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Created: April 19, 2005.
News: Cover StoriesPrevious News ItemNext News Item

OASIS TC to Finalize WS-ReliableMessaging and WS-RM Policy Assertion Specifications.

Contents

Update 2007-05-15: WS-ReliableMessaging Version 1.1 was submitted for ballot as an OASIS Standard in May 2007. Four years in development, WS-RM has three parts. The core "WS-ReliableMessaging V1.1" document defines a protocol for reliable message exchange even in the presence of network/system failures. The protocol allows Web service nodes to implement a variety of delivery assurances, including 'At Most Once', 'At Least Once', 'Exactly Once', and 'In Order' delivery of messages. "WS-ReliableMessaging Policy 1.1" defines an XML policy language that enables Web services to advertise their support for the WS-ReliableMessaging specification; it is is designed for use with the WS-Policy Framework. "WS-MakeConnection" defines a protocol for two-way communication when only a transport specific back-channel is available. See "WS-ReliableMessaging Version 1.1 Submitted for Ballot as an OASIS Standard."

Update 2005-05-03: On May 03, 2005, OASIS announced a Call for Participation in the new OASIS Web Services Reliable Exchange (WS-RX) Technical Committee. The new TC operates in the "RF on RAND Terms" IPR mode as defined in the OASIS IPR Policy dated April 15, 2005. The TC Charter was supported by some forty-one (41) individuals, identified as 'Proposers' of the TC, including the companies ACORD, Actional, Adobe, Arjuna, BEA Systems, Blue Titan, Choreology, Entrust, Ericsson, Hitachi, IBM, IONA, Microsoft, NEC, Nortel, Novell, OAGi, Oracle, Reactivity, SAP, SeeBeyond, Sonic Software, Sun Microsystems, Systinet, TIBCO, United Kingdom e-Government Unit, The University of North Carolina at Chapel Hill, and webMethods.

[April 19, 2005] Twenty-five months after the first public announcement for the Web Services Reliable Messaging Protocol (WS-ReliableMessaging), the co-authors BEA Systems, IBM, Microsoft, and TIBCO have announced that the WS-ReliableMessaging and WS-RM Policy specifications will be submitted to OASIS for further refinement and finalization as a Web services standard.

In February 2005, WS-RM was re-published as two separate specifications: one for the core protocol elements and one for the related policy assertion. WS-ReliableMessaging "describes a protocol and SOAP binding that allows messages to be delivered reliably between distributed applications in the presence of software component, system, or network failures. The protocol is described in this specification in a transport-independent manner allowing it to be implemented using different network technologies. The protocol depends upon other Web services specifications for the identification of service endpoint addresses and policies." The Web Services Reliable Messaging Policy Assertion (WS-RM Policy) specification refactors the Reliable Messaging policy assertion into a discrete specification.

Reliable message-based communication, according to the recent announcement, is a "vital element in enterprise-critical applications. Reliable messaging includes the ability to ensure that a message exchange has been completed correctly with no messages lost or duplicated. For example, within an order processing system, it is critical for the application to know that all items have been received and none have been duplicated. If a client using this application temporarily loses network connectivity during the course of order submission, reliable messaging ensures that the order is received once and only once. In some applications, it can also be important to know the correct sequencing of messages. The WS-RM protocol, together with the other Web services specifications such as those related to security, policy, transactions and coordination, helps provide a more secure, robust and scalable approach to reliable messaging."

The WS-RM co-authors have drafted a proposal for a new OASIS Technical Committee that will be chartered to finalize work on the Web Services Reliable Messaging specification. The proposed charter is based upon "extensive industry support and interoperability with a number of implementations beyond the authoring companies as a result of a series of feedback and interoperability workshops." An April 13-14, 2005 "WS-ReliableMessaging and WS-SecureConversation Composability Interop Workshop" hosted by Microsoft Corporation tested tested composition between WS-ReliableMessaging and the WS-SecureConversation and WS-Trust specifications, as described in a Secure WS-ReliableMessaging Scenarios document prepared for the Workshop participants.

