Subject: RE: [XCON] DP4/4.1: Common Conference Information and Templates (in/out problem)

From: "Mary Barnes" <[email-masked]>
Date: Wed, 28 Dec 2005 10:03:41 -0600

I think the objective is as you state in that everything in the end does
get created from a blueprint (basic or customized).  

We were debating how customizable are the templates - I guess I don't
see the impact on the inheritance model.  If there doesn't seem to be
the need for this "by-reference" and multiple templates concept, then
that does simplify things (but restricts future flexibility and
applicability of the framework). I guess it might be reasonable at this
point to suggest that the data model and associated protocols will only
support the by-value and a single template model initially.  [That seems
to be what Brian Rosen is also arguing for in his response.]

Mary

-----Original Message-----
From: Henning Schulzrinne [mailto:[email-masked]] 
Sent: Saturday, December 24, 2005 8:08 AM
To: Barnes, Mary [RICH2:B601:EXCH]
Cc: [email-masked]
Subject: Re: [XCON] DP4/4.1: Common Conference Information and Templates
(in/out problem)

I'm concerned that we're adding too many related, but subtly, different 
inheritance concepts.

I'm still not quite sure I understand blueprints, but as described 
below, this seems awfully close to the concept of inheritance of 
individual instances ("tree").

Thus, I wonder if the two concepts can't be unified. Essentially, a 
"blueprint" becomes the root of the inheritance tree.

That way, we only have one dynamic (value) inheritance concept. This 
also makes it easy to create custom inheritance, such as "our weekly 
departmental meeting". It simply gets created from one of the 
system-defined 'blueprints'.

Henning

Mary Barnes wrote:
> Hi all,
> 
> There's been a group of us (XCON FW authors, current template authors
> and data model authors) discussing this point and a couple of related
> issues around the Common conference information, templates and
> blueprints offline since the IETF meeting.  We've come to tenuous
> agreement amongst ourselves on a couple of aspects of this topic and
> wanted to continue and complete the discussion with the WG.  I'm
> summarizing the issues and the changes proposed at this point to the
> framework to accomodate current thinking.   I've labeled the related
> questions/topics we've discussed for convenience as DP4.2 and DP4.3
and
> I'll post those in separate threads to facilitate tracking the issues.
> Feedback would be appreciated - ideally supported by alternative
and/or
> additional text . 
> 
> Per discussion at the IETF-64, there still seemed to be some debate
> (beyond the basic data model approach discussed in the "Call for
> Consensus:Data model" thread initiated by Adam) on some fundamentals
of
> the model defined in the framework.  Basically, this is the DP4 issue
as
> to whether the template is in the same object as the common conference
> information (i.e. "in") or whether it is a separate object (i.e.
"out").
> The framework has been based on the "in" concept barring any other
> conclusion by the WG, noting that the current definition of blueprint
is
> quite explicit about this:
>      "A conference blueprint is a static conference
>       object within a conferencing system, which describes a typical
>       conference setting supported by the system.  A conference
>       blueprint is the basis for creation of dynamic conference
objects.
>       A system may maintain multiple blueprints, each comprised of the
>       common conference information, along with any number of
> templates."
> 
> The discussion amongst the group seemed to lead to it's not being an
> in/out issue as much as it is either by-value or by-reference.  It was
> suggested that we just chooose by-value for now, but that wasn't
deemed
> practical in terms of the model put forth in the framework in terms of
> lots of flexibility, with optionality of templates. We did (tenuously)
> agree to support both.  The Blueprint concept really requires that we
> support by-reference, and that's consistent with the current approach
> whereby the client fetches any templates from the server that it
doesn't
> understand.  At the same time, a barebones system could initially just
> support a few templates and by-value might make sense.  But, again, I
> think it's too limiting for the vision represented in the framework to
> be the only option supported.   
> 
> At this time, we're proposing something like the following be added
> after the 1st paragraph in 7.3 (where 7.3 is the "Advanced Example"
> section that introduces the blueprint concept) supporting the concept
of
> by-value or by-reference.  It might be useful to add more text
including
> some background for the context for using one or the other, as well:
>  "As defined within this framework, a blueprint is comprised of the
> common conference information and one or more templates.  The
templates
> within the blueprint can either be included by-value or by-reference
> depending upon the system implementation." 
> 
> Mary.
> 
> 
> _______________________________________________
> XCON mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/xcon

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---

From: "Henning" <[email-masked]>
Date: Thu, 29 Dec 2005 11:57:17 +0100

Your note makes me worry that I still don't understand the template concept.

I had earlier provided a brief definition of a template. Is that in 
agreement with yours?

In short: Template = class definition (data types); blueprint = initial 
values (dynamic). Obviously, a blueprint only makes sense within a 
particular template.

----- Original Message ----- 
From: "Mary Barnes" <[email-masked]>
To: "Henning Schulzrinne" <[email-masked]>
Cc: <[email-masked]>
Sent: Wednesday, December 28, 2005 5:03 PM
Subject: RE: [XCON] DP4/4.1: Common Conference Information and 
Templates(in/out problem)

---

From: "Brian Rosen" <[email-masked]>
Date: Thu, 29 Dec 2005 08:46:13 -0500

FWIW, my conception of Blueprint is the same as Henning's.  A template is a
definition; there is a document that describes it, and probably something
like a schema.  

The Blueprint is the set of initial values assigned to an object conformant
to the schema. 

Brian  

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Henning
Sent: Thursday, December 29, 2005 5:57 AM
To: Mary Barnes
Cc: [email-masked]
Subject: Re: [XCON] DP4/4.1: Common Conference Information
andTemplates(in/out problem)