NodeJS Workshop for JS Foo 2015

1. NodeJS
JsFoo!

2. Wifi Details
• SSID:
• HasGeek
• HasGeek-Wifi
• Password:
• geeksrus

3. About me
• Currently Head of Engineering @
Hopscotch
• Xoogler
• Entrepreneur
• Corporate Trainer
• Author
• AngularJS & AngularJS Up &
Running for O’Reilly
• MBA
• Geek!

4. Agenda
• 1 day
• Smaller, multiple sessions
• Code Along
• As fast or slow as needed
• Questions, interrupt any time

5. Agenda - Continued
• Introduction
• JS on the Server
• NodeJS Concepts
• Starting NodeJS
• NPM & Requires

6. Agenda - Continued
• Working with Node
packages
• Async
• Express
• Routes & Config
• NPM & Requires

7. Agenda - Continued
• Middleware
• Working with MongoDB
• Build & Deploy
• Sockets?

8. Requirements
• NodeJS (http://nodejs.org)
• A good IDE (Recommend Webstorm)

9. Getting the Code Base
http://is.gd/nodejsfoo

10. The Basics

11. Agenda
• Introduction
• JS On the Server & Evolution
• NodeJS - How it works
• Basic Concepts and Terminologies
• Hello NodeJS
• NPM & Requires

12. Evolution of Server side
programming
• CGI / Perl
• Java / ASP
• Ruby, PHP, Python
• Move towards reusable, maintainable, fast
• MVC, Components

13. Why JS on the server side
sounds crazy!
Single Threaded Slow, Clunky
No OO! No Type Safety

14. What changed?
libev V8
• Event Engine
• Non blocking
• Core underlying
NodeJS
• JS Engine
• From Chromium
• Super Fast!

15. So what is NodeJS?
Not a programming language, but not simply
a framework either. For servers as well as for
scripts!

16. Core NodeJS Concepts
Event Loop! Non blocking
Single
Threaded
Callbacks
FTW!

17. A Thinking Paradigm Shift
teams = teamsDb.getTeams();
for (var i = 0; i < teams.size(); i++) {
team = teams.get(i);
team.setExtraInfo(
teamsDb.getTeamExtraInfo(team.getId());
}
return teams;

18. How would we speed it up?
• Threading?
• Parallelization?
• Identifying the bottlenecks

19. What if?
• teamDb.getTeams was asynchronous
• teamDb.getTeams(function(teams) {});
• Same for teamDb.getTeamExtraInfo
• teamDb.getTeamExtraInf(function(team) {});

20. A Thinking Paradigm Shift
teamsDb.getTeams(function(teams) {
for (var i = 0; i < teams.size(); i++) {
team = teams.get(i);
teamsDb.getTeamExtraInfo(team.getId(),
function(teamExtra) {
team.setTeamExtraInfo(teamExtra);
});
}
// return teams; ?????
});

21. Now what about NodeJS?
• Callback oriented
• Forced to think about what to do about
callback
• Forces you to think if you need to wait for it
or continue
• Parallel friendly approach —> Default

22. Installing Node
• Directly, from nodejs.org
• Using nvm – Node Version Manager
– Easier to update, and switch versions

23. When to use NodeJS?
• IO intensive
– File, DB
• Web Servers
– More concurrent connections, cheaper!
• Scripts / Tools
– Command line toolbelt

24. When to avoid NodeJS
• CPU intensive
• Long running synchronous tasks
• Mathematical Operations – Floating
Numbers

25. So how do we start?
• Hello world example

26. Code-along starts now

27. Github Repo
http://is.gd/nodejsfoo

28. Code Along – Initial Setup
Checkout:
git clone https://github.com/Fundoo-
Solutions/nodejsfoo.git
cd nodejsfoo

29. Code Along
Step 1 - Simple Hello World
Step 2 - Handling Arguments & Inputs
Step 3 - Using Inbuilt Libraries
Step 4 - Event Handling & Callbacks
Step 5 - Sharing Logic Between Files

30. Step 1 – Simple Hello World
• console.log
• With multiple arguments
• Running it
• node <filename>

31. Step 2 - Handling Arguments and
Inputs
• process.argv
• First two arguments
• node
• filename
• Then
• arguments in order from command line
• array of strings

32. Step 3 – Inbuilt Libraries - fs
• Pull in libraries using
• require()
• require(‘fs’);
• fs.readFileSync(filename, encoding);
• fs.readFile is better!
• Read as pure string!

