Practical XMPP

By Lloyd Watkin and David Koelle

About This Book

• Learn about the fundamentals of XMPP and be able to work with the core functionality both server-side and in the browser
• Build a simple 1-to-1 chat (the “Hello World” of XMPP), explore multi-user chat, publish subscribe systems, and work with a decentralized social network
• Author Lloyd Watkins is a member of the XMPP standards committee

Who This Book Is For

If you want to learn about the fundamentals of XMPP, be able to work with the core functionality both server-side and in the browser then this book is for you.No knowledge of XMPP is required, or of TCP/IP networking. It's important that you already know how to build applications of some form, and are looking get a better understanding of how to implement XMPP for one or more of its many uses. You should be interested in the decentralized web, know HTML, and likely know JavaScript and NodeJS. You will probably know JSON, and hopefully XML (this is the native output of XMPP).

• Language: English
• Publisher: Packt Publishing
• Release date: Sep 30, 2016
• ISBN: 9781785282096

Book preview

Table of Contents

Practical XMPP

Credits

About the Authors

About the Reviewers

www.PacktPub.com

eBooks, discount offers, and more

Why subscribe?

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. An Introduction to XMPP and Installing Our First Server

What is XMPP?

Uses of XMPP

XMPP and the Web

Installing Node.js and library dependencies

Installing our XMPP server

Installing the server

Configuring the server

Testing our setup

Creating a test account

Installing an XMPP client

Summary

2. Diving into the Core XMPP Concepts

Introducing the Jabber ID

Message routing

Basic building blocks of XMPP communication

Presence subscriptions

Directed Presence

Client capabilities

Presence overloading

Delivery receipts

XHTML-IM

Chat state notifications

Summary

3. Building a One-on-One Chat Bot - The Hello World of XMPP

C2S connection life cycle

Authenticating with a server

Installing node-xmpp-client

Building our echo bot

Creating a new user

Connecting to the server

Telling the server we're online

Listening for incoming stanzas

Reading the chat stanza with ltx

Responding to incoming messages

Extending our echo bot

Responding to presence subscription requests

Returning results from DuckDuckGo Instant Answers API

Sending chat state notifications

Signing off

Summary

4. Talking XMPP in the Browser Using XMPP-FTW

Interacting with XMPP in the browser

BOSH

The WebSocket protocol

Introducing XMPP-FTW

Installing XMPP-FTW

Playing with XMPP-FTW using the demo application

Talking to our bot from the browser

Building a WebSocket-enabled web server in Node.js

Talking WebSockets from a browser

Installing XMPP-FTW and getting messaging!

Chatting with our XMPP bot

Login

Interacting with the chat bot

Seeing what the chat bot is up to...

Hello (hello, hello...)! Is there anybody out there?

Summary

5. Building a Multi-User Chat Application

The basics of MUC

Joining a room

Your role and identity within a room

Sending and receiving messages

Discovering MUC

Configuring our chat room using data forms

The basics of the data form

Getting our MUC room configuration

Updating the room configuration

Data forms in XMPP-FTW

Creating a chat room

Managing the users

Configuration updates

Leaving a room

Destroying the room

Building with XMPPMUC

Updating Prosody to provide an MUC service

Connecting with our XMPP client

Extending our chat bot to work with an MUC

Writing a browser-based MUC client

Setting things up server-side

Building the client

Connecting anonymously

Listing the available chat rooms

Where the action happens

Displaying the chat room HTML and handling users

Handling incoming messages

Sending a message

Wrapping up

Summary

6. Make Your Static Website Real-Time

Are we there yet?

Interacting with Publish-Subscribe

Discovery

Subscribing

Subscriptions, affiliations, and access models

Creating and configuring nodes

Retrieving items

Publishing items

Making your website real-time

Configuring Prosody

Building a server-side publishing mechanism

Building our real-time client

Setting up the server

Lining up our static website

Let's get real-time...

