Subject: [lemonade] partial fetches with IMAP URLs?

From: Philip Guenther <[email-masked]>
Date: Mon, 22 Nov 2004 13:59:07 -0800

IMAP URLs, like HTTP URLs, do not provide a syntax for specifying
a specific byte-range of the indicated object, even though the
underlying protocol does.  Should URLFETCH provide a way to do
partial fetches?  How about BURL or CATENATE?

My gut reaction is that partial fetches wouldn't be useful enough
with CATENATE or BURL to be worth adding them there, but that it
may be useful for URLFETCH to support them for the same reasons
that HTTP supports byte-range retrieval (restarting of interrupted
retrievals, efficient random access to large objects, etc).

Yes, adding a syntax for partial fetches to URLFETCH but not BURL
or CATENATE would make them basically irrelevant to the lemonade
forward-without-download profile.

Philip Guenther

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From: Pete Resnick <[email-masked]>
Date: Mon, 22 Nov 2004 21:45:59 -0600

On 11/22/04 at 1:59 PM -0800, Philip Guenther wrote:

>IMAP URLs, like HTTP URLs, do not provide a syntax for specifying a 
>specific byte-range of the indicated object, even though the 

There was discussion not too long ago that IMAPURL needed to be 
updated anyway. Adding byte-ranges to the URL would get them into 
URLFETCH, BURL, and CATENATE by reference automatically.

(I think I had offered to pick up that token, but I thought Mark or 
someone else wanted it instead. Who's got the token on IMAPURL-bis?)

pr1
-- 
Pete Resnick <http://www.qualcomm.com/~presnick/>
QUALCOMM Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102

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From: Mark Crispin <[email-masked]>
Date: Mon, 22 Nov 2004 19:56:17 -0800 (Pacific Standard Time)

On Mon, 22 Nov 2004, Pete Resnick wrote:
> There was discussion not too long ago that IMAPURL needed to be updated 
> anyway. Adding byte-ranges to the URL would get them into URLFETCH, BURL, and 
> CATENATE by reference automatically.

Actually, not; since the byte-range would be determined by whatever entity 
generated the URL, whereas the need is for the entity that is fetching the 
data.

Not to belittle the idea of adding byte ranges to IMAP URLs, or for 
generator-determined byte ranges.  But that solution won't solve this 
need.

> (I think I had offered to pick up that token, but I thought Mark or someone 
> else wanted it instead. Who's got the token on IMAPURL-bis?)

I don't have it.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.

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From: Philip Guenther <[email-masked]>
Date: Mon, 22 Nov 2004 20:28:30 -0800

>URLFETCH, BURL, and CATENATE by reference automatically.

While this makes sense, I'm a bit concerned by the http precedent:
HTTP-the-protocol support sub-ranges retrieval, why doesn't
http-the-schema?  Is it because HTTP has difficulty with mutable
resources, as seen in the rules around validators and sub-range
requests?  If so, then adding byte-range syntax to the imap schema
should be fine, at least when a UIDVALIDITY is also specified, as IMAP
provides strong immutability guarantees in that case.

Are there any existing schemata that define byte-range (subobject?)
access whose example the imap schema could follow

Philip Guenther

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From: Alexey Melnikov <[email-masked]>
Date: Tue, 23 Nov 2004 14:10:19 +0000

> URLFETCH, BURL, and CATENATE by reference automatically.

Yes, exactly my thoughts.

> someone else wanted it instead. Who's got the token on IMAPURL-bis?)

I've offered to take this one recently.