I am using express.io and am trying to craft a middleware that requires a connection to a remote server via two sockets. However, I am having a problem.
var net = require('net');
module.exports = function (host, port) {
return function (req, res, next) {
req._messages = net.connect(port, host);
req._commands = net.connect(port, host);
req._messages.on('data', function (data) {
req.io.broadcast('data', data.toString('ascii'));
});
req._messages.write('CF I\r'); // initialization command
next();
}
}
then in my main app:
var port = process.env.CYLON_PORT;
var host = process.env.CYLON_HOST;
var app = require('express.io').http().io();
app.use(require('./cylon/controller')(host, port));
module.exports = app;
However, I am coming across a problem. On each request, it attempts to reconnect. This causes an Error: connect ECONNREFUSED. Ideally, I would like this to connect once when the application starts and maintain that socket, but it needs to intercept each connect.
How can I use sockets in middleware?
You can try that way:
var net = require('net');
module.exports = function (host, port) {
var messagesConnection = net.connect(port, host);
var commandsConnection = net.connect(port, host);
return function (req, res, next) {
req._messages = messagesConnection;
req._commands = commandsConnection;
req._messages.on('data', function (data) {
req.io.broadcast('data', data.toString('ascii'));
});
req._messages.write('CF I\r'); // initialization command
next();
}
}
The call to require('./cylon/controller')(host, port) will start the connections and they will then be reused each time the middleware is called.
Edit: I'm wondering whether you really need to set all those new fields on you req object. You could have some files that export io, messagesConnection and commandsConnection for instance, and you could require them when needed.
Here you end up adding an even listener on messagesConnection each time the middleware is called, which is everything but good.
Edit2: What you could do instead, because you seem to be using express-io:
var net = require('net');
module.exports = function (io, host, port) {
var messagesConnection = net.connect(port, host);
var commandsConnection = net.connect(port, host);
messagesConnection.on('data', function (data) {
io.broadcast('data', data.toString('ascii'));
});
messagesConnection.write('CF I\r'); // initialization command
return function (req, res, next) {
req._messages = messagesConnection;
req._commands = commandsConnection;
next();
}
}
And in your main file:
var port = process.env.CYLON_PORT;
var host = process.env.CYLON_HOST;
var app = require('express.io').http().io();
app.use(require('./cylon/controller')(app.io, host, port));
module.exports = app;
Related
i am working on a chatapp project that needs a real time chatting so i have used socketio in my server side which is written in nodejs and than used socketio-client in my main chatapp react-native project.
But now a problem is coming my socket is not initializing. I'm not able to connect my server with my main app. I am using socketio and socketio client my both the socket version are same 4.5.1 but it's not even connecting. I have tried to use old version of socket but its also not working and I have also tried to change my localhost port to 4000 but it's also not working.
My server code:
const express = require('express');
var bodyParser = require('body-parser');
const app = express();
const http = require('http');
const server = http.createServer(app);
const { Server } = require("socket.io");
const io = new Server(server);
const port = process.env.PORT || 3000;
require('./src/config/database')
const user_routes = require('./src/user/users.routes');
app.use(bodyParser.urlencoded({extended: true}))
app.use(express.json())
app.get('/', (req, res) => {
res.sendFile(__dirname + '/index.html');
});
app.use('/User', user_routes)
io.on('connection', (socket) => {
console.log('a user connected');
socket.on('send_message',(data)=>{
console.log("received message in server side",data)
io.emit('received_message',data)
})
socket.on('disconnect', () => {
console.log('user disconnected');
});
});
server.listen(port, () => {
console.log( `Server running at http://localhost:${port}/`);
});
My app socketservice file code:
import io from 'socket.io-client';
const SOCKET_URL = 'http://localhost:3000'
class WSService {
initializeSocket = async () => {
try {
this.socket = io(SOCKET_URL, {
transports: ['websocket']
})
console.log("initializing socket", this.socket)
this.socket.on('connect', (data) => {
console.log("=== socket connected ====")
})
this.socket.on('disconnect', (data) => {
console.log("=== socket disconnected ====")
})
this.socket.on('error', (data) => {
console.log("socekt error", data)
})
} catch (error) {
console.log("scoket is not inialized", error)
}
}
emit(event, data = {}) {
this.socket.emit(event, data)
}
on(event, cb) {
this.socket.on(event, cb)
}
removeListener(listenerName) {
this.socket.removeListener(listenerName)
}
}
const socketServcies = new WSService()
export default socketServcies
Where I have marked it should be connected = true but it's false in the dev console I have done console log so check that it's connecting or not and I can see that it's not connecting. How to make it connect?
There is no error in my app or server I have checked many times and my server is also running when I am running my app.
