Introduction to Node.js

Node.js goal
● Provide easy way to build scalable network
application

Node.js not
● Another Web framework
● For beginner
● Multi-thread

Node.js is
● Server side JavaScript
● Fun !!!

Node.js why
● Non Blocking I/O
● V8 Javascript Engine
● Single Thread with Event Loop
● 40,025 modules
● Windows, Linux, Mac
● 1 Language for Frontend and Backend
● Active community

Node.js for
● Web application
● Websocket server
● Ad server
● Proxy server
● Streaming server
● Fast file upload client
● Any Real-time data apps
● Anything with high I/O

Who use Node.js
http://nodejs.org/industry/

Node.js installation
● Download package from Nodejs.org

Demo :: Hello World
● Create file hello.js
console.log( “Hello World” );
● Run with Node
$node hello.js
>> Hello World

Blocking vs Non-Blocking
● Topic :: Read data from file and show data

Blocking
● Read data from file
● Show data
● Do other tasks
var data = fs.readFileSync( “test.txt” );
console.log( data );
console.log( “Do other tasks” );
http://nodejs.org/api/fs.html

Non-Blocking
● Read data from file
○ When read data completed, show data
● Do other tasks
fs.readFile( “test.txt”, function( err, data ) {
console.log(data);
});
console.log(“Do other tasks”);
Callback

Callback syntax
fs.readFile( “test.txt”, function( err, data ) {
console.log(data);
});
fs.readFile( “test.txt”, callback )
var callback = function( err, data ) {
console.log(data);
}
As same as

Blocking vs Non-Blocking
var callback = function(err, data) {
console.log(data);
}
fs.readFile("test.txt", callback);
fs.readFile("test2.txt", callback);

Recommended modules
● Async
○ https://github.com/caolan/async
● Step
○ https://github.com/creationix/step

Demo :: Basic HTTP
#hello_server_01.js
var http = require('http');
http.createServer( function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
}).listen(1337, '127.0.0.1');
console.log('Server running at http://127.0.0.1:1337');

Demo :: Basic HTTP
$node hello_server_01.js
>Server running at http://127.0.0.1:1337/
Check result from browser http://127.0.0.1:1337

Demo :: Basic HTTP ( Refactor )
var server = http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
});
server.listen(1337, ‘127.0.0.1’);
console.log('Server running at http://127.0.0.1:1337/');

Event Loop ?
….
});
server.listen(1337, ‘127.0.0.1’);

Event Loop ?
….
});
server.listen(1337, ‘127.0.0.1’);
Start Event Loop

Event Loop ?
….
});
server.listen(1337, ‘127.0.0.1’);
Checking
Event
Known Event
Request
Run callback

Event Loop
Checking
Event
Known Event
Request
Event
Close
Connection
Request

Handle Event
var server = http.createServer();
server.on('request', function(req, res){
res.write('Got requestn');
res.end();
});
server.listen(1337, ‘127.0.0.1’);
http://nodejs.org/api/http.html

Demo :: Echo server
var server = http.createServer( function(req, res) {
res.writeHead(200);
req.on('data', function(data) {
res.write(data);
});
req.on('end', function(){
res.end();
});
});

Demo :: Echo server
$curl -d "somkiat" http://localhost:1337

Demo :: Echo server
res.writeHead(200);
req.on('data', function(data) {
res.write(data);
});
req.on('end', function(){
res.end();
});
});
Pipe data from
request to response

Demo :: Echo server + Pipe
res.writeHead(200);
req.pipe(res);
});

Demo :: Upload file
http.createServer(function(req, res) {
var newFile = fs.createWriteStream("uploaded.txt");
req.pipe(newFile);
req.on('end', function() {
res.end('uploaded!');
});
}).listen(1337);
Create file on server
and pipe data to file

Demo :: Upload file
http.createServer(function(req, res) {
var newFile = fs.createWriteStream("uploaded.txt");
req.pipe(newFile);
req.on('end', function() {
res.end('uploaded!');
});
}).listen(1337);
Handle end event on
request

Demo :: Upload file
$curl --upload-file test.txt http://localhost:1337

Demo :: Upload file with progress

Node.js Modules
● https://npmjs.org/
● # of modules = 40,025

Install module
$npm install <module name>

Using module
var http = require(‘http’);
var fs = require(‘fs’);
var express = require(‘express’);

Working with Express
● http://expressjs.com

Working with Express
● Inspire from Sinatra
● Fast
● Flexible
● Simple

Installation express
$npm install express

Demo :: Express
var express = require('express');
var app = express();
app.get('/', function (req, res) {
res.setHeader('Content-Type', 'text/plain');
res.end('Hello, world!');
});
app.listen(1337);
console.log('Listening on port 1337');

Demo :: Manage package
$npm init
$npm info express version

Demo :: package.json
{
"name": "hello-world",
"description": "hello world test app",
"version": "0.0.1",
"private": true,
"dependencies": {
"express": "3.3.x"
}
}

Demo :: Install and run
$npm install
$node http_express.js

Develop REST API
● REST = REpresentational State Transfer
● Not new technology
● Architectural style for client-server
http://en.wikipedia.org/wiki/Representational_state_transfer

