Subject: RE: [Sipping] draft-elwell-sipping-redirection-reason-01

From: "Mary Barnes" <[email-masked]>
Date: Wed, 9 Feb 2005 18:34:19 -0500

One (hopefully) final thing on History-Info that I'll point out is that the
reference in the draft is incorrect - it should be
draft-ietf-sip-history-info-06 (rather than the old SIPPING WG draft).

Mary

-----Original Message-----
From: Barnes, Mary [NGC:B601:EXCH] 
Sent: Wednesday, February 09, 2005 5:32 PM
To: 'Paul Kyzivat'; Elwell, John
Cc: [email-masked]'
Subject: RE: [Sipping] draft-elwell-sipping-redirection-reason-01

Paul,

The Reason that's included as part of the History-Info isn't a separate
field in the header as we're re-using the "Reason" header as an escaped part
of the URI (per RFC 3261 and based on a suggestion from Rohan several years
(literally) ago and discussed on the list and at meetings way long ago).  

It is discussed in section 4.1 of the draft:
"Reason: An optional parameter for History-info, reflected in the 
        History-Info header by including the Reason Header [RFC3326] 
        escaped in the hi-targeted-to-uri. A reason is not included for 
        a hi-targeted-to-uri when it is first added in a History-info 
        header, but rather is added when the retargeting actually 
        occurs.  Note, that this does appear to complicate the security 
        problem, however, retargeting only occurs when the hi-targeted-
        to-uri indicates a domain for which the processing entity is 
        responsible, thus it would be the same processing entity that 
        initially added the hi-targeted-to-URI to the header that would 
        be updating it with the Reason. "

Mary

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Paul Kyzivat
Sent: Wednesday, February 09, 2005 4:32 PM
To: Elwell, John
Cc: [email-masked]'
Subject: Re: [Sipping] draft-elwell-sipping-redirection-reason-01

Elwell, John wrote:
> Paul,
> 
> In-line.
> 
> John
>  
> 
> ....
> 
>>Aside from the meanings of specific codes, I have some other issues:
>>
>>- How does the use of the Reason header with these causes relate
>>   to the request or response in which it appears?
>>
>>   E.g. in a request, does the cause describe why the R-URI is what
>>   it is? Or what?
> 
> [JRE] It would go in hist-info field as a parameter of the URI from which
> targeting has occurred, to augment the reason for that retargeting.

I have to admit that I hadn't looked at the details of the H-I draft in 
a long time. I had forgotten how this reason is being carried there.

I looked at the syntax of the H-I header, didn't find a parameter for 
the cause, and assumed it wasn't in there. After seeing more of this 
discussion, I went back and looked again, and found it by looking at the 
examples. IMO is is a *perversion* to me to carry this info as an 
embedded header in the uri. And if the cause is so important to 
interpretting H-I, then why isn't it discussed in the draft? Examples 
aren't normative.

Maybe I can think of some other headers that could be embedded in the 
H-I URI and then interpretted. Any guidelines here about this?

>>   In a 3xx response, I suppose the cause describes why the call is
>>   being redirected. But what, if anything, does it mean in a 2xx
>>   or 4xx, 5xx, or 6xx?
> 
> [JRE] I don't think it has a meaning in these responses.
> 
> 
>>   If a 3xx is returned with a reason, is that reason to be included
>>   in the request that results from retrying with the contact(s) from
>>   the 3xx?
> 
> [JRE] No it would be included in the history-info field of the retargeted
> (recursed) request based on the contact in the 3xx.

Note my comment above. Where is there any explanation of this behavior?

>>- Exactly how does it relate to the entries in the H-I header?
>>
>>   As the request progresses, and entries are added to H-I,
>>   in principle there could be a reason for each entry.
>>   Interpretation of H-I could conceivably require that info,
>>   but it isn't present in H-I.
> 
> [JRE] The Reason header is present in H-I, so this new set of codepoints
in
> Reason helps to give more useful information in H-I.

Sorry for not realizing this before.

	Paul

[snip]

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_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [email-masked] for questions on current sip
Use [email-masked] for new developments of core SIP