Five middleware vendors published a set of technology guidelines Monday that could prove helpful to businesses trying to orchestrate groups of online transactions using Web services.
Sun Microsystems Inc., Oracle Corp., Fujitsu Software Corp., Iona Technologies PLC and Arjuna Technologies Ltd. published the Web Services Composite Applications Framework (WS-CAF), designed to solve problems that arise when groups of Web services are used in combination to complete a transaction or share information, the companies said in a joint statement Monday.
They plan to submit WS-CAF to an industry standards group and will allow for its use on a royalty-free basis, moves intended to promote its broad use. The initiative appears to lack support so far from some key Web services players, however, including IBM Corp., BEA Systems Inc. and Microsoft Corp., which were not part of the announcement.
Web services use standard technologies such as Simple Object Access Protocol (SOAP) and XML to link disparate applications in a way that’s supposed to be more affordable and flexible than using proprietary messaging systems.
Some transactions, such as purchasing a book, are relatively simple to complete, in part because they can be finished instantaneously. Others, such as fulfilling a purchase order or completing an insurance claim, can take days or weeks to process and as such pose problems for Web services developers, the companies said.
WS-CAF aims to solve those problems by defining a set of rules for coordinating transactions in such long-running business processes, the group said. WS-CAF actually is a collection of three specifications: Web Service Context (WS-CTX), Web Service Coordination Framework (WS-CF), and Web Service Transaction Management (WS-TXM).
Web Service Context is the core of the three, according to Rob Cheng, principle product marketing manager for Web services and emerging standards at Oracle. The other two specifications “provide more practical examples of how to use WS-CTX,” he said.
WS-CTX ties together the various transactions involved in an activity by providing a common context – for example, associating the booking of a flight, a rental car and a hotel room with the idea of attending a particular conference.
WS-CF is a mechanism for sharing that context with services, notifying them of the outcome of particular transactions. “WS-CF makes sure information is propagated around, but it can’t interpret that information,” said Mark Little, chief transactions architect for Arjuna Technologies.
WS-TXM allows participants in an activity to negotiate their behaviour, and is particularly important if something goes wrong with a transaction. In the case of making multiple reservations to attend a conference, “WS-TXM is responsible for ensuring that if one reservation is cancelled, the others get cancelled,” said Jeff Mischkinsky, director of Web services standards at Oracle.
It comprises specifications for managing three types of transactions: simple transactions, for interoperability with existing Web services; long-running activities, which may span hours, days or even months; and business process models, which provides a link with existing IT infrastructures, Little said. “That’s one of the main differentiators of our specifications, allowing people to leverage what they have already dished out money for,” he said.
Analyst Stephen O’Grady of research firm RedMonk LLC praised the specification, but said that adoption would depend on more than just its technical merit.
“It’s a nice piece of technology and we definitely see a market for it and a business need for it,” O’Grady said. “There are other pieces of technology that touch on composite applications but this is the first one specifically designed with composite applications in mind.”
However, choosing to implement Web services standards is not just a technology question, it’s more a political question, he said. “You have to evaluate what your partners are using, the underlying technologies. But just as much you have to pay attention to who’s supporting them and what adoption might look like.”
The new specifications add to an already tangled clump of Web services coordination specifications with varying degrees of support from standards bodies.
One such, Business Process Execution Language for Web Services (BPEL4WS), has been adopted by OASIS, the Organization for the Advancement of Structured Information Standards, but it still leaves significant gaps that need to be filled, according to Mischkinsky.
“There are all sorts of grandiose claims for that, but if you actually try to do an implementation of BPEL one of the first things you run into is that you need to share context, and all that is left as an exercise for the reader, or programmer, at this point,” he said.
Last year, Microsoft and IBM published specifications entitled Web Services Transaction and Web Services Coordination, but according to Oracle’s Cheng these overlap with WS-CAF in name only, and aren’t going anywhere. “They haven’t really done anything with them, and haven’t taken them to any standards bodies,” he said.
The issue of taking the specification to a standards body could be irrelevant, according to RedMonk’s O’Grady.
“The market is much more vendor-driven than standards body-driven,” he said.
WS-CAF doesn’t require the use of any particular transaction protocol, and businesses that adopt it can use all or part of the specification, the group said. Each vendor has published information about WS-CAF on its Web site.
Sun’s is at http://developers.sun.com/techtopics/webservices/wscaf/index.html.
