9. Dynamic Interaction between Client and Server with Socket.IO | Node.js Web Development

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Table Of Contents

Node.js Web Development - Third Edition

By : David Herron

4.1 (18)

Node.js Web Development

4.1 (18)

By: David Herron

Overview of this book

Node.js is a server-side JavaScript platform using an event driven, non-blocking I/O model allowing users to build fast and scalable data-intensive applications running in real time. Node.js Web Development shows JavaScript is not just for browser-side applications. It can be used for server-side web application development, real-time applications, microservices, and much more. This book gives you an excellent starting point, bringing you straight to the heart of developing web applications with Node.js. You will progress from a rudimentary knowledge of JavaScript and server-side development to being able to create and maintain your own Node.js application. With this book you'll learn how to use the HTTP Server and Client objects, data storage with both SQL and MongoDB databases, real-time applications with Socket.IO, mobile-first theming with Bootstrap, microservice deployment with Docker, authenticating against third-party services using OAuth, and much more.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. About Node.js

1. About Node.js

The capabilities of Node.js

Why should you use Node.js?

Summary

2. Setting up Node.js

2. Setting up Node.js

System requirements

Installing Node.js using package managers

Installing from source on POSIX-like systems

Installing developer tools on Mac OS X

Node.js versions policy and what to use

Running and testing commands

NPM – the Node.js package manager

Node.js and ECMAScript 6 (ES-2015, ES-2016, and so on)

Summary

3. Node.js Modules

3. Node.js Modules

Defining a module

Node.js's algorithm for require (module)

npm – the Node.js package management system

A quick note about CommonJS

Summary

4. HTTP Servers and Clients – A Web Application's First Steps

4. HTTP Servers and Clients – A Web Application's First Steps

Sending and receiving events with EventEmitters

HTTP server applications

ES-2015 multiline and template strings

HTTP Sniffer – listening to the HTTP conversation

Web application frameworks

Getting started with Express

Calculating the Fibonacci sequence with an Express application

Making HTTP Client requests

Calling a REST backend service from an Express application

Summary

5. Your First Express Application

5. Your First Express Application

ES-2015 Promises and Express router functions

Express and the MVC paradigm

Creating the Notes application

Theming your Express application

Scaling up – running multiple Notes instances

Summary

6. Implementing the Mobile-First Paradigm

6. Implementing the Mobile-First Paradigm

Problem – the Notes app isn't mobile friendly

Mobile-first paradigm

Using Twitter Bootstrap on the Notes application

Mobile-first design for the Notes application

Building a customized Bootstrap

Summary

7. Data Storage and Retrieval

7. Data Storage and Retrieval

Data storage and asynchronous code

Logging

Storing notes in the filesystem

Summary

8. Multiuser Authentication the Microservice Way

8. Multiuser Authentication the Microservice Way

Creating a user information microservice

The Notes application stack

Summary

9. Dynamic Interaction between Client and Server with Socket.IO

9. Dynamic Interaction between Client and Server with Socket.IO

Introducing Socket.IO

Initializing Socket.IO with Express

Real time updates on the Notes home page

Inter-user chat and commenting for Notes

Summary

10. Deploying Node.js Applications

10. Deploying Node.js Applications

Notes application architecture

Traditional Linux Node.js service deployment

Node.js microservice deployment with Docker

Summary

11. Unit Testing

11. Unit Testing

Testing asynchronous code

Assert – the simplest testing methodology

Testing a model

Using Docker to manage test database servers

Testing REST backend services

Frontend headless browser testing with CasperJS

Summary

Index

Index

Real time updates on the Notes home page

The first thing we'll do with Socket.IO is change the Notes home page to automatically update the list of notes as notes are edited or deleted. It means a little bit of work in routes/index.js and views/index.ejs, and a lot of work in the Notes model.

Where the Notes model so far has been a passive repository of documents, it now needs to emit events to any interested parties. This is the listener pattern, and, in theory, there will be code that is interested in knowing when notes are created, edited, or destroyed. At the moment, we'll use that knowledge to update the Notes home page, but there are many potential other uses of that knowledge.

The Notes model as an EventEmitter class

The EventEmitter is the class that implements listener support. Let's create a new module, models/notes-events.js, containing the following:

'use strict';

const EventEmitter = require('events');
class NotesEmitter extends EventEmitter {}
module.exports = new NotesEmitter...

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