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Process control Ontology

From: ±θΗΠ·‘ <hlkim@dku.edu>
Date: Wed, 1 Oct 2003 12:05:00 +0900
To: <www-ws@w3.org>
Message-ID: <000801c387c8$ce292dc0$77cf66d2@rainmaker>

Hi,
I am trying to understand a concept and usage of the DAML-S. 
According to a technical overview, process control ontology doesn't
define in the current version. I think this concept is very important
to implement a semantic web services. But I don't know what kinds of
languages or topics used for this one.  Many languages are already
implemented for defining the processes. eg. UPML, PSL, RuleML.
I'd like to know related topics and any plan for defining a process
control ontology. 

Any thoughts appreciated.

Cheers,

====================================================
Hak Lae Kim
Knowldege Engineering Research Laboratory
Dankook University, Korea
Ontology Engineering Group
+82-(0)11-395-0407, +82-(0)41-550-1742
http://www.ontology.or.kr
====================================================
 

-----Original Message-----
From: www-ws-request@w3.org [mailto:www-ws-request@w3.org] On Behalf Of
Charlie Abela
Sent: Monday, September 22, 2003 4:11 PM
To: Monika Solanki
Cc: www-ws@w3.org
Subject: Re: Model of Concurrency in DAML-S


Quoting Monika Solanki <monika@dmu.ac.uk>:

> 
> In DAML-S we have the notion of an Atomic service and a Composed 
> Service. Composed services are built out of Atomic Services using 
> Control constructs. The control constructs that we can use for 
> specifying concurrency are Split, Concurrent, Parallel, Split-Join, 
> Fork-Join, unordered etc. Now as per my understanding, if I specify
say 
> Split as a control construct, for a composite service built out of
two 
> atomic services, it would mean that both of them execute
independently.. 
> Basically as per my conclusion, atomic services  can either execute 
> sequentially or in parallel, independent of each other.
> 
> For a scenario given below, I have two thoughts
> 
> 1. There are 3 composite processes, A, B and C.
> 2. All the 3 start execution in parallel i.e split.Now after some 
> computation, B needs a value from A.It requests A for the value, gets 
> the value and carries on computation.
> 3. After some time B needs value from C. It requests C for the value, 
> gets it and carries on computation, and finally terminates
> 4. In some cases it may happen that one of the processes may have to 
> wait for some value from some other process, because it did not
finish 
> on time .
> 
In DAML-S specs, there is a mention of some scheduling (process
control) 
ontology that has yet to be built. I think that the necessary features
to 
obtain such controlled states would be catered for in this ontology.
IMHO 
workflow and scheduling should go together, you cannot have one without
the 
other, for complex compositions. 

> Option 1:
>  >From here we see that some kind of a synchronization is needed
between 
> the 3 processes. Can we capture that in the DAMl-S model ? Is such a 
> specification part of the model ? Do we have control constructs for
them?
>  From all the examples that we have on the website and the 
> documentation, I have not been able to answer all these questions. I 
> want to build up such kind of an example and analyse the level of 
> complexity that can be handled through the DAML-S specs.
> 
I also add that there is no specific example that shows how the
majority of the 
control constructs can be used.

> Option 2:
> Since communication will actually happen within the atomic services
of 
> these composite services and since atomic services can execute 
> sequentially or independently in parallel with each other, the 
>  representation of this problem in DAML-S is possible in terms of
atomic 
> services and control constructs.
>

I think that if services A, B and C are composed then this does not
mean that 
all the atomic services in every composite one would be involved.
Altough it 
could be the case that for example some B' would require the output of
Services 
A (hence this would have to totally execute to give the required
output). I'd 
say that there will be some limit to the possible decomposition of a
composite 
service into its atomic ones. Since some of the atomic services would
be 
defined as a black box, and the developer doesn'want to expose them. 

What seems to be an issue is the how to generate the new DAML-S spec
for such a 
service. I think that this issue has not been tackled, at least not on
this 
list, after all composition should be delegated to an agent, that could 
possibly be able to reason and plan with a number of web services. Is
it not 
time that composition issues be tackled with such perspective in mind?

> I am certain abut option 1, however option 2 may solve this problem.
I 
> want a second opinion about option 2. Will the actual solution need
new 
> constructs or is option 2 the solution
> 
> Thanks,
> 
> Monika
> -- 

Charlie 
-- 
Charlie Abela
Research Student,
CSAI, Department,
University of Malta

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Received on Tuesday, 30 September 2003 23:05:43 GMT

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