Francesco Banconi and I have produced a possible specification for the new charm store API, combining features from the existing charm store API and the charmworld API. Please take a look and see if it correlates reasonably with your own needs. https://docs.google.com/a/canonical.com/document/d/1ILHRpOe-qDlmjxHBbLUea7InDpehx5_roJ1ynZmcZDc