In July 2002, BEA, IBM, and Microsoft released a trio of specifications
designed to support business transactions over Web services. These
specifications - BPEL4WS, WS-Transaction, and WS-Coordination - together form
the bedrock for reliably choreographing Web services-based applications,
providing business process management, transactional integrity, and generic
coordination facilities respectively.
This article introduces the underlying concepts of Web Services Coordination,
and shows how a generic coordination framework can be used to provide the
foundations for higher-level business processes. In future articles, we will
demonstrate how coordination allows us to move up the Web services stack to
encompass WS-Transaction and on to BPEL4WS.
Coordination
In general terms, coordination is the act of one entity (known as the
coordinator) disseminating information to ... (more)
In July 2002, BEA, IBM, and Microsoft released a trio of specifications
designed to support business transactions over Web services. These
specifications, BPEL4WS, WS-Transaction, and WS-Coordination, together form
the bedrock for reliably choreographing Web services-based applications,
providing business process management, transactional integrity, and generic
coordination facilities respectively.
In our previous article (WSJ, Volume 3, issue 5), we introduced
WS-Coordination, a generic coordination framework for Web services, and
showed how the WS-Coordination protocol can be ... (more)
Web services have become the integration platform of choice for enterprise
applications. Those applications by the very nature of their enterprise-scale
components can be complex in structure, which is compounded by the need to
share common data or context across business processes supported by those
applications. Those processes may be very long lived, and may contain periods
of inactivity, for example, where constituent services require user
interactions.
In response to these issues, WSCAF (Web Services Composite Application
Framework) was publicly released in July 2003 after ... (more)
In July 2003 a consortium of Web services vendors released the Web services
Composite Application Framework (WS-CAF) to the community. WS-CAF is
comprised of three specifications that together provide a means of reliably
composing individual Web services into larger aggregate applications. The
cornerstone of this suite is the management of stateful interactions between
Web services that is the domain of the WS-Context specification. WS-CAF was
subsequently submitted to OASIS and an effort to standardize the framework is
currently underway.
In January 2004 a group of industry and... (more)
Use of atomic transactions is a well-known technique for guaranteeing
consistency in the presence of failures. The ACID properties of atomic
transactions (Atomicity, Consistency, Isolation, Durability) ensure that even
in complex business applications consistency of state is preserved.
Transactions are best viewed as "short-lived" entities operating in a closely
coupled environment, performing stable state changes to the system; they are
less well suited for structuring "long-lived" application functions (e.g.,
running for hours, days, etc.) and running in a loosely coupled enviro... (more)