Subject: Double fetching Message-ID

From: Chris Newman <[email-masked]>
Date: Thu, 11 Feb 1999 14:30:43 -0800 (PST)

Given that Message-ID is in the envelope is there a reason the
imap_overview() function explicitly asks for the Message-ID header in
addition to the envelope on a 4rev1 server?
 
                - Chris

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From: Mark Crispin <[email-masked]>
Date: Thu, 11 Feb 1999 15:02:50 -0800 (PST)

> addition to the envelope on a 4rev1 server?

Yes, there is.  Unfortunately.

The server can return the requested data in any order (or even in a separate
untagged FETCH response.  Consequently, when the HEADER.FIELDS from the
extraheaders are parsed, the ENVELOPE may not be there yet.  However, the
Message-ID is needed for parsing the extraheaders; it is examined to see if
the other extraheaders should be used or ignored.

If certain individuals, notably two with initials of JS and RD, had not had
their crania wedged firmly up their posterior orifices, this ugly and
disgusting kludge would be unnecessary.

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From: Chris Newman <[email-masked]>
Date: Fri, 12 Feb 1999 17:31:44 -0800 (PST)

> the other extraheaders should be used or ignored.

FYI, the Cyrus message store caches certain headers which are commonly
fetched with a "HEADER.FIELDS".  If a "HEADER.FIELDS" request only
requests cached headers, then it is significantly faster.  It would be
foolish to cache the Message-ID header when it's in the pre-generated
ENVELOPE anyway.  And a Message-ID header can't be correctly regenerated
from the ENVELOPE since the LWSP was discarded.  So clients which fetch
the Message-ID header this way will take a significant performance hit
against Cyrus and Cyrus-based servers.
 
> disgusting kludge would be unnecessary.
 
In theory, that behavior is a consequence of a purist untagged data model. 
But splitting attributes from a single fetch request into multiple
responses is taking the purist model too far, IMHO.  I wonder if it would
be possible to reach a compromise position that all fetch attributes on a
given fetch command should be returned in the same fetch response although
arbitrary order within that response is permitted?  If you think it would
be worthwhile, I'd be glad to propose this on the IMAP protocol list. 
 
                - Chris

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From: Mark Crispin <[email-masked]>
Date: Fri, 12 Feb 1999 18:15:04 -0800 (PST)

On Fri, 12 Feb 1999 17:31:44 -0800 (PST), Chris Newman wrote:
> I wonder if it would

It is entirely too late to consider such a change to IMAP.  Furthermore, the
"wrong" order in the same response is just as problematic as multiple
responses.

If Cyrus has a performance problem with arbitrary headers, this sounds like a
problem in Cyrus that needs to be addressed.  I do not believe that it is
reasonable to expect a static list of "certain headers which are commonly
fetched."

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From: Mark Crispin <[email-masked]>
Date: Fri, 12 Feb 1999 18:20:47 -0800 (PST)

It also needs to be noted that the problem with obstreperous individuals has
nothing to do with IMAP per se, but rather with the curious notion that
certain headers mean different things depending upon whether they come from
email or news.  In the absence of a "Path:" header or a Message-ID with
certain characteristics, those headers must be disregarded.

It is a disgusting kludge.

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From: Chris Newman <[email-masked]>
Date: Fri, 12 Feb 1999 18:48:54 -0800 (PST)

> reasonable to expect a static list of "certain headers which are commonly

Cyrus has no performance problems with header fetches (I expect it's
faster than the c-client server).  It has a performance enhancement if a
fetch command is restricted to cached information.  Clients which fetch
uncached headers will not get responses as fast as clients which stick to
cached information. 

		- Chris

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From: shilpa <[email-masked]>
Date: Sat, 13 Feb 1999 22:37:16 +0530

That was good writing!
I mean the literature angle.
I am richer by two words which I never knew existed before!
Although dictionary gave the meaning, its good usage was shown in your letter.
regards,
S..//
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