[aparajithsairam]

What are the restrictions that should be taken care of while developing a web application for mobile phones?

[BetaWar]

You will want to make sure that your site doesn't use large images. Most mobile browsers aren't really built to work with large sites, in fact some of them don't work unless you have the site specifically sized for them (though they are older and probably not widely used these days). You want to make sure that the navigation is easy to access and that you don't use too much scripting, remember that Phones don't have the most RAM and aren't made to be extremely flashy on the web. Most also don't support Adobe Flash content, so you won't be able to use that. In general I believe the largest cell phone screen size is around 480x320, so you will want to make your site easily fit within those bounds at least.

[aparajithsairam]

I have created an interface in my mobile, I only need to fill in the data at appropriate places. So, is it possible to send just the data through GPRS/3G. The mobile user sends a request for info. through the interface and then server sends a reply, just the info., not an entire web page. Is it possible to implement this?

[iPhun]

It's possible on the iPhone. I only develop for iPhone, so I'm not that familiar with other platforms, but Apple has great example code and tutorials just on this subject. With iPhone you certainly can view the entire website using an NSURL - very easy - without resizing the website itself. However, it is not that pretty - even though it resizes. The best direction for iPhone is to look at Apple's "Reachability" example. You could easily strip down the classes and make it work on an application.