Several other companies and organizations have already "expressed support for the launch of this Technical Committee at OASIS: Actional, Adobe, Arjuna, Blue Titan, Choreology, Ericsson, IONA, OAGi, Reactivity, Sonic, Sun Microsystems, Systinet, webMethods, the U.K. government, and the University of North Carolina, Chapel Hill.

The announcement confirms that the specification authors will not collect royalties for use of intellectual property in WS-RM, as stated in the most recent version of the specification: [the co-authors each] "agree to grant you a license, under royalty-free and otherwise reasonable, nondiscriminatory terms and conditions, to their respective essential patent claims that they deem necessary to implement the Specification." This "RF" declaration eliminates one of the most onerous terms allowed under (sic!, so-called) "RAND" licensing.

Note: Reliable message transfer is a natural concern in any context where communication takes place through "messaging" protocols; some of these mechanisms are referenced in the topic document "Reliable Messaging." Of special interest is Web Services Reliability Specification (WS-Reliability), an OASIS Standard produced by members of the OASIS Web Services Reliable Messaging (WSRM) Technical Committee. Upon creation of the new OASIS TC proposed by the authors of WS-RM specification, OASIS will be host to two similar (arguably, "competitive") specifications. Such an event is inevitable given the OASIS TC Process, which allows independent groups to form different TCs in which competitive standardization efforts co-exist, at least initially.

Bibliographic Information

  • Web Services Reliable Messaging Protocol (WS-ReliableMessaging). February 2005. Edited by Christopher Ferris (IBM) and David Langworthy (Microsoft). 37 pages. Copyright (c) 2002-2005 BEA Systems, IBM, Microsoft Corporation, Inc, and TIBCO Software Inc. All rights reserved. XML namespace URI: http://schemas.xmlsoap.org/ws/2005/02/rm.

    Authors: Ruslan Bilorusets (BEA), Don Box (Microsoft), Luis Felipe Cabrera (Microsoft), Doug Davis (IBM), Donald Ferguson (IBM), Christopher Ferris (IBM, Editor), Tom Freund (IBM), Mary Ann Hondo (IBM), John Ibbotson (IBM), Lei Jin (BEA), Chris Kaler (Microsoft), David Langworthy (Microsoft, Editor) Amelia Lewis (TIBCO Software), Rodney Limprecht (Microsoft), Steve Lucco (Microsoft), Don Mullen (TIBCO Software), Anthony Nadalin (IBM), Mark Nottingham (BEA), David Orchard (BEA), Jamie Roots (IBM), Shivajee Samdarshi (TIBCO Software), John Shewchuk (Microsoft), and Tony Storey (IBM).

  • Web Services Reliable Messaging Policy Assertion (WS-RM Policy). February 2005. Edited by Stefan Batres (Microsoft) and Christopher Ferris (IBM). 11 pages. Copyright (c) 2002-2005 BEA Systems, IBM, Microsoft Corporation, Inc, and TIBCO Software Inc. All rights reserved. XML namespace URI: http://schemas.xmlsoap.org/ws/2005/02/rm/policy.

    Authors: Stefan Batres (Microsoft, Editor) Ruslan Bilorusets (BEA), Don Box (Microsoft), Luis Felipe Cabrera (Microsoft), Derek Collison (TIBCO Software), Donald Ferguson (IBM), Christopher Ferris (IBM, Editor), Tom Freund (IBM), Mary Ann Hondo (IBM), John Ibbotson (IBM), Lei Jin (BEA), Chris Kaler (Microsoft), David Langworthy (Microsoft), Amelia Lewis (TIBCO Software), Rodney Limprecht (Microsoft), Steve Lucco (Microsoft), Don Mullen (TIBCO Software), Anthony Nadalin (IBM), Mark Nottingham (BEA), David Orchard (BEA), Shivajee Samdarshi (TIBCO Software), John Shewchuk (Microsoft), Tony Storey (IBM).

Overview of WS-RM: Reliable Messaging Model and Assertion Model

Reliable Messaging Model: [As described in Web Services Reliable Messaging Protocol (WS-ReliableMessaging)] Many errors may interrupt a conversation. Messages may be lost, duplicated or reordered. Further the host systems may experience failures and lose volatile state.

