Server Synchornized web slide show?

I am creating a web application, that is going to be used in our college for teachers to conduct E-classes using laptops(teacher + students) on an adhoc network.

Inspiration:
In poor countries where technology can be costly for products such as Projectors etc.
Due to ongoing efforts, in the near future low-cost laptops are going to be available.
We want to create an "EClass Application Suite" that require student nodes to be able to support only a browser at minimum(which is very much possible).
Our teacher node can be a little advanced.

Scenario:
Students should be ale to view a web slide show on their browsers, which is synchronized based on the teacher(servers) instructions.

if the teacher(server) presses "show next slide to students" button, the next slide(web page) should be displayed automatically on all the student(client) browsers.

in short:
The server should be able to redirect the web pages displayed on the client browsers without any request from the clients. how to do this? [not at regular intervals using a timer,but according to the teachers actions]

lets assume i am storing each slide as a html(or jsp) file, i am running a tomcat server in eclipse.

I am new to programming and java/jsp development please give me some very specific ideas on how to tackle this problem(shown in red above).

That's not going to happen.

You can have the individual browsers poll the server now and again to see if it's time to update, but the action must be initiated from the browser.

Well i think it must be possible.

i am new to all this , so please correct me if i am wrong
so, then how does live sports-match scores get displayed on certain web pages? does the client keep polling the server?

sachin modiyil wrote:i am new to all this , so please correct me if i am wrong

You are wrong.

so, then how does live sports-match scores get displayed on certain web pages? does the client keep polling the server?

Most likely. Or they are using an applet, or ActiveX, or flash.

Just considering the requirement , the same can be achieved through screen sharing which might be easy to implement. Also there are few free softwares for the same.

Vikas Kapoor wrote:Just the considering the requirement , the same can be achieved through screen sharing.

hmmm i did some searching and all i could find that did 1-to-many streaming was
http://showmypc.com/hosting/online-broadcasting.html
and a few more

but its not free! so i am back to square one.

Not really; you've already been given one possible solution.

You could also use an applet, or a Java Web Start application, or an open-source whiteboard application.

Hey guyz, it CAN be done!!!

i kind of found the answers i was looking for ,from stackoverflow.com ,its called:

http://en.wikipedia.org/wiki/Comet_%28programming%29
http://tomcat.apache.org/tomcat-6.0-doc/aio.html

also one more way is
AJAX Push using JSF

http://www.icefaces.org/main/ajax-java/ajaxpush.iface

http://www.ape-project.org/

Cheers,

Yes, Comet is another way, but be aware that holding a connection open for long periods is a very expensive way to do this. I'd investigate some of the other techniques before resorting to that.

AJAX Push looks interesting... I guess even browser embedded messengers like GTalk pane in Gmail etc uses this technique.
In that case I think it should be able to update.