Web services specification aims at collaboration

Sun Microsystems Inc., SAP AG, BEA Systems Inc. and Intalio Inc. have developed an XML-based interface description language called the WSCI (Web Service Choreography Interface) to describe the flow of messages exchanged in Web services.

According to information on Sun’s Web site, WSCI describes the “dynamic interface of the Web service participating in a given message exchange by means of reusing the operations defined for a static interface.”

WSCI describes the observable behaviour of a Web service in terms of temporal and logical dependencies among exchanged messages. Sequencing rules, correlation, exception handling, and transactions are features. A global, message-oriented view of interactions is provided.

The behavioural description provided by WSCI enables developers, architects, and tools to describe and compose a global view of the dynamic of a message exchange by understanding interactions with the Web service, according to Sun’s site.

Analyst Joanne