- From: Sheshagiri, Mithun <Mithun.Sheshagiri@hp.com>
- Date: Fri, 12 Sep 2003 17:53:57 +0100
- To: "'Sheila McIlraith'" <sam@ksl.Stanford.EDU>, Monika Solanki <monika@dmu.ac.uk>
- Cc: www-ws@w3.org
I might be be wrong but I think Monika and Sheila are talking about two different conditions. Monika is talking about Effect of execution being a condition and this she terms as postcondition. (ceEffect points to a concept which is a subclassof process:#Condition. And Sheila is talking about the condition being pointed by ceCondition which decides the effect. mithun > -----Original Message----- > From: Sheila McIlraith [mailto:sam@ksl.Stanford.EDU] > Sent: Thursday, September 11, 2003 5:45 PM > To: Monika Solanki > Cc: www-ws@w3.org > Subject: Re: Preconditions /effects vs Preconditions/Postconditions > > > > > > Monika, > > In DAML-S we are able to express conditional effects. These > are the side effects of a web service, as contrasted with its > output. E.g., AcmeBookSeller Web Service: > *output* is purchase receipt > *conditionalEffect* is comprised of a *condition* and an *effect* > the *effect* is that the book is sent to the customer, > under the *condition* that the book is in stock. > > Side effects of services are critical to encode for the > purposes of automated WS composition, where such effects must > be considered in composing and executing services. > (Something we humans do all the time.) > > As to how this relates to the wschor document you were > reading, it would be helpful to have the citation, but > without seeing it, here is a general answer. In the AI > planning literature the term "effect" is often used > synonymously with the term "postcondition". It is used > generically to captures the notion of effects which are > either conditional (i.e., conditional effects) or unconditional. > > I'm guessing that ws-chor's notion of "postcondition" is used > in this context. It is possible that they have done away > with the notion of condition in their "postcondition", > because this is simpler, but I would argue, is not > sufficiently expressive to capture the true side effects of > web services. > > As for what we need for WS composition, we need both the > *effect* and the *condition*, but the *effect* is the key notion. > > Regards, > Sheila McIlraith > > > On Thu, 11 Sep 2003, Monika Solanki wrote: > > > > > In DAML-S we have Preconditions and Effects(Conditions and Effect). > > > > BPEL4WS does not have the notion of Preconditions and > Postconditions( > > to the best of my knowledge). However the ws-chor group > have defined > > Precondition and Postcondition for the use cases in their > requirement > > document. > > > > I am wondering if the semantics of the "Conditions" for > "Effects" as > > defined in DAML-S are different from "Post conditions" in > ws-chor doc, > > as what we are really interested in is the condition itself. What > > would be lost (just for the sake of argument) if we were to discard > > the notion of "effect" and retain only the condition part > of "Effect" > > i.e if I may call it, "Post condition". I say this because I feel > > that in some way the effect part gets reflected in the > output. Maybe > > "Effect" makes it more explicit. I guess even for service > composition, > > what we are really interested in apart from input -output is the > > conditions that are captured in Preconditions and Effects. I guess > > what I am really trying to say is can we simplfy the notion of > > Conditional effects by attributing it as "post condition" without > > compromising anything that is not covered in any other property > > parameter. > > > > Any comments / thoughts well appreciated > > > > Thanks, > > > > Monika > > > > -- > > **>><<**>><<**>><<**>><<**>><<**>><<**>><<** > > 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 > > **>><<**>><<**>><<**>><<**>><<**>><<**>><<** > > > > > > ============================================================== > ================ > > *** Moving to Dept. Computer Science, University of Toronto *** > > Sheila McIlraith, PhD Phone: 650-723-7932 > Senior Research Scientist Fax: 650-725-5850 > Knowledge Systems Lab > Department of Computer Science > Gates Sciences Building, 2A-248 > http://www.ksl.stanford.edu/people/sam > Stanford University > E-mail: sam-at-ksl-dot-stanford-dot-edu > Stanford, CA 94305-9020 > > > > >
Received on Friday, 12 September 2003 13:04:25 UTC