The Cover PagesThe OASIS Cover Pages: The Online Resource for Markup Language Technologies
SEARCH | ABOUT | INDEX | NEWS | CORE STANDARDS | TECHNOLOGY REPORTS | EVENTS | LIBRARY
SEARCH
Advanced Search
ABOUT
Site Map
CP RSS Channel
Contact Us
Sponsoring CP
About Our Sponsors
NEWS
Cover Stories
Articles & Papers
Press Releases
CORE STANDARDS
XML
SGML
Schemas
XSL/XSLT/XPath
XLink
XML Query
CSS
SVG
TECHNOLOGY REPORTS
XML Applications
General Apps
Government Apps
Academic Apps
EVENTS
LIBRARY
Introductions
FAQs
Bibliography
Technology and Society
Semantics
Tech Topics
Software
Related Standards
Historic
Created: June 03, 2004.
News: Cover StoriesPrevious News ItemNext News Item

Proposed Technical Specification for Web Services Addressing and Referencing Framework.

Contents

Update 2004-10-07 In October 2004, W3C chartered a new Web Services Addressing Working Group as part of the W3C Web Services Activity. The goal of the Working Group is to produce a W3C Recommendation for Web Services Addressing by refining the WS-Addressing Member Submission. See details in the news story "W3C Announces Formation of New Web Services Addressing Working Group."

Update 2004-08-10: see "WS-Addressing Specification Presented to W3C as a Member Submission."

A bold move to catalyze standards convergence and create a public Web Services Addressing specification has been published on W3C's open Web services mailing list. Representatives from eleven major companies have proposed the creation of a new technical activity to "bring about industry convergence in the area of Web Service Referencing and Addressing." An open letter from Jeff Mischkinsky (Oracle) to the W3C AC Forum contains the proposal from W3C Advisory Committee members representing Arjuna, CycloneCommerce, Enigmatec, Fujitsu, Hitachi, Iona, NEC, Nokia, Oracle, SeeBeyond, and Sun.

Two principal specifications in the web services addressing and referencing area would be used as input to the new technical activity; the working group would "use these inputs without prejudice or restriction and, evaluate them on their technical merit,in its deliberations to create deliverables which satisfy the Charter requirements," together with other contributions which conform to the goals and scope of the proposed Charter. One is the the Web Services Addressing (WS-Addressing) specification, provided that it is submitted for such use. WS-Addressing is a proprietary specification in three published versions, owned by BEA, IBM, and Microsoft. The second key specification is WS-MessageDelivery Version 1.0, which "defines an abstract set of message delivery properties enabling message delivery for Web services that utilize Message Exchange Patterns associated with WSDL documents." WS-MessageDelivery is already a W3C Member Submission, contributed by a subset of W3C members companies that drafted the new proposal.

Key deliverables from the proposed working group would include a WS-Addressing and Referencing Framework Recommendation and a corresponding primer which introduces the new specification, including use cases and scenarios.

As justification for the new activity, the proposers reference the substantial informal discussion about how to bring about industry convergence in the area of web services addressing and are seeking to create a technical activity that "would have the participation of the entire web service community: we believe that the requirements are clear and that substantial contributions exist. With industry recognition of these elements, and contribution of their use, it is apparent that reasonable convergence should be feasible now."

According to the a proposed Scope statement, "The ability to identify participants in a Web service message exchange is fundamental to the dynamic and ever changing world of on-line business. WSDL provides mechanisms to define and describe the server side of an interaction (i.e. where to send a one way or a request messages to), but there are no standardized mechanisms to identify other delivery destinations that may exist in a message exchange pattern, such as a reply-to destination."

The purpose of the proposed working group would be to "define extensible and reusable mechanisms to reference Web Services, to allow such Web service references to be passed in messages, and to support WSDL Messsage Exchange Patterns. The specification would support the MEPs in WSDL 1.1, the MEPs anticipated in WSDL 2.0 if it is sufficiently progressed, and may define support for other useful MEPS such as basic callback."

As proposed, the new W3C working group would "collaborate with W3C efforts within the Web Service Activity including WSD, XMLP, WS-Chor as appropriate. [It would] collaborate with relevant OASIS TCs such as WS-RF, WS-N, WS-CAF, WS-BPEL, ASAP as appropriate." The authors of the proposal welcome debate and comments, either publicly or privately.

From the Open Letter to the W3C AC Forum

Excerpt only. See the complete text for context.

An Open Letter to the W3C AC Forum from the AC Representatives:

There has been lots of informal discussion of how to bring about industry convergence in the area of Web Service Referencing and Addressing. We all know that there are two major specifications "out there": WS-MessageDelivery [2], published by the W3C as a Member Submission, and two public versions of WS-Addressing. WS-MessageDelivery can be found at [2] and the latest version of WS-Addressing can be found at [3].

