I'm learning Node js and I'd like to understand why the output or result set is showing twice in the browser (tried with different browsers) and how to fix the issue to show the result set only once.
Here is my sample code :
// JavaScript source code
var express = require('express'); // Web Framework
var app = express();
var sql = require('mssql'); // MS Sql Server client
// Connection string parameters.
const pool = new sql.ConnectionPool({
user: 'myuser',
password: 'password123',
server: 'localhost',
database: 'Sample'
})
var conn = pool;
// Start server and listen on http://localhost:8080/
var server = app.listen(8080, function () {
var host = server.address().address
var port = server.address().port
console.log("app listening at http://%s:%s", host, port)
});
app.get('/groups', function (req, res) {
conn.connect().then (function() {
var request = new sql.Request(conn);
request.query('SELECT TOP 10 * FROM [Sample].[Table1]',function(err, recordset) {
if(err) console.log(err);
res.end(JSON.stringify(recordset)); // Result in JSON format
conn.close();
});
});
})
please advice.
Thanks.
Related
I want to pull a URL from the DB and use it as the proxied URL. However the setup I've come up with initializes a new BrowserSync server for each URL, using incrementing port numbers.
Is there a way to accomplish this without initializing a new BrowserSync server every time?
Or should I be using another approach?
var bs = require("browser-sync");
var express = require("express");
var router = express.Router();
var app = express();
router.get("/", function(req, res){
var proxyUrl = getUrl() //get url from db (www.example.com)
bs.create("bs1").init({
notify: false,
open: false,
ui: false,
port: 10000,
proxy: proxyUrl
});
res.send();
});
app.use(router);
app.listen(8080, function(){
console.log('listening on *:8080');
});
The above is fine(ish) but is it good practice to be initializing a new server for every URL (potentially thousands)?
And is it safe to be exposing a new port number to every user of the system? (Can I mask this with a subdomain?)
Update
My end goal is to use a unique subdomain to refer to each proxy url.
For example:
sub1.mysite.com proxies www.example.com,
sub2.mysite.com proxies www.example2.com
Browser-sync will not work as the proxy is tie to server setup.
I use following packages:
express
express-http-proxy
vhost (express vhost)
const port = 8080;
var app = require('express')();
var proxy = require('express-http-proxy');
var url = require('url');
var vhost = require('vhost');
app.listen(port);
/* Assuming getUrl() will return an array of sites */
// var sites = getUrl();
// DO NOT put '/' at the end of site
var sites = [
'http://www.bing.com',
'http://samanthagooden.com',
'http://www.courtleigh.com'
];
var i = 0;
sites.forEach(site => {
i++;
var subDomain = 'sub' + i + '.mysite.com';
app.use(vhost(subDomain, proxy(site, {
forwardPath: (req, res) => url.parse(req.url).path,
intercept: (rsp, data, req, res, callback) => {
if (res._headers['content-type']) {
var contentType = res._headers['content-type'];
if (
contentType.indexOf('text') !== -1 ||
contentType.indexOf('javascript') !== -1
) {
// Replace link if content-type = text or javascript
var reg = new RegExp(site, 'g');
res.send(data.toString().replace(reg, ''));
} else {
res.send(data);
}
} else {
res.send(data);
}
}
})));
console.log(subDomain + ':' + port + ' proxy: ' + site);
});
The above example will create following proxies:
sub1.mysite.com:8080 proxy: www.bing.com
sub2.mysite.com:8080 proxy: www.example.com
Maybe I'm misunderstanding what you are trying to do, but Browsersync and express seems a bit overkill in this case, why not just use node-http-proxy with the native http module?
var http = require('http')
var httpProxy = require('http-proxy')
var options = ...
var proxy = httpProxy.createProxyServer(options)
var server = http.createServer(function (req, res) {
var proxyUrl = getUrl()
proxy.web(req, res, { target: proxyUrl })
})
server.listen(8080, function () {
console.log('listening on *:8080')
})
As per me If you want SAAS service using proxy is not the good idea to go is what am thinking.. if you are going with proxy for each client will create process with new port... My Solution is to create node server with listen localhost and map *.domain.com to the server..
