I really hope to find some answers here as i tried everything by now.
Background:
Overtime we deploy code to web server, we need to do a cache warm up, i.e. access the site and make sure it loads. First load is always the slowest since IIS require to do some manipulations with a new code and cache it.
Task:
Create a page which will a checkbox and a button. Once button is pressed, array of links sent to server. Server visits each link and provides a feedback on time it took to load each page to the user.
Solution:
I am using node JS & express JS on server side. So far i manage to POST array to the server with links, but since i have limited experience with node JS, i can not figure out server side code to work.
Here is a code i got so far (it is bits and pieces, but it gives an idea of my progress). Any help will be greatly appreciated!!!
var express = require("express");
var app = express();
var bodyParser = require('body-parser');
var parseUrlencoded = bodyParser.urlencoded({ extended: false});
var http = require("http");
function siteToPrime(url){
http.get(url, function (http_res) {
// initialize the container for our data
var data = "";
// this event fires many times, each time collecting another piece of the response
http_res.on("data", function (chunk) {
// append this chunk to our growing `data` var
data += chunk;
});
// this event fires *one* time, after all the `data` events/chunks have been gathered
http_res.on("end", function () {
// you can use res.send instead of console.log to output via express
console.log(data);
});
});
};
//Tells express where to look for static content
app.use(express.static('public'));
app.post('/', parseUrlencoded, function(request, response){
var newBlock = request.body;
console.log(Object.keys(newBlock).length);
var key = Object.keys(newBlock)[0];
console.log(newBlock[key]);
siteToPrime("www.google.com");
response.status(201);
});
app.listen(3000, function(){
console.log("Server listening on port 3000...");
});
Assuming that you have access to the array in the post route:
var express = require("express"),
request = require("request"),
app = express();
var start = new Date();
app.use(express.static('public'));
app.use(bodyParser.urlencoded({extended: false}));
function siteToPrime(req, res, urls) {
urls.forEach(function(url)) {
request(url, function(error, res, body) {
if (!error && res.statusCode == 200) {
console.log(url +' : ' + body);
console.log('Request took: ', new Date() - start, 'ms');
}
});
}
res.redirect('/');
};
app.post('/', function(req, res){
var urls = req.body.urls // Array os urls.
siteToPrime(req, res, urls);
});
app.listen(3000, function(){
console.log("Server listening on port 3000...");
});
Related
I have implemented a user interface to do some wizard of oz testing. I have a user-side page (Page A), and a second page, the wizard page (Page B). They use the same data and page B receives some information from page A to load the correct data. When the user asks questions on page A, the question is sent to page B, and an answer should be sent back to page A. The problem is that Page A is open on device A and page B is open on Device B (both are on the same server).
I am trying to implement the communication between page A and page B using socketIO. I searched for hours and didn't find a complete example of connecting two apps using socketIO. They usually open the same app in multiple windows. That won't help me. My understanding so far is that I should create a server for each app, and then have the two servers communicate with each other. What I have so far doesn't work and no communication is happening. What I have is as follow:
for page A (index.html):
I added a index.js server file:
// Import packages
const express = require("express");
const socketIO = require("socket.io");
const path = require("path");
// Configuration
const PORT = process.env.PORT || 3000;
//const INDEX = path.join(__dirname, 'index.html');
const INDEX = path.join(__dirname, 'index.html');
console.log("INDEX", INDEX);
//const WIZARD = path.join(__dirname, 'wizard.html');
// Start server
const server = express()
//.use((req, res) => res.sendFile(INDEX), (req, res) => res.sendFile(WIZARD))
.use((req, res) => res.sendFile(INDEX))
.listen(PORT, () => console.log("Listening on localhost:" + PORT));
// Initiatlize SocketIO
const io = socketIO(server);
var other_server = require("socket.io-client")('http://localhost:4000');
other_server.on("connect",function(){
other_server.on('message',function(data){
// We received a message from Server 2
// We are going to forward/broadcast that message to the "Lobby" room
io.to('lobby').emit('message',data);
});
});
io.sockets.on("connection",function(socket){
// Display a connected message
console.log("User-Client Connected!");
// Lets force this connection into the lobby room.
socket.join('lobby');
// Some roster/user management logic to track them
// This would be upto you to add :)
// When we receive a message...
