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From: rees@pisa.citi.umich.edu (Jim Rees)
Newsgroups: news.software.b
Subject: Re: Ideas for Message-ID's
Message-ID: <5084abb1.1bc5b@pisa.citi.umich.edu>
Date: 22 Mar 91 15:39:53 GMT
References: <3427@litchi.bbn.com> <1991Mar22.050749.22115@looking.on.ca>
Sender: usenet@terminator.cc.umich.edu (usenet news)
Reply-To: rees@citi.umich.edu (Jim Rees)
Organization: University of Michigan IFS Project
Lines: 12

There are lots of times when you want a unique identifier.  NFS file
handles, user/group identifiers, IPC port ids, and so on.  Some operating
systems provide a way to get an opaque bag-of-bits that is unique for all
time, for any application that needs it.

The OS that I use has such a feature, so I use it to generate message ids.
They contain a time stamp and a cpu serial number.

I'm not sure why Mach doesn't have unique ids (uids), as many older CMU OSs
had them, as did Eden, which was partly CMU inspired (Guy Almes was from
CMU).  Uids may be just another Multics-era idea that got lost in the quest
for "simplicity" (is Unix still simpler than Multics?)