Persistence services are achieved through the use of a PersistenceService class that saves FileContents objects given a URL as a key. The local file system works like a cache for this data that is always thought of as being a copy of data stored on the server. The whole concept is inspired by the cookies mechanism; the primary difference being that the space allowed on the disk is bigger and more flexible.
The URL-keys work hierarchically. That is, common directories are shared by applications sharing portions of their codebase.
For example, two applications having codebases can see each other application's data at locations http://www.asite.org/pub/ and http://www.asite.org/: