Single web app for all device?

When i create web app for all mobile devices, what are all things need to follow,

1. Is it enough to create single html app for all device?
2. Or, create every single app for a device based on web browser?
3. Is there any Framework has overcome above mentioned issues?

Thanks in advance,

sr开发者_运维知识库i

1. No - different phone browser have different levels of HTML compliance. Compare iPhone/Android browser with, say, a 3 year old Nokia phone (that most corporate users probably have to use)

2. No - there are far too many browser/device/operator combinations for you to write individual web apps. This is known as the mobile web fragmentation problem.

3. Luckily yes - have a look at http://wurfl.sourceforge.net/ or http://deviceatlas.com/. These frameworks let you write one web app (within some limits). These frameworks will recognise the browser (through the User Agent) and output the most appropriate HTML for that device. They can also deal with issues like resizing images for lower end devices.

You need to be aware of the screen size as i think it's bad form to have to scroll left and right as well as up and down.

also, keep the page sizes small as your page may not be the only one open so you want to give users the ability to open more than a single page. also helps in speed and keeping the cost for the user down.

remember to have text size at a readable scale as mobiles are used not only stationary but also when in motion and being bumped around.