Re: discussion about temporal scenario modelisation

Thanks for your interesting paper. Sorry for taking so much 
time before sending this reaction/question.

In your paper you distinguish between a hierarchical and 
a constraint-based approach to specify temporal structure.

If I understand you, you categorize SMIL and CMIF as members 
of the first type, and Madeus (among others) as representative 
of the other type. I have to confess that I do not know much 
about CMIF and Madeus.

What I get from the figures in your document, in Madeus you 
specify constraints between media-objects; sets of media-objects 
with their constraints can be taken together into logical groups.

Is this correct?
Is there any additional semantics to these logical groups
eg. are there (structured) dependicies between these groups?

As an example of a constraint-based specification you give

  A meets B
  B meets C
  I starts A

Your suggestion is that this approach is more author friendly.

I would say that this type of authoring is also supported by SMIL:

  <B begin="id(A)(end)"/>
  <C begin="id(B)(end)"/>
  <A begin="id(I)(begin)"/>

In addition SMIL provides for a (temporal) grouping mechanism, 
allowing to construct a temporal hierarchy in a tree structure.

It is up to the author to derive the tree, possibly out of 
the constraints.

In SMIL it is not allowed to specify constraints over the 
boundaries (scope) of a node (siblings) of the tree.
This indeed yields the grouping effect: it suffices to observe 
the constraints per parent/children group; altering the temporal 
constraints within that scope will not directly influence (invalidate) 
the dependicies between the other media-objects in the document: 
the tree-hierarchy is maintained.

Kind regards,
Warner ten Kate.

Philips Research Labs. WY21 ++ New Media Systems & Applications
Prof. Holstlaan 4 ++ 5656 AA  Eindhoven ++ The Netherlands
Phone: +31 4027 44830
Fax:   +31 4027 44648

Muriel Jourdan wrote:
> Dear SMIL editor,
> In a previous email
> (
> we tried to clarify the concept and the semantic of the SMIL proposal.
> In the following paper, we compare two paradigms used for modeling
> temporal scenarios:
>      * hierarchical structure as defined in the SMIL working draft or
> in  Cmifed, and
>      * temporal constraints as defined in MADEUS, ISIS, HPAS, ...
> We base our analysis upon the example given at the end of the SMIL
> working draft.
> Our objective clearly is to motivate an evolution of SMIL, in order that
> it can better take into acount authoring requirements.
> The paper is written in html.  You can find it at the following http
> address :
> Any comments are welcome,
> Cecile Roisin and Muriel Jourdan,
> --
> __________________________________________________
> Tel :            Fax :
>         Unite de Recherche INRIA Rhone-Alpes,
>      projet OPERA ( )
>           ZIRST, 655 avenue de l'Europe,

Received on Monday, 9 February 1998 08:06:34 UTC