W3C home > Mailing lists > Public > www-ws-arch@w3.org > November 2002

RE: Proposed Draft Charter for Choreography WG

From: David Orchard <dorchard@bea.com>
Date: Fri, 8 Nov 2002 11:39:09 -0800
To: <edwink@collaxa.com>, "'Jeff Mischkinsky'" <jeff.mischkinsky@oracle.com>, <www-ws-arch@w3.org>
Message-ID: <024e01c28769$c2fe5980$1f02a8c0@beasys.com>
MessageThe need for transactional models is why bpel uses ws-transaction
which specifies two phase and compensating tx.

BEA is also interested in the visualization aspects.  Though we do like the
idea of reusing UML in this regard.  However, are we ready to start
standardization on this?  Doesn't seem to be the same momentum.

I'd like to suggest that our architecture has to include these transaction
and visualization aspects in discussions around choroegraphy.  We need
glossary terms, requirements, etc.

  -----Original Message-----
  From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On
Behalf Of Edwin Khodabakchian
  Sent: Thursday, November 07, 2002 2:35 PM
  To: 'Jeff Mischkinsky'; www-ws-arch@w3.org
  Subject: RE: Proposed Draft Charter for Choreography WG


  It seems that the working group is walking towards a spefication that
describes/combines both the public protocol/interface and the private
implementation (executable workflow language).

  If that is the case, shouldn't the requirements for private implementation
also include the need for a transactional model? Exceptions are really what
make execution of compositions/workflows complex by increasing the
variability of the fabric that ties the services together. As discussed in
the mailing list earlier, exceptions can not be abstracted out of the
workflow logic. It seems that the only way to reduce this complexity and
make the solution viable for production systems is to have a framework for
cancellation/compensation/transactions built into the language.

  Also visualization/notations are a very important aspect of the problem:
XML is a pretty inhuman programming language and therefore the goal/dream
here is that most of the private implementations will be generated by visual
tools. BPMI for example has be working on a notation language for about a
year or so. BPML learned the hard way that the notation language was a very
important aspect of the usability and therefore could not be an after

  Any thoughts?


    -----Original Message-----
    From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org] On
Behalf Of Jeff Mischkinsky
    Sent: Thursday, November 07, 2002 1:57 PM
    To: www-ws-arch@w3.org
    Cc: Steve Bratt; C. M. Sperberg-McQueen
    Subject: Proposed Draft Charter for Choreography WG


    Web Services Choreography Working Group Charter Proposal
      1.. Goals and Scope of the Web Services Choreography Working Group
        1.. Inputs
        2.. Deliverables
      2.. Out of Scope
        1.. Qualities
        2.. Mappings to Programming Languages
      3.. Schedule
      4.. Relationships with Other Work
        1.. W3C Groups and Activities
        2.. External Groups
      5.. Participation, Meetings, and Logistics
        1.. Participation
        2.. Email Communication
        3.. Group Home Page
        4.. Meetings
        5.. Resources
        6.. W3C Team Involvement
        7.. Intellectual Property
      6.. References
    1 Goals and Scope of the Web Services Choreography Working Group
    It has become clear that a next step in the evolution of Web services
will be the ability to compose and describe the relationships between Web
services. Although differing terminology is used in the industry, such as
orchestration, collaboration, coordination, conversations, etc., the terms
all share a common characteristic of defining linkages and usage patterns
between web services. For the purpose of this document, and without
prejudice, we use the term choreography as a moniker to denote this space.

    Many presentations at the W3C Workshop on Web services of 11-12 April
2001 pointed to the need for a common interface and composition language to
help address choreography. The  Web Services Architecture Requirements
working draft created by the Web Services Architecture WG also lists the
idea of Web service choreography capabilities as a Critical Success Factor,
in support of several different top-level goals for the nascent Web services

    Two technical submissions -- WSCL[6], and WSCI[2], have recently been
published by the W3C as Technical Notes. There are other industry efforts in
the area of choreography languages, such as BPML[7] (defined by BPMI.org),
BPSS[8] (defined by ebXML.org),  IBM's
    WSFL[9], MSFT's XLANG[10], and IBM/MSFT/BEA's BPEL4WS[3] and their
companion specifications WS-Coordination[4] and WS-Transaction[5]), etc.

