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Re: Doubt about Parameter during execution

From: Evren Sirin <evren@cs.umd.edu>
Date: Wed, 29 Dec 2004 02:17:43 -0500
Message-ID: <41D25A17.9010104@cs.umd.edu>
To: Tatiana Vieira <tascvieira@yahoo.com.br>
CC: public-sws-ig@w3.org

Tatiana Vieira wrote:

> Hi Evren,
>  
> I understood that it's expected that everybody explicitly says that a 
> Parameter is an Input or an Output, for instance, instead of simply 
> saying that it's a Parameter. However, I continue with my doubt...
>  
> Thinking about the execution of the process I specified, if I put that 
> a process A has as output the parameter named "OutputA" 
> (process:Output rdf:ID="OutputA"), which is of type MyClass,

So we have: OutputA parameterType MyClass

> is it expected that during execution an instance of OutputA is generated?

OutputA is an instance itself so you wouldn't generate an instance of 
that individual. Note that OutputA is the description of the output 
parameter and fifferent from the values that are retrieved from the Web 
Sservice.

> I mean, will the execution generate, for example, an instance 
> OutputA_a that is of type MyClass?

This is not the same as the above but it is more accurate. For example, 
if the parameterType of the output is books:Book (assuming Book is a 
class defined in the books ontology) then when you execute the service 
you may recevie a result like this from the service:

<books:Book>
    <books:hasTitle>...</books:hasTitle>
    <books:hasAuthor rdf:resource="..."/>
...
</books:Book>

There may or may not be an ID associated with this Book instance 
depending on how the service works.

>  
> I'm asking it because I'm constructing a system that have some rules 
> associated with some variables, specially with the processes output 
> variables and I (the system) must test if the value of one output was 
> "X", for example. So, how do I have to test it? If an instance is the 
> generated, I would have to test the value of this instance...if not, I 
> would have to test the value of OutputA, don't I?

I'm not sure what you mean by "the value of OutputA" but as far as I 
understand your problem it seems that you need to use the instance 
returned by the service. This is how the preconditions and effects are 
evaluated anyway. If the expression in the effect refers to an output 
parameter then after execution the value returned from the service is 
replaced in the expression and applied to the current state.

Hope this helps,
Evren

>  
> Thank you again,
> Tatiana.
>
>
> */Evren Sirin <evren@cs.umd.edu>/* wrote:
>
>
>     Hi Tatiana,
>     The "instantiation" of Parameter class is not related to the
>     execution
>     of processes. It is related to the OWL individuals found in the OWL-S
>     descriptions. It simply says that we don't expect anybody to create a
>     "direct" instance of Parameter class, i.e. having only one type
>     assertion for a parameter like this:
>
>
>
>     In your OWL-S description, it is expected (though not mandatory) that
>     you will explicitly say that a parameter is an input or output,
>     i.e. by
>     saying
>
>     OR
>
>     There are also different subclasses of Parameter class defined in
>     OWL-S
>     1.1, such as Local and ResultVar, which you might use. Of course
>     you can
>     also extend the OWL-S ontologies to define your own subclasses of the
>     Parameter class.
>
>     Regards,
>     Evren
>
>
>
>     Tatiana Vieira wrote:
>
>     > Hi people,
>     > In the "OWL-S: Semantic Markup for Web Services" document,
>     > Section 4.2.3, when there is a description about "hasParameter", we
>     > found the following sentence: "...we do not expect this class to be
>     > instantiated. It's role is solely making domain knowledge
>     explicit".
>     > What does it mean? What happens when a process is executed: does it
>     > create an instance of each output parameter class?
>     > Thank you in advance,
>     > Tatiana.
>     >
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Received on Wednesday, 29 December 2004 07:18:25 GMT

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