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RE: Revised: Mission Statement

From: Martin Chapman <martin.chapman@oracle.com>
Date: Mon, 7 Jul 2003 09:04:52 -0700
To: "Champion, Mike" <Mike.Champion@SoftwareAG-USA.com>, <public-ws-chor@w3.org>
Message-ID: <PEEBJKKCFNCENDPJDEMIIEJNDGAA.martin.chapman@oracle.com>

I think Mike has made a good point here. If a composition presents a new
wsdl, it has to be hosted somewhere, even if its job is just to delegate out
to the parties (Yaron made a similar point the other week). I thought we had
ruled out this sort of central controller, for autonomous peer-peer
environments.
Thinking about this a little more, the only way I can see nesting of
choreographies is for one choreography to take on the role(s) defined in
another choreography. Something like:

Choreo 1: pay
	role payer
	role payee
	role cardagency

	payer sends payment details to cardagency
	//cardagency verifies and does stuff
	cardagency deposits money from payers card
	cardagency credits money (minus fee) to payees account

Choreo 2: Purchase goods
	role buyer
	role seller
	reuses Choreo 1: buyer=payer, seller=payee

	buyer submits PO
	seller checks warehouse
	seller send invoice to buyer
	buyer submits payment details (kicks off choreo 1)

	blah, blah

Something like that anyway.

Martin.

> -----Original Message-----
> From: public-ws-chor-request@w3.org
> [mailto:public-ws-chor-request@w3.org]On Behalf Of Champion, Mike
> Sent: Monday, July 07, 2003 7:20 AM
> To: public-ws-chor@w3.org
> Subject: RE: Revised: Mission Statement
>
>
>
>
>
> > -----Original Message-----
> > From: Monica J. Martin [mailto:monica.martin@sun.com]
> > Sent: Monday, July 07, 2003 10:02 AM
> > To: Jim Hendler
> > Cc: Steve Ross-Talbot; Nickolas Kavantzas; Cummins, Fred A; Martin
> > Chapman; Yaron Y. Goland; public-ws-chor@w3.org
> > Subject: Re: Revised: Mission Statement
> >
>
> > mm1: Then could we revise this working definition?
> >
> > > **A service composition is a composition of services that
> > results in a
> > > ANOTHER service. THIS service can be the combination of
> > distinct parts
> > > to form a whole of the same generic type. The web services could be
> > > combined to achieve a specific goal.*
>
> I appreciate the power of recursion as much as anyone <grin> but
> defining a
> service composition as a composition of services is not likely to win us
> great praise  for our grasp of the subtlties here.  Could we say "is a
> [concatenation | embedding | nesting | combination | whatever
> combination ]
> ..."? Or something  other than "composition" anyway.   Or is "composition"
> well-defined somewhere else?
>
> Also, we need to keep the other parts of the mision statement in
> mind here.
> If, when when one is combining services to present a single WSDL interface
> to the outside world and the global state of the interaction does not have
> to be exposed, one is doing that O-word thing rather than "Choreography."
> How can we distinguish Composition in the BPEL sense from
> Composition in the
> Choreography sense?
>
>
Received on Monday, 7 July 2003 12:04:53 GMT

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