Subject: [Sipping] conferencing framework and policy

From: "Drage, Keith (Keith)" <[email-masked]>
Date: Thu, 30 Dec 2004 16:38:46 -0000

I had a look through the latest version of the conferencing framework document in http://www.ietf.org/internet-drafts/draft-ietf-sipping-conferencing-framework-03.txt and had the following comments on it in relation to the description of policy:

1)	Given the existence of the XCON framework document, I don't think there is any need any more to distinguish between different types of policy. In many instances this is simple, the document talks in the same line about "conference policy and media policy"; as media policy is part of conference policy, in these instances we obviously only need to talk about conference policy. In other cases it is more complex, but I have come to the conclusion that either the sentence or passage making the distinction is no longer relevant, or that the more general reference to comference policy is sufficient and better because we are interested in talking about the SIP reaction, rather than what specifically caused it. Sometimes the references are no longer accurate in current thinking, e.g. references to media policy control protocol. Any text proposed for deletion however shopuld probably be carried into the XCON framework document.

2)	In a couple of places we refer to the conference notification service. Obviously this SIPPING framework document does need to talk about the event package currently under development by the SIPPING group in http://www.ietf.org/internet-drafts/draft-ietf-sipping-conference-package-08.txt. However decisions in the XCON/SIPPING group have identified that this package will be limited to fundamental conference description, and XCON will define an extension that will carry more complex information, e.g. changes in conference policy. http://www.ietf.org/internet-drafts/draft-barnes-xcon-framework-01.txt is already setting out to describe the framework for these extensions. My question is therefore whether any discussions of information carried in the XCON package should be deleted from the SIPPING framework, or whether we should describe the entire conference notification service in the SIPPING framework document, and delete any mention from the XCON framework. If the latter, we!
  should still generalise any mention of policy in accordance with 1) above.

I believe the above comments need addressing at the following points in the document, taking the main body of the document first, and leaving the terminology until later:

-	Section 3, 2nd paragraph (top of page 7). Text: "The focus uses the media policy to determine the proper configuration of the mixers." should be deleted as it is irrelevant to the operation of any of the SIP aspects of the conference.

-	Section 3, 3rd paragraph, change "conference and media policies" to "conference policy" twice. Media policy is a subset of conference policy.

-	Section 3, figure 2, delete "Membership & Media Policy" from figure as in the context of the figure "Conference Policy" is sufficient. I suspect also we should be attempting to generalise the label "Conference Policy Control Protocol" as this is the specific XCON solution here (and in current thinking only part of it), and there may be other solutions that may be completely appropriate for use in conjunction with the SIP aspects. Can we just label it "Policy control"?

-	Section 3, paragraph following figure 2 (9th paragraph - top of page 9), text: "Through this mechanism, it can learn about changes in participants (effectively, the state of the dialogs), the media policy, and the membership policy.". See point 2) above; we can either delete "the media policy, and the membership policy", or just replace it with "and the conference policy".

-	Section 3, 10th paragraph (top of page 9). Sentence "The participant can communicate with the conference policy server using a conference policy control protocol." As in comment on figure 2, should not mention specific XCON protocol name. 

-	Section 3.1, 5th paragraph (top of page 10). Text: "A conference URI can be obtained from a conference policy control protocol, which can be used to create conferences and the policies associated with them." I believe we can delete this sentence as the issue relevant to SIP is already covered in the earlier parts of the paragraph.

-	Section 4.1, 1st paragraph, change "membership policy" to "conference policy" (1 instance).

-	Section 4.1, 2nd paragraph, change "membership policy" to "conference policy" (3 instances).

-	Section 4.1, 3rd paragraph, change "membership policy" to "conference policy" (1 instance).

-	Section 4.1, 4th paragraph, change "membership policy" to "conference policy" (1 instance).

-	Section 4.1, 5th (last) paragraph (top of page 12). Delete sentences: "A similar model exists for media policy." and "Alternatively, if the video is being centrally mixed, it could inform the mixer to send a black screen to that participant.  The means by which the policy is implemented are not subject to specification." Change "media policy" to "conference policy" in remaining text.

-	Section 4.3, 1st paragraph, change "media policy" to "conference policy".

-	Section 4.4, 3rd (last) paragraph, change "media policy" to "conference policy".

-	Section 4.4, See point 2) above; and depending on decision may need to delete all references to conference policy.

-	Section 4.6, 2nd (last) paragraph; delete reference to "conference policy control protocol" (2 instances) and refer to [16] only for conference policy.

-	Section 5.1, 2nd paragraph, text: "When a media and conference policy are created, they are established with default rules that are implementation dependent.  If the creator of the conference wishes to change those rules, they would do so using a non-SIP mechanism." I can see no reason relating to the SIP aspects for retaining this paragraph, and therefore propose that it is deleted.

-	Section 5.5, 2nd paragraph. Change "the conference and media policies" to "the conference policy". Delete sentence: "Any attempts to read or write those policies results in a protocol error." as it is not relevant to the SIP aspects of discussion.

-	Section 5.8, 4th paragraph (penultimate), change "media policy" to "conference policy". 

-	Section 6.3, 1st paragraph (following figure 6). Change "the membership and media policies" to "the conference policy".

-	Section 6.3, 2nd paragraph (top of page 23), Change instances of "membership policy" and "media policy" to "conference policy".

-	Section 6.3, 3rd (last paragraph), change "is unaware of any conference or media policies" to "is unaware of any conference policy".

-	Section 6.4, 1st paragraph, change "which implements the focus, conference policy server, and media policy server" to "which implements the focus, and conference policy server"

Assuming these changes are accepted, then the following changes need to be made to the terminology in section 2.

-	Delete terms "media policy" and "membership policy" as they will no longer be used in the document.

-	Term: "Conference Notification Service". See point 2) above, and at minimum delete reference to "media policy" as covered in "conference policy".

-	Term: "Conference policy server". Delete "and include membership policy and media policy".

-	Term: "Conference policy". Delete "The policy includes membership and media policies.  The conference policy is used to specify and control the operation of a conference instance.", which in any case says the same thing twice.

-	Term: Conference-Aware Participant. Needs modification in regard to protocol support statements, as decisions have moved on from this in XCON. Possibly reuse text from paragraph immediately following figure 2.

regards

Keith

Keith Drage
Lucent Technologies
[email-masked]
tel: +44 1793 776249

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