[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Simple] Re: Presence Data Model: Overriding services (tuples)
Henning Schulzrinne wrote:
To add to this: I think it is generally a bad idea to rely on URI
comparisons outside the protocol context, as this tends to require
fairly detailed knowledge about URI schemes from elements that otherwise
can and should remain ignorant about such things. Why should a composer
be required to know whether two h323 URIs are the same? (Encoding rules
and issues as to which parameters matter and which ones don't make
"blind" comparison error-prone, i.e., two non-equal-looking URIs may
indeed be the same to an entity that actually understands the scheme.)
Using the URI equivalence to decide on override is just the proposed
default composition policy, nothing more.
It is my suspicion that this is a problem in theory and not in practice.
By the time we have systems running composition across URIs for services
they don't even understand, my guess is that you'll have the ability to
express composition policies that can do whatever you really want.
I'm not opposed to having smart composers that are indeed clever enough
to merge two tuples based on recognizing that the URIs are indeed
semantically the same, but don't want every implementation to have to
have such knowledge. (Smart composers might further recognize that
alice at example.com and alice.smith at example.com are aliases of each other
and there's no point in reporting both.)
As above, perhaps the problem here is that folks are interpreting the
model to imply that you have to do composition differently based on
whether two services are "conflicting" - i.e., have the same URI, or
not. You don't have to. This is a suggested default policy to allow what
seems to be a desired feature to take place in an interoperable way
prior to the arrival of specifications that allow a user to control
their composition policy.
-Jonathan R.
--
Jonathan D. Rosenberg, Ph.D. 600 Lanidex Plaza
Chief Technology Officer Parsippany, NJ 07054-2711
dynamicsoft
jdrosen at dynamicsoft.com FAX: (973) 952-5050
http://www.jdrosen.net PHONE: (973) 952-5000
http://www.dynamicsoft.com
_______________________________________________
Simple mailing list
Simple at ietf.org
https://www1.ietf.org/mailman/listinfo/simple