I put together a draft description of Airavata's GFac in the wiki [1] that is now open for comment. The draft has two normative sections (Definitions and Steps) and several informational sections. The document does not match the current GFAc implementation in some places (particularly monitoring).
Feedback is welcome. I plan to draft descriptions of other components in the coming weeks. Thanks-- Marlon [1] https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=40511561
