Book Image

Socket.IO Real-time Web Application Development

By : Rohit Rai
Book Image

Socket.IO Real-time Web Application Development

By: Rohit Rai

Overview of this book

<p>The expectations of users for interactivity withweb applications have changed over the past few years. No more does the user want to press the refresh button to check if new messages have arrived in their inbox; people expect to see updates in their applications in real-time. Mass multiplayer online games have given up the requirement of plugins and are built entirely in JavaScript. Socket.io enables you to build these highly interactive applications that work cross-browser.<br /><br />"Socket.io Real-time Web Application Development" is a guide to building, deploying, and scaling highly interactive real-time web applications using socket.io. This book will guide you through the building of a chat system using Node.js and socket.io, helping you get familiar with various features of the framework. Going further it will empower you to deploy and scale your applications in production.<br /><br />Introducing web application development with Node.js, this book walks you through developing of a full-fledged chat system built with socket.io and introducing all the concepts of socket.io and its usage in the process.<br /><br />It introduces you to the different approaches of bidirectional communication between the browser and the web server and will show you how socket.io abstracts all this for you to provide a single unified and uniform API for messaging and eventing to develop cross-browser applications. It explains how to authenticate your users, segregate the communication to channels, build chat rooms, and handle and scale sessions. It explains the mechanics behind socket.io and it also introduces you to what is involved in deploying the application to production and the intricacies involved in scaling it. <br /><br />This book will introduce you to all that is needed in browser-server communication to develop the next generation of interactive applications and games.</p>
Table of Contents (16 chapters)
Socket.IO Real-time Web Application Development
Credits
About the Author
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface
Index

The client


In this section we will get to know the client APIs.

Connecting to a socket

We connect to a socket using the connect method on the io object in the client:

var socket = io.connect(<uri>);

Here, uri is the server URI to connect to. It can be absolute or relative. If it is other than /, or an absolute equivalent of that, it will connect to the namespace.

Listening to events

We can attach event handlers to a socket using the on method:

socket.on(<event>, function(event_data, ack_callback){});

Here, event is the event to listen for, event_data is the data for the event, and ack_callback is the optional callback method to call to acknowledge the receipt of the event.

Emitting an event

We use the emit method to trigger an event. This event will be handled on the server:

socket.on(<event>, <event_data>, ack_callback);

Here, event is the name of the event to trigger, event_data is the event data as a JSON object, and ack_callback is the optional callback function that is invoked on the successful receipt of the message on the server.

Sending a message

The send method is used to send a message to the server:

socket.send(<message>, ack_callback);

Here, message is the message that will be sent to the server and ack_callback is the optional callback function that is invoked on the successful receipt of the message on the server.