User agent based output by Drupal CMS/

I need to develop an online service layer that will provide multi-role interactivity to end users on the beh开发者_高级运维alf user agent/device/application (desktop or web widget) or output type (XML) they use.

So...

• How is drupal as choice?
• Is it possible to develop output templates for each output type required?
• How to switch theme or output mode on the behalf of user agent?

The services module may do some of what you want in terms of providing a service.

In terms of switching the theme based on the user agent, try Browscap in conjunction with Switch Theme.