Subscribing to a node

Retrieving historical results

Getting real-time

Taking things further

Summary

7. Creating an XMPP Component

Connection flow for components

Configuring a component in Prosody

Building our first XMPP component

Creating a component and connecting it to the server

Receiving a stanza and responding to a DISCO#info query

Responding to a chat message

Creating a client that connects to the component

Running your new component and client

Summary

8. Building a Basic XMPP-Based Pong Game

Overview of Basic XMPP Pong

Getting Started

Developing the HTML canvas

Adding the mouse listeners for moving the paddle

Drawing and updating the game

Sending and receiving XMPP messages in Pong

Sending and receiving a Hello message

Sending a paddle update

Receiving a paddle update

Connecting the clients

Advertising the Pong feature of clients (Client DISCO)

Issues with a basic implementation

Summary

9. Enhancing XMPPong with a Server Component and Custom Messages

Designing the information flow for XMPPong

Developing the XMPP component for XMPPong

Setting up a game loop in the component

Starting and updating the game

Maintaining the ball state in the component

Bounces and misses

Expecting paddle updates

Implementing messages from the component to the clients

Handling incoming messages from the clients

Handing DISCO#info requests

Creating an XMPP-FTW extension to read messages within our namespace

Developing the client

Starting the XMPP-FTW server

Checking in to the component and receiving dimensions

Drawing code in the client

Modifying the browser view

Running the server and clients

Summary

10. Real-World Deployment and XMPP Extensions

Server Modules

DNS setup and SRV records

Server-to-server communications

XMPP security

XMPP scalability

User Registration

About the XMPP Standards Foundation

XMPP and the new rise of multi-user chat

XMPP and the Internet of Things

XMPP and Universal Plug-n-Play

XMPP and WebRTC

The Future of XMPP

Summary

Practical XMPP

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Practical XMPP

Copyright © 2016 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author(s), nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: September 2016

Production reference: 1280916

Published by Packt Publishing Ltd.

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ISBN 978-1-78528-798-5

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Credits

About the Authors

Lloyd Watkin has over 10 years of experience in building for the Web. A great believer in open source and open standards, he has contributed to, started, and led many successful open source projects and is also an international conference speaker.

Lloyd was knowingly introduced to XMPP in 2012 and hasn't looked back. Its open standard base and the ability to code clients, servers, components in any language leads to a very diverse and healthy environment. Its relevance only seems to increase as new technologies (not imagined at the time of creation) come into existence.

I would like to thank my family and friends for their support and damaged ear drums. I would also like to thank the XSF and the XMPP community as a whole for being supportive, welcoming, and always striving to improve and extend the XMPP ecosystem.

David Koelle is a principal software engineer at Charles River Analytics Inc. in Cambridge, Massachusetts, USA, where he has employed XMPP on projects to facilitate collaboration and shared situational awareness among distant teams. He is also the author of JFugue, a popular open source music programming API for Java and other JVM languages, and he is a co-organizer for the Boston Android Meetup.

David has delivered several award-winning talks at high-profile conferences including JavaOne and SXSW. In addition to his technical work in software engineering and systems engineering, he finds opportunities to mentor engineers to help them grow in their careers and recognize the value that proactive leadership can bring to engineers and their environments. David is a graduate of Worcester Polytechnic Institute (WPI).

About the Reviewers

Emilien Kenler, after working on small web projects, began focusing on game development in 2008 while he was in high school. Until 2011, he worked for different groups and specialized in system administration.

In 2011, he founded a company that sold Minecraft servers while studying Computer Science Engineering. He created a lightweight IaaS (https://github.com/HostYourCreeper/) based on new technologies such as Node.js and RabbitMQ.

Thereafter, he worked at TaDaweb as a system administrator, building its infrastructure and creating tools to manage deployments and monitoring.

In 2014, he began a new adventure at Wizcorp, Tokyo. The same year, Emilien graduated from the University of Technology of Compiègne, France.

Since 2016, he’s a systems engineer at Vesper, the company behind TableSolution, a leading restaurant reservation and CRM system.

Emilien has written MariaDB Essentials, Packt Publishing. He has also contributed as a reviewer on Learning Nagios 4, MariaDB High Performance, OpenVZ Essentials, Vagrant Virtual Development Environment Cookbook, Getting Started with MariaDB Second Edition and Mastering Redis, all by Packt Publishing.

Ian Wild's career has always focused primarily on communication and learning. Ian, a physicist by profession, spent 15 years in private industry designing communication systems software (Lucent Technologies, Avaya) before specializing in the development and deployment of learning management systems. Ian has a particular interest in the integration of legacy systems. He is currently the lead developer for Skills for Health, the sector skills council for the UK's health sector. He is responsible for one of the country's busiest online learning platforms (the National Skills Academy for Health).

