Yes, because you are
using the 3261 use of target and the
4244bis introduced definition of
retarget. I thought it was clear that
we need other words as those
definitions don't match the target-uri
drafts use of the terms. Also
they do not suffice to provide a solution
for the use cases in the
target-uri draft.
The 3261 text you
refer to is exactly about the case where the
home proxy overwrites the
Request-URI with a new target. This target is
teh registered contact
address. And hence this would be what target-uri
calls a hop or a
route. This case and this is where it gets confusing is
not a
"retarget" in the target-uri draft use of the term.
The target-uri draft states:
"To avoid confusion, we
refer to a SIP URI that is an address for a user or resource
as
a
"target" and a SIP URI that is a
hop for reaching that user
as a
"hop".
Apparently that does
not suffice to avoid confusion.
As for
the tagging, speaking about the solution before agreeing
on the
terminology and the problem it should solve is meaningless.
/Hans Erik van Elburg
On Thu, Mar 12, 2009 at 2:33 AM, Mary Barnes
<
mary.barnes at nortel.com>
wrote:
Responses below [MB].
-----Original Message-----
From: Hans Erik van Elburg
[mailto:
ietf.hanserik at gmail.com]
Sent: Wednesday, March 11,
2009 6:42 PM
To:
Barnes, Mary (RICH2:AR00)
Cc: Shida Schubert;
sip at ietf.org
Subject: Re: Terminology (was RE: [Sip] Fwd:
I-D
ACTION:draft-rosenberg-sip-target-uri-delivery-01.txt
I was talking about the
concept.
The
use cases only describe cases where the target-uri
(lets call
that
current
target from now) has been lost when an initial
request for a
dialog or standalone
request arrives at the UAS.
[MB] And I think this is where the terminology
confusion
starts - I
don't think of the "lost" target-uri as being
the
"current" target. In
my mind, the "current" target is reflected by the
last
hi-entry and the
request-uri in the incoming request at the UAS. If
the
entity that sent
the request was the entity that added the last
hi-entry,
then the uri in
that hi-entry is the same as the request-URI in the
SIP
request that
arrives at the UAS. I refer to the "lost" uri as the one
that
was
"retargeted"
- that's the one the UAS wants to pull from
the hi-entries
in the incoming request.
That hi-entry was not the one
that was just
added by the entity that built the
request just received
by the UAS.
That hi-entry is tagged with whatever name we are
going
to tag it with
BEFORE the request is forwarded (using the term
forward
per section 16.6
of RFC 3261). That tag is added once the target set
of
potential
candidates for the new request uri are determined in
section 16.5
of
3261 (with
"target set" being a 3261 term), just before
the request is
forwarded in section 16.6
to one of those targets. A
new hi-entry
(which will be the last hi-entry in the
request received
by the UAS) is
added in section 16.6 of 3261 as the request
is
forwarded. At this
point in time, the lost information is in the
previous
hi-entry when the
outgoing request is sent. [/MB]
What has been lost is the current
target of the request:
[MB] Right - at which point in my mind, it's no longer
the
current
target
;) Maybe we call it "lost". [/MB]
Current
target
The current target of an initial request for a dialog
or
standalone
request is the name or address to which the request is
targeted,
i.e.
either the initial target inserted in the Request-URI
by the UAC
that
originates the request, or when a retarget occurred,
the
target
provided in that retarget operation. Reroute
and
translation
operations never change the current target.
[MB] I don't think this
definition fits what you want -
i.e., if there
is no retargeting, then none of the
hi-entries are
tagged - i.e., you
won't have your concept of current. The way it works
is
that if no
hi-entries are tagged, then you know that there was
no
retargeting, thus
you know the request-uri has not been lost.
[/MB]
This defintion only makes sense when the following
definitions
are used:
Name:
A name is a moniker for an entity which refers to it
in a way
which
reveals nothing about where it is in a network. In
SIP, tel
URI
which doesn't represent the location of the entity is
a
name.
Address:
An address is an identifier for an entity which
describes
it by its
location on the network. In SIP, the SIP URI itself
is a
form of
address because the host part of the URI, the only
mandatory part
of
the URI besides the scheme itself, indicates the
location of a
SIP
server that can be used to handle the request.
Route:
Finally, a route is a
sequence of SIP entities
(including the UA
itself!) which are
traversed in order to
forward a request to an address
or name.
Retarget (other term might be needed, as
this is highly
confusing):
A Request-URI rewrite operation that changes
the
target identity of
the request.
Reroute (other term might be needed):
A Request-URI rewrite
operation that does not change
the current
target of the request, but
determines the route/next
hop taken to
reach the target-identity.
/Hans
Erik