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Re: automatic web service discovery?

From: Monika Solanki <monika@dmu.ac.uk>
Date: Fri, 24 Oct 2003 10:33:15 +0100
Message-ID: <3F98F1DB.7040307@dmu.ac.uk>
To: Davy Vermeir <davermei@vub.ac.be>, www-ws <www-ws@w3c.org>

Hi Davy,

Pls find a quick answer below.

Davy Vermeir wrote:

>Hello,
>
>I'm a student at the VUB doing an apprenticeship on Semantic Web Services
>at the SSEL-lab at the VUB.
>While performing a survey on some approaches on how to describe Web
>Services in a semantic way, i found the DAML-s approach, but I still have
>some things in mind that are not very clear to me.
>
>In the documents I found on DAML-s on the website, a Web Service can be
>described based on the IOPE's, and they claim that this is enough for
>automatic web service discovery. 
>Since "EFFECTS" here are described as physical effects, I don't understand 
>how these IOPE's can fully describe a web service for automatic discovery.
>
>An example to make it clearer:
>A Concrete Service A implementing an operation to look for all available
>rooms in a hotel.
><profile:input>
>  <profile:ParameterDescription rdf:ID="availableHotelRoomsInput">
>  <profile:parameterName>availableHotelRoomsInput</profile:parameterName>
>    <profile:restrictedTo
>rdf:resource="http://exampleontology#Hotel">
>    <profile:refersTo rdf:resource="http://notimportant">
>  </profile:ParameterDescription>
></profile:input>
>
><profile:output>
>  <profile:ParameterDescription rdf:ID="availableHotelRoomsOutput">
>  <profile:parameterName>AvailableHotelRoomsOutput</profile:parameterName>
>    <profile:restrictedTo
>rdf:resource="http://exampleontology#listOfRooms">
>    <profile:refersTo rdf:resource="http://notimportant">
>  </profile:ParameterDescription>
></profile:output>
>
>A Conrete Service B that implements an operation to look for all rooms in
>a hotel that have a minimum amount of quality
>
><profile:input>
>  <profile:ParameterDescription rdf:ID="qualityHotelRoomsInput">
>    <profile:parameterName>qualityHotelRoomsInput</profile:parameterName>
>    <profile:restrictedTo
>rdf:resource="http://exampleontology#Hotel">
>    <profile:refersTo rdf:resource="http://notimportant">
>  </profile:ParameterDescription>
></profile:input>
>
><profile:output>
>  <profile:ParameterDescription rdf:ID="qualityHotelRoomsOutput">
>    <profile:parameterName>qualityHotelRoomsOutput</profile:parameterName>
>    <profile:restrictedTo
>rdf:resource="http://exampleontology#listOfRooms">
>    <profile:refersTo rdf:resource="http://notimportant">
>  </profile:ParameterDescription>
></profile:output>
>
>As you can see, both these services share the same semantic descriptions
>of the inputs and outputs of their operation. The inputs map to the
>"Hotel" - concept in the ontology , while the outputs map to the
>"listOfRooms" - concept.
>The operations implemented by these services have no preconditions or
>effects (since the retrieval of information has no physical effect).
>
>Problem:
>If a client would have a request for a service that has a "Hotel" as an
>input and a "listOfRooms" as an output both of these service could be
>returned as a match, while the operations implemented by these services
>have a totally different meaning(one is for lookin up available rooms and
>the other is for looking up rooms that have a certain amount of quality).
>  
>
If you observe, there is a difference in the two specification. The 
first one is output without a condition and the second one is output 
with a condition, the condition being the required "quality"  The 
minimum amount of quality required has to be quantified and expressed in 
the form of a condition.  This has also to be specified explicitly in 
the request. Now, If  you express the output property for the second 
service as conditional output with a condition on the quality of 
service, it makes the two service description different and the 
semantics are captured in this form, although there are no preconditions 
and effects. DAML-S has constructs for specifying conditional output.

Hope this helps.

>Is there a way to solve this in DAML-S? 
>
>Greetings,
>
>Davy Vermeir
>
>
>
>
>  
>

-- 
**>><<**>><<**>><<**>><<**>><<**>><<**>><<**
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 Friday, 24 October 2003 05:30:53 GMT

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