Minutes W3C WS Choreography WG con call held on 6th May 2003, 1pm PDT.


1.            Role Call

2.            Confirm scribe

The following is a list of recent scribes (in order): Mike Champion, Abbie Barbir, David Burdett, John Dart, Carol MacDonald, Yaron Goland, Daniel Austin, Jim Hendler,  Peter Furniss, Ed Peters, Greg Ritzinger, Leonard Greski

3.             Approve minute


5.             Minutes29April.htm


6.             Action Item Review



7.            Dynamically changing participants in a choreography (hot topic from public mailing list)

Various emails plus some usecases

1.                         1.   FinancialServices Use case

2.                         2.   Use case on choreography negotiation

8.                 Formal models and choreography (hot topic from public mailing list)

a.                      The value of the value of the pi-calculus

b.                   What about petrinets

c.                   What is a process (hot topic from the mailing list)

9.             AOB.

10.        Summary of New Actions

Role Call:




 Martin Chapman


Steve Ross-Talbot




W3C Staff Contacts


Hugo Haas









Yaron Goland

BEA Systems

Mayilraj Krishnan

Cisco Systems Inc

Francis McCabe

Fujitsu Ltd

Yoko Seki

Hitachi, Ltd.

Assaf Arkin

Intalio Inc.

Ravi Byakod

Intalio Inc.

Richard Bonneau


Sanjay Patil


Eunju Kim

National Computerization Agency

Abbie Barbir

Nortel Networks

Greg Ritzinger


Jeff Mischkinsky

Oracle Corporation

Nickolas Kavantzas

Oracle Corporation

Kevin Liu


Michael Champion

Software AG

Carol McDonald

Sun Microsystems, Inc.

Jon Dart

TIBCO Software

Daniel Austin

W. W. Grainger, Inc.

Jean-Jacques Dubray




Raw IRC log at:   http://www.w3.org/2003/05/06-ws-chor-irc


Appointment of scribe:


Francis McCabe, Fujitsu, kindly volunteered to scribe for the meeting.



Minutes Approval:

Draft minutes at  http://lists.w3.org/Archives/Member/member-ws-chor/2003May/att-0008/Minutes29April.htm

Minutes approved with minor comments sent to list and role call updates.


Action Item Review

ACTION :          F2F planning.



New ACTION: on Yves should ensure a registration page for f2f

New ACTION: Daniel to post logistics information for June f2f


ACTION :     Harvesting of use cases by Steve

Done See is http://lists.w3.org/Archives/Member/member-ws-chor/2003May/0019.html


10 potential use cases

Steve needs comments, brick-bats and other bats

new version of requirements in approx 2 weeks from Daniel

missing callback use case (two use cases in Mchapmans doc)



ACTION :     Everyone should review requirements doc and provide feedback to editors. Editors consider response satisfactory. 


ACTION :     Everyone should read CSF part of WSA spec.  Daniel sent list of CSF references.



CSF sounds good

we need consensus? on the CSF approach for requirements

               Group agreed to work on CSFs

What is our mission statement ?


New ACTION: Daniel to kick off discussion on mission statement


WSA is commenting on choreography


New ACTION: John Dart to summarize WSA position on choreography wrt mission statement and goals


New ACTION: summarize use cases from privacy discussions



ACTION :     (clarifying) SRT will harvest use cases, URIs, and publish them – NO PROGRESS


ACTION:    SRT will continue to monitor use cases -- He spent 5 hours going through emails and summarized to list. 

ACTION:     ALL, feedback on usecase summary to SRT.

ACTION :     Collect list of technologies we should harvest from (Open)


Daniel: What are existing technologies we need?


Martin: key input technologies


JJ: I volunteer for BPSS

CarolMcD :subject experts reporting sounds like a good idea

Yaron:  Gee, I'm guessing I could take BPEL

SRT: Leveling the playing field on new technologies based on appointed experts gets my vote.

Daniel: Need volunteers to represent and explore technologies.


Examples: BPEL, WSCI,


Steve: more examples: BPSS, BPML, DAML-S

JJ: PIPs are probably covered by BPSS

Arkin: XPDL?

CarolMcD: bpml damls pips

Yaron: I thought RosettaNet hadn't officially adopted BPSS?


John takes on Rosetta-net?

Jj: Yes but BPSS was created by RN people


Main features, why are we interested, and maybe why not



WSCI is a significant input


We need to know what is good and what is less than good


New ACTION: Carol to look into WSCI and to pester Assaf



ACTION :     SRT will capture requirements from this discussion OPEN

ACTION :     SRT let's capture these use cases in our documents open

ACTION:    DavidB should send these use cases in to the list open


Dynamically changing participants in a choreography

In financial services, need to participate with different partners chosen on a dynamic basis

Rules of engagement can be seen as choreography

Which attributes are relevant to choreography?

