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It has been suggested that this article or section be merged into Comet (programming). (Discuss)

It has been suggested that this article or section be merged into Ajax (programming). (Discuss)

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 mechanism for pushing server data back to the browser.^[1][2]

This server–client communication takes one of two forms:

• Client polling, the client repetitively queries (polls) the server and waits for an answer.
• Server pushing, a connection between a server and client is kept open, the server sends data when available.

Reverse Ajax describes the implementation of any of these models, including a combination of both. The design pattern is also known as Ajax Push, Full Duplex Ajax and Streaming Ajax.

Contents 1 Examples 2 See also 3 References 4 External links

[edit] 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

Note that with reverse Ajax less traffic is generated and the message has been transferred with less delay (low-latency).

[edit] See also

• Ajax
• BOSH
• Comet
• Icefaces
• Push technology
• Pull technology

[edit] References

[edit] External links

• The Slow Load Technique/Reverse AJAX - Simulating Server Push in a Standard Web Browser
• Exploring Reverse Ajax
• Reverse Ajax with DWR (an Java Ajax framework)
• Changing the Web Paradigm - Moving from traditional Web applications to Streaming-AJAX
• Ajax Push Engine An open source web server for pushing real-time data to Rich Internet Applications using Comet

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