@jef @nblr Both came out of Barbara Liskov's research group. In 1994, although Scheifler had moved on, Barbara and her group were still there, around the corner and down the hall from me.

The 5th floor of 545 Tech Square was an astonishingly productive place: X, the End-to-End Principle, library operating systems, packet audio and video over wide-area networks, "soft state", RSVP, mesh networks, content-addressable file systems, TCP time-sequence plots, ...