    The problems posed by the lack of a widely adopted choreography
specification,  the current proliferation of overlapping work, and the time
required to complete this effort merit the chartering a new W3C WG now. This
WG should address the choreography space encompassed by the input documents
and deliverables. This WG should also coordinate with other WGs within the
Web Service Activity, with the aim of developing an interoperable and open
standard for Web service choreography

    WSDL has proved very useful for describing a single service. Currently
complex natural language describing the obligations of the participants
detailing how to use a service (sequencing, state management, etc.) have to
accompany a WSDL description. The next step is to partially replace these
somewhat imprecise instructions with precise language. This will simplify
the daunting task companies now face when trying to use web services to
integrate their business processes. In a B2B context such a specification
could reduce the cost of integrating with new trading partners and
responding to changes in existing interfaces. In addition, creating a
standard language to describe the relationships between document exchanges
will be helpful to other standards bodies, such as RosettaNet or CIDX,
giving them a standard infrastructure for message choreography and enabling
them to focus on the core competencies relevant to their domain.

    The Web Services Choreography Working Group, part of the Web Services
Activity, is chartered to create the definition of a choreography,
language(s) for describing a choreography,  as well as the rules for
composition of, and interaction among, such choreographed Web services. The
language(s) should  build upon the foundation of the Web Service Description
Language (WSDL).

    1.1 Inputs
    The Working Group shall start by considering the various input documents
listed below and refine the scope and  factorization of the choreography
space. The Working Group is also expected to be aware of other work that has
been published in this area, although it is not a formal input.

    The Working Group shall consider, at a minimum, as input:

      a.. Web Services Architecture [1]
      b.. BPEL4WS [3] (if made available to the W3C by its owners)

      c.. WSCI [2]
      d.. W3C Choreography Workshop [date tbd]
    1.2 Deliverables
    The Working Group shall produce the following deliverables:

      a.. A requirements document. including a detailed description of the
factorization of the Choreography space
      b.. Usage scenarios
      c.. One or more specifications of choreography language(s) and its XML
      d.. A Primer
      e.. A test suite
    A test suite will be developed by the Working Group in order to assess
advancement to Proposed Recommendation stage and to promote
interoperability. The Working Group is expected to demonstrate two
interoperable implementations during the Candidate Recommendation phase.
Conformance requirements must be clearly stated in the specification

    The choreography specification(s) shall define (at a minimum) the
behavior and language constructs for the following key concepts:

      a.. Composition features
        a.. The ability to define a choregraphy as a web service, i.e. a
recursive composition model.
        b.. Definition of the choreography's externally observable behavior.
        c.. Ability to specify externally defined constraints.

        d.. Ability to represent stateful choreographies.
        e.. Definition of the identity of a choreography instance.
        f.. Lifecycle management (e.g. creation, termination, etc.).
        g.. Message exchange interactions between web services (e.g.
receive, invoke, etc.).
        h.. Behavior definitions (e.g. sequencing, looping concurrent
execution, etc.).
        i.. Scoping rules.
        j.. Activities.

      b.. Associations
        a.. Roles based on web service use.
        b.. Linkages between web services.
        c.. References to web services.

      c.. Message exchanges
        a.. Conversations - correlated message exchanges that define
interactions between web services.
        b.. Correlations and their life cycle management.
        c.. Correlation relationships with choreography instances and state.
      d.. State Management
        a.. Definition, manipulation, and query capabilities

    2 Out of Scope
    2.1 Qualities
    It is obvious that transactions, security, reliability, availability,
and other such qualities are intimately related with Web service
choreography, some more than others. It is not the goal of this group to
define these mechanisms, but it must clearly articulate the boundaries.

    2.2 Mappings to Programming Languages
    Web services are composed of interfaces to applications, which can be
written in different programming languages. The purpose of the Working Group
is to provide a framework that supports a wide variety of applications and
programming languages, and is not geared towards any programming language.
Given the wide variety of programming languages, the Working Group should
not define mappings to any programming languages.