33. Step 4 – Event handling and
callbacks
• var stream = fs.createReadStream(filename)
• stream.on(‘data’, function(data) {})
• stream.on(‘end’, function() {})
• stream.on(‘error’, function(err) {})

34. Step 5 – Sharing logic
between files
• module.exports = {getStocks:}
• require
• Starting with ./ for relative!
• fs.readFile
• Pass callback for async activity finish!

35. Core Inbuilt Libraries
• fs
• http
• url

36. What about?
• Sockets
• Web Servers
• Configuration
• Database / ORM
• Something else?

37. Introducing NPM
• Node Package Manager
• Equivalent to Maven in Java
• Comprises
• package.json
• Global + local packages

38. How many NPM Packages are out
there?
1,80,000+

39. How does a package.json
look like?
{
"name": ”DEMO App",
"description": "DEMO App for Workshop",
"version": "0.0.1",
"private": true,
"engines": {
"node": "0.10.x",
"npm": "1.3.x"
},
"dependencies": {
"express" : "4.1.1",
"body-parser" : "1.0.2",
…
}
}

40. Installing a package
npm install package-name

41. Installing a global package
npm install –g package-name

42. Installing all packages for a
project
npm install
(assuming a package.json file)

43. Installing a package & saving it to
package.json
npm install --save package-name

44. Start to server

45. Agenda
• Working with Node packages
• NPM & Requires
• Async
• Express
• Routes & Config

46. How does a package.json
look like?
{
"name": ”DEMO App",
"description": "DEMO App for Workshop",
"version": "0.0.1",
"private": true,
"engines": {
"node": "0.10.x",
"npm": "1.3.x"
},
"dependencies": {
"express" : "4.1.1",
"body-parser" : "1.0.2",
…
}
}

47. Package.json syntax &
versioning
• MAJOR.MINOR.PATCH
• “primus”: “1.2.3”
• Specific
• *, x - wildcard support
• “async”: “*”
• ~ - Atleast, in this minor release
• “async”: “~0.8.1”
• >= 0.8.1
• < 0.9.0

48. Package.json syntax &
versioning
• ^ - More relaxed versioning
• “async” : “^0.8.0”
• >= 0.8.0
• < 1.0.0
• Recommendation:
• Use ^, the default

49. Package.json – Dependencies vs
Dev Dependencies
• dependencies
• Always needed
• Production!
• devDependencies
• Same syntax
• Installed unless NODE_ENV=production

50. npm Scripts
• scripts: {}
• test, start, whateveryouwant
• Shell commands
• echo “Deploying…”
• node index.js
• Shortcuts
• Run using npm run

51. async
• For easier dealing with multiple asynchronous
calls
• Point in case, async.parallel
• An array or object with functions
• Each function takes a callback as parameter
• Once all functions are done, proceeds to a
final block

52. Code Along
Step 6 - Init your package.son
Step 7 - Install and use async

53. Step 6 - Initing Package.son
npm init
(And answer all the questions)

54. Step 7 – Use async
• npm install --save async
• Understanding async parallel
• read files in async.parallel
• Do composite work in final callback

55. Express
• A web server framework for NodeJS
• The de-facto web server for most NodeJS apps
• The E in MEAN stack
• Configurable, extensible
• Middleware based plugins