socket.on("message",function(data){
// We need to just forward this message to our other guy
// We are literally just forwarding the whole data packet
other_server.emit("message",data);
});
socket.on("disconnect",function(data){
// We need to notify Server 2 that the client has disconnected
other_server.emit("message","UD,"+socket.id);
// Other logic you may or may not want
// Your other disconnect code here
});
});
For the same app, to the index.html I added the following script:
<script type="text/javascript">
// Get WebSocket
var socket = io.connect('http://localhost:3000');
// Client
socket.on('connect', function(){
socket.emit("message","This is my message");
socket.on('message',function(data){
console.log("We got a message: ",data);
});
});
// Join a channel
var room = "test";
socket.emit("join", room);
let msg = "hello helloo helloooo from index.html";
socket.emit("new_message", msg);
socket.on("new_message", function (msg) {
console.log("sending a message through server from index.html", msg);
});
</script>
For the second app, wizard.html I added a server file, index.js:
// Import packages
const express = require("express");
const socketIO = require("socket.io");
const path = require("path");
// Configuration
const PORT = process.env.PORT || 4000;
//const INDEX = path.join(__dirname, 'index.html');
const INDEX = path.join(__dirname, 'wizard.html');
console.log("INDEX", INDEX);
//const WIZARD = path.join(__dirname, 'wizard.html');
// Start server
const server = express()
//.use((req, res) => res.sendFile(INDEX), (req, res) => res.sendFile(WIZARD))
.use((req, res) => res.sendFile(INDEX))
.listen(PORT, () => console.log("Listening on localhost:" + PORT));
// Server 2
const io = socketIO(server);
io.sockets.on("connection",function(socket){
// Display a connected message
console.log("Server-Client Connected!");
// When we receive a message...
socket.on("message",function(data){
// We got a message. I don't know, what we should do with this
});
});
and to the wizard.html, I added the script below:
<script type="text/javascript">
// Get WebSocket
//var socket = io();
var socket = io.connect('http://localhost:4000');
// Join a channel
var room = "test";
socket.emit("join", room);
let msg = "hello helloo helloooo from wizard";
socket.emit("new_message", msg);
socket.on("new_message", function (msg) {
console.log("sending message through server from wizard", msg);
});
/*
*/
</script>
I also added <script src="/socket.io/socket.io.js"></script> to both apps, index.html, and wizard.html.
In wizard.html I get this error:
POST http://localhost:4000/socket.io/?EIO=3&transport=polling&t=OAp7bZr 400 (Bad Request)
and in index.html I get this error:
Access to XMLHttpRequest at 'http://localhost/socket.io/?EIO=3&transport=polling&t=OAp7k5w' from origin 'http://localhost:3000' has been blocked by CORS policy:
If you can help me figure out what I am missing or if you know of any complete working example similar to what I am trying to accomplish, I would very much appreciate it if you let me know.
It would be even more helpful if someone could use the code and scenario I provided here and write a minimum working example in which the two apps, a.html, and b.html, can communicate through socketIO.
I'm working on a SPA website with node.js, jQuery, mongoose and MongoDB for a shopping website.
The ajax requests and responses work perfectly when starting from the index.html file. So for example begining on http://localhost:3000 and someone clicks on a link called 'products' I send an ajax request to the the server and the server sends the necessary product information back asynchronously which lead to http://localhost:3000/products. But the problem is that if someone types http://localhost:3000/products directly in the search bar it will show the json representation of the products.
This is my code:
script.js
function redirect (link) {
$.ajax({
type: 'GET',
url: 'http://localhost:3000/' + link,
contentType: 'application/json',
data: {
link
},
success: function (res) {
let container = $('#contentToSwap');
container.html('');
res.products.forEach(function (products_) {
...
});
}
});
}
app.js
var Product = require('./models/product');
var mongoose = require('mongoose');
var bodyParser = require('body-parser');
var path = require('path');
var express = require('express');
var app = express();
mongoose.connect('mongodb://localhost:27017/shopping');
var PORT = process.env.PORT || 3000;
app.use(express.static(path.join(__dirname, 'public')));
app.use(bodyParser.json());
app.get('*', function(req, res) {
Product.find(function(err, docs) {
let productChunks = [];
let chunksize = 4;
let display = [];
for (var i = 0; i < docs.length; i++) {
if (docs[i].productType == req.query.link) display.push(docs[i]);
}
for (var i = 0; i < display.length; i += chunksize) {
productChunks.push(display.slice(i, i + chunksize));
}
res.send({ products: productChunks });
});
});
app.listen(PORT, function () {
console.log('Listening on port ' + PORT);
});
So I need some sort of frontend routing if the user doesn't start at the index.html file. I know that I could write my own router to route the urls correctly and that I could route all requests back to the index.html like
app.get('*', function(req, res) {
res.sendFile(__dirname + '/public/index.html');
});
But then I cannot load all the necessary product information from the server when someone clicks a link. So I'm a little bit confused on hwo to tackle this issue. Any help is appreciated
This is usually achieved by separating api routes from normal ones by adding specific url prefixes such as /api for all routes that return json data. What you can do is to specify /api/whatever-you-want, make it the target for your ajax call and place it above app.get('*' ....
Since routes and middleware functions are resolved top to bottom, it will be matched by your ajax call only, leaving the /products unaffected.
answer to question -- Is it possible to redirect user from /api/products to /product if the request wasn't generated by ajax?
Yes, it is possible by adding request query parameter to ajax call which will not be present on normal call and then check those on the server side and decided what to do if it (that specific query parameter) is missing or not.