If you are using individual database for each client :-
in node logic get cname from request host and use that reference to connect database.
Final Controller code would be..
var express = require('express');
var router = express.Router();
var MongoClient = require('mongodb').MongoClient;
/* GET home page. */
router.get('/', function(req, res, next) {
var client = req.subdomains[0];
console.log(client);
MongoClient.connect('mongodb://localhost:27017/'+client, function(err, db) {
if (err) {
throw err;
}
db.collection('app1').find().toArray(function(err, result) {
if (err) {
throw err;
}
console.log('data');
console.log(result);
});
});
res.render('index', { title: 'Express' });
});
module.exports = router;
~
~
In future if you get more clients you can implement node cluster or standard Ubuntu cluster using webservice
I would like use nodeJS to refresh my view, every time a function has made changes to the database. If we take MEAN-stack as an example, I don't want to send an $http-request every x seconds to check if changes have been made to the database. I would like the front end to get notified automatically and then update the view.
What are best practices for this? I would use some kind of Oberserver pattern in the server side, but do not know how I could notify the front end with that.
To get the front end to get notified automatically and then update the view you could use Socket.io framework.
You can find all of the documentation on their site: http://socket.io/
And here is a basic example:
app.js ( to set up the server)
var http = require('http');
var express = require('express');
var port = normalizePort(process.env.PORT || '1000');
var app = express();
var server = http.createServer(app);
server.listen(port);
io = require('socket.io')(server);
///ROUTES
var routes = require('./routes/index')(io);
var users = require('./routes/users');
///////
I pass the io object to route index(and ofcourse there is a lot more stuff on app.js..this is just a basic example...).
mysql.js (to create a pool for connections)
var mysql = require("mysql");
var pool = mysql.createPool({
host : 'host',
user : 'user',
password : 'pass',
database : 'db_name',
connectionLimit: 1000
});
exports.pool = pool;
index.js
module.exports = function(io) {
var express = require('express');
var router = express.Router();
var mysql = require('../mysql.js').pool;
io.on('connection', function (socket) {
socket.on('event_name', function (data) {
mysql.getConnection(function(err,connection){
if (err) {
connection.release();
return;
}
connection.query("SQL STUFF",function(err,rows){
if(rows.length>0){//checks if there are more than 0 rows returned.....
socket.emit('do_something',data_you_want_to_pass);
}
else{
socket.emit('do_something_else',data_you_want_to_pass);
}
connection.release();
});
connection.on('error', function(err) {
return;
});
});
});
});
router.get('/', function(req, res) {
res.render("index");
});
return router;
}
And then on html page you have socket.emit and socket.on again.....
I recommend you take a look at the documentation and a few other examples...
I hope I helped you.
I have a node js ( supported by express js ) http application. So I had a server.js file as follows(not there complete code).
var app = require('./app/app');
var server = http.createServer(app);
server.listen(port, host);
server.on('error', onError);
server.on('listening', onListening);
I later added websocket server to there. So it is like this now.
// app server
var app = require('./app/app');
var server = http.createServer(app);
server.listen(port, host);
server.on('error', onError);
server.on('listening', onListening);
/**
* websocker Server
*/
var WebSocket = require('ws');
var wsServer = http.createServer();
var url = require('url');
var WebSocketServer = require('ws').Server;
var wss = new WebSocketServer({ server: wsServer });
var express = require('express');
var wsApp = express();
var port = 1337;
wsApp.use(function (req, res) {
res.send({ msg: 'hello' });
});
wss.on('connection', function connection(ws) {
console.log((new Date()) + ' Connection from origin ');
ws.on('message', function incoming(message) {
console.log('received: %s', message);
var json = JSON.stringify({ type:'message', data: {hello : 'hello'} });
ws.send(json);
});
var json = JSON.stringify({ type:'message', data: {hello : 'hello'} });
ws.send(json);
});
wsServer.on('request', wsApp);
wsServer.listen(port, function () { console.log('Ws server Listening on ' + wsServer.address().port); });
Now these two are working happily. What I want is on a POST call to the http server, I want to trigger the web socket server to broadcast something to all clients. My problem is How I can trigger websocket server from http server?
