Subject: [Fwd: Re: [Simple] Duration of URIs in application/uri-list for Presenc e]

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 19 Dec 2001 12:44:24 -0500

Resend due to some unusual mailing problems....

[email-masked] wrote:

 > Hi All,
 >
 >
 >>I agree with Ben. Although you raise good points Paul.
 >>Can we all agree to:
 >>1. The URL is good for the interval expressed in the EXPIRES
 >>header of the notification which contained the presence
 >>document URL, or the Subscription-Expires (soon to be
 >>Subscription-State), whichever is shorter.
 >>
 >
 > Overall, I like the sound of this proposal. However, a distinct linking
 > like
 > this between the Subscription-Expires and Expires assumes that
 > subscriptions
 > always establish a session. This assumption makes a fetch of event state
 > impossible using the URL mechanism.

Good point.

Why don't we simplify this, then, and state that the URL is valid for
duration in the Expires, if present, otherwise, the duration of the
subscription, and that the next NOTIFY overrides the previous URL. This
way, if you want the URL validity to be less than the subscription
duration, you can do that (Expires < Subscription-Expires), equal to it
(no Expires) or greater than it (Expires > Subscription-Expires). We
also say that in absense of reasons to do so otherwise, the URL SHOULD
be valid for the duration of the subscription, and for fetches, for some
reasonable interval, say 2 min.

That is, we specify semantics that enable any policy, and state a
recommended baseline policy.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue
Chief Scientist                         First Floor
dynamicsoft                             East Hanover, NJ 07936
[email-masked]                 FAX: (973) 952-5050
http://www.jdrosen.net                  PH:  (973) 952-5000
http://www.dynamicsoft.com

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