Microsoft, Others Publish Metadata-Exchange Standard

Microsoft and IBM introduced a new Web services standard and also updated an existing spec.

Microsoft Corp., IBM and friends introduced a new Web services standard and enhanced another, extending the tandems might in the Web services standardization arena while raising caution for some in the space.

Microsoft, IBM, BEA Systems Inc. and SAP AG on Tuesday announced the publication of the WS-MetadataExchange specification. In addition, Microsoft, IBM and BEA announced an update to the existing WS-Addressing specification. Both specifications are part of an existing Web services architecture laid out by Microsoft.

According to Microsoft, the WS-MetadataExchange specification expands the current Web services architecture to govern the transfer of metadata, enabling endpoints to leverage other Web services specifications for secure, reliable, transacted message delivery.

Meanwhile, the update to the WS-Addressing specification enables messaging systems to support message transmission in a transport-neutral manner through networks, including networks with processing nodes, such as endpoint managers, firewalls and gateways, Microsoft officials said. The changes reflect community feedback and experience gained by vendors in implementing the technology and from interoperability workshops, company officials said. The changes include an improved definition-of-request reply and a new WSDL (Web Services Description Language) binding and fault codes, Microsoft officials said.

"WS-MetadataExchange—as well as WS-Addressing—is a key step on the WS roadmap," said Jason Bloomberg, an analyst with ZapThink LLC, in Waltham, Mass. "WS-MetadataExchange is a key part of enabling the standards-based exchange of metadata. We like to say that metadata is the lifeblood of service-oriented architecture [SOA], because the core layer of abstraction behind SOAs—what provides flexible services and hides the complexity of heterogeneous back-ends—runs on metadata. These announcements also show that IBM and Microsoft are still working together to further standardization efforts across the industry."

Bloombergs partner at ZapThink, Ronald Schmelzer, said, "This [WS-MetadataExchange] spec is really an incremental piece of the puzzle that helps to complete the overall picture for self-described and discoverable services. In combination with WS-Policy and WS-Discovery, WS-MetadataExchange allows systems to bootstrap their way into a directory or onto a network so that they can be consumed by other services that know nothing about them."

Some question whether the appearance of WS-MetadataExchange signals that UDDI (Universal Description, Discovery and Integration) could go by the wayside, since it has never gained the level of adoption many expected.

"One of the fundamental problems in distributed computing is discovery," said Eric Newcomer, chief technology officer at IONA Technologies Inc., in Waltham, Mass. "The find-bind-invoke architecture is tried and true. Without the find part, Web services remain weak compared with things like CORBA. And specifications like WS-MetadataExchange find themselves trying to provide useful features while still recognizing the validity of UDDI. They are likely to come under fire from both the [Representational State Transfer] camp, who say everything can be done with HTTP, and the distributed computing camp, who will say that CORBA and other established technologies have better solutions to the discovery problem."

Moreover, "The new specifications continue the recent practice by IBM and Microsoft of combining private specifications with public specifications," Newcomer said.

"The specifications seem to provide useful functionality, but the continued mixing of private specifications such as WS-Policy, WS-Addressing and WS-MetadataExchange with public specifications such as WSDL, SOAP and XML exacerbates the current problem of a lack of overall industry vision and direction around Web services," Newcomer said. "We are very interested in seeing these private specifications progress toward standardization in open forums, as the specification owners have promised. And we are happy to participate in the feedback sessions they hold toward that end. However, we find ourselves in a very difficult situation with regard to implementing specifications such as these in our Artix product line, since we cannot be sure what direction they will take in the future."