Re: [OWL-S]: Proposal for 1 new control construct

> > [David Martin]
> >Here's an initial strawman proposal for this new construct, which 
> >indicates the use of a Web service that's defined elsewhere.  It's 
> >syntactically about the same as the "invoke" construct proposed earlier -- 
> >but it doesn't carry the same implications about what's going to happen where.
> >
> >We've been calling one of these things a "Reference" in conversations, but 
> >to me that's not really very helpful, so I'm proposing  "Use". Other 
> >suggestions are welcome.  ("Employ", "enact", "execute", "do", "run", 
> >"apply" ?)
> 
> [Austin Tate]
> We are really talking about a more abstract specification of a process as 
> opposed to something that can be directly invoked with some known protocol 
> I assume.
> 
> PIF work (which was the basis for the core of NIST PSL) used a term 
> "perform" for an activity if that is useful.  It may be sufficiently far 
> from the lower level direct "invoke" (invocation of a service) to be helpful?
> 

There are three items we want to distinguish:

The definition of a process:
     
        <Process id="foo" ...>  ... </Process ....>

The textual occurrence of a process:

      <Process id="baz" ...> 

          <Loop>

              <Perform rdf:resource="#foo">
                  ...inputs etc.
	      </Perform>
	  </Loop
          <Perform rdf:resource="#foo"/>
 </Process>

The execution of a process:

   On 5th invocation of 'baz', the Loop is iterated 27 times.
   On the 19th iteration, an execution of 'foo' occurs.

There is/are

    1 definition of 'foo'
    
    2 occurrences, or references, of 'foo' within the definition of
      'baz' 

    27 executions of 'foo' within the 5th execution of 'baz'

I think Austin's proposal is for a synonym of "execution."  I think
David's question concerned a synonym of "reference."  

Note that there is always at most one definition of a process, and
there is almost always a small number of references to the process,
but the number of executions can be anything from 0 to ... some very
big possibly infinite number.  In a case like this:

    <If>
       <Iftrue>
          <Perform rdf:resource="#foo"/>
       </Iftrue>
       <Iffalse>
          <Perform rdf:resource="#foo"/>
       </Iffalse>
    </If>

there are two references, but only one execution per execution of the
'If'.

                                             -- Drew


-- 
                                             -- Drew McDermott
                                                Yale University CS Dept.

Received on Wednesday, 11 February 2004 15:47:12 UTC