Subject: [Geopriv] Question on use of normative language for LIS behaviors in L7-LCP requirements

From: "Mary Barnes" <[email-masked]>
Date: Thu, 10 Jan 2008 11:44:30 -0600

Hi all,

I'm making the changes to the HELD document and one of the changes was
to remove the normative language associated with LIS behaviors. In doing
the changes, one of the LIS MUST statements is actually in the appendix
which summarizes the protocol against the L7-LCP requirements.  For
example, L7-10 says that " When a LIS creates a PIDF-LO per RFC 4119
then it MUST put the <geopriv> element into the <device> element of the
presence document (see RFC 4479)."   Based on our discussions, it would
seem that this MUST should be changed to a "should".  Or, am I taking
this suggestion too far, since this is a specific protocol element, can
we be normative on what the LIS MUST do?    The answer to this will help
me understand where folks think we need to draw the line as I had
originally thought that such a MUST was totally appropriate, but thought
that was not the conclusion of the discussion in Vancouver.

Thanks,
Mary. 
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From: Henning Schulzrinne <[email-masked]>
Date: Thu, 10 Jan 2008 13:59:32 -0500

I'll be beating the same old tired drum, but I think SHOULDs, in  
general, are unhelpful unless qualified in some way. How is an  
implementor to know what to do, with no guidance from the spec? In  
this particular case, multiple different choices are likely to cause  
interoperability problems. Is there a case where the choice suggested  
is not appropriate?

Henning

On Jan 10, 2008, at 12:44 PM, Mary Barnes wrote:

> Hi all,
>
> I'm making the changes to the HELD document and one of the changes  
> was to remove the normative language associated with LIS behaviors.  
> In doing the changes, one of the LIS MUST statements is actually in  
> the appendix which summarizes the protocol against the L7-LCP  
> requirements.  For example, L7-10 says that " When a LIS creates a  
> PIDF-LO per RFC 4119 then it MUST put the <geopriv> element into the  
> <device> element of the presence document (see RFC 4479)."   Based  
> on our discussions, it would seem that this MUST should be changed  
> to a "should".  Or, am I taking this suggestion too far, since this  
> is a specific protocol element, can we be normative on what the LIS  
> MUST do?    The answer to this will help me understand where folks  
> think we need to draw the line as I had originally thought that such  
> a MUST was totally appropriate, but thought that was not the  
> conclusion of the discussion in Vancouver.
>
> Thanks,
> Mary.
>

---

From: "Mary Barnes" <[email-masked]>
Date: Thu, 10 Jan 2008 14:09:35 -0600

Henning,

I agree with you on the SHOULDs versus MUSTs in general.  The point
discussed in the meeting (based on my memory, since I wasn't taking
notes when I presented) was that we can't mandate LIS behavior, BUT I
think from a protocol perspective we can state that a LIS that supports
HELD MUST populate the elements appropriately. So, I will only make the
changes to the normative language in cases where we are not discussing
specific protocol elements, but more general things like accuracy of the
location information. The primary concerns on the normative language
were on the new text in section 4. There are quite a few MUSTs for the
LIS in section 6, but I will leave the majority of those "as is" since
they are describing details of the protocol parameters (this is
consistent with the summary in the minutes). 

Thanks,
Mary. 

-----Original Message-----
From: Henning Schulzrinne [mailto:[email-masked]] 
Sent: Thursday, January 10, 2008 1:00 PM
To: Barnes, Mary (RICH2:AR00)
Cc: Hannes Tschofenig; [email-masked]
Subject: Re: Question on use of normative language for LIS behaviors in
L7-LCP requirements

I'll be beating the same old tired drum, but I think SHOULDs, in
general, are unhelpful unless qualified in some way. How is an
implementor to know what to do, with no guidance from the spec? In this
particular case, multiple different choices are likely to cause
interoperability problems. Is there a case where the choice suggested is
not appropriate?

Henning

> to remove the normative language associated with LIS behaviors.
> on our discussions, it would seem that this MUST should be changed to 
> a "should".  Or, am I taking this suggestion too far, since this is a 
> specific protocol element, can we be normative on what the LIS
> think we need to draw the line as I had originally thought that such a

> MUST was totally appropriate, but thought that was not the conclusion 
> of the discussion in Vancouver.
>
> Thanks,
> Mary.
>

---

From: Hannes Tschofenig <[email-masked]>
Date: Fri, 11 Jan 2008 09:27:52 +0200

Hi Mary,

there are various options where to put the <geopriv> element in a 
PIDF-LO. In this specific use case where a LIS adds it I believe the 
MUST is correct.

Ciao
Hannes

---

From: Hannes Tschofenig <[email-masked]>
Date: Fri, 11 Jan 2008 09:33:53 +0200

In this specific case we can dictate the LIS behavior.