56. Express Components
Routing Handlers
Middlewares
Templating /
Rendering

57. Creating an Express NodeJS
App
If from scratch
(npm install –g express)
express init

58. AngularJS + Express?
Use the angular-fullstack Yeoman generator

59. Express Router
• app.
• get
• post
• put
• delete
• patch
• and more…

60. Express Handlers
• function(req, res) {}
• function(req, res, next) {}
• What’s next?
• function(err, req, res, next) {}

61. Code Along
Step 8 - Start an express app
Step 9 - Create routes and handlers
Step 10 - Handling post requests

62. Step 8 – Start Express App
• npm install --save express
• var express = require(‘express’);
• var app = express();
• app.listen(port, function() {});
• app.get(‘/’, function(req, res) {});

63. Step 9 – Create routes and
handlers
• Move logic into get(‘/)
• res.send(json);
• or res.json(json);
• Parametrized get (‘/:id’)
• Access using req.params.id
• res.status(400) if not found, along with json payload

64. Step 10 – Handling post
routes
• npm install --save body-parser
• app.use(bodyParser.urlencoded({extended: true}));
• app.use(bodyParser.json());
• app.use(express.static(__dirname + '/public'));
• app.post('/register', function(req, res) {});
• req.body
• Watch out for ordering of routes and collisions!

65. Express Configuration
• Environment based
• Global + Environment Specific
• Express settings & Middlewares

66. Express Routers - Advanced
• var router = express.Router(optionsObj)
• caseSensitive
• strict
• /foo and /foo/ same by default
• router.use
• router.get / post / …
• app.use(‘/api/test’, router);

67. Nesting Routers
• var router1 = express.Router(optionsObj)
• var router2 = express.Router(optionsObj)
• router1.get(‘/user’, …)
• router1.post(‘/user’/, …)
• router2.use(‘/api’, router1);
• /api/user routes will be created

68. Multiple Environments
• Common configuration
• Environment specific
• development
• production
• Environment variables + configured constants
• Secure Info -> Environment Variables
• Otherwise, in code, checked in

69. What can you configure?
• DB urls
• application urls
• social media integration
• Anything and everything

70. Middlewares
• Extension, without inheritance
• Layered approach
• Decide if ok to proceed
• or skip to error

71. Code Along
Step 11 - Use nested routers
Step 12 - Understanding middlewares

72. Step 11 – Use nested routers
• Create stocks.routes.js, user.routes.js
• var express = require(‘express’);
• var router = express.Router()
• router.get(‘/’, function(req, res) {});
• module.exports = function(app) {
app.use(‘/path’, router);
}

73. Step 12 – Understanding
Middleware
• function(req, res) {}
• function(req, res, next) {}
• What’s next?
• Common Error Handling
• function(err, req, res, next) {}
• Ordering is important!

74. Configuration in NodeJS
• JSON Config files
• One per environment, one global
• Set environment variable before running app
• Read from process.env
• Load file
• export

75. A note about authentication
• Don’t reinvent the wheel
• Connect -> Middleware for common use cases
• Passport -> Out of the box authentication framework
for NodeJS & Express
• Support for DB backed
• FB, Google, Twitter OAuth
• And more!

76. Agenda
• Working with MongoDB & SQL
• Build & Deploy
• Best Practices
• Further Readings

77. Using Databases
• MongoDB -> JSON object store
• SQL -> not natively JSON
• Use ORMs when possible

78. When does NoSQL make
sense?
• Non relational data
• Transactions not required
• Atomic, single document commits
• Fast!!!
• Document store

79. Mongoose for MongoDB
• ORM layer for MongoDB
• Define
• Schemas
• Validations
• Pre/post save hooks
• Querying capabilities

80. Code Along
Step 13 - Switch to MongoDB

81. Step 13 – Using MongoDB
• Create Schemas & Models (stocks.model.js)
• var StockSchema = new mongoose.Schema({// def //})
• var StockModel = mongoose.model(‘Stock’, StockSchema);
• Export it
• Controller
• Require model, and use find and findOne
• Same callback structure
• index.js
• mongoose.connect('mongodb://jsfoo:jsfoo2015@ds049997.mongolab.com:4999
7/nodejsfoo')