Modeling of time and observable state

Participants change based on the logic of the choreography

Can you dynamically bind different endpoints to role during a choreography

Do we need this power?

Can I dynamically introduce new role/types on the fly?

What about a trader changing roles during a trade?

Can you change roles during a choreography

What is a role?

Agents must? be able to take on different roles?

JJ: role is a place holder for a binding

MChapman: A role defines responsibilities of a particular partner in a choreography

JJ: Can you have changing roles if the choreography is static?

JJ: more than one level of role.

JJ: E.g. is buyer a role

JD: Delegation allows one to enter a choreography and delegate to another the completion of the choreography

Mchapman: when a choreography is instantiated, endpoints have to be bound. (Buyer = A, Shipper=C, Seller=B) Are these immutable - that is the question.

CarolMcD: bound or not bound - that is the question

Frankmccabe: sees two questions: do we want to allow dynamic re-assignment of roles, and techniques for doing this

Steve: if a role is public then anonymity becomes very difficult.

Steve: a trader does need to change roles dynamically

overlapping choreographies active simultaneously

MChapman: buyers and seller, credit card agencies represent roles.

MChapman: a role refers to a participant in particular MEP

Trader has to has selling interface, trading interface, price fixing interface ...

mchapman: roles are statically defined, participants are not defined?

we want to be able to define choreographies to permit participants to change roles dynamically

jd: Requirement to permit participants to dynamically join and leave choreographies. This could

likely fulfill the use cases

that call for role re-assignment. E.g. a trading scenario can be

modelled by having a participant

enter one or more choreographies (possibly overlapping in time) as a

buyer or seller. It is not

necessary to have a participant bound into a buyer role morph into a seller.


Frank McCabe followed up by remarking: "an auctioneer isn't ever a


JD: making (I think) the same point; roles are distinct, transformation of role isn't necessary.


Formal models


SRT:most has been said about pi calculus


JJ: two comment on formal models

JJ: pi-calculus good model for theory, but it has many concepts missing

SRT:I like the idea of the notion of auctioneer never being a punter. The should be true in wholesale banking. This is what Eliot Spitzer wants from investment banking. It's case of enforcing chinese walls.


JJ: chor is an expression of a sequence of message exchanges.

JJ: can be modeled in pi-cal but modeling is difficult

??: (Do I hear intractable?)

jj: Expressivity is low

jj: all sides need to be understood  together.


Nick: Agree in parts A formal model describes an abstract computation not a complete language

nick: Expressiveness is different to programmabliity

Mchapman: pi should be seen as an assembly langauge type thing. we need to derive the appropriate abstractions useful to define choreography


SRT: +1 to nick - he says showing his bias


nick: Pi-calculus's composition gives a global view?

nick: maybe there is a subset of pi; e.g., CCS.

Frankmccabe: (PI is not enough - my comment)


Daniel: heard a lot about PI, not much about others. What are the requirements of choreographies

E.g., grove and hedge models, graph theories

Who is the intended audience for formal models.

(Double/triple PhDs)

Utility should drive approach

PI-calculus is cool

What are we looking for?

What theorems do we wish to be able to prove


frankmccabe: I'm in favour of event calculus myself




ISSUE: dynamic choreographies

Arkin: I'm in favor of anything that can be reduced to 0


ACTION: resolve the ISSUE of dynamic choreographies


ACTION: people to propose alternate formal models


ACTION: Steve to dig up more references







Summary of New Actions


ACTION: on Eve W3C should ensure a registration page for f2f

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-18-43


ACTION: Daniel to post logistics information

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-19-10


ACTION: Daniel to kick off discussion on mission statement

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-25-36


ACTION: John Dart to summarize WSA position on choreography wrt mission statement and goals

                               recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-28-21


ACTION: summarize use cases from privacy discussions

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-30-39


ACTION: Carol to look into WSCI and to pester Assaf

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-37-21


ACTION: SRT will capture requirements, referring to last discussion in conference call

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-39-08


ACTION: SRT to capture reqs from minutes

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T20-39-33


ACTION: resolve the ISSUE of dynamic choreographies

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T21-30-53


ACTION: people to propose alternate formal models

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T21-32-29


ACTION: Steve to dig up more references

recorded in http://www.w3.org/2003/05/06-ws-chor-irc#T21-32-55