DataStore has landed. This new API has been written to share data between different applications.
The idea behind it aims to have apps with a set of DataStores, to store data into them and to let other apps access this data when the former app is not running.
DataStores have revisions. Those revisions can be used to synchronize apps and retrieve what is changed while an app was not active. All this process is protected by permissions and security checks. At the moment, it’s meant to be only for Firefox OS.
I do not wish to write too much about it, especially because I don’t want to duplicate the wonderful documentation I and the WebAPI team wrote here: https://wiki.mozilla.org/WebAPI/DataStore
However, if you are a b2g developer and you want to share data with other apps (contacts? bootmarks? weather reports?) - this API is for you.
If you want to see how DataStore API evolves, there is a meta-bug on bugzilla: Bug 916089.