SWT Tech Sharing: Node.js + Redis

Node.js@khasathan
SWT Tech share
23/12/2013
17/6/2015

Outline
●Introduction to Node.js
●Node.js Anatomy 101
●Node Package Manager (NPM)
●Node.js Control Flow
●Developments
●Deployments
●Let's play with workshop
Example codes: https://github.com/khasathan/learning-node

JavaScript can run on server side?

What is Node.js?
●“Node.js is a platform built on Chrome's
JavaScript runtime for easily building fast,
scalable network applications.”
- Nodejs.org

What is Node.js? (2)
Server side JavaScript

So what's IO.js?
●Node.js fork
●Bring ES6 to Node community
●NPM compatible

Why use Node.js?
●Non-Blocking I/O
●V8 JavaScript engine (like Google Chrome run-
time)
●Many modules (> 40,000)
●NPM package manager
●Use same language as Back-end/Front-end
●High concurrent connections

Node.js use for ...
●Modern Web application
●Real-time application
●Event-based application

Simple server
http = require('http');
http.createServer(function(req, res) {
res.writeHead(200, {
'Content-Type': 'text/html; charset=utf-8'
});
res.write('Simple Node.js Server');
res.end();
}).listen(3000, '127.0.0.1');

Express
●Web framework for Node.js
●MVC
●Template
●Pretty URL
$npm install express

RESTful web service
●$npm install restify

Socket.io
●Real-time application
●WebSockets
$npm install socket.io

Socket.io (2)
● Socket.io transport
● Websocket
● Xhr-polling
● Jsonp-polling
● Flashsocket
● htmlfile

Real-Time Application
http://thstream-khasathan.rhcloud.com

Real-Time Application
Entzonet Notification

Event-Based Application
MyCat Back-end
Workers pool - Read un-reviewed documents
- Create files queue
- Watching status files
- Distribute tasks to workers
idle
busy
Files queue
idle

Shouldn't be used for...
●RDBMS, transaction
●Heavy computation/Huge data processing

Blocking vs Non-Blocking
●Blocking
Timeline
1
2
3

Blocking vs Non-Blocking
●Non-Blocking
Timeline
1
2
3

Async Programming
● Do next task without waiting for current task
end
fs = require('fs')
fs.readFile('bigfile.txt', function(err, data) {
console.log(data)
})
console.log('Read big file')

Async Programming (2)
$node read-big-file.js
> Read big file
> . . . data from big file . . .

SWT Tech Sharing: Node.js + Redis

Event Loop
console.log('print 1');
compute(data, function(item) {
processItem(item);
});
doLargeCompute();
console.log('print 2');
Call stack
Run-time
Event loop
Message queue
DoLarge
Compute
Event loop

NPM
●Package manager for JavaScript
●Dependencies management

First step with NPM
●$npm init
name: (learning-node)
version: (1.0.0)
description: Example code for Node.js tutorial
entry point: (index.js)
test command:
git repository: https://github.com/khasathan/learning-
node
keywords:
author: khasathan
license: (ISC)
●$npm init
Now, we got package.json file

npm install/uninstall
# install locally
$npm install <package_name>
# install globally
$npm install -g <package_name>
# uninstall locally
$npm uninstall <package_name>
# uninstall globally
$npm uninstall -g <package_name>

npm install/uninstall (2)
● “-g” option you may be use “sudo”
● Globally installation you can use its like ls,
cd, cp, mv etc.
●
Locally installation modules are located in
node_modules/

--save options
$npm install - -save redis

--save-dev options
$npm install - -save-dev mocha

npm search
$npm search <keyword>

Node.js Control Flow
●Callback
●Promise
●Event

Callback vs Promise vs Event
●Callback is “Function”
●Promise is “Object”
●Event is “Event”

Callback
fs = require('fs');
fs.readFile('bigfile.txt', function(err, data) {
console.log(data);
});
console.log('print this');

Callback (2)
fs = require('fs');
var readfile = function (err, data) {
console.log(data);
}
fs.readFile('bigfile.txt', readfile);

Callback (3)
fs = require('fs');
var readfile = funtion (err, data) {
if(err) throw err;
console.log(data);
}
●How does callback work?

Callback (4)
fs = require('fs');
var readfile = funtion (err, data) {
Cb1(function (data1) {
... do something ...
});
});
});
});
};
console.log('print this first');
●Callback pyramid hell

Promise
●Delay? Future?
●Object that holds value

Promise (2)
Fulfilled
The action relating to the promise succeeded.
Rejected
The action relating to the promise failed.
Pending
Hasn't fulfilled or rejected yet.
Settled
Has Fulfilled or rejected.

Promise
See weather-reporter-promise.js

Event
●
Do function when event fired

Event (2)
var mytask = doMyTask();
mytask.on('success', function() {
// do this if success
});
mytask.on('progress', function() {
// do this if in progress
});
mytask.on('error', function() {
// my task if error
});

When we use callback?
When we use promise?
When we use event?

Control Flow Libraries
●Async
●Step
●Q
●EventEmitter built-in←

Developments
●Make your own function with callback
●Custom module
●Code quality
●Unit testing
●Logging
●Node Version Manager (NVM)

Make Function with Callback
See function-with-callback.js

Custom module
See folder custom_module/

Code Quality
$npm install -g jslint
$jslint file.js

Unit testing
●Make small unit works
●Unit testing frameworks
●Nodeunit
●Mocha
●Chai
●TDD/BDD

Node Version Manager (NVM)
●Use several version of Node, IOjs on one
machine
●Website https://github.com/creationix/nvm

Deployments
●Reverse Proxy – use app on port 80
●Forever – running app forever

Reverse Proxy
●Nginx - Supported (>= V1.3)
●HAProxy - Supported
●Apache2 (>=V2.4 with websocket tunnel
module)
●For Apache < 2.4 you may be use transport
such as xhr-polling, jsonp-polling

Forever
●Process monitoring for Node.js
●Keep application always running
$sudo npm -g forever
$forever list
$forever [start|stop] app.js
$forever --help

Redis
●Redis Stands for “REmote Dictionary Server”
●Key-value NoSQL database
●PUBLISH/SUBSCRIBE provided

Publish/Subscribe
●Sometime we know as “Pub/Sub”
●Message-oriented middleware system
Channelsubscriber subscriber
subscriber
publisher
subscribersubscriber

The Funny Scoreboard
https://github.com/khasathan/learning-node

SWT Tech Sharing: Node.js + Redis

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