Web Development with AngularJS, NodeJS and ExpressJS

Laboratory of Databases and Web
Applications
Web development using
Express, Node, Angular
João Rocha da Silva (FEUP InfoLab, room I123) Contact: joaorosilva@gmail.com

Contents
1. The MEAN Stack
2. NodeJS
High-performance Javascript-based runtime environment
3. ExpressJS
An MVC web applications framework
4. AngularJS
Google framework for client apps in the browser
5. Live coding session + questions

Javascript across the whole stack
Image from https://codegeekk.
wordpress.com/2015/03/07/explore-
mean-stack-at-2015/

NodeJS
● JavaScript “on the server side”
● Built on Google’s Chrome V8 Javascript engine
○ Compiles JavaScript code to native machine code instead of
interpreting in real time
● Vibrant open-source community
○ Huge ecosystem of free libraries

NodeJS (continued)
● Single thread, event-driven
○ Asynchronous, nonblocking I/O (i.e. not blocking the main thread)
○ Numerous & simultaneous I/O operations become faster
● Very low memory consumption vs PHP, for example
○ Single process
○ Many more simultaneous connections per server instance
○ Node sleeps when there is nothing to be done
● Multicore support also available for clusters
In https://nodejs.org/en/about/
http://blog.soulserv.net/tag/node-js-vs-php/

// Load the http module to create an http server.
var http = require('http');
// Configure our HTTP server to respond with Hello World to all requests.
var server = http.createServer(function (request, response) {
response.writeHead(200, {"Content-Type": "text/plain"});
response.end("Hello Worldn");
});
// Listen on port 8000, IP defaults to 127.0.0.1
server.listen(8000);
// Put a friendly message on the terminal
console.log("Server running at http://127.0.0.1:8000/");
In https://nodejs.org/en/about/

Image from http://javascript.tutorialhorizon.com/2014/09/19/understanding-expressjs-middleware-with-a-visual-example/

id username firstname surname
1 joao João Rocha
Example: Listing all users
Database table

Route (JS)
GET /users/all ->
function(req,res)
{
//1. Fetch from DB
User.findAll(
…
//2. Render view
res.render(
‘users/all’,
{
users : users
}
);
}
[
{
"id" : 1,
"username" : "joao",
"firstname" : "João",
"surname" : "Rocha"
}
]
<html>
<h1>Viewing users</h1>
<% for (var user in
users… )
{ %>
Username : <%=user.
username%>
First Name:
<%=users.firstname%>
<% } %>
</html>
Model Route View
Client requests http://127.0.0.1:3000/users/all
Return Object array

Database Querying API
Model
instancesModel
Object-Relational Mapping (ORM) for NodeJS
● User “Class”
“One for each DB table”
● Instances
“One for each table row”

Sequelize is a promise-based ORM for Node.js and io.
js. It supports the dialects PostgreSQL, MySQL,
MariaDB, SQLite and MSSQL and features solid
transaction support, relations, read replication and
more.
Sequelize API Docs:
http://docs.sequelizejs.
com/en/latest/api/model/#findalloptions-
promisearrayinstance

Lots of libraries on the ecosystem
Package manager for the web
CSS, JS, HTML, Images...
Bower
Package manager for NodeJS
Libraries
Node Package Manager

AngularJS
● HTML is good for presenting information
○ But NOT good for storing it
● jQuery uses the DOM to store information, and you need to
set and get by element ID (usually)
○ Huge side effects as the code grows and different parts of the web
page are modified at the same time by many events
○ Harder and harder to debug and maintain
● No one likes to maintain spaghetti code...

● Angular separates business logic and data from the
presentation
○ Services and Factories for data access and storage
○ Views for presentation
○ Controllers are the “glue” between data and presentation
○ Routes switch between Views (Single Page Application)
AngularJS (cont’d)

Image from https://www.
mutuallyhuman.
com/blog/2014/05/08/angularjs-
services-and-factories-done-
right/

AngularJS + ExpressJS are good friends
● Excellent for supporting Mobile Apps + Web site
○ Implement a single JSON-based API
○ Consume JSON on mobile devices
○ Same JSON can be used to generate HTML on the client
○ No need to test two separate APIs, because the site itself uses the
“mobile” API

Code for this presentation available at
https://github.com/silvae86/lbaw_2016_tutorial
João Rocha da Silva is just finishing an Informatics
Engineering PhD at FEUP. He specializes on research data
management, applying the latest Semantic Web Technologies
to the adequate preservation and discovery of research
data assets.
He is experienced in many programming languages
(Javascript-Node, PHP with MVC frameworks, Ruby on Rails,
J2EE, etc etc) running on the major operating systems
(everyday Mac user). Regardless of language, he is a
quick learner that can adapt to any new technology
quickly and effectively.

Web Development with AngularJS, NodeJS and ExpressJS

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