WS-ReliableMessaging provides an interoperable protocol that a Reliable Messaging (RM) Source and Reliable Messaging (RM) Destination use to provide Application Source and Destination a guarantee that a message that is sent will be delivered. The guarantee is specified as a delivery assurance. The protocol supports the endpoints in providing these delivery assurances. It is the responsibility of the RM Source and RM Destination to fulfill the delivery assurances, or raise an error. The protocol defined here allows endpoints to meet this guarantee for the delivery assurances defined below.

Persistence considerations related to an endpoint's ability to satisfy the delivery assurances defined below are the responsibility of the implementation and do not affect the wire protocol. As such, they are out of scope of this specification.

There are four basic delivery assurances that endpoints can provide:

  • AtMostOnce: Messages will be delivered at most once without duplication or an error will be raised on at least one endpoint. It is possible that some messages in a sequence may not be delivered.
  • AtLeastOnce: Every message sent will be delivered or an error will be raised on at least one endpoint. Some messages may be delivered more than once.
  • ExactlyOnce: Every message sent will be delivered without duplication or an error will be raised on at least one endpoint. This delivery assurance is the logical "and" of the two prior delivery assurances.
  • InOrder: Messages will be delivered in the order that they were sent. This delivery assurance may be combined with any of the above delivery assurances. It requires that the sequence observed by the ultimate receiver be non-decreasing. It says nothing about duplications or omissions..."

Assertion Model: [As described in Web Services Reliable Messaging Policy Assertion (WS-RM Policy)]: The RM policy assertion indicates that the RM Source and RM Destination must use WS-ReliableMessaging to ensure reliable message delivery. Specifically, the WS-ReliableMessaging protocol determines invariants maintained by the reliable messaging endpoints and the directives used to track and manage the delivery of a Sequence of messages.

The assertion defines an inactivity timeout parameter that either the RM Source or RM Destination may include. If during this duration, an endpoint has received no application or control messages, the endpoint may consider the RM Sequence to have been terminated due to inactivity.

This assertion also defines a base retransmission interval parameter that the RM Source may include. If no acknowledgement has been received for a given message within the interval, the RM Source will retransmit the message. The retransmission interval may be modified at the Source's discretion during the lifetime of the Sequence. This parameter does not alter the formulation of messages as transmitted, only the timing of their transmission.

Similarly, this assertion defines a backoff parameter that the RM Source may include to indicate the retransmission interval will be adjusted using the commonly known exponential backoff algorithm.

Finally, this assertion defines an acknowledgement interval parameter that the RM Destination may include. Per WS-ReliableMessaging, acknowledgements are sent on return messages or sent stand-alone. If a return message is not available to send an acknowledgement, an RM Destination may wait for up to the acknowledgement interval before sending a stand-alone acknowledgement. If there are no unacknowledged messages, the RM Destination may choose not to send an acknowledgement. This parameter does not alter the formulation of messages or acknowledgements as transmitted; it does not alter the meaning of the wsrm:AckRequested directive. Its purpose is to communicate the timing of acknowledgements so that the RM Source may tune appropriately..."

From the Announcement (April 19, 2005)

BEA Systems Inc., IBM Corp., Microsoft Corp. and TIBCO Software Inc. today announced they will submit the latest version of the Web Services ReliableMessaging (WS-RM) specification, comprising both protocol and policy assertions, to the Organization for the Advancement of Structured Information Standards (OASIS) for further refinement and finalization as a Web services standard. Incorporating broad industry feedback, the co-authors proposed a technical committee and charter to enable further review and industry collaboration on the proposed standard.

WS-RM has received extensive industry support and interoperability with a number of implementations beyond the authoring companies as a result of a series of feedback and interoperability workshops, with the most recent workshop having been held April 13-14, 2005. In addition to the co-authors, a wide range of companies and organizations, including Actional, Adobe, Arjuna, Blue Titan, Choreology, Ericsson, IONA, OAGi, Reactivity, Sonic, Sun Microsystems, Systinet, webMethods, the U.K. government, and the University of North Carolina, Chapel Hill, have expressed support for the launch of this effort in OASIS.

