About logical clocks in atom:modified: --On February 21, 2005 3:30:13 AM +1100 Eric Scheid <[EMAIL PROTECTED]> wrote: > > Semantically, it would work ... for comparing two instances of one entry. It > wouldn't work for establishing if an entry was modified before or after > [some event moment] (eg. close of the stock exchange).
Establishing sequences of events is rather tricky. See Leslie Lamport's "Time, Clocks, and the Ordering of Events in Distributed Systems" for how to do it with logical clocks. The core part of the paper is short, maybe five pages, and definitely worth reading if you care about this stuff. <http://research.microsoft.com/users/lamport/pubs/time-clocks.pdf> Synchronized clocks make this simpler. If Atom depends on comparing timestamps from different servers, then synchronized clocks are a SHOULD. See the text in PaceCaching for an example. Synchronized clocks are already a SHOULD for HTTP. wunder -- Walter Underwood Principal Architect, Verity
