We will need to settle on the requirements.

1. Immediate needs
2. Future needs (That we may want into consideration now or keep for later to achieve the immediate needs
3. Things that are out of scope (for clarity)

The requirements should help defining the API and model. The storage implementation is mainly done though, based on Cassandra: https://docs.jboss.org/author/display/RHQ/Cassandra+Back+End+Design+Notes

So I started a doc here: [Deprecated] High Level Requirements but it's still very naïve, I wanted something to get started with, but let us know how you interpret RHQ Metrics and what you would like to see. Now is the time...