The co-authors are committed to the development of open industry standards to help drive widespread adoption of Web services and will not charge royalties in conjunction with WS-RM. The co-authors are looking forward to future collaboration in helping to bring together a more cohesive and composable Web services architecture.

"BEA is pleased to join with the co-authors and co-proposers on WS-RM to establish a technical committee for ongoing refinement efforts within OASIS," said David Orchard, director of technology at BEA Systems. "We look forward to continued engagement with our industry partners to help further promote the adoption of Web services."

"Our customers will benefit from the functions that WS-RM provides as they develop more secure, reliable business applications based on Web services," said Karla Norsworthy, vice president of software standards at IBM. "With this technology, delivery of messages between partners, suppliers and customers can be assured in an efficient and scalable way that will support both enterprise-level applications utilizing middleware and simpler point-to-point applications. With the submission to OASIS, we look forward to further industry contributions and adoption."

"The submission of WS-RM to OASIS is an important step toward achieving a cohesive and composable architecture for secure, reliable, transacted Web services," said Ari Bixhorn, director of Web Services Strategy for Microsoft. "We look forward to refining and finalizing the reliable messaging specification with OASIS and our industry partners in order to best meet the needs of our customers."

"TIBCO is committed to driving the development of open industry standards and the widespread adoption of Web services. WS-RM extends both the reliability and reach of a messaging backbone beyond the enterprise and over the Internet," said Matt Quinn, vice president of Product Strategy at TIBCO Software. "As a co-author of the WS-RM specification, TIBCO has contributed years of enterprise messaging knowledge and experience into the development of this specification and will continue to support the evolution of this into an OASIS standard."

WS-ReliableMessaging and the Basic Business-to-Business (B2B) Profile 1.0

IBM highlights the key role of the WS-ReliableMessaging specification in the recently published Basic B2B Profile Version 1.0. Details are presented in Section 5 "Reliable Delivery of Messages," pages 9-13:

The WS-I Basic Profile (BP) and Basic Security Profile (BSP) are profiles that "go a long way toward improving interoperability in many different scenarios. However, in order to ensure that its profiles lead to broad interoperability, WS-I requires a very high level of industry consensus on which Web services specifications it will include in its profiles and looks for broad support of those specifications through implementation in products such as application development tools, middleware, and solution components. Because the industry has not yet reached consensus on some of the advanced Web services specifications, it could be some time before WS-I incorporates them into its profiles.

Many B2B scenarios require more functionality than what the current set of WS-I profiles provides. Specifically, two types of functionality that are currently not supported by any of the WS-I profiles, yet are required for many B2B scenarios, are asynchronous message exchange patterns, and reliable delivery of messages. The WS-Addressing specification provides the former, and the WS-ReliableMessaging specification provides the latter. These two specifications, together with the WS-I Basic Profile and Basic Security Profile, make up the basis of the guidance provided by the Basic B2B Profile, which should enable the use of Web services to satisfy the requirements of most basic B2B integration scenarios..." [from the reference page]

Adding support for WS-ReliableMessaging (WS-RM): "The choice of a specification to satisfy the reliable messaging requirements for B2B supply chain integration was not as easy, because there are at least two notable specifications from which to choose — the WS-Reliability OASIS Standard and the WS-ReliableMessaging specification. Ultimately, the decision was made to go with WS-ReliableMessaging because it has been specifically designed to compose with WS-Addressing and WS-Security (as well as a number of other WS-* specs)... As with WS-Addressing, the [B2B] profile provides guidance as to which of the WS-RM elements must include a soap:mustUnderstand attribute with a value of '1' (wsrm:Sequence). It also provides guidance as to how the specification should be used in composition with WS-Addressing by constraining against the use of the WS-Addressing Anonymous URI for the wsa:ReplyTo SOAP header block's value in the context of an input (request) message of an operation that is using WS-RM for both the request and response messages of the operation. Finally, the profile adds guidance regarding composition with WS-Security (BSP) by specifying which of the WS-RM elements need to be digitally signed along with the contents of the SOAP Body, ensuring the integrity of the Sequence (wsrm:Sequence, wsrm:SequenceAcknowledgement)..." [from the 2005-04 technical paper by Chris Ferris]

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