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Re: Multiple inputs and multiple outputs

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Sun, 28 Sep 2003 15:01:57 -0400 (EDT)
Message-Id: <200309281901.h8SJ1vL00183@pantheon-po02.its.yale.edu>
To: www-ws@w3.org


   [Yuzhong Qu" <yzqu@seu.edu.cn>]
   As we know, a process in DAML-S can have multiple inputs and multiple (conditional)outputs.
   (From http://www.daml.org/services/owl-s/1.0/Process.owl
   http://www.daml.org/services/owl-s/0.9/Process.owl)

   1. In the case of  multiple inputs

       It seems to me that the process specified should take multiple
       inputs satisfying corresponding type constraint.
       Am I right?

Yes.

       But, how do you know the exact number of inputs? You just know
       what you know, maybe there is another statement about a new
       input (another input may be specified in other place) due to
       the openness of the Semantic Web (it's not a closed world).

Good point.  We really need a fixed list of inputs and another of outputs.

[It would be interesting denial-of-service attack to tell a service
that it needed another input and have it then stall because no one is
supplying it. :)  Of course, this scenario would depend on a service
using an open RDF spec as the actual code that it uses when running,
which is not likely.  More likely, potential clients would be the ones
to run into trouble.]

   2.  In the case of  multiple outputs

       What's the intended meaning?

Putting aside the issue of conditional outputs for a moment, if the
process has outputs A,B,C, it just means (in essence) that the output
is a record whose fields are called A, B, and C.

A conditional output might not even exist, so you can picture it has
always being there, but having a Null value when the condition isn't
true.

-- 
                                             -- Drew McDermott
                                                Yale Computer Science Department
Received on Sunday, 28 September 2003 15:02:00 GMT

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