEach(function (client) {
// Don't want to send it to sender
if (client === sender) return;
client.write(message);
});
// Log it to the server output too
process.stdout.write(message)
}
}).listen(80);
// Put a friendly message on the terminal of the server.
console.log("TCP Server running at localhost port 80\n");
Both are copied out of the internet for testing some cases

Create a TCP server (NodeJS example)
var net = require("net");
var server = net.createServer(function(c) { //'connection' listener
console.log('server connected');
c.on('end', function() {
console.log('server disconnected');
});
c.write('hello\r\n');
c.pipe(c);
});
server.listen(8124, function() { //'listening' listener
console.log('server bound');
});
Then in the same file (optionally of course) create a WS server with different port number
var WebSocketServer = require("ws").Server;
var wss = new WebSocketServer({
port: 8080
});
wss.on("connection", function(ws) {
console.log("CONNECTED");
// ws.on("message"), ws.on("close"), ws.on("error")
});
Now you should have two servers, one for regular sockets and another one for WebSockets.
// As I mentioned in the previous question and Pete as well, it is a lot better to use WebSockets in C++ as well instead of creating two servers...

Drop the TCP server and make the C++ client connect to the websockets server instead. You'll need to implement the websockets protocol on top of your TCP connection at the C++ end (all you really need is a bit of pre-amble to negotiate the websocket). You have problems here with both servers trying to use port 80.
By the way, you should also consider using HTTPS for the websocket instead of HTTP since it avoids problems with proxy traversal. But get the HTTP case working first as this will be more complicated to implement on the C++ end.

WebSocket connection established, but can't receive messages

I've written a short WebSocket example server in PHP yesterday. When the client connects to the server, the server reads the client Handshake and sends the server Handshake back with the appropriate key. onopen() of the client gets fired and the server and client seem to be connected.
My problem is: The server can't receive client messages and the client can't receive server messages. onmessage() wasn't triggered once and socket_select() never gives back the client that sent the message on server side.
function connect() {
try {
var webSocketURL = "ws://" + serverAddress + ":" + serverPort;
socket = new WebSocket(webSocketURL);
socket.onopen = function() {
log("Connected! (" + this.readyState + ")");
}
socket.onclose = function() {
log("Closed! (" + this.readyState + ")");
socket.close();
}
socket.onerror = function(error) {
log("Error: " + error.data);
socket.close();
}
socket.onmessage = function(message) {
log("Message from server: " + message.data);
}
}
catch (e) {
alert("Error: " + e);
}
}
The server code is a bit longer, but you can find it here.
Can anyone tell me what's wrong there? Is the handshake incorrect?
Client output:
Connected! (1)
Message to server: 0USERchannel
Server output.
Help is much appreciated, thank you.

On client side, enshure your socket variable is global.