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Preface

XMPP has been around since 1999, and in that time has been rediscovered several times over by generation after generation of programmers. Originally started to unify what was a massively fragmented instant messaging scene, XMPP has continued to show its relevance as new technologies and technology uses emerge.

We'll be making use of the Prosody XMPP server, a fast, resource light system written in LUA, as well as Node.js to write our own projects. The two main libraries we'll be using to interact with XMPP are node-xmpp on the server side and XMPP-FTW, a translation layer between XMPP’s XML messages and JSON, which is massively popular for use in the browser.

Through this book, you'll learn about the core concepts of XMPP, build basic clients that will allow you to interact with the XMPP ecosystem at large, build time-saving bots, and even build an entire custom application using XMPP standards and your own extensions.

The skills you'll learn in this book will allow you to create the next massively popular chat application built on the core standards, through to your own full-fledged Internet of Things (IoT) device that will collect, share, and respond to data from interconnected servers all over the world!

What this book covers

Chapter 1, An Introduction to XMPP and Installing Our First Server. Provides a brief introduction to the history of XMPP and its uses as well as installing and interacting with our first XMPP server.

Chapter 2, Diving into the Core XMPP Concepts, reveals that XMPP covers a vast number of areas but at its core is very simple and extensible. Here we learn about the core concepts so when we come to building our XMPP applications later we understand what's going on.

Chapter 3, Building a One-on-One Chat Bot - The Hello World of XMPP, show us how to build a simple chat bot and interact with it via a standard client.

Chapter 4, Talking XMPP in the Browser Using XMPP-FTW, we introduce XMPP-FTW and shows us how to build some basic functionality.

Chapter 5, Building a Multi-User Chat Application, how to  create a very basic multi user chat client in the browser and begin chatting with our XMPP users.

Chapter 6, Make Your Static Website Real-Time, takes a standard static website and add real time data to it pushed via XMPP, making even the dullest website dynamic and exciting!  

Chapter 7, Creating an XMPP Component, shows how to create our first server-side component, which let you develop business logic without modifying the server itself.

Chapter 8, Building a Basic XMPP-Based Pong Game, how to create a simple application, using standard chat messages to convey game state. We also learn about Client DISCO for discovering capabilities of a client connected to a chat server.

Chapter 9, Enhancing XMPPong with a Server Component and Custom Messages, explains how to develop a full-fledged XMPP demonstration application, including a server-side component, an XMPP-FTW extension that allows us to create our own messages, and clients that talk to the server using those messages.

Chapter 10, Real-World Deployment and XMPP Extensions, presents considerations for deploying your app, including security and scalability. These capabilities are described in XMPP Extension Protocols (XEPs), and in this chapter we also take the opportunity to introduce several additional XEPs that describe emerging XMPP features, including Internet of Things and WebRTC.

What you need for this book

The requirements for all sections of this book after fairly minimal. Any computer built within the past five years that supports a recent version of Linux, Mac, or Windows will be sufficient. An up-to-date browser will be required for websocket support, but even then the project is able to fall back to standard HTTP. You machine should have at least 128 Mb of free RAM and the same amount of hard drive space.

Who this book is for

If you want to learn about the fundamentals of XMPP, be able to work with the core functionality both server-side and in the browser, then this book is for you. No knowledge of XMPP is required, or of TCP/IP networking. It's important that you already know how to build applications of some form, and are looking get a better understanding of how to implement XMPP for one or more of its many uses. You should be interested in the decentralized web, know HTML, and know JavaScript and NodeJS. You will probably know JSON, and hopefully XML (this is the native output of XMPP).

Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: First we'll install libicu and libexpat-dev.

A block of code is set as follows:

modules_enabled = {

        roster;

        saslauth;

        tls;

        dialback;

        disco;

        version;

        uptime;

        time;

        ping,

        register;

        posix;

        bosh;

};

Any command-line input or output is written as follows:

$ curl https://raw.githubusercontent.com/creationix/nvm/v0.32.0/install.sh | bash $ source ~/.bashrc $ nvm install 6 $ node -v

New terms and Important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: The shortcuts in this book are based on the Mac OS X 10.5+ scheme.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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Downloading the example code

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