Subject: [Simple] PUBLISH and REGISTER relationship

From: "Avshalom Houri" <[email-masked]>
Date: Tue, 6 May 2003 08:21:02 +0300

In a system that has both a registrar and a presence server what should be 
the relationships between
REGISTER and PUBLISH?

* Should a REGISTER make the user on-line even though PUBLISH was not sent 
yet?
* Should PUBLISH be considered as a login to the system as REGISTER?

To some extent it seems that PUBLISH and REGISTER have a similar 
functionality but one is for the registrar
while the other is for the presence server.

Avshalom

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From: Ben Campbell <[email-masked]>
Date: 06 May 2003 10:12:51 -0500

I think that is entirely a question of local policy. There is no
protocol requirement for the two operations to be linked in any way, but
a given service provider might choose to do so.

If you _do_ link them, you are making assumptions about a relationship
between the device doing the publishing and the device doing the
registering that may or may not exist.

---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 07 May 2003 14:28:29 -0400

I'm assuming you are questioning the relationship between requests that 
start out somethin like:

	REGISTER sip:example.com
	To: sip:[email-masked]
	...

and

	PUBLISH sip:[email-masked]
	To: sip:[email-masked]
	...

If so, I think there is some probable precedence of the REGISTER over 
the SUBSCRIBE. The REGISTER affects the candidate set of contacts for 
address sip:[email-masked]. It is not routed according to the prior set 
of registered contacts for that address.

OTOH, the PUBLISH, at least in principle, is just an ordinary message, 
and is routed based on the registered contacts, plus local policy of the 
proxy/registrar.

So, the REGISTER *could* have been installing a contact for the presence 
server itself. In that case, prior to the register the PUBLISH might 
have failed, whereas after it might succeed. I don't think the converse 
is a likely scenario. (That before the publish the register would fail, 
but after the register would succeed.)

I do agree that there are similarities between REGISTER and PUBLISH. I 
can imagine a system that supports PUBLISH and not REGISTER, and does 
all routing based on presence, using the contact addresses in presence 
tuples. That would be an unusual sip system today, though it may be less 
so in the future.

I also agree with Ben that there is plenty of opportunity for local 
policy to determine what happens here. I expect there will be plenty of 
systems where the registrar, presence server, and proxy are all bundled 
together and cooperate via local configuration.

	Paul