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RE: The Unordered control construct in DAML-S 0.7

From: Paul Buhler <pbuhler@cs.cofc.edu>
Date: Mon, 21 Oct 2002 11:37:49 -0400
To: "'Monika Solanki'" <monika@dmu.ac.uk>, "'www-ws'" <www-ws@w3.org>
Message-id: <000c01c27917$d208b570$67110999@cs.cofc.edu>
The description of Unordered states, "Note that, while the unordered
construct itself gives no constraints on the order of execution,
nevertheless, in some cases, there may be constraints associated with
subcomponents, which must be respected."
 
My interpretation of this is that the constraints imposed on the
composite processes X and Y are preserved. IMO, once X and Y have been
declared, it become counter productive to examine lower level execution
order. By this I mean that the explanation of possible execution order
for a, b, c and d are insufficient and incomplete because the notation
';' meaning excites before does not take into account concurrency.
 
It should be sufficient to say that Z = (Unordered X Y) allows composite
process X to execute before, after, or at the same time as Y.
 
Regards,
 
Paul

-----Original Message-----
From: Monika Solanki [mailto:monika@dmu.ac.uk] 
Sent: Monday, October 21, 2002 10:19 AM
To: Paul Buhler; www-ws
Subject: Re: The Unordered control construct in DAML-S 0.7


Thanks for your Reply.

As mentioned by you:

The important thing to note is that in each of the possible execution
orders, the sequence a;b and c;d are preserved.

As mentioned in the documnetation, 

(Unordered a b) could result in the execution of a followed by b, or b
followed by a.

Which means that (Unordered X, Y) could result in the exceution of X,
followed by Y or Y followed by X.

Hence we have two sets of execution ordering, ( I think)

{(a;b), (c;d)} or {(c;d), (a;b)}

Since the individual processes have been defined to be executed in
sequence, I believe that their respective orders will be retained.

However as mentioned further in the documentation, these processes could
be executed in any order and certain sets of execution have been
defined. Therefore, I have a feeling that the orders a;b & c;d are not
necessary to be preserved. This is the cause of my confusion.

I would apprecitae any further clarifications in this regards.

Thanks

Monika


Paul Buhler wrote:


Hi Monika,
 
IMO, the DAML-S specification needs to be corrected to account for the
inconsistencies that you have pointed out. I suggest the following
fixes...
 
The line that currently reads "Z=(Unordered A B)" should read
"Z=(Unordered X Y)"
 
Likewise the duplicate entry (a;c;d;b) should be removed from the list.
The important thing to note is that in each of the possible execution
orders, the sequence a;b and c;d are preserved.
 
Regards,
 
Paul Buhler 

-----Original Message-----
From: www-ws-request@w3.org [mailto:www-ws-request@w3.org] On Behalf Of
Monika Solanki
Sent: Monday, October 21, 2002 4:21 AM
To: www-ws
Subject: The Unordered control construct in DAML-S 0.7


 I am a bit confused over the control cnstruct " unordered" as defined
in DAML-S 0.7:

Let a, b, c, and d be atomic processes, and X, Y, and Z be composite
processes:
X = (Sequence a b)
Y = (Sequence c d)
Z = (Unordered A B)

 do X & Y correspond to A & B respectively or am I missing something.

Z, then, translates to the following partial ordering:
{(a;b), (c;d)}
where ';' means \executes before", and the possible execution sequences
(total
orders) include
{(a;b;c;d), (a;c;b;d), (a;c;d;b), (a;c;d;b),
(c;d;a;b), (c;a;d;b), (c;a;b;d)}

are the repeition of execution sequence ordering a typo or intentional.

Any comments will be helpful.

Thanks

Monika


-- 
>**<>**<>**<>**<>**<>**<>**<>**<>**<>**< 
Monika Solanki
De Montfort University 
Software Technology Research Laboratory
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/
<http://www.cse.dmu.ac.uk/%7Emonika/>  
>**<>**<>**<>**<>**<>**<>**<>**<>**<>**< 



-- 
>**<>**<>**<>**<>**<>**<>**<>**<>**<>**< 
Monika Solanki
De Montfort University 
Software Technology Research Laboratory
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/
<http://www.cse.dmu.ac.uk/%7Emonika/>  
>**<>**<>**<>**<>**<>**<>**<>**<>**<>**< 
Received on Monday, 21 October 2002 11:39:13 GMT

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