The Definitive Guide to HTML5 Websocket Copyright © 2013 by Vanessa Wang, Frank Salim, Peter Moskovits This Work Is Subject to Copyright
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The Definitive Guide to HTML5 WebSocket Vanessa Wang Frank Salim Peter Moskovits Apress The Definitive Guide to HTML5 WebSocket Copyright © 2013 by Vanessa Wang, Frank Salim, Peter Moskovits This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. 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To Julian, my partner in hijinks. —Vanessa Wang For everyone working to buid a better Web and a better world. —Frank Salim To Danka, Lea, and their little and not so little cousins: Gego, Luca, Bence, Aaron, and Noah. —Peter Moskovits Contents at a Glance Foreword ........................................................................................ xiii About the Authors ............................................................................ xv About the Technical Reviewer ....................................................... xvii Acknowledgments .......................................................................... xix N Chapter 1: Introduction to HTML5 WebSocket ................................ 1 N Chapter 2: The WebSocket API ..................................................... 13 N Chapter 3: The WebSocket Protocol ............................................. 33 N Chapter 4: Building Instant Messaging and Chat over WebSocket with XMPP ......................................................... 61 N Chapter 5: Using Messaging over WebSocket with STOMP .......... 85 N Chapter 6: VNC with the Remote Framebuffer Protocol ............. 109 N Chapter 7: WebSocket Security .................................................. 129 N Chapter 8: Deployment Considerations ...................................... 149 N Appendix A: Inspecting WebSocket Traffic ................................. 163 N Appendix B: WebSocket Resources ............................................ 177 Index .............................................................................................. 183 v Contents Foreword ........................................................................................ xiii About the Authors ............................................................................ xv About the Technical Reviewer ....................................................... xvii Acknowledgments .......................................................................... xix N Chapter 1: Introduction to HTML5 WebSocket ................................ 1 What is HTML5? ...................................................................................... 1 HTML5 Connectivity ................................................................................. 2 Overview of Older HTTP Architectures .................................................... 3 HTTP 101 (or rather, HTTP/1.0 and HTTP/1.1) ...........................................................3 The Long Way Around: HTTP Polling, Long Polling, and Streaming ...........................5 Introducing WebSocket ........................................................................... 7 Why Do You Need WebSocket? ................................................................ 7 WebSocket is about Performance ............................................................................8 WebSocket is about Simplicity .................................................................................8 WebSocket is about Standards .................................................................................8 WebSocket is about HTML5 ......................................................................................8 You Need WebSocket! ...............................................................................................9 WebSocket and RFC 6455 ....................................................................... 9 The World of WebSocket .......................................................................... 9 WebSocket Options ................................................................................. 9 The WebSocket Community: It Lives!......................................................................10 Applications of WebSocket .....................................................................................10 vii NCONTENTS Related Technologies ............................................................................ 10 Server-Sent Events .................................................................................................10 SPDY .......................................................................................................................11 Web Real-Time Communication .............................................................................11 Summary ............................................................................................... 12 N Chapter 2: The WebSocket API ..................................................... 13 Overview of the WebSocket API ............................................................ 13 Getting Started with the WebSocket API .............................................. 14 The WebSocket Constructor ...................................................................................14 WebSocket Events ..................................................................................................17 WebSocket Methods ...............................................................................................20 WebSocket Object Attributes ..................................................................................22 WebSocket Object Attribute: bufferedAmount ........................................................23 Putting It All Together ............................................................................ 24 Checking for WebSocket Support .......................................................... 26 Using HTML5 Media with WebSocket ...................................................