Answering my own question
The problem was i was using android emulator and android in an emulator can't connect to localhost you need to use the proxy ip so when i add http://10.0.2.2:3000 in const SOCKET_URL = 'http://10.0.2.2:3000' than its working fine
credit goes to gorbypark who told me this in discord
I'm assuming that your front and back runs in localhost. The documentation says that if the front-end is in the same domain as the back-end, you don't need to use the URL. Since you have the options parameter declared, you can use the default argument window.location in first place:
class WSService {
initializeSocket = async () => {
try {
this.socket = io(window.location, {
transports: ['websocket']
})
console.log("initializing socket", this.socket)
this.socket.on('connect', (data) => {
console.log("=== socket connected ====")
})
this.socket.on('disconnect', (data) => {
console.log("=== socket disconnected ====")
})
this.socket.on('error', (data) => {
console.log("socekt error", data)
})
} catch (error) {
console.log("scoket is not inialized", error)
}
}
emit(event, data = {}) {
this.socket.emit(event, data)
}
on(event, cb) {
this.socket.on(event, cb)
}
removeListener(listenerName) {
this.socket.removeListener(listenerName)
}
}
Don't specify the host/port for socket-io to connect to. It can figure it out on its own.
Per documentation, it tries to connect to window.location if no URL is specified as an argument.
So instead of
this.socket = io(SOCKET_URL, {
transports: ['websocket']
})
Just do
this.socket = io()
I am not sure it works with other arguments. You could try like this
this.socket = io(undefined, {
transports: ['websocket']
})
I'm new to Node and am trying to build a simple server in Node using Express. The requests are in the form of say /input00001/1/output00001. What I need to do is to parse this request and if the flag is 1 (middle value), I need to replace the file \home\inputfiles\input00001.txt with file \home\outputfiles\output00001.txt. How is it possible to do that?
Here is my simple server so far. I'm OK with not using the Express and pure NodeJs if that makes things easier.
const express = require('express');
const app = express();
const port = 8000;
app.get('/', (request, response) => {
response.send('Hello from Express!');
request.param
});
app.get('/*', (request, response) => {
response.send('Start!');
var url = request.originalUrl;
});
app.listen(port, (err) => {
if (err) {
return console.log('something bad happened', err);
}
console.log(`server is listening on ${port} for incoming messages`);
});
You should set up a route that expects these items as url parameters and then use those parameters to do what you want. For example if you're url is /input00001/1/output00001 then you could set up a route like this:
app.get('/:input/:flag/:output', (req, res) => {
var params = req.params
var input = params.input //input0001
var flag = params.flag // 1
var output = params.output //output0001
// now do what you need to with input, flag, and output
if(typeof flag!=='undefined' && flag==1){
var file_name_string = '\home\inputfiles\input00001.txt';
var res = file_name_string.replace("input", "output");
}
console.log(input, flag, output)
res.send("done")
})
I have a server.js file.
Inside, i defined my routes.
// routes
var mainRoutes = require('./routes/main.js')(app, express);
var apiRoutes = require('./routes/api.js')(app, express);
var socketRoutes = require('./routes/socket.js');
app.use('/', mainRoutes);
app.use('/api', apiRoutes);
// socket.io communication
io.sockets.on('connection', socketRoutes);
My socket.js file looks like that :
module.exports = function (socket) {
console.log('user connected');
socket.on('myEvent', function(data) {
// whatever ...
});
}
Inside this function, i can catch events and send some.
BUT i need to send a message to everyone at some point. Let say when i receive an 'myEvent' event.
So basically, i would like to do :
io.sockets.emit('messageForEveryone', "This is a test");
But here, i can only work on the 'socket' argument, which is for 1 person only i guess.
I would like to pass io from server.js, to socket.js.
I tried that (in server.js) :
var socketRoutes = require('./routes/socket.js', io);
And that (in socket.js) :
module.exports = function (io, socket)
Obviously, it's not working. I don't even understand where the socket argument is coming from.
Question : How can i work on io object, when i'm inside the module.export of the sockets.js file ?
I would really appreciate any help, i'm new to all of this.
Thanks !
Since you just want to emit to all clients, instead of passing io to socketRoutes, you can simply do this.
module.exports = function (socket) {
var sockets = this;
console.log('user connected');
socket.on('myEvent', function(data) {
sockets.emit('hello_all_clients',data);
});
}
You could return a function from exports as such.
module.exports = function (io) { // pass io to initialize
return function (socket) {
// io and socket are both scoped
}
}
then in server.js
// socket.io communication
io.sockets.on('connection', socketRoutes(io));
I am trying to build a simple node.js based streaming API. All I want to do is as I hit the server url, the output should stream a set of test data(JSON) like twitter streaming API.
var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
server.listen(8083);
app.get('/', function (req, res) {
res.write(io.on('connection', function (socket) {
socket.emit('item', { hello: 'world' });
}));
});
So, If i do curl http://localhost:8083/, I want output something like:
$ curl http://localhost:8083/
{hello: 'world'}
{hello: 'world'}
{hello: 'world'}
{hello: 'world'}
...
I am new to node.js and web sockets. I might be horribly wrong on the basics of how node works, let me know the best solution.
