Subject: [Simple] Question regarding NOTIFY messages using UDP.

From: "Brian Stucker" <[email-masked]>
Date: Tue, 20 Nov 2001 15:18:40 -0600

Hi all,

I have a new question for the list... 

In the case where a client can only use UDP to communicate with a presence
server, the size of presence messages gets quite large. Would there be a
problem introduced if the presence document were split up across multiple
NOTIFY messages (perhaps a few presence tuples at a time)? It would be one
PA sending all of the pieces of the presence document, just instead of in
one NOTIFY, in many over a short period of time to avoid fragmentation
issues.

The only issue I see is if a client sends a fetch subscribe, it might not
expect multiple NOTIFY messages, but from discussions about merging state
earlier it seemed there wasn't an issue with sending the presence document
in parts, just that it needs to be aggregated before sending (which it still
would be).

Thoughts?

Brian

---

From: [email-masked]
Date: Tue, 20 Nov 2001 15:34:11 -0600

Once your presence documents exceed 64 kbytes, this becomes a
problem. This seems extremely unlikely.

In the short term, I propose that you send complete presence
documents. As they become larger than the path MTU, you might
see a nominal increase in retransmissions, but I doubt it will
become unacceptable. (This is based on implementation
experience, not random guessing).

For the long term (post-sip-presence-RFC), you probably want to
toy around with defining a mechanism for sending state deltas,
as is described in the sip-events draft. I propose that you not
worry about this for now; there are more pressing issues.

/a

-----Original Message-----
From: Brian Stucker [mailto:[email-masked]]
Sent: Tuesday, November 20, 2001 3:19 PM
To: [email-masked]; [email-masked]
Cc: [email-masked]
Subject: Question regarding NOTIFY messages using UDP.

Hi all,
I have a new question for the list...
In the case where a client can only use UDP to communicate with a presence
server, the size of presence messages gets quite large. Would there be a
problem introduced if the presence document were split up across multiple
NOTIFY messages (perhaps a few presence tuples at a time)? It would be one PA
sending all of the pieces of the presence document, just instead of in one
NOTIFY, in many over a short period of time to avoid fragmentation issues.
The only issue I see is if a client sends a fetch subscribe, it might not
expect multiple NOTIFY messages, but from discussions about merging state
earlier it seemed there wasn't an issue with sending the presence document in
parts, just that it needs to be aggregated before sending (which it still would
be).
Thoughts?
Brian

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