In the brain of Peter Lubbers Building Real‐Time  Applications with HTML5 Web  Sockets Club Corfair, Paris, 9 December 2009 1 Qui C’est Ce Mec? Peter Lubbers • Director of documentation and training at Kaazing • Skills Matter and Zenika HTML5 training courses • Co-author Apress Book Pro HTML5 Programming (Spring 2010) 2 © 2009 –Kaazing Corporation 3 © 2009 –Kaazing Corporation Agenda • Introduction • History of the real-time Web • WebSocket and Server-Sent Events • Cross-Document Messaging and XHR Level 2 • Beyond WebSocket • Questions? 4 © 2009 –Kaazing Corporation 5 © 2009 –Kaazing Corporation 6 © 2009 –Kaazing Corporation Today’s Requirements • Today’s Web applications demand reliable, real-time communications with near-zero latency • Examples: • Financial applications • Social networking applications • Online games • Smart power grid 7 © 2009 –Kaazing Corporation HTTP Limitations • Until now, this has been cumbersome to achieve, primarily due to the limitations of HTTP • HTTP is half-duplex (traffic flows in only one direction at a time) • HTTP is a stateless, request-driven protocol 8 © 2009 –Kaazing Corporation HTTP Limitations • Header information is sent with each HTTP request and response, which can be an unnecessary overhead • After a response is sent, the server may choose to close the socket • Rich Internet Applications (with Ajax, Comet, Silverlight, and Flash) are becoming richer, but still limited by HTTP 9 © 2009 –Kaazing Corporation Ajax and Comet • Ajax (Asynchronous JavaScript and XML) is a technique for building highly interactive applications for the Web • Content can change without loading the entire page • Ajax Delivers: • User-perceived low latency • Single page • “Real-time” often achieved through polling and long-polling (Comet) 10 © 2009 –Kaazing Corporation