Routes of http server is defined in app.js file. from there how can I call websocker server function?
If you encapsulate your ws functionality in one single javascript file (e.g: websocket.js) you could export your websocket object as a module.
module.exports = wss;
and then require it in your http controller
var wss = require(websocket.js)
In this case it should be easy to use wss.send({...}) wherever you like.
This peace of code is working to me:
//websocket.js
'use strict';
var io = require('socket.io');
var callme;
function Websocket(server) {
var server = io(server);
server.on('connection', function(socket){
console.log('Do something here');
});
callme = function (val) {
//you my choose a specific cliente if you want, read the socket.io doc
server.emit('I may emit it ' + val);
console.log("Called " + val);
return 'Somebody got it';
}
}
Websocket.route = function(req, res, next) {
if(typeof callme == 'function'){
res.send(callme(req.param('t')));
}else{
res.send('Websocket server is not running');
}
};
module.exports = Websocket;
On the express app definition, I put
var Websocket = require('./websocket');
app.use('/blablabla', Websocket.route);
Then, on the server js file, which run the application, I put
var server = http.createServer(app);
var s = new Websocket(server);
This last line works like the tradicional io(server); would work.
After that, when you request the address /blablabla the route will execute your websocket method.
My solution is not in production yet, let me know if somebody got an error.
I am new to node js and socket.io. i am implementing chat module on my website using node js and socket.io. I have successfully implement it on my localhost and it's working fine but after uploading files on the live server it doesn't work.
The error i am getting while running app.js file on server-
var chatpage=io.of('/chatpage').authorization(function (handshakeData, callbac
^
TypeError: Object # has no method 'authorization'
here is my app.js file code-
var express = require('express');
var app = express();
var socket = require('socket.io');
var server = app.listen(3000);
var io = socket.listen(server);
var async = require('async');
var mysql= require('mysql');
var pool = mysql.createPool({
host : 'localhost',
user : 'root',
password : 'admin',
database : 'mychat'
});
var chatserver=require('./chatserver.js');
var chatpage=io.of('/chatpage').authorization(function (handshakeData, callback) {
console.dir(handshakeData);
handshakeData.page = 'chatpage';
callback(null, true);
}).on('connection', function (socket) {
console.dir(socket.handshake.page);
chatserver.getUserFeeds(chatpage,socket,io,pool,async);
});
and connection on client page -
var socket = io.connect('http://localhost:3000');
var chatpage=socket.of('/chatpage')
.on('connect_failed', function (reason) {
console.error('unable to connect chatpage to namespace', reason);
})
.on('error',function(reason){
console.error('unable to connect chatpage to namespace', reason);
})
.on('reconnect_failed',function(){
})
.on('connect', function () {
console.info('sucessfully established a connection of chatpage with the namespace');
chatpage.emit('senddata',{user_id:user_id,room_id:room_id});
});
Please help me out where i am doing wrong.
