From: Clive D.W. Feather (clive@demon.net)
Date: Mon Apr 30 2001 - 05:23:53 CDT
Claus Färber said:
>>> Xref is part of the NNTP protocol. Defining its semantics in the
>>> USEFOR context isn't a good idea, I think.
>
>> Uh, no, Xref was originally invented for use by reader software. It has
>> turned out to have considerable utility for server and transport software
>> as well. It's not just an NNTP thing, unfortunately.
>
> Which protocols is the Xref header actually used for? NNTP (or
> NNRP) and the "/var/spool/news protocol", I presume.
> To define Xref, you actually need the concept of a "same server"
> and of "message numbers", which only exist in the context of these
> protocols, not in the context of the message format.
Very true.
For example, one might imagine a system that worked rather like NEWNEWS on
NNTP; the basic commands are:
* Which articles arrived in group(s) G (, G2, G3, ...) between times T1
and T2 ?
* Give me the article(s) with message-ID(s) A (, A2, A3, ...), perhaps
batched in some way for speed.
On such a system the Xref-equivalent data would be:
X-Xref-equiv: server=my.server.org ISO=2001-04-30T08:40:45Z E70=988620045
giving the arrival time in ISO and seconds-past-epoch-of-1970 formats.
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