Mozilla2 Talk:Multi User Sharing
Disclaimer: I'm mostly interested in this from the point of view of ACAP: https://bugzilla.mozilla.org/show_bug.cgi?id=31766
I think the first thing to do would be to set up a standard API which can store lists, trees, and blobs, as these were the three data types mentioned on the main page. Then, as everyone starts using it, the implementation of the API can be changed to HTTP, LDAP, ACAP, or whatever.
This means that the ACAP people, if they so desired, would be able to eg. store bookmarks on an ACAP server, and delegate all other information back to the local store (ie. while storing, do nothing, as it also gets stored locally, and while non-bookmark information is being retrieved, return "not available", so that it will be gotten from the local store). This would naturally not be the desired state for an end product, but it would mean that people would at least have roaming bookmarks via ACAP.
This does mean that the backends would need a reasonable amount of intelligence (in the example above, be able to recognise a bookmark), but it seems to me to be the simplest and most flexible solution. However, it would mean that entire blobs would be stored.
Please give an example of something that's stored in a blob; all the information you listed would make sense as either trees or lists-of-lists, which can be mapped onto trees, but no doubt I've missed something.