Epic: Metadata provider design

[msarahan]

In community discussions, the CLI was suggested as the best place for metadata providers to have their UI. This is because the installer tools that exist are already cross-language. Having a subprocess shell out to a standalone executable is preferable to needing some large runtime to run a script.

What remains to be decided is:

• What functionality should a metadata provider provide?
  • enumerating which variant names it provides
  • output valid values for the variants that it supports
  • output current state of the system in terms of variant names and values
• How should multiple metadata providers interact?
  • How are conflicts detected?
  • Is there a meta-metadata-provider that aggregates and processes output from multiple metadata providers, or is aggregation left to the (installer) tools that are using the providers?