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Re: Mobility, pi calculus and Web service Choreography

From: <kohei@dcs.qmul.ac.uk>
Date: Tue, 30 Aug 2005 17:07:01 +0100 (BST)
Message-ID: <43073.>
To: "Monika Solanki" <monika@dmu.ac.uk>
Cc: public-ws-chor@w3.org, kohei@dcs.qmul.ac.uk

Dear Monica,

Following Steve's message, here are two relevant scenes where
"mobility helps".

(1) As Steve wrote, in some business protocols you do pass
channels dynamically during communication --- a party may
not know existence of some channel, but later acquire it
from another party, and interact through that channel. This
is the first example where channel passing is important.

(2) Another, and more subtle, usage is a way to combine actions
in CDL. This has been somewhat implicit so far (but is going
to be explicit in the final spec I believe). In essence, when
you write in CDL there are a sequence of interactions, these
are assumed to belong to a certain logical unit, not to be
interfered by another instance of the same or different choreo-
graphy description. This is most easily represented formally
as interactions using private channels which is initially passed
from an invoker to the invoked, used throughout the scenario.
(This is a logical description, not how you should implement.)

* * *

I think (1) is fairly obvious, but (2) is somewhat as important,
since it underlies CDL even if we do not use channel passing

Please let me know if you have further inquiries. As Steven wrote,
pi4tech site would have good examples.

Best wishes,


> Hello,
> I am trying to understand in a bit more detail, how the mobility part in
> Pi calculus helps Web service composition. Please can someone help me
> here. I have read a lot of papers that talk about establishing
> behavioural equivalence between pi calculus and XML-Based languagaes,
> Incidentally none of them highlighted the importance of mobility.
> Thanks,
> Monika
Received on Tuesday, 30 August 2005 16:07:08 UTC

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