Re: Performatives and IDL

From: Kaj Gronbak (kgronbak_at_intermedia.aau.dk)
Date: Fri 25 Sep 1998 - 12:45:45 CDT



At 18:41 +0200 24/09/98, Dave Millard wrote:
> We believe that this now allows us to talk about the performatives
>and the
>OHP-Nav actions independently. We could in fact agree on these actions and
>move on to writing the IDL definition of OHP-Nav. Unfortunately we need to
>define both OHP-Nav and the OHP or performative layer to be interoperable.
> We see the following approaches to including performatives using IDL.
>
>1) Compile an exhaustive list of performative/action/object IDL functions.
>E.g. askCreateNode. This will result in a huge list of approximately 500
>functions; it also makes it more difficult to later extend the set of
>performatives; the advantage is that is very straight forward.
>
>2) Define performatives in IDL as separate interfaces (that could be
>extended in the future). These would build a basic layer on top of which
>other IDL definitions for other domains would be specified. The problem is
>we are unsure of how to do this in IDL.
>
>3) The third option is to define the performatives and their meaning
>(semantics)in natural language and have a flag (parameter) in each of the
>IDL functions.
>
> Sigi and I feel that we could do this in the proposed common
>document as
>performatives are essentially 'operations on' or 'context of' whatever
>domain actions they are carrying. We could use any of the above approaches
>and we are open to any other suggestions.

We don't think it makes sense to start the definition of 500 ops, we are working on a list here in Århus, that is approx. 120 ops, including some which are common to structure servers, e.g. location and session management.

We'll send you this list together with the revised datamodel Monday or Tuesday next week, we can use this list as input for a discussion of the role of performatives in the IDL specs. We beleive, we have solved many of the problems, that were poited out in Soton...

/Kaj


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