UserPrefs vs AppData

From OpenSocial

First proposed for OpenSocial v0.9, there is a good discussion here

The proposal is to enhance AppData so that UserPrefs are no longer necessary. Changes include:

1. Private AppData. Data that is only visible to the user it belongs to.
2. AppData preloading. Declare which appdata you want and have it directly loaded and usable via template substitution, perhaps substituted server-side.
3. Appdata namespaces. No namespace implies 0.9 compatible appdata. The namespace gadgets/userprefs could encapsulate the userpref values, and gadgets/ui could cover skins and other such data.

Some related use cases

* Global (all gadgets for all users .... think of a web resource like a news feed)
* Per user (all gadgets ... think of accessibility settings)
* Per gadget (unique to the gadget, but shared by all instances and all users)
* Per gadget, per user (shared by all instances of the gadget)
* Per gadget instance (shared by all users)
* Per gadget instance, per user (still can be shared if gadget instance can be placed on multiple "pages" ...)
* Per gadget instance placement, all users
* Per gadget instance placement, per user