I\'ve just started developing an ExtJS application that I plan to support with a very lightweight JSON PHP service. Other than that, it will be standalone. My question is,
I would start here http://blog.extjs.eu/know-how/writing-a-big-application-in-ext/
This site gives a good introductory overview of how to structure your application.
We are currently using these ideas in two of our ASP.NET MVC / ExtJS applications.