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Re: atomic services with no effects or outputs

From: Mithun Sheshagiri <mits1@csee.umbc.edu>
Date: Wed, 26 Mar 2003 15:14:08 -0500 (EST)
To: www-ws@w3.org
Message-ID: <Pine.LNX.4.44.0303261506390.12954-100000@linuxserver1.cs.umbc.edu>

I was talking about services without outputs or effects in my very 
first mail. I made a typo in my message which might have made you 
believe that I was talking about services without PEs. Sorry about that!

peace
mithun 


On Wed, 26 Mar 2003, Chintan Patel wrote:

> 
> Exactly, we dont require to always specify PEs for all types of services. 
> Although we are required to specify PEs for complex services whereas for 
> simple services we can do with just IO concepts matching !!
> 
> >Well, for simple sequential service compositions this may be the case, 
> >however when we think about complex services(which most of the real life 
> >services would be) being composed and executed concurrently, there may be 
> >interdependencies and therefore specification of preconditions and effects 
> >become necessary.
> 
> by *neccessary*, do you mean mandatory ?
> 
> 
> >
> >Regards,
> >
> >Monika
> >
> >Chintan Patel wrote:
> >
> >>
> >>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/ 
> >>><http://www.cse.dmu.ac.uk/%7Emonika/>
> >>> >**<>**<>**<>**<>**<>**<>**<>**<>**<>**<
> >>>"NOTE: The information transmitted is intended only for the person or 
> >>>entity to which it is addressed and may contain confidential and/or 
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> >>>use of, or taking of any action in reliance upon this information by 
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> >>>
> >>>
> >>
> >>
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> >
> >--
> > >**<>**<>**<>**<>**<>**<>**<>**<>**<>**<
> >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/ 
> ><http://www.cse.dmu.ac.uk/%7Emonika/>
> > >**<>**<>**<>**<>**<>**<>**<>**<>**<>**<
> >"NOTE: The information transmitted is intended only for the person or 
> >entity to which it is addressed and may contain confidential and/or 
> >privileged material. Any review, retransmission, dissemination or other use 
> >of, or taking of any action in reliance upon this information by persons or 
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> >this in error, please contact the sender and delete the material from any 
> >computer"
> >
> >
> 
> 
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Received on Wednesday, 26 March 2003 15:15:20 GMT

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