Let's assume some client side JS that generates ajax call.
fetch('/api/products?api=true')
.then((data) => data.json())
.then((json) => console.log(json));
Notice the request url - /api/products?api=true
Now assume a normal call from html file.
products
These two calls differ in that api query parameter (ajax call has it, the other one doesn't).
And for the server side part of the task -- request query parameters object can be accessed via query property on request object (req.query).
app.get('/api/products', (req, res) => {
if (!req.query.api) {
// if get request doesn't contain api param. then
// handle it accordingly, e.g. do redirect
return res.redirect('/products');
}
// request comming from ajax call, send JSON data back
res.json({ randomStuff: 'abcd' });
});
I have this node.js server. The problem is sometimes I notice that it gets stuck. That is the client can make requests, but the server doesn't respond, rather it doesn't end the response, it just gets stuck in the server side. If I look in client side dev tools on the http request, it has a gray circle icon meaning waiting for server response. Even if I wait 10 minutes, nothing happens.
The server side also writes things to console on the requests, which doesn't happen when it gets stuck.
On the node.js console, if I then press ctrl+c when it got stuck, I then suddenly see all the console.log messages just appear on the console, and at the same time, the dev tools, recieves all the responses from the server side, i.e. the gray circle changes to green.
Does anyone know what this problem is?
Thanks
var express = require('express');
var https = require("https");
var fse = require("fs-extra");
var bodyParser = require('body-parser');
// INFO
var root = __dirname + '/public';
setUpServer();
// SET UP SERVER
function setUpServer() {
var app = express();
app.use(express.static(root));
app.use(bodyParser.urlencoded({ extended: false }))
app.get('/', function (req, res) {
var dest = 'index.html';
res.sendFile(dest, { root: root + "/pong" });
});
app.post('/get_brain', function (req, res) {
res.end("1");
console.log('Sent master brain to a client!');
});
app.post('/train_and_get_brain', function (req, res) {
res.end("1");
console.log('Sent master brain to a client!');
});
var privateKey = fse.readFileSync('sslcert/key.pem', 'utf8');
var certificate = fse.readFileSync('sslcert/cert.pem', 'utf8');
var credentials = {key: privateKey, cert: certificate};
var httpsServer = https.createServer(credentials, app);
httpsServer.listen(process.env.PORT || 3000, function () {
var host = httpsServer.address().address;
var port = httpsServer.address().port;
console.log('AI started at https://%s:%s', host, port);
});
}
I have an executable library in C (sudo ./ads1256_test adc.txt) where data are acquired from an ADC, likewise these data are automatically save in a text file (adc.txt).
On the other hand, I have a server in node.js (see code) in which would like to execute this program when a button in the website is pressed. For this, I tried to implement this process using the child process .exec('sudo ./ads1256_test adc.txt') but it did not work. It apparently runs but the values saved in the file are always zero. That is totally different to the obtained result when I execute the same command in terminal. I would appreciate if anybody could help me.
//Importing the core modules
var express = require('express');
var path = require('path');
var sys = require('sys');
var fs = require('fs');
var util = require('util');
var sleep = require('sleep');
var app = express();
var exec = require('child_process').exec;
var spawn = require('child_process').spawn;
app.get('/', function(req,res){
res.sendFile(path.join(__dirname + '/public/index.html'));
});
//Static Directories
app.use(express.static(__dirname + '/public'));
app.post('/test', function (req, res) {
exec('sudo ./ads1256_test adc.txt');
});
//Server Starting
var server = app.listen(8080, function(err){
if(err){
console.log('Error starting http server');
} else{
console.log('Sever running at http://localhost:8080 ');
}
});
first thing first, fix your code to
- asynchronously handle the cp spawn
- show errors
Example with tree, may you adapt it to your binary and check the response, it should help you go forward.
app.post('/test', function (req, res) {
var cp = spawn('tree', []);
cp.stdout.pipe(res);
cp.stderr.pipe(res);
cp.on('close', function () {
res.end();
cp.stdout.unpipe();
cp.stderr.unpipe();
});
});
I am using Express, node.js and socket.io. What I would like to implement is a system in which everytime a user connects to the page (upon 'connection' event), an SQL request is performed so the results are emitted to the user by trigerring the event 'get_recipes'. However, after refreshing the page several times, the event 'get recipes' is not triggered anymore... Can someone tell me what is wrong with my code (do I need to log out from the database ? If so, how ?) ? Thanks a lot !
app.js :
var express = require('express');
var app = express();
var http = require('http');
var server = http.createServer(app);
var io = require('socket.io').listen(server);
var pg = require('pg').native;
var db_URL = "tcp://user1:default#localhost/dbtest";
...
io.sockets.on('connection', function (socket) {
pg.connect(db_URL, function(err, client) {
client.query("SELECT * FROM Recipes", function(err, results) {
socket.emit('get_recipes', results);
});
});
});