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Re: Preconditions /effects vs Preconditions/Postconditions

From: Monika Solanki <monika@dmu.ac.uk>
Date: Tue, 16 Sep 2003 14:04:31 +0100
Message-ID: <3F670A5F.9030202@dmu.ac.uk>
To: www-ws@w3.org

Drew McDermott wrote:

>   [Charlie Abela]
>   I wonder whether it is expected for a Web Service developer creating such a 
>   service to go into such a hussle as to identify all these possible combinations 
>   of pre and postconditions, effects, you name it. 
I am  not sure, when you say "Web service developer", it means :

(a) The guy who is actually providing such a service and therefore also 
providing all the models with it
(b) The guy who has actually all the models before him and trying to put 
them together for a specific goal.

If it is (a) (which I strongly believe it is) then, I believe it is 
necessary for him to actually identify the required parameters to ensure 
that his service is indeed usable by other agents for whatever task - 
discovery, composition etc.

>   I think the more this is complicated the less it is looked at in a favourable 
>   way. I also think that there should be some way by which to say that given a 
>   number of preconditions and postconditions or effects then a service can be 
>   identified, and other extended information regarding such service would be made 
>   available in some other location, maybe also in some repository that defines 
>   general business logic.
>You've got a good point.  The major beneficiaries of a detailed model
>of a web service are agents that want to reason about what it can do,
>and in particular agents that want to combine it in creative ways with
>other web services --- the "composition" problem.  Web services
>themselves want to _prescribe_ how they are to be used; they have
>little motivation to enable other uses.
I understand that prescribing the fact about how to use, includes 
identifying all the details like IOPEs as well, or am I missing 
something. I am not sure what is meant by other uses. Now whatever means 
are used in identifying/prescribing those (provider or third party)do 
not really matter or do they?

>I've always imagined that _third parties_ might produce more detailed
>models of web services and get paid for keeping them up to date as the
>services evolve.  E.g. amazon.com.com might maintain a declarative
>model of amazon.com.
I believe, it does not really matter if the service developer (provider) 
maintians it himself or delegates it( This could be a hidden fact as 
well). As long as the properties are available, everything should be fine.
Monika Solanki
Software Technology Research Laboratory(STRL)
De Montfort University
Hawthorn building, H00.18
The Gateway
Leicester LE1 9BH, UK

phone: +44 (0)116 250 6170 intern: 6170
email: monika@dmu.ac.uk
web: http://www.cse.dmu.ac.uk/~monika
Received on Tuesday, 16 September 2003 08:58:58 UTC

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