WS-I and W3C

IBM and Microsoft recently launched another Web services-related effort - the Web Services Interoperability Organization (www.ws-i.org), or WS-I for short. Its charter is to promote Web services interoperability across platforms, operating systems, and programming languages. I, for one, view interoperability as absolutely critical to the success of Web services technology. I don't think I'm alone in the view, since more than 60 companies joined the consortium within the first week. Obviously the formation of this group is a "good thing."

So I was a bit amused by the immediate defensive response that occurred after the announcement. How does WS-I relate to the World Wide Web Consortium (W3C - www.w3.org)? Isn't W3C supposed to define the interoperability standards? And what about the SOAPBuilders group (http://groups.yahoo.com/group/soapbuilders)? Aren't they taking responsibility for SOAP interoperability?

Interoperability has always been a core goal of all the various Web services platform vendors, and an informal organization centered around the SOAP Builders discussion group has been working for the past year on this issue. This group holds quarterly interoperability labs at which the vendors get together, test their products, and uncover interoperability issues. The last interoperability lab (Round 3) was sponsored by IONA Technologies in February 2002. (www.whitemesa.net/r3/interop3.html).

I don't expect WS-I to compete with the SOAPBuilders group. The SOAPBuilders participants work at uncovering and fixing interoperability issues. The WS-I organization will define profiles that help users easily understand what levels of interoperability they can expect from various Web services technologies. WS-I will publish white papers, guidelines, and other documentation to guide developers. They also plan to develop tools and test suites to help developers and vendors verify that their Web services comply with the standards. Obviously the two efforts are complementary.

The relationship between W3C and WS-I should also be complementary, although for the moment their efforts are orthogonal. W3C is working on building the next generation of Web services standards. WS-I focuses on ensuring interoperability using today's Web services technology: SOAP 1.1 (www.w3.org/TR/SOAP), WSDL 1.1 (www.w3.org/TR/wsdl), and UDDI 1.0 (www.uddi.org/specification.html). None of these specifications are W3C standards.

"Wait," you say. "What do you mean SOAP and WSDL aren't W3C standards? Look at the URLs. You get them from W3C. They must be W3C standards." While it's true that W3C has posted these specs, they're not official W3C Recommendations. These specifications (and the intellectual property contained within them) are, in fact, owned by IBM, Microsoft, and a few of their closest friends. If you look on the first page of both the SOAP and WSDL specifications, you'll find this little disclaimer:

This document is a NOTE made available by the W3C for discussion only. Publication of this Note by W3C indicates no endorsement by W3C or the W3C Team, or any W3C Members. W3C has had no editorial control over the preparation of this Note. This document is a work in progress and may be updated, replaced, or rendered obsolete by other documents at any time.

As I said, W3C is developing the next generation of SOAP and WSDL. The current SOAP and WSDL specifications aren't perfect. They contain errors, omissions, and inconsistencies. It's appropriate to have a formal venue in which to nurture and develop these specifications. W3C initiated the XML Protocol Working Group (XMLP - www.w3.org/2000/xp/Group) in September 2000 to develop a standard XML Protocol based on the SOAP 1.1 specification. Draft specifications of W3C SOAP 1.2 are available on the XMLP Web page. W3C SOAP is now described by two specifications:

Part 1: Messaging Framework (www.w3.org/TR/soap12-part1): Defines the basic SOAP envelope and the protocol binding framework.

Part 2: Adjuncts (www.w3.org/TR/soap12-part2): Defines SOAP encoding, SOAP RPC, features and binding conventions, message exchange patterns, and the HTTP binding.

The W3C Web Services Description Working Group (WS-Desc; www.w3.org/2002/ws/desc) was formed in February 2002, so they're just getting started. It will be a little while before they manage to produce a specification.

Both the XMLP and WS-Desc groups are part of the new W3C Web Services Activity (www.w3.org/2002/ws). There's one other working group in this activity, the W3C Web Services Architecture Working Group (WS-Arch; www.w3.org/2002/ws/arch). The goal of the WS-Arch group is to produce an architecture that supports a fully automated, functional, distributed system based on Web services. The architecture must identify the technologies necessary for Web services to be described, discovered, and used. The WS-Arch group must also identify gaps in the architecture and propose new technologies that must be developed to fill those gaps.

As Web services technologies mature and people start building serious application systems requiring security, reliability, and transactions, these gaps will become much more apparent. For these applications, interoperability will require more than just guidelines and white papers. It will require new standard specifications that allow heterogeneous Web services to exchange security information and transaction context.

Today, Web services platform vendors are starting to add advanced features to their products. Unfortunately, there's no consensus among the vendors on how to represent information on things such as remote references, sessionIDs, or security context, and each vendor does so in a slightly different way. These little details make interoperability challenging. Without standard specifications, the only way to guarantee interoperability is to take a least-common-denominator approach and to avoid using any of these advanced features. WS-I will help define the least common denominator. W3C will define the standards that allow us to take Web services to the next level.

Author Bio
Anne Thomas Manes is the CTO of Systinet, a Web services infrastructure company. Anne is a recognized industry spokesperson and has published on a range of technology issues. ATM@SYSTINET.com

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