WebRTC 最好的入门书籍，《WebRTC权威指南》的英文原版，第三版。WebRTcAPIs and RTcWEBProtocols of the hTml5Real-Time WebAlanb. johnstonDaniel c. burnettThird editionDigital Codex LLC0010O Copyright 20 14 Digital Codex LlCP O. Box 9131St Louis. Mo63117USAhttp://digitalcodexllc.comKindle e Book editionAll rights reservedall trademarks are the property of their respective holdersISBN-13:978-0-98597887-7ISBN-10:0985978872DEDICATIONFor Aidan nora and craig fionaACKNOWLEDGMENTSWe would like to thank our technical reviewers Alex Agranovsky, CarolDavids, emil lvov, David Kemp, Henry Sinnreich, Harvey Waxman, and DanYork. We would also like to thank marina burnett and chris comfort for theirproofreading and comments. We would also like to thank our families for theirencouragement and supportAnd finally, we would like to acknowledge our colleagues in W3C and theIETF who are working incredibly hard at creating the WebrtC standardsPREFACEThe changes in the world of WebrTC are amazing, but they sometimes feelsschizophrenic. At times, it is moving forward rapidly, making major strides. Atother times, it seems slow and almost glacial in its progress. Interoperabilitytoday is superb, and making our demo application work between browsersChrome and Firefox)and platforms ( Windows and Mac) with voice, video,and the data channel has been a breeze on the other hand there are someinteroperability clouds on the horizon with potential video interop issues andeven alternative APisTime will tell which personality will dominate going forward. Certainly, thestandards and implementations are maturing and converging, and this makesour code writing and book writing much easier than it was back in the days ofthe first editionThis edition has new content in the form of an enhanced demo applicationwhich now shows the use of the data channel for realtime text sent directlbetween browsers. Also, a full description of the browser media negotiationprocess including actual SDP session descriptions from Firefox and ChromeHints on how to use Wireshark to monitor Webrtc protocols, and examplecaptures are also included. TURn server support for nat and firewalltraversal is also newThis edition also features a step-by-step introduction to WebrtC, withconcepts such as local media, signaling, and the Peer Connection introducedthrough separate runnable demos. as always all our code is available fordownloadathttp:/webrtcbook.com/code3.htmlandisupandrunningathttp://demo.webrtcbook.comforyoutotryeBook Note: Code and lists will look best with the smallest font size of yourleviceWe hope this new edition will be helpful to you in your WebRTCdevelopment and integrationPREFACE TO SECOND EDITIONWebrtC continues to evolve and grow in the handful of months since wepublished the first edition of Webrtc. apis and protocols of the html5RealTime WebThere has been real progress in many areas in the IETF and w3C standardsalthough much work remains. Eventing, stream representation at the protocollevel, and even the syntax for some callbacks are all still very much underdiscussion, while details such as how multiple video tracks within a singleMedia Stream work and what should happen when a Media stream attached toan html element has tracks added or removed are only now beginning to beconsidered. Nevertheless, the core APIs are firming up. On the usage sideconferences, meetups, and startups have sprung up and are growing rapidly insize, with the World seeking to understand WebRTC's impact andopportunitiesOther trends have become clear as well. The disagreement about codecsespecially video codecs is escalating from a fight, to a war, to mutuallyAssured Patent Destruction. The authors sincerely hope that the standards andindustry come to agreement quickly on the mandatory to implement videocodec very soon.While the basic parts of WebrtC are working well in demos andapplications today, many of the concerns and issues with WebrTC revolvearound security and the signaling channel, which have complete new chaptersin this second edition. Additionally, the sample code out there on the Webtoday is often either too complex or insufficiently explained, motivating thecomplete running and completely explained example in this new edition. Thisdemo code, running on both Chrome and Firefox is also on our website atttp//demo.webrtcbook.comWe hope that this new updated edition keeps you excited and informed aboutWebRTC. Happy reading!