    3 Schedule
    These are subject to revision due to editorial needs and external
scheduling issues; updates will be negotiated with the related groups and
recorded on the Web Services Choreography Working Group home page. Meeting
dates are mentioned here for planning purposes.

    December 2002

    Working Group chartered

    January 2003

    W3C Workshop on Web Services Choreography

    February 2003

    First Working Group face-to-face meeting

    April  2003

    First requirements document for Web services choreography

    July 2003

    First Working Draft of the Web services choreography specification.

    January  2004

    Candidate Recommendation for the Web services choreography

    June 2004

    Recommendation for the Web services choreography specification.

    June 2004

    Working Group ends

    The target duration of the Working Group is 2 years, through June 2004.
Experience suggests that 6 months of contingency should be allowed to
accommodate unexpected obstacles to progress.

    4 Relationship with Other Work
    4.1 W3C Groups and Activities
    XML and XML derived activities have become a strategic technology in W3C
and elsewhere. Each deliverable of any Working Group must satisfy the
dependencies from other W3C Working Groups before it can advance to
Candidate Recommendation.

    Web Services Activity

    The Web Services Architecture Working Group has been chartered to create
a document describing the architecture of Web services. A working draft of
this document is now available. The Working Group will continue to take this
document into account while designing the choreography language in order to
make sure that Web services can be deployed in an optimal way, as
recommended by the Web Services Architecture Working Group.

    The Working Group must describe services accessible via WSDL 1.2 defined
by the Web Services Description Group.

    It is expected that other Working Groups will be formed to deal with
different aspects of the Web services architecture. The Working Group will
closely coordinate its work with any other Working Group formed within the
Web Services Activity and generally in the Web services area, as well as
with relevant Working Groups outside of the Web Services Activity.

    The Working Group will participate in the Web Services Coordination

    XML Activity

    The typing of the messages must be possible using XML Schema. While no
dependencies other than the one with the XML Schema Working Group are
presently identified, the Web Services Description Working Group should be
prepared to coordinate with the XML Activity as necessary.

    QA Activity

    The Working Group will develop a primer and a test suite in order to
improve the quality of the documents produced and their implementations.

    Internationalization Activity

    The Internationalization Working Group will review work to ensure that
principles developed by that group are consistently applied.

    Web Accessibility Initiative

    The work of the Working Group will be subject to review by this project.

    XForms Working Group

    XForms can be seen as providing a user interface for Web services. The
Working Group will call for requirements from the XForms Working Group, if

    4.2 External Groups
    The Web Services Choreography Working Group should liaise with at least
the following groups outside W3C (see also W3C liaisons with other

    ebXML Joint Co-ordination Committee

    The ebXML initiative was a joint activity of UN/CEFACT (the United
Nations body responsible for UN/EDIFACT) and OASIS (Organization for the
Advancement of Structured Information Standards). Their charter was to
develop an XML-based infrastructure for electronic commerce, with a
particular focus on making connections between EDI and XML. While the
original ebXML initiative's charter ended in May of 2001, the work
transitioned to the respective sponsoring organizations (OASIS and
UN/CEFACT) under the auspices of an MOU signed by the two in May of 2001.

    UN/CEFACT (United Nations Centre for Trade Facilitation and Electronic
            The International Trade and Business Processes Group (TBG)
maintains ebXML Business Process Specification Schema, a metamodel for
business processes that is part of the ebXML framework.

            BPMI.org is a non-profit working towards establishing standards
for the management of business processes that span multiple applications,
corporate departments and business partners.

    Workflow Management Coalition

    The Workflow Management Coalition, founded in August 1993, is a
non-profit, international organization of workflow vendors, users, analysts
and university/research groups. The Coalition's mission is to promote and
develop the use of workflow through the establishment of standards for
software terminology, interoperability and connectivity between workflow

    5 Participation, Meetings, and Logistics
    5.1 Participation
    To join the Web Services Choreography Working Group, please follow the
instructions of section 4.2.3 of the Process Document, sending email to the
Working Group Chair and the W3C Team contact. The nomination must include
explicit agreement to this charter, including its goals, an IPR disclosure
and the level of effort required of the representative.

