shahzaibalikhan

###Prerequesites

• Install node.js from http://nodejs.org
• Make sure you install git from http://git-scm.com

Install flightplan globally

npm install -g flightplan

Install flightplan in your project folder

shahzaibalikhan

Deploying a node app with Forever is great...until your server restarts unexpectedly. Then your app stops running and you have to re-deploy.

To get around this, we're going to run our node app as an Upstart service. Upstart services are great, because, once started, the system auto-restarts them if they fail, or if the server restarts.

###Step 1: Create a service for your node app

• ssh in as root ssh root@youripaddress
• Create a node-app.conf file in /etc/init
  IMPORTANT: whatever filename you pick is what you will use to start|stop|restart your service i.e. service node-app start

shahzaibalikhan

##Setup your server (this would ideally be done with automated provisioning)

• add a deploy user with password-less ssh see this gist
• install forever npm install -g forever

##Install flightplan

• npm install -g flightplan
• in your project folder npm install flightplan --save-dev
• create a flightplan.js file

shahzaibalikhan

(wherever it says url.com, use your server's domain or IP)

Login to new server as root, then add a deploy user

sudo useradd --create-home -s /bin/bash deploy
sudo adduser deploy sudo
sudo passwd deploy

And Update the new password

shahzaibalikhan

Here's all you have to do to add clustering to your node.js application.

• save this code as cluster.js, and run cluster.js instead of server.js (or /bin/www, or whatever it's called for your project)
• the only line you'll need to change is the last line - it needs to point to the location of your server.js file

var cluster = require('cluster');

if (cluster.isMaster) {
  // Count the machine's CPUs
 var cpuCount = require('os').cpus().length;

shahzaibalikhan

##Example Task: Make 2 parallel (simultaneous) async calls, then one async call when they've resolved##

##The Good Way: Promises##

//with bluebird library
var parallelCalls = [
  getUrl('/api/profile'),
  getUrl('/api/accounts')
];
//spread is like .then(), except it apply()s the array of responses as individual arguments

shahzaibalikhan

##The Good, The Bad, & The Ugly Ways of handling Async Operations With Javascript## #####Callbacks < Promises < Generators#####

---

###An Example: 5 in-sequence Async Operations### (also see parallel-sequence example: https://gist.github.com/willrstern/af3a3308fc5864cf48f8)

---

###The Ugly Way: Callbacks### After each function takes place, handle any errors & do the next thing - It's easy to walk through the code and understand what's going on...but it's ugly as sin

shahzaibalikhan

###Doing Express.js Async With Generators###

Using Co library, run generators as responses by wrapping Co and adding an extra function to handle errors

• Because Co always runs the last argument as a callback...so it would always runs next() by default
• This function only runs next if there's an error

//assign this to the Co module somewhere in application bootstrapping, 
//so you can do var ce = require('co').coExpress in each router file
co.coExpress = (generator) => {
  return (...args) => {

shahzaibalikhan

##what are generators##

• They're pausable functions, pausable iterable functions, to be more precise
• They're defined with the *
• every time you yield a value, the function pauses until .next(modifiedYieldValue) is called

var myGen = function*() {
  var one = yield 1;
  var two = yield 2;
  var three = yield 3;
 console.log(one, two, three);

shahzaibalikhan

upstream project {
  server 22.22.22.2:3000;
  server 22.22.22.3:3000;
  server 22.22.22.5:3000;
}

server {
  listen 80;

  location / {