Essentials of Javascript - Cultural View

John Resig 123
External links
• John Resig - About Me [10]
• John Resig: JavaScript's Chuck Norris [11]
References
[1] http://ejohn.org
[2] http://ejohn.org/blog/
[3] http://www.infoworld.com/article/07/10/04/Code-library-aims-to-fuel-easier-JavaScript-handling_1.html
[4] http://www.rit.edu/alumni/ihf/inductee.php?inductee=10
[5] http://ejohn.org/blog/tags/extensions/
[6] http://ejohn.org/blog/new-processingjs-and-sizzlejs-sites/
[7] http://www.webpronews.com/topnews/2005/07/11/google-maps-address-hack
[8] http://www.ejohn.org/blog/
[9] http://twitter.com/jeresig/statuses/1090013257
[10] http://ejohn.org/about/
[11] http://benalman.com/news/2009/12/john-resig-javascripts-chuck-norris/
• Presentation on JavaScript & jQuery @ NEU ACM (http://video.google.com/
videoplay?docid=-7485992465859932389)
Reverse Ajax
Reverse Ajax refers to an Ajax design pattern that uses long-lived HTTP connections to enable low-latency
communication between a web server and a browser. Basically it is a way of sending data from client to server and a
[1] [2]
mechanism for pushing server data back to the browser.
This server–client communication takes one of two forms:
• Client polling: the client repeatedly queries (polls) the server and waits for an answer.
• Server pushing: a connection between a server and client is kept open and the server sends data when available.
Reverse Ajax describes the implementation of either of these models, or a combination of both. The design pattern is
also known as Ajax Push, Full Duplex Ajax and Streaming Ajax.
Examples
The following is a simple example. Imagine we have 2 clients and 1 server, and client1 wants to send the message
"hello" to every other client.
With traditional Ajax (polling):
• client1 sends the message "hello"
• server receives the message "hello"
• client2 polls the server
• client2 receives the message "hello"
• client1 polls the server
• client1 receives the message "hello"
With reverse Ajax (pushing):
• client1 sends the message "hello"
• server receives the message "hello"
• server sends the message "hello" to all clients
Less traffic is generated with Reverse Ajax and messages are transferred with less delay (low-latency).