I'm using Node & Express 4.0 deployed on Heroku, and I'm trying to implement Socket.io with Redis as aa session store. So I have this as my current code:
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io').listen(server);
var RedisStore = io.RedisStore;
if (process.env.REDISTOGO_URL) {
// inside if statement
var rtg = require("url").parse(process.env.REDISTOGO_URL);
var redis = require("redis").createClient(rtg.port, rtg.hostname);
redis.auth(rtg.auth.split(":")[1]);
} else {
var redis = require("redis").createClient();
}
/** Initialize RedisStore for socket.io **/
io.set('store', new RedisStore({
redis : redis
}));
But I get the following error:
14:25:03 web.1 | io.set('store', new RedisStore({
14:25:03 web.1 | ^
14:25:03 web.1 | TypeError: undefined is not a function
I've also seen this way of defining a RedisStore:
var redis = require('socket.io/node_modules/redis');
var RedisStore = require('socket.io/lib/stores/redis');
However, my installed version of socket.io, installed using npm install --save socket.io, doesn't include stores in the lib directory:
EDIT
I saw this on the socket.io page in regards to their 1.0 release:
// 2. Implement the socket.io-redis adapter
var io = require('socket.io')(3000);
var redis = require('socket.io-redis');
io.adapter(redis({ host: 'localhost', port: 6379 }));
But there's no other documentation I could find regarding this new module, and since I'm new to this whole stack, I don't think I could figure it out on my own.
The trend among node.js modules is to remove functionality that isn't truly core to the module.
Which is why socket.io 1.0 no longer supports redis out of the box.
So step one is to track down the functionality you need.
http://socket.io/docs/server-api/
https://github.com/Automattic/socket.io-adapter
https://github.com/Automattic/socket.io-redis
Then you need to install the other module npm install socket.io-redis --save
And finally configure your app.
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io').listen(server);
var redis = require('socket.io-redis');
io.adapter(redis(process.env.REDISTOGO_URL));
The nice part is the socket.io-redis adapter accepts redis urls and defaults to localhost:6379 so you (should) be able to simple pass in the REDISTOGO_URL
I had to parse libraries above to get this example, so I figured I would post a full blown example, but I must admit there are a couple of things off, this uses REDISCLOUD, it is on Heroku, it does work. I'll post this elsewhere and maybe put it in a doc too.
var redis = require('redis');
var ioredis = require('socket.io-redis'); //Adapter
var url = require('url');
var redisURL = url.parse(process.env.REDISCLOUD_URL );
var pub = redis.createClient(redisURL.port, redisURL.hostname, {return_buffers: true});
var sub = redis.createClient(redisURL.port, redisURL.hostname, {return_buffers: true});
pub.auth(redisURL.auth.split(":")[1]);
sub.auth(redisURL.auth.split(":")[1]);
var redisOptions = {
pubClient: pub,
subClient: sub,
host: redisURL.hostname,
port: redisURL.port
};
io.adapter(ioredis(redisOptions));
Following code works for me with Heroku Redis, hope this helps.
var app = express();
var server = require('http').Server(app);
var io = require('socket.io')(server);
var redis = require('redis');
var redisAdapter = require('socket.io-redis');
io.adapter(redisAdapter({
pubClient: redis.createClient(process.env.REDIS_URL, {return_buffers: true}),
subClient: redis.createClient(process.env.REDIS_URL, {return_buffers: true})
}));
For the ones interested,
this is my prototype chat server running on newest socket.io with express, multiple cores and redis as an intermediate.
Broadcasted messages are send to all room users no matter if they are connected to a different node and port instance.
Just run
node server.js
and on other machines
node client.js
or for testing node client.js 7001, 7002, 7003 ......
server.js
var options = {
//workers: 2, // total workers (default: cpu cores count).
first_port: 7000, // 8000, 8001 are worker's ports (default: 8000).
proxy_port: 5000, // default (5000).
session_hash: function (req, res) { return req.connection.remoteAddress; },
no_sockets: false // allow socket.io proxy (default: false).