We believe the time as come to have an open and honest debate within the Advisory Committee to see if there is a way to charter a Working Group which would have the participation of the entire web service community. The benefits to the Web services user community of a successful outcome which results in a widely adopted open standard are obvious. What is not obvious is how to get there from here.

We float the following (WS-)strawman in the spirit of cooperation. We view it as a means to "test the waters" to see if there is the reasonable possibility of convergence within the Advisory Committee as to desirability of starting this work within the W3C community — now, and under these or similar conditions...

Possible Draft Charter, 2004-06-01: Web Services Addressing and Referencing Framework WG

Statement of Purpose

The purpose of this WG is to define extensible and reusable mechanisms to reference Web Services, to allow such Web service references to be passed in messages, and to support WSDL Messsage Exchange Patterns.

The specification must support the MEPs in WSDL 1.1, the MEPs anticipated in WSDL 2.0 if it is sufficiently progressed, and may define support for other useful MEPS such as basic callback [1].

Scope

The ability to identify participants in a Web service message exchange is fundamental to the dynamic and ever changing world of on-line business. WSDL provides mechanisms to define and describe the server side of an interaction (i.e., where to send a one way or a request messages to), but there are no standardized mechanisms to identify other delivery destinations that may exist in a message exchange pattern, such as a reply-to destination.

The following points constitute the requirements and scope for the output of this WG:

  1. A way to reference Web services (stateful or stateless), and other delivery destinations that participate in an MEP, in a way that enables those references to be passed around.

  2. Definition of abstract properties to identify recipients, senders, messages, reply-to, fault destinations, message correlation(s) between messages etc, in order to support MEPs as defined in WSDL 1.1 and anticipated for WSDL 2.0.

  3. Definition of bindings for SOAP 1.1 and 1.2, by mapping the abstract properties to SOAP 1.1 and SOAP 1.2 header blocks, including the normative use of the SOAP header blocks for each MEP

  4. Definition of callback pattern(s) and header blocks used to support point-to-point asynchronous communication. Other MEPs may also be considered

  5. Given a Web service reference, define normative mechanisms to obtain the service's WSDL description, referenced documents and related metadata. For example, WSDL 2.0 contains a wsdli:wsdlLocation attribute although its usage is undefined. Rules for its use and a similar mechanism for WSDL 1.1 could be defined.

  6. Discussion of non-normative scenarios and use cases describing possible ways to compose and use the specifications to be defined by the WG with other ongoing work, e.g., WS-RF, WS-Context, WSDM, etc.

Deliverables

  • A WS-Addressing and Referencing Framework Recommendation

  • A primer introducing the above specification, including use cases and scenarios as appropriate as described in 6. above.

Inputs

[We realize that this is one major contentious issues and in the spirit of compromise propose the following.]

The primary input to this WG will be the WS-Addressing [3] Member Submission published on <fill in date once it has been submitted>. Other contributions, including the W3C Member Submission WS-MessageDelivery [2] published on 26th April 2004, shall also be accepted, provided they conform to the goals and scope of this Charter.

The WG shall use these inputs without prejudice or restriction and evaluate them on their technical merit,in its deliberations to create deliverables which satisfy the Charter requirements.

Related Activities

The WG will collaborate with W3C efforts within the Web Service Activity including WSD, XMLP, WS-Chor as appropriate. The WG will collaborate with relevant OASIS TCs such as WS-RF, WS-N, WS-CAF, WS-BPEL, ASAP as appropriate.

References

[1] WS-I Usage Scenarios, Version 1.01, December 2003.
      http://www.ws-i.org/SampleApplications/SupplyChainManagement/2003-12/UsageScenarios-1.01.pdf

[2] WS-MessageDelivery, Version 1.0, 26 April 2004.
      http://www.w3.org/Submission/2004/SUBM-ws-messagedelivery-20040426/

[3] WS-Addressing, March 30, 2004
      http://www-106.ibm.com/developerworks/library/specification/ws-add/

About WS-Addressing

A Web Services Addressing (WS-Addressing) specification from BEA, IBM, and Microsoft was published on March 13, 2003 and was re-issued with modifications (apparently) in May 2003 though carrying the same "13 March 2003" publication date. According to the document's status statement, "WS-Addressing and related specifications are provided as-is and for review and evaluation only. BEA, IBM, and Microsoft hope to solicit your contributions and suggestions in the near future. BEA, IBM, and Microsoft Corporation make no warrantees or representations regarding the specifications in any manner whatsoever."

