IBM, Sun and Computer Associates have jumped aboard in support of the WS-Eventing specification for subscribing to Web services-based events, joining original developers Microsoft, BEA Systems, and Tibco Software.The specification is intended to define a baseline set of operations that allow Web services to provide asynchronous notifications to interested parties. For example, an event notification could pertain to shipping of an order or e-mail arriving. Microsoft officials cited desires for interoperability between different specifications as reasons why rivals such as Sun and IBM are climbing aboard."I think overall, there was a goal to kind of rationalize the way this specification was being developed going forward so that it will factor well with other things that are out there and hopefully drive a lot of interoperability for customers," said Pete McKiernan, Microsoft's lead product manager for developer platform evangelism. Microsoft plans to support WS-Eventing in the Indigo Web services applications framework to be included in the Longhorn release of Windows planned for 2006.IBM has had a similar specification to WS-Eventing, called WS-BaseNotification, which was submitted to OASIS in April as part of IBM's WS-Notification specifications submission. But IBM's participation in WS-Eventing does not spell the end for WS-BaseNotification and WS-Notification. In fact, the company still plans to support its WS-Notification specifications to enable publish-subscribe functionality for Web services in its WebSphere application server, said Karla Norsworthy, director of dynamic business technologies at IBM. The company's products, however, will be able to communicate with systems that use WS-Eventing, she said."We decided the best (choice) for us was to drive these (specifications) close together, but it doesn't change our commitment to WS-Notification at all," Norsworthy said. Over the long term, IBM would like to see WS-Eventing converged with its own technologies into one specification."I think as a long-term strategy, we'd love to see that, but at this point, we're trying to make sure that we can factor these things (so) that it's easy for them to work together in customer environments that end up with both of them," Norsworthy said. WS-Notification supports intermediary brokering technologies for publish-and-subscribe Web services paradigms, but WS-Eventing currently does not, she said.Additionally, the WS-Eventing specification on Tuesday is being updated to support endpoint references as a more specific way to subscribe to asynchronous Web services notifications than the previous method support, called Subscription ID, which provided an arbitrary identifier. Endpoint references serve as a URL-like mode for addressing a Web service, according to Microsoft. The revisions also clear up ambiguities and can support new delivery modes that may arise for asynchronous Web services.An analyst described the collaboration on WS-Eventing as a victory for interoperability."IBM and Sun and Tibco joining Microsoft in their WS-Eventing spec is definitely a major win for Web services and SOA (service-oriented architecture) adoption," said Ron Schmelzer, senior analyst at ZapThink. "I think we're finally seeing convergence and coalescence on a set of specifications that (is) gaining market traction. In this case, it is important for the industry vendors to all agree about how events and asynchronous publish-subscribe style notifications will happen in a standards-based way."Sun's participation in WS-Eventing is part of the company's collaboration with Microsoft on Web services standards, according to a Sun representative. The company has not yet determined which of its products will support the specification.WS-Eventing has not yet been submitted to a standards body such as OASIS for consideration as an industry standard, but plans are afoot to do that when the proposal is deemed solid enough, according to Microsoft.