W3C raises the bar with SOAP standard

MarketWatch: Application Development, June 27, 2003

A leading internet standards body claims to have eliminated 400 technical issues in Simple Object Access Protocol (SOAP), in an update it believes will prompt the specification's widespread deployment.

The World Wide Web Consortium (W3C) announced ratification of SOAP 1.2, an implementation of the standard that sees improvements in message handling and the elimination of ambiguities found in previous versions of the standard.

Implementations of SOAP 1.2 are already available from Apache Software Foundation, BEA Systems Inc, Microsoft Corp and Tibco Software Inc among others.

David Fallside, chairman of the W3C XML Protocol Working Group that developed SOAP 1.2, said previous versions of SOAP had seen successful uptake, but that changes to this edition would make the specification ready for the "big time".

"By that, I mean widespread deployment and interoperability," Fallside said. "Version 1.1 tweaked everyone's interest in web services but 1.2 is more up-to-date."

SOAP was the first major web services specification, hatched by Microsoft and IBM Corp. It sits at the bottom of a stack of web services specifications and proposed specifications, which includes things like Web Services Description Language (WSDL).

Previous versions of SOAP, though, contained 400 issues and ambiguities that hindered more widespread uptake of the specification, according to Fallside. These included XML schema that weren't defined in SOAP, meaning that two different vendors could implement an XML schema in different ways resulting in interoperability difficulties.

Version 1.2 of SOAP re-works the way errors and messages are handled as a result. Prior to 1.2, the order in which headers inside a SOAP message were handled was not specified.

SOAP 1.2 specifies more clearly the rules for processing the parts of a message and the circumstances under which an error message will be generated.

SOAP 1.2 handles XML messages via a two-part framework, consisting of the Messaging Framework and Adjuncts. The Messaging Framework includes a processing model that sets the rules for the processing of messages, an extensibility framework that enables developers to use extensions, message constructs, and a protocol binding framework to specify the exchange of SOAP messages over underlying protocols such as HTTP.

The Adjuncts includes various rules to represent remote procedure calls, encode SOAP messages and describe SOAP features and bindings, and rules for the standard binding of SOAP to HTTP.

W3C has also established tools to test implementations of SOAP 1.2 for compatibility.