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SOAP 1.2 Becomes a Standard

Debate and uncertainty about an important specification for Web services ended Tuesday when the World Wide Web Consortium (W3C) released SOAP Version 1.2 as a recommendation, officially making it a standard.

The standard, designed to enable the exchange of XML-based information between computers in a decentralized, distributed environment, is crucial to the advancement of Web services, experts say. This is because secure, fluid data transport is vitally important to modern computing, at a time when much of it occurs over the Web.

Because XML is the lingua franca, or common language on which to build data exchange, the challenge is for the sender and the receiver of messages to agree on whether the transfer is to occur between software programs, machines, or organizations. That is what SOAP 1.2 offers.

The passage of SOAP 1.2 brings closure to a contentious issue that sprouted last year when two firms, webMethods and Epicentric, said they were concerned SOAP 1.2 might feature technology they owned copyrights to. Epicentric renounced its position while webMethods had yet to ever formally reconcile its position on the matter, although webMethods officially supports SOAP 1.2

The W3C's XML protocol working group has worked on both XML protocol requirements and the SOAP 1.2, using the W3C Note SOAP 1.1 as a starting point, since September 2000. The group, whose members include IBM, Microsoft, Sun Microsystems, and BEA systems, has produced multiple drafts, received much feedback from developers, and identified interoperable implementations, en route passing the spec. The group resolved over 400 technical and editorial issues raised in public review of SOAP 1.1 and the resulting SOAP Version 1.2.

"Web services customers and developers alike demand an XML-based Web services protocol that powers the full range of applications and Web technologies they can imagine using," explained Tim Berners-Lee, W3C Director. "Now that SOAP Version 1.2 is here, they have it."

Industry experts praised the passage of SOAP 1.2, with an eye toward the future.

"With all the sturm and drang over the details of some of the newer Web services specifications, it's always nice to take a moment and reflect upon the fact that yes, core Web Services standards like SOAP are maturing," said ZapThink Senior Analyst Jason Bloomberg, whose firm researches XML and Web services. "We are making real progress in establishing the ground rules for standards-based computing. It's time for the industry to take a brief moment to pat itself on the back, and then get back to work."

Zapthink Senior Analyst Ronald Schmelzer summed up his feeling on the ratification of SOAP 1.2.

"Well, it's definitely good that SOAP 1.2 has been "put to bed" since it's the foundation for most of the activity going on right now in Web Services and SOAP," Schmelzer said. "But it also signals that at least one part of the Web Services market has started to mature. SOAP 1.2 is a fairly complete, mature, and well-established protocol. While there might continue to be development on additional versions of SOAP, this latest version may well end up being the version of the protocol that has the greatest longevity. Certainly, there no longer is any clamor for additional revisions. So could it finally be that one part of the Web Services stack has finally solidified?"

What's next for the W3C and Web services? Schmelzer said he next expects two companion standards of SOAP, WSDL and UDDI to solidify soon, and then parts of the security stack.

"The rest, however, is still up for contention and it's not clear how those specs will sort out, but we can safely guess that BPEL and WS-Security will probably get to a stable and well-adopted state fairly soon."

While the standards is described in developer's parlance as a lightweight protocol, the documentation on it is anything but, consisting of the SOAP Version 1.2 Primer, SOAP Version 1.2 Messaging Framework, SOAP Version 1.2 Adjuncts, and the SOAP Version 1.2 Specification Assertions and Test Collection.

The primer describes the features of SOAP Version 1.2 through examples and links to the specification. The actual specification provides a framework for XML-based messaging in two parts, the Messaging Framework and Adjuncts. To help developers write SOAP processors, the W3C has authored the Specification Assertions and Test Collection to provide a set of tests drawn from the assertions found in the Messaging Framework and Adjuncts.