    Each Member organization may have at most two participants in the
Working Group. Only Working Group participants may engage in formal votes on
substantive issues. When a formal vote is required, each Member organization
or group of related Members is allowed one vote, even though the Member may
have several participants in the Working Group.

    The W3C Team is expected to have at most two participants in the Working
Group (including the Team contact). When a formal vote is required, the Team
is allowed one vote.

    Membership is also open to invited experts from the community, selected
by the Chair in order to balance the technical experience of the group.

    Each participant should expect to spend one day per week on work for
this Working Group.

    5.2 Email Communication
    The Working Group will utilize a public mailing list <www-ws-xxx@w3.org>
for its technical email communications. It is referred to in the rest of thi
s document as the Working Group mailing list.

    A Member-only mailing list <w3c-ws-xxx@w3.org> is available for
administrative purposes only.

    5.3 Group Home Page
    The Working Group has a home page that records the history of the group,
provides access to the archives, meeting minutes, updated schedule of
deliverables, membership list, and relevant documents and resources. The
page is available to the public and should be maintained by the Chair in
collaboration with the W3C Team contact.

    5.4 Meetings
    The Working Group will have distributed and face-to-face meetings.

    A one- to two-hour Working Group distributed meeting will be held every
week. When necessary to meet agreed-upon deadlines, distributed meetings may
be held twice a week.

    The Working Group may schedule face-to-face meetings in a manner that
maximizes co-location with events that Working Group members would be
attending anyway.

    Participation in meetings (distributed or face-to-face) is limited to
participants in good standing and individuals invited at the discretion of
the Chair to specific meetings.

    Decisions taken in meetings must be announced on the Working Group
mailing list. Observers may take part in decision-making at the discretion
of the Chair.

    Meeting records must include attendance, the results of group decisions,
and action items. They must be made publicly available except for
non-technical issues that do not directly affect the output of the Working
Group. The Chair will decide which issues are not made public.

    5.5 Resources
    To be successful, we expect the Working Group to have approximately 20
to 30 active participants. A large public review group that will participate
in the mailing list discussions is expected.

    The Chair for the Web Services Choreography Working Group will be XXXX.

    5.6 W3C Team Involvement
    The W3C Team expects to dedicate the time of the services of one Team
Contact, full-time, for the 2-year duration of the Working Group. XXXX will
provide this effort.

    5.7 Intellectual Property
    W3C promotes an open working environment. Whenever possible, technical
decisions should be made unencumbered by intellectual property right (IPR)
claims. W3C's policy for intellectual property is set out in section 2.2 of
the W3C Process document.

    Members of the Working Group are expected to disclose any intellectual
property they have in the area. This WG will work on a royalty-free basis,
as defined in the W3C Current Patent Practice document. The Working Group is
thus obliged to produce a specification which relies only on intellectual
property available on a royalty-free basis.

    If it proves impossible to produce specifications implementable on a
royalty-free basis, then a Patent Advisory Group will be launched as
described in the W3C Current Patent Practice document.

    Members disclose patent and other IPR claims by sending email to
<patent-issues@w3.org>, an archived mailing list that is readable by Members
and the W3C Team. Members must disclose all IPR claims to this mailing list
but they may also copy other recipients. IPR disclosures are expected to be
made public; Members should specify if their disclosure is confidential.

    6 References
    [1] http://www.w3.org/2002/ws/arch/2/08/wd-wsa-arch-20020821.html
    [2] http://www.w3.org/TR/wsci/
    [3] http://www-106.ibm.com/developerworks/library/ws-bpel/
    [4] http://www-106.ibm.com/developerworks/library/ws-coor/
    [6] http://www.w3.org/TR/wscl10/
    [7] http://www.bmpi.org
    [8] http://www.ebxml.org/specs/ebBPSS.pdf
    [9] http://www-3.ibm.com/software/solutions/webservices/pdf/WSFL.pdf
    [10] http://www.gotdotnet.com/team/xml_wsspecs/xlang-c/default.htm


    Team Contact: XXXXX
Received on Friday, 8 November 2002 15:59:59 UTC

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