upgrading rails 2.3.5 apps to 3.0

I would l开发者_如何学Cike to upgrade my 2.3.5 apps to 3.0.

But i want to be careful in doing it. what are the places where i cannot rely on backwards compatibility.

How do i upgrade in one step if possible?

Edit: Thanks anand for the link... I also have another doubt... Is it advisable to upgrade applications that are live?

Is the 3.0 beta stable or should i wait?

Ryan Bates has a wonderful 3 part screen casts dedicated to the same topic on railscasts.com

http://railscasts.com/episodes/225-upgrading-to-rails-3-part-1

Edit: Here's the link to Rails 3.0 stable -> http://github.com/rails/rails/tree/3-0-stable

I would not risk doing major upgrades on my production box, my suggestion is to first upgrade your development box, iron out any issues (if any!!) and then deploy the upgraded application to production.

HTH