Where the Standards Stand

Computerworld - By their very nature, Web services require strong standards for interoperability, security and reliability. Yet so far the standards are immature, and they aren't yet adequate for the most sophisticated business processes.

Standards developers and IT vendors generally see the standards glass as half full, pointing out that many companies have already set up useful and workable Web services applications. But many users see it as half empty, saying more remains to be done before they would consider using mission-critical Web services applications. Some even question whether the functions contemplated by some of the standards can be automated at all.

Users also say they're confused and worried about what they see as overlap and competition among IT vendors and standards bodies.

Web services are a language-neutral, platform-independent way to loosely couple applications across an intranet, extranet or the Internet. They exchange documents, transactions and remote procedure calls using Web-based protocols.

Kelly Adams, director of client technology at Deutsche Bank AG in New York, says Web services may at last deliver on the promise of distributed, heterogeneous computing. "CORBA [Common Object Request Broker Architecture] was supposed to be the be-all and end-all, but it didn't quite turn out that way," he says. "But it looks like the sort of self-describing, easy interpretation nature of XML has opened up a lot of possibilities."

The Basics

The most fundamental Web services standards are the following:

• XML: The Extensible Markup Language is a simple, flexible text format derived by the World Wide Web Consortium (W3C) from the Standard Generalized Markup Language, a system for organizing and tagging elements of a document. The open XML standard is emerging as the method of choice for exchanging information among computer systems. The W3C has also developed specifications for XML schemas, which define how markup tags should be interpreted, and for XML namespaces, a way of naming XML document elements and attributes so they can be recognized by various kinds of software.

• SOAP: The XML-based Simple Object Access Protocol began life at Microsoft Corp. but is now maintained and developed by the W3C. Often called a "message envelope," it consists of three parts: an envelope that describes what is in a message and how to process it, rules for encoding data, and a convention for representing remote procedure calls and responses.

• WSDL: Originally proposed by IBM and Microsoft, the Web Services Description Language describes Internet services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. It allows a Web service to describe its capabilities by defining Web services interfaces and describing how to access them. The W3C owns the latest version of WSDL.