};
require('sticky-socket-cluster')(options, start);
function start(port) {
// requirements
var express = require('express');
var http = require('http');
var socketio = require('socket.io');
var path = require('path');
var sticky = require('sticky-session');
var app = express();
var server = http.createServer(app);
var io = socketio.listen(server);
var redis = require('socket.io-redis');
io.adapter(redis({ host: 'localhost', port: 6379 }));
server.listen(port, function() {
console.log(' - listening on ' + port+ ' ' + __dirname);
});
// require our chatserver
var ChatServer = require('./chatserver');
// initialize a new chat server.
new ChatServer({io: io, port: port}).init();
}
chatserver.js
RoomUtil = (function(){
roomMessages = {};
return {
getMessages : function(room_id,limit,cb){
//TODO
cb(roomMessages[room_id] || []);
},
postMessage : function(message,room_id,cb){
if (!roomMessages[room_id]) roomMessages[room_id] = [];
roomMessages[room_id].push(message);
cb();
}
}
})();
var Server = function(options) {
var self = this;
self.io = options.io;
// users array
self.users = [];
// initialize function
self.init = function() {
console.log("init");
// Fired upon a connection
self.io.on('connection', function(socket) {
console.log("incoming connection");
// var ru = new RoomUser();
self.handleConnection(socket,options.port);
});
}
// socket handler for an incoming socket
self.handleConnection = function(socket,port) {
// wait for a login message
socket.emit("incoming connection",{});
socket.on("joinroom",function(data,joinroom_callback){
console.log("attempt to join room ",data.room_id," on port ",port);
if (!data.room_id){
console.log("cannon join room -> no room id given");
return socket.disconnect();
}
else{
var room_id = data.room_id;
socket.join(room_id,function(){
console.log(socket.rooms);
RoomUtil.getMessages(data.room_id,50,function(messages){
console.log("client succesfully joined room ",data.room_id);
joinroom_callback(null,{'messages':messages});
});
socket.on("login",function(data,login_callback){
if (!data.username){
login_callback("invalid userdata",null);
}
else{
login_callback(null,1);
socket.on("post_message",function(data,message_callback){
if (!data.message || data.message == ""){
console.log("empty message posted. ignore");
message_callback("invalid_message",null);
}
else{
console.log("received message on port ",port,data.message);
message_callback(null,1);
RoomUtil.postMessage(data.message,room_id,function(){
RoomUtil.getMessages(room_id,50,function(messages){
console.log("emit messages to room id ",room_id);
//socket.to(room_id).emit('update_messages', messages);
//socket.broadcast.to(room_id).emit('update_messages', messages);
//socket.broadcast.to(room_id).emit('update_messages', messages);
//self.io.to(room_id).emit('update_messages', messages);
self.io.in(room_id).emit('update_messages', messages);
});
})
}
});
}
});
});
}
});
}
}
module.exports = Server;
client.js
var servercon = 'http://localhost:'+(process.argv[2] || 5000);
console.log("going to connect to "+servercon)
var socket = require('socket.io-client')(servercon);
var readline = require('readline');
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
socket.on('connect', function(){
console.log("connected, going to login");
socket.emit("joinroom",{"room_id":123123}, function(error,data){
if (error){
console.log("cannot join room ",error);
}
else{
console.log("succesfully joined room -> going to login now");
console.log("received messages count",data.messages.length);
socket.emit("login",{username:"John Mckain"}, function(error, message){
if (error){
console.log("error logging in ",error);
}
else{
console.log("logged in succesfully -> post message now");
var readline = function(){
rl.question("type in a message -> ", function(message) {
socket.emit("post_message",{'message':message}, function(error, message){
if (error){
console.log("error posting message");
readline();
}
else{
console.log("succesfully posted message");
readline();
}
});
});
}
readline();
}
});
socket.on("update_messages",function(data){
console.log("received new messages count ",data.length,data);
});
}
});
});
socket.on('event', function(data){
console.log("event send",data);
});
socket.on('disconnect', function(e){
console.log("disconnected",e);
});
socket.on("welcome",function(data){
console.log("on welcome ",data)
})
socket.on("pong",function(e){
console.log("pong")
})