Asynchronous Updates Between Web Clients

[Bryan]

I think it's okay to ask this question in this group, but if not please
point me to the correct one!

How does one go about doing asynchronous updates between two web
clients? Take Google Chat for example... how does Google Chat update a
chatter's chat window with text entered by the other chatter?

 

[Michi]

Hi,

How does one go about doing asynchronous updates between two web
clients? Take Google Chat for example... how does Google Chat update a
chatter's chat window with text entered by the other chatter?

Have a look at "AJAX" i.e. at
http://developer.mozilla.org/en/docs/AJAX:Getting_Started

greets

Michael

 

[Tom Cole]

I think it's okay to ask this question in this group, but if not please
point me to the correct one!

How does one go about doing asynchronous updates between two web
clients? Take Google Chat for example... how does Google Chat update a
chatter's chat window with text entered by the other chatter?

It doesn't work client to client. It works client to server, both
clients communicating with the server as the bridge.

User types message into Client 1. Client 1 sends message to server.
Server stores message. Client 2 polls server for new messages, server
sends message to client 2. Client 2 displays message to User 2. User 2
enters message. Client 2 sends message to server....on and on and on.

 

[evgenyg]

It's either "pull" or "push".

"Pull" is a more standard out-of-the-box way when clients are pulling
server periodically for updates (usually, using Ajax requests on the
background).

"Push" is more advanaced technique where server is sending data to the
clients. It's supposed to be less resource-consuming but it's not
widely supported, some people might say it actually consumes even more
resources as it requires the server to keep open connections to all
clients. Google for "comet Ajax".
http://www.ajaxian.com/archives/comet-a-new-approach-to-ajax-applications,
for example