Goals of REST
● General interface
● Scalability of component interface
● Reduce latency
● Encapsulate legacy system

SOA is DEAD !!!
http://www.zdnet.com/blog/service-oriented/you-cant-beat-the-dead-soa-horse/3708

HTTP Method
● GET
● POST
● PUT
● DELETE

HTTP Method with CRUD
● POST => Create
● GET => Read
● PUT => Update
● DELETE => Delete

Demo :: REST with JSON
app.get('/', function (req, res) {
res.json(persons);
});
app.post('/', function (req, res) {
res.json(persons);
});

Demo :: REST with JSON
app.put('/', function (req, res) {
res.json(persons);
});
app.delete('/', function (req, res) {
res.json(persons);
});

Demo :: Refactoring
app.get('/', callback);
var callback = function getData(req, res) {
res.json(persons);
}

Working with Persistence
● MySQL
● MongoDB
● Redis

Working with Persistence
REST API Person service
MySQL
Redis
MongoDB

REST API
Method URL Action
GET / Get all person
GET /person/3 Get person by id=3
POST /person Add new person
PUT /person Update person by id
DELETE /person/3 Delete person by id=3

Demo :: REST API
var express = require('express');
var service_person = require('./service_person')
var app = express();
app.get('/', service_person.all);
app.get('/person/:id', service_person.one);
app.post('/person', service_person.insert);
app.put('/person', service_person.update);
app.get('/person/:id', service_person.delete);
app.listen(process.env.PORT || 1337);

Working with MySQL
● RDBMS
● Module => see in npmjs.org ( a lot !!!! )
○ "mysql": "2.0.0-alpha9"

Design Table
● Table name = person
○ Column
■ id
■ name
■ gender

Demo :: Connect to MySQL
var mysql = require('mysql');
var connection = mysql.createConnection(
{
host: <db server>,
user: <username>,
password: <password>,
database: <database name>
}
);

Demo :: Retrieve all data
connection.query('select * from person',
function(err, rows, fields) {
res.contentType('application/json');
res.write(JSON.stringify(rows));
res.end();
}
);

Demo :: Retrieve data with criteria
var sql = 'select * from person where id=?';
connection.query( sql, [id],
res.contentType('application/json');
res.write(JSON.stringify(rows));
res.end();
}
);

Demo :: Create new data
var sql = 'insert into person (name, gender)
values (?, ?)
';
connection.query( sql, [name, gender],
res.json(true);
}
);

Working with MongoDB
● NoSQL
● Document-oriented stoarage
● Keep data in BSON format
● http://www.mongodb.org/
○ "redis": "0.8.4"
http://en.wikipedia.org/wiki/BSON

Start MongoDB server
$mongod.exe --dbpath /some/data/path

Demo :: Connect to MongoDB
var mongo = require('mongodb');
var Server = mongo.Server,
var server = new Server(
'localhost',
27017,
{auto_reconnect: true}
);
db = new Db('persons', server);

Demo :: Connect to MongoDB
db.open(function(err, db) {
if(!err) {
db.collection('persons', {strict:true},
function(err, collection) {
if (err) {
populateDB();
}
});
}

Demo :: Retrieve all data
exports.all = function(req, res){
db.collection('persons', function(err, collection) {
collection.find().toArray(function(err, persons) {
res.send(persons);
});
});
};

Demo :: Retrieve data by id
exports.one = function(req, res){
var personId = req.params.id;
collection.findOne(
{'_id':new BSON.ObjectID(personId)},
function(err, person) {
res.send(person);
});
});
};

Demo :: Create new data
exports.insert = function(req, res){
collection.insert( person, {safe:true},
function(err, result) {
});
});
});

Demo :: Update data
collection.update( {
'_id':new BSON.ObjectID( personId )},
updatePerson,
{safe:true},
});
});
});

Demo :: Delete data by id
collection.remove( {
'_id':new BSON.ObjectID( personId )},
{safe:true},
});
});
});

Design Document
● Collection = persons
● Document structure
○ name
○ gender

Working with Redis
● NoSQL
● Key-value data store
● http://redis.io
○ "redis": "0.8.4"

Install Redis
● Download from http://redis.io/
● For Windows OS
○ https://github.com/dmajkic/redis/downloads

Start Redis server
$redis-server
Let’s fun with Redis
$redis-cli

Design Key-Value
● Key = person_list
○ type = List
○ value = id
● Key = id
○ type = Hash
■ id = <id>
■ name = <name>
■ gender = <gender>

Demo :: Connect to Redis
var redis = require('redis');
var connection = redis.createClient(
{
host: 'localhost',
port: '6379'
}
);

Favorite Modules
● express
● underscore
● request
● async
● mysql
● Find more in npmjs.org

Another project like Node.js
● Vert.x => Polygot programming
● Akka => Scala and Java
● Tornado => Python
● Libevent => C
● EventMachine => Ruby

Resources
● Sourcecode for demo https://github.
com/up1/demo_nodejs
● https://npmjs.org
● http://nodejs.org/
● http://callbackhell.com/
● http://nodeframework.com/

Introduction to Node.js

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