Update 2005-10: On October 01, 2005 OASIS announced a Call for Participation in a new Web Services Transaction (WS-TX) Technical Committee. According to the Charter, the purpose of the WS-TX Technical Committee is "to define a set of protocols to coordinate the outcomes of distributed application actions. The TC will specify an extensible framework for developing coordination protocols through continued refinement of the Web Services Coordination (WS-Coordination v 1.0) specification; in addition, the TC will continue refinement of protocols for two coordination types that use the WS-Coordination framework: atomic transaction (AT) and business activity (BA), based on the Web Services Atomic Transaction (WS-AtomicTransaction v 1.0) and Web Services Business Activity (WS-BusinessActivity v 1.0) specifications submitted to the TC. Collectively, these three specifications will be referred to as the WS-TX Specifications..."

[August 12, 2002] Microsoft, IBM, and BEA have announced the publication of three specifications which "collectively describe how to reliably define, create, and connect multiple business processes in a Web services environment. The specifications will help organizations coordinate business processes and transactions within the enterprise and with partners and customers across heterogeneous systems and within the enterprise. Announced were the new specifications to address transacted communications of Web services (WS-Coordination, WS-Transaction) and a new language to describe business processes (Business Process Execution Language for Web Services, or BPEL4WS). BPEL4WS allows companies to describe business processes that include multiple Web services and standardize message exchange internally and between partners. WS-Coordination and WS-Transaction provide companies with a reliable and durable way of handling multiple Web services interactions, regardless of the underlying computing infrastructure."

From the announcement: "A business process describes the flow of tasks, the order in which they need to be performed, the type of data shared and how other partners are involved... Once the business process and the connections with customers, partners and internal entities are defined using BPEL4WS, the next step is to coordinate the various activities that occur within a business process, in order and at the right time for completion. WS-Coordination and WS-Transaction complement BPEL4WS by providing a way for companies to coordinate and integrate a number of distinct Web services and business processes, consistently and reliably, across a variety of implementation environments to ensure the right outcome... For example, a travel agency that exposes its business travel processes -- such as hotel, flight or car rental reservation applications -- as Web services can integrate and transact with the business travel processes of its customers and partners. Using BPEL4WS, WS-Coordination and WS-Transaction, the travel agency's customer could electronically submit a travel itinerary to an agent; the agent's system can automatically procure the appropriate airline, hotel and car reservations from partners to match the customer request; and the system can then send confirmation of all reservations back to the customer once the itinerary processing is complete. In case one of the applications fails, tasks that have already been completed can be automatically undone..."

Business Process Execution Language for Web Services abstract: "This document defines a notation for specifying business process behavior based on Web Services. This notation is called Business Process Execution Language for Web Services (abbreviated to BPEL4WS in the rest of this document). Processes in BPEL4WS export and import functionality by using Web Service interfaces exclusively. Business processes can be described in two ways. Executable business processes model actual behavior of a participant in a business interaction. Business protocols, in contrast, use process descriptions that specify the mutually visible message exchange behavior of each of the parties involved in the protocol, without revealing their internal behavior. The process descriptions for business protocols are called abstract processes. BPEL4WS is meant to be used to model the behavior of both executable and abstract processes. BPEL4WS provides a language for the formal specification of business processes and business interaction protocols. By doing so, it extends the Web Services interaction model and enables it to support business transactions. BPEL4WS defines an interoperable integration model that should facilitate the expansion of automated process integration in both the intra-corporate and the business-to-business spaces... This is an initial public draft release of the BPEL4WS specification. We anticipate a number of extensions to the feature set of BPEL4WS that are discussed briefly at the end of the document. BPEL4WS represents a convergence of the ideas in the XLANG and WSFL specifications. Both XLANG and WSFL are superseded by the BPEL4WS specification."

Web Services Coordination abstract: "This specification describes an extensible framework for providing protocols that coordinate the actions of distributed applications. Such coordination protocols are used to support a number of applications, including those that need to reach consistent agreement on the outcome of distributed transactions. The framework defined in this specification enables an application service to create a context needed to propagate an activity to other services and to register for coordination protocols. The framework enables existing transaction processing, workflow, and other systems for coordination to hide their proprietary protocols and to operate in a heterogeneous environment. Additionally this specification describes a definition of the structure of context and the requirements for propagating context between cooperating services... By using the SOAP and WSDL extensibility model, SOAP-based and WSDL-based specifications are designed to be composed with each other to define a rich Web services environment. As such, WS-Coordination by itself does not define all the features required for a complete solution. WS-Coordination is a building block that is used in conjunction with other specifications and application-specific protocols to accommodate a wide variety of protocols related to the operation of distributed Web services. The Web service protocols defined in this specification should be used when interoperability is needed across vendor implementations, trust domains, etc. Thus, the Web service protocols defined in this specification can be combined with proprietary protocols within the same application."

Web Service Transaction overview: "This specification describes coordination types that are used with the extensible coordination framework described in the WS-Coordination specification. It defines two coordination types: Atomic Transaction (AT) and Business Activity (BA). Developers can use either or both of these coordination types when building applications that require consistent agreement on the outcome of distributed activities... WS-Transaction is a building block used with other specifications of web services (e.g., WS-Coordination, WS-Security) and application-specific protocols that are able to accommodate a wide variety of coordination protocols related to the coordination actions of distributed applications... An atomic transaction (AT) is used to coordinate activities having a short duration and executed within limited trust domains. They are called atomic transactions because they have an "all or nothing" property. The Atomic Transaction specification defines protocols that enable existing transaction processing systems to wrap their proprietary protocols and interoperate across different hardware and software vendors. A business activity (BA) is used to coordinate activities that are long in duration and desire to apply business logic to handle business exceptions. The long duration prohibits locking data resources to make actions tentative and hidden from other applications. Instead, actions are applied immediately and are permanent. The Business Activity specification defines protocols that enable existing business process and work flow systems to wrap their proprietary mechanisms and interoperate across trust boundaries and different vendor implementations..."

Websites for the published specifications:

• Microsoft: http://msdn.microsoft.com/webservices/
• IBM: http://www.ibm.com/webservices/
• BEA: http://dev2dev.bea.com/techtrack/standards.jsp

Bibliographic information:

Business Process Execution Language for Web Services. Version 1.0. 31-July-2002. By Francisco Curbera (IBM), Yaron Goland (BEA Systems), Johannes Klein (Microsoft), Frank Leymann (IBM), Dieter Roller (IBM), Satish Thatte (Microsoft - Editor), and Sanjiva Weerawarana (IBM). Copyright 2001-2002 BEA Systems, International Business Machines Corporation, Microsoft Corporation, Inc. Also available from BEA.

Web Services Coordination (WS-Coordination). August 9, 2002. By Felipe Cabrera (Microsoft), George Copeland (Microsoft), Tom Freund (IBM), Johannes Klein (Microsoft), David Langworthy (Microsoft), David Orchard (BEA Systems), John Shewchuk (Microsoft), and Tony Storey (IBM). Also available from BEA and Microsoft.

Web Service Transaction (WS-Transaction). August 9, 2002. By Felipe Cabrera (Microsoft), George Copeland (Microsoft), Bill Cox (BEA Systems), Tom Freund (IBM), Johannes Klein (Microsoft), Tony Storey(IBM), and Satish Thatte (Microsoft). Also available from Microsoft.