First, it's better to put the JSONStream part inside a middleware like so:
var _ = require('lodash');
// https://github.com/smurthas/Express-JSONStream/blob/master/index.js
function jsonStream(bytes) {
return function jsonStream(req, res, next) {
// for pushing out jsonstream data via a GET request
var first = true;
var noop = function () {};
res.jsonStream = function (object, f) {
f = _.isFunction(f) ? f : noop;
if (!(object && object instanceof Object)) {
return f();
}
try {
if (first) {
first = false;
res.writeHead(200, {
'Content-Type': 'application/json',
'Cache-Control': 'no-cache',
'Connection': 'keep-alive'
});
}
res.write(JSON.stringify(object) + '\n');
} catch (err) {
return _.defer(f.bind(null, err));
}
f();
};
next();
};
}
Then, let's say you want to be notified via this API each time someone connects to socket.io
var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
var _ = require('lodash');
var EventEmitter = require('events').EventEmitter;
server.listen(8083);
var mediator = new EventEmitter();
io.on('connection', function (socket) {
mediator.emit('io:connection:new', socket);
});
// the second parameter, specify an array of middleware,
// here we use our previously defined jsonStream
app.get('/', [jsonStream()], function (req, res) {
function onNewConnection(socket) {
res.jsonStream({
type: 'newConnection',
message: 'got a new connection',
socket: {
id: socket.id
}
});
}
// bind `onNewConnection` on the mediator, we have to use an mediator gateway
// because socket.io does not offer a nice implementation of "removeListener" in 1.1.0
// this way each time someone will connect to socket.io
// the current route will add an entry in the stream
mediator.on('io:connection:new', onNewConnection);
// unbind `onNewConnection` from the mediator
// when the user disconnects
req.on('close', function () {
mediator.removeListener('connection', onNewConnection);
});
res.jsonStream({
type: 'welcome',
message: 'waiting for connection'
});
});
Finally, if you want to test this code without connecting to socket.io use the following simulator:
// Simulate socket.io connections using mediator
(function simulate() {
var dummySocket = {
id: ~~(Math.random() * 1000)
};
mediator.emit('io:connection:new', dummySocket);
setTimeout(simulate, Math.random() * 1000);
})();
I am working on an app which, among other things, pushes data to the client when an updation occurs on the database. The trouble is that the websocket on node.js listens to the databse on a different port then the node. The guy before me wrote a piece of code and then dumped it on me. The node looks somewhat like this:
var handler=http.createServer(function(req, res){
session(req, res, function(req, res, body) {
if (!req.session || !req.session.data || !req.session.data.uid || req.session.data.uid == '' || !req.session.data.role || req.session.data.role =='') {
var uri = url.parse(req.url).pathname;
if(req.method == 'GET' && uri =="/attendance-node/getMonthFromReport") {
var uri = url.parse(req.url).pathname;
var url_parts = url.parse(req.url,true);
processgetMonthFromReport(req, res, uri, url_parts.query);
return;
}
res.writeHead(401, {"Content-Type": "text/plain"});
res.write("401 Unauthorized");
res.end();
return;
}
if(req.method == 'POST') {
var uri = url.parse(req.url).pathname;
var qs = require('querystring');
var POSTVAR = qs.parse(body, '&', '=', {"maxKeys" : 0});
//var POSTVAR=JSON.parse(body);
handleRequest(req, res, uri, POSTVAR);
}
if (req.method=='GET') {
var uri = url.parse(req.url).pathname;
var url_parts = url.parse(req.url,true);
handleRequest(req, res, uri, url_parts.query);
}
});
}).listen(3014,"127.0.0.1");
var io = require('socket.io').listen(8077,"127.0.0.1");
sys.puts("websocket Server running on port 8077");
io.configure(function () {
io.set('transports', ['websocket', 'flashsocket', 'xhr-polling','jsonp-polling']);
io.set('log level', 0);
});
io.sockets.on('connection', function (socket) {
io.sockets.emit('init',"i am working via websocket");
});
As you can see the node is listening on 3014 and the socket on 8077. Now how am I suppossed to provide an handler for the message received on the socket and forward it to the node's client?
Note: I am fairly new to web development. So basically I was thrown in the water and now I am learning to swim.
P.S. Also, what would the client side of the socket look like?
P.P.S. The database sending update notification to the socket is already taken care of. It comes as a POST request.
Thanx in advance!!
It sounds like you want to have socket.io also on the client side (browser?) as well.
I'd say the best solution would be to have socket.io run on the same port as your web server. However, if it this not possible and you must keep the web socket that the database uses separate from the web server you could run two instances of socket.io.
One would be attached to the web server, and the other would be for the database.
var app = require('http').createServer(handler)
, IO = require('socket.io')
, web_io = IO.listen(app)
, data_io = IO.listen(8080)
, fs = require('fs')
app.listen(80);
function handler (req, res) {
fs.readFile(__dirname + '/index.html',
function (err, data) {
if (err) {
res.writeHead(500);
return res.end('Error loading index.html');
}
res.writeHead(200);
res.end(data);
});
}
web_io.sockets.on('connection', function (socket) {
socket.on('some_event', function (data) {
console.log(data);
});
});
data_io.sockets.on('connection', function (socket) {
socket.on('database_update', function (data) {
// Will be sent to everyone socket listening on port 80 (browser sockets mostlikely)
web_io.sockets.emit('database_update', data);
});
socket.on('disconnect', function () {
io.sockets.emit('user disconnected');
});
});