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Re: atomic services with no effects or outputs

From: Chintan Patel <chintanop@hotmail.com>
Date: Wed, 26 Mar 2003 19:01:58 +0000
To: monika@dmu.ac.uk, mits1@cs.umbc.edu, www-ws@w3.org
Message-ID: <F224SZ3Zs3Mpw6yL2m900007522@hotmail.com>

What i believe is that the Services for which the composition task can be 
handled by "Genie" by just matching the Input/Output(IO) Concepts without 
considering the PreConditions and Effects(PE) then i believe there is no 
harm in not specifying the PE for those atomic Services.

comments ?

Regards,
Chintan

================
Graduate Research Assistant
School of Interdisciplinary Computing and Engineering
University of Missouri - Kansas City
Kansas City - MO -64110

Ph : 816-931-9981 (R)
     816-235-2396 (O)





>From: Monika Solanki <monika@dmu.ac.uk>
>To: Mithun Sheshagiri <mits1@cs.umbc.edu>, www-ws@w3.org
>Subject: Re: atomic services with no effects or outputs
>Date: Fri, 21 Mar 2003 22:03:49 +0000
>
>Just an info: there is a note in the comment tag of the file that states:
>
>NOTE: This is a sketch; not a complete example
>
>The example therefore can be made more sell sufficient.
>
>For effective service composition, I agree with you, that ideally the IOPEs 
>of every collaborating service would have to be exposed. I am not sure at 
>this moment, if and how these should be made mandatory, in some way in the 
>service description. Probably a parser encapsulating certain rules could be 
>used. However there is little that can be achieved without the IOPEs.
>
>Regards,
>
>Monika
>
>Mithun Sheshagiri wrote:
>
>>
>>Hi all,
>>        There are several atomic services described in the CongoProcess 
>>file that neither have outputs nor effects. I was wondering how can these 
>>services be of use to us (entities other than the author). In my 
>>understanding services either provide you with some information (e.g.. 
>>ISBN lookup service with the ISBN number as the output) or do some world 
>>altering activity (e.g. the ExpressCongoBuy service whose execution 
>>results in the book being shipped to its destination). The former has an 
>>output and the latter has some effect. Here the output or effect implies 
>>some sort of a change.
>>If a service does not indicate a change of state (i.e., if it does not 
>>have i/e) then how can someone who discovers the service use it (say for 
>>composition). Something does change when the service is executed but the 
>>service does not reveal it. I would like to draw an analogy between such 
>>services with methods that have return type "void". Take the example of a 
>>program that implements a counter. The increment method in this program 
>>returns void after incrementing the counter. I further name the method 
>>foo. If I advertise this method as a web service how will one use it since 
>>he/she has no idea about its internal workings. But if I return a message 
>>(add an effect/output) that says "Counter_Incremented" then won't it be 
>>much easier to comprehend what the service does (assuming there is a Genie 
>>that maps Counter_Incremented to an my concept of counter increment)..
>>What I make out of this is that as long as I don't provide an output or 
>>effect, only I, as the writer of the program can use it. By describing the 
>>effect, I describe the service to the extent that someone else might be 
>>able to use it.
>>Do I make any sense or have I completely lost it.
>>
>>mithun
>>
>>
>
>--
> >**<>**<>**<>**<>**<>**<>**<>**<>**<>**<
>Monika Solanki
>De Montfort University
>Software Technology Research Laboratory
>Hawthorn building, H00.18
>The Gateway.
>Leicester LE1 9BH, UK
>
>phone: +44 (0)116 250 6170 intern: 6170
>email: monika@dmu.ac.uk <mailto:monika@dmu.ac.uk>
>web: http://www.cse.dmu.ac.uk/~monika/ 
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Received on Wednesday, 26 March 2003 14:02:36 GMT

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