A technology for layered software development using files is disclosed. In
one method a runtime environment for a class of a layered software
application is developed. A layer file folder is opened. The layer file
folder is located in a computer file system and is for storing classes
belonging to a layer of the layered software application. A class file is
opened in the layer file folder. The class file comprises a text file
representing the class of the layered software application that is being
developed into a runtime environment. The class file further comprises
data describing a method performed as part of the class. It is then
determined if the method of the class file has been previously loaded
into the runtime environment.