1. 1/ November 2008 / EDS Internal Web Push Technology Dušan Chromý SOA Integration Consulting Reverse Ajax/Comet Explained

2. 2/ November 2008 / EDS Internal Web Push Technology Agenda Why Comet, first? How to Comet? Relation to Ajax Comet by Example: ODI Showcase

3. 3/ November 2008 / EDS Internal Web Push Technology Why Comet? The web interaction model is characterized by a client requesting information from the web server –Even Ajax, however novel, follows this model A web server cannot choose when to send updated information to a web browser –This makes development of a whole class of applications difficult for the web, including: Stock Price Tickers (and event monitoring applications in general) Chat & Instant Messaging Online Multiplayer Games Online Collaboration How to notify the web browser timely of server events? –Frequent polling used to be the only option…before Comet The Challenge

4. 4/ November 2008 / EDS Internal Web Push Technology How to Comet? 1. HTTP Streaming Never-ending stream of JavaScript tags 2. Long Polling Slowly answered server request via XMLHttpRequest or dynamic script tag “Hang on - I’ll see if I have news for you” 3. HTML5 Server-Sent Events HTTP Streaming standardized, cleaned 4. HTML5 WebSocket Brave new upgrade of the HTTP protocol The Approaches

5. 5/ November 2008 / EDS Internal Web Push Technology Comet is to Ajax as –Java is to.NET –Audi is to Mercedes –Coke is to Pepsi The name “Comet” is a play on “Ajax” Both Ajax and Comet are umbrella terms for groups of techniques addressing different needs –Ajax enables interactive web applications –Comet enables web applications to receive events from the server The Comet concept is known by several other names –Ajax Push, Reverse Ajax, Two-way-web, and others Relation to Ajax

6. 6/ November 2008 / EDS Internal Web Push Technology Comet by Example: ODI Showcase The Showcase lets the user submit a file to ODI through a web page and shows the progress of the running ODI process Server-side Technology –ODI sends JMS progress messages –Java Servlet delivers the messages to the client –Oracle ADF Faces web application with JSP display technology Client-side Technology – Dojo Toolkit to simplify JavaScript development Let’s see it in action!

7. 7/ November 2008 / EDS Internal Web Push Technology Links and References (1) Wikipedia: Comet Wikipedia: Comet (2) http://cometdaily.com http://cometdaily.com (3) XML.com: JSON Dynamic Script Tags XML.com: JSON Dynamic Script Tags (4) Opera Labs: Server-Sent Events Opera Labs: Server-Sent Events (5) My Tech Rantings: HTML5 WebSocket My Tech Rantings: HTML5 WebSocket

8. 8/ November 2008 / EDS Internal Web Push Technology EDS and the EDS logo are registered trademarks of Electronic Data Systems Corporation. EDS is an equal opportunity employer and values the diversity of its people. © 2007 Electronic Data Systems Corporation. All rights reserved. Dušan Chromý SOA Integration Consulting EDS Operations Services GmbH Eisenstraße 56 65428 Rüsselsheim Germany Phone:+49-(0)6142 80 5431 mailto:dusan.chromy@eds.com