Re: Current thoughts and doubts

Dear all,



I think Gerrit is right that we have to stay focused on the objective of
providing a clean and simple meta-model for the AUI, as well as for the
other components of the standard. However, I do not feel that the
discussion of the last two weeks was straying from this line.



I think the focus is actually on what must go in the metamodel of the AUI,
i.e. those concepts which refer to the abstract notion of interaction unit,
and what must go in different places, for example a comprehensive metamodel
of behaviour, which can be reused in several places, and which is not a
component of the AUI metamodel.

In this direction, we were thinking of how can one specify behaviours, and
we seem to agree on the use of a common formalism of type
Event-Condition-Action, and how interaction units are connected to
behaviours. This connection should be in two directions. On the one hand,
interaction units can trigger events, (and in this sense they provide some
support for event generation), on the other hand, the consequences of the
behaviour have to be represented in some form through the unit).

Hence, we should define how to establish this connection. This can be done
in three ways (I will exemplify with respect to the event generation case):
by directly defining the interaction unit as the generator / producer /
sender of the event, by associating the unit to the events, by introducing
a specific concept of event support, associated with events, as was
proposed in Pisa. For the representation of consequences the same
alternatives occur. Of course, these should be adopted in pairs in a
consistent way.

So, if we all agree on this view, it is a matter of convenience (and
possibly of scientific and pragmatic investigation) which alternative to
adopt. I prefer the third option (explicit event support), but I can also
live with the association, as both allow for flexible associations of units
with events, while for the first option (units as producers of events) I
find that it might incur in a rigid structure, and one that might meet with
fewer implementations.



All of this derives from the fact that the current version of the
metamodel, in the document as it was last week did not provide any way to
relate an interaction unit to a behaviour specification (they were just
seen as two different types of components of the AUI metamodel, without any
connection between them). I think everybody will agree that this is a
serious limitation of the current model, and this is why we were discussing
the best way to overcome this.



The other thing that was discussed was, admittedly, one with minor direct
impact on the metamodel, as it concerned the idea whether to have a very
generic notion of behaviour, to provide a basic semantics for actions, and
for the different types of behaviours one can have to model (task-related
processes, navigation, data transformations at the domain level, or
syntactic feedback). This is where different proposals have been presented.
Depending on the adopted model of behaviour, the connection with the
interaction unit will occur through some specific component of this. Even
if this might seem a fine issue, it would provide a basis for reasoning at
the abstract level, which should provide several benefits, so that one
should not think of a specific way of expressing behaviour for each
different type.



Finally, the model of interaction unit should be separated by the model of
the behaviour, and this is a matter of cleanness, not so much a research
theme, and we should provide for the possibility that an interaction unit
provides support to several behaviours, possibly connected with one another.




Hope this helps clarify the matter


best

paolo

2012/11/26 Gerrit Meixner <Gerrit.Meixner@dfki.de>

> Dear colleague,
>
> after our last telco I took some time to think about the current situation
> in our working group and the current draft documents. In the last telco
> several members (e.g., Joelle, Gaelle, Fabio) expressed that they could not
> fully follow the current discussions concerning the meta-model for the AUI
> specification. Therefore I started a discussion with Fabio (as co-chair)
> and
> Dave (as W3C contact) at the end of last week. Here're our thoughts.
>
> We think that we're running too much into scientific discussions with only
> little practical relevance. In the last telco we had in-depth scientific
> discussions concerning the AUI meta-model. It seems to be that the AUI
> meta-model is now getting too complex rather than to be easily useful for
> industrial companies. We have to distinguish between scientific work and
> work for practical standardization. It would be better to have a clean AUI
> meta-model, understandable, focused on the AUI concepts, without
> introducing
> too many additional things related to other models or issues. Furthermore
> the goal of our charter is to develop a standard that can be readily
> exploited by industry for interchange of UI designs between different
> editing tools (http://www.w3.org/2011/01/mbui-wg-charter). An overly
> complex
> meta-model may harm the realization of that goal and we would rather start
> from a simpler core set of features and allow for future extensions in
> response to industry need rather than second guessing what those might be.
>
> To draw a conclusion I would suggest to try to publish a first les complex
> AUI meta-model which could be easily used in industry. An extended version
> could then be published in future. The current AUI specification must not
> be
> perfect, but we have to remember the target audience of the specification:
> practitioners in industry. Perhaps the way forward is to see if we can
> prioritize the features and try to get a feel for which ones are core and
> which ones have only marginal interest? Would it even be worth thinking
> about how we could reach out to industry via a survey of some kind?
>
> I would be happy to get your opinions. Thanks.
>
> Best regards
> Gerrit
>
> ========================
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>
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-- 

Paolo Bottoni

Associate Professor of Computer Science

Email: bottoni@di.uniroma1.it

Website:
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Phone: +39 06 49255369

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