Re: [sipcore] Fwd: New Version Notification for draft-sparks-sipcore-refer-clarifications-03.txt

[Ivo Sedlacek <[e-mail]>]

I understand the difficulty in formulation.

Would the following be acceptable?


   In general, UAs that support receiving REFER requests need to include

   a GRUU in the Contact header field of all INVITE requests.  This

   ensures that out-of-dialog REFER requests corresponding to any

   resulting INVITE dialogs are routed to the correct user agent.  UAs

   that will >>>not accept any out-of-dialog REFER requests corresponding to dialog(s) created by an INVITE request

   are exempted from including a GRUU in the Contact header field of the INVITE request.<<<

Kind regards

Ivo Sedlacek

From: Adam Roach [mailto:[e-mail]]
Sent: 29. července 2014 17:19
To: Ivo Sedlacek; Robert Sparks; [e-mail]
Subject: Re: [sipcore] Fwd: New Version Notification for draft-sparks-sipcore-refer-clarifications-03.txt

On 7/29/14 09:52, Ivo Sedlacek wrote:

Thus, the text should state:


   In general, UAs that support receiving >>and accepting an out-of-dialog<< REFER request >>corresponding to a dialog established by an INVITE request<< need to include
   a GRUU in the Contact header field of >>the<< INVITE request.  This
   ensures that out-of-dialog REFER requests corresponding to any
   resulting INVITE dialogs are routed to the correct user agent.  UAs
   that will never create a implicit subscription in response to a REFER
   (that is, those that will reject any REFER that might result in an
   implicit subscription) are exempted from this behavior.

I helped with the phrasing here, and one of the goals here was to make the first sentence cover the vast majority of the cases (hence "in general"), with the exceptional cases described later. The problem was that the overall concept was getting lost in a maze of twisty clauses: the clarification had become worse than the source text; it was actually more confusing.

Your proposal returns it to this very confusing state, and is way, way out into the realm of exceptional cases.

So I'll counterpropose:

   In general, UAs that support receiving REFER requests need to include

   a GRUU in the Contact header field of all INVITE requests.  This

   ensures that out-of-dialog REFER requests corresponding to any

   resulting INVITE dialogs are routed to the correct user agent.  UAs

   that will not create a implicit subscription in response to a REFER

   for the resulting dialog(s) -- that is, those that will reject a

   corresponding REFER that might result in an implicit subscription --

   are exempted from this behavior.

/a