Specification abstract: "WS-Addressing provides transport-neutral mechanisms to address Web services and messages. Specifically, this specification defines XML elements to identify Web service endpoints and to secure end-to-end endpoint identification in messages. This specification enables messaging systems to support message transmission through networks that include processing nodes such as endpoint managers, firewalls, and gateways in a transport-neutral manner."

The WS-Addressing specification makes normative use of WS-Policy.

According to Sections 1-2 of the specification:

"Web Services Addressing (WS-Addressing) defines two constructs that convey information that is typically provided by transport protocols and messaging systems in an interoperable manner. These constructs normalize this underlying information into a uniform format that can be processed independently of transport or application. The two constructs are endpoint references and message information headers.

A Web service endpoint is a (referencible) entity, processor, or resource where Web service messages can be targeted. Endpoint references convey the information needed to identify/reference a Web service endpoint, and may be used in several different ways: endpoint references are suitable for conveying the information needed to access a Web service endpoint, but are also used to provide addresses for individual messages sent to and from Web services. To deal with this last usage case this specification defines a family of message information headers that allows uniform addressing of messages independent of underlying transport. These message information headers conveys end-to-end message characteristics including addressing for source and destination endpoints as well as message identity.

Both of these constructs are designed to be extensible and re-usable so that other specifications can build on and leverage endpoint references and message information headers..."

About WS-MessageDelivery

On April 26, 2004 W3C has acknowledged receipt of a WS-MessageDelivery Version 1.0 specification which "defines an abstract set of message delivery properties enabling message delivery for Web services that utilize Message Exchange Patterns associated with WSDL documents."

According to the announcement, "WS-MessageDelivery will make it easier to build complex applications using Web services by standardizing the way Web service endpoints are referenced when multiple Web services are engaged in common message exchange patterns. Designed to facilitate the patterns outlined in Web Services Description Language (WSDL), this specification lays a foundation to achieve far more sophisticated message-based interactions without sacrificing the loosely coupled model that underlies Web services. An example of a message exchange pattern enabled by WS-MessageDelivery is the 'callback pattern' — where one service sends a request to a second service, but instead of waiting idly for a reply, continues doing other work until notified that the second service has finished processing the request. Prior to WS-MessageDelivery, proprietary messaging constructs were needed to identify the callback service, limiting the development and interoperability of this key capability between vendors."

The W3C Member Submission was prepared by Oracle, Arjuna, Cyclone Commerce, Enigmatec, IONA, Nokia, SeeBeyond, and Sun Microsystems.

According to the W3C staff comment, the WS-MessageDelivery proposal is similar to the WS-Addressing proposal from BEA, IBM, and Microsoft: "while addressing the same scope as the WS-Addressing document, WS-MessageDelivery is more fully integrated with WSDL, by defining its relations with the WSDL Message Exchange Patterns or by introducing a WSMD description for WSDL. It also follows the current work of the W3C Web Services Description Working Group, and the service references introduced in WSDL 2.0. WS-Addressing, while relying on the WSDL concepts, does not use the WSDL service element as a service reference. WS-MessageDelivery relies on the implicit open content model of WSDL for extensions, while WS-Addressing uses an explicit 'reference properties' extension mechanism."

The WS-MessageDelivery Version 1.0 specification abstract summarizes: "[This] specification defines a mechanism to reference Web services (WSRef), essential abstract message delivery properties (AMDP), a SOAP binding for those properties, and the relationship of those properties to WSDL definitions and message exchange patterns. These properties enable SOAP messages to be transport independent — extending messaging capability to use separate transport protocol sessions or even using different transport protocols within the context of a message exchange pattern (MEP). Message delivery details are surfaced to the application layer, extending SOAP processors to use a wider range of message patterns and transport protocols to accomplish a Web service interaction. The abstract message delivery properties include web service references, message identification and message references. This specification outlines in detail how to build message exchange patterns consistent with WSDL 1.1 or WSDL 2.0 using the definitions in the specification. The semantics and mapping for the Callback Pattern, a commonly used message exchange pattern as a composite pattern, is defined. The Web service References (WSRef), Abstract Message Delivery Properties and a SOAP binding are designed for interoperability and extensibility."

The submission request provides royalty-free license terms from the eight sponsor companies for use of the WS-MessageDelivery technology.

Principal References
Hosted By
OASIS - Organization for the Advancement of Structured Information Standards

Sponsored By

IBM Corporation
ISIS Papyrus
Microsoft Corporation
Oracle Corporation

Primeton

XML Daily Newslink
Receive daily news updates from Managing Editor, Robin Cover.

 Newsletter Subscription
 Newsletter Archives
Bottom Globe Image

Document URI: http://xml.coverpages.org/ni2004-06-03-a.html  —  Legal stuff
Robin Cover, Editor: robin@oasis-open.org