82. SQL in NodeJS
• Sequelize
• BookshelfJS
• Both offer no MSSQL support
• msnodesql
• node-odbc
• mssql-orm

83. Debugging NodeJS
• WebStorm
• Debug mode
• Create run configurations
• Start debugging
• Add breakpoints

84. Debugging NodeJS
• http://nodejs.org/api/debugger.htm
• Manually
– Add debugger statement to code
– Run using node debug index.js
– c, n, s, o
• continue, next, step in, out
– repl
• evaluate commands on the fly

85. Build & Deploy
• Grunt / Gulp
• Run the tests before deploying
• No node_modules
• Ship entire folder
• Run npm install at installation location
• Point at main entry point
• Environment driven!

86. Structuring your Express Codebase
• Folders
– api
• route level
• controller, spec, model, routes
– auth
• routes
• strategies
• common
– config
• passport
• express
• environment based
– views
– components

87. Keeping the server running
• NodeJS crashes and stops
• Use forever
• Or an external process to keep restarting it

88. Best Practices
• Structure, modules
• Parallelize when possible
• Think about it at every step
• Use libraries like async, underscore
• Search for existing npm packages
• Use Middlewares
• over calling functions in controllers and handlers
• ^ or ~ versions in package.json
• Otherwise keep it up to date on a monthly basis

89. Best Practices
• Follow the callback pattern
• Don’t break the err, data structure in your code
• Watch out for async behavior within loops
• Closure, but extract functions instead of inline
• Use javascriptlint
• or something similar
• Use forever, nodemon, or something similar
• To ensure your app doesn’t crash and burn
• Can use it locally as well Restart on file change

90. Other Useful Libraries
• async
• underscore
• RabbitMQ – for Queues and RPC Servers
• SocketIO / SockJS

91. Code Along
Socket based NodeJS App

92. AngularJS + NodeJS Chat App
• Setup Socket Listeners and Posters on NodeJS
• Using SocketIO
• Client side already setup
• io.on(‘connection’, function(socket) {});
• socket.on(‘event’, function(data) {});
• io.emit(‘event’, data)
• broadcast to all!

93. Further Reading
• Clusters
• RabbitMQ
• SocketIO
• vasync
• More observable, async
• restify
• Pure RESTful services, not web apps

94. Cluster Example
var cluster = require('cluster');
var http = require('http');
var numCPUs = require('os').cpus().length;
if (cluster.isMaster) {
// Fork workers.
for (var i = 0; i < numCPUs; i++) {
cluster.fork();
}
cluster.on('exit', function(worker, code, signal) {
console.log('worker ' + worker.process.pid + ' died');
});
}

95. Cluster Example - continued
else {
// Workers can share any TCP connection
// In this case its a HTTP server
http.createServer(function(req, res) {
res.writeHead(200);
res.end("hello worldn");
}).listen(8000);
}

96. How it works
• Child processes spawned using fork
• Communicate with parent using IPC
• Pass server handles back and forth
• Server.listen in child
• Serializes arguments
• Passes to master process
• Handle to server created or passed to child
• OS responsible for load balancing across processes
sharing same resource

97. In summary

98. Thank you
• Contact
• shyam@hopscotch.in
• @omniscient1
• Come join me at Hopscotch if you want to work
on exciting stuff with a great company!
• WE ARE HIRING!

99. Hopscotch in Brief
• Customer focused, Content oriented, discovery oriented shopping experience for moms!
• Not an Amazon/Flipkart model
• Vertical focused
• Great leadership team
• Harvard, INSEAD, Amazon, Google…
• Amazing investors
• Eduardo (FB Co-founder), Velos Partners, and more!
• Customer focused, smart and rapid growth
• 20-30% month on month!
• Scrappy, hacker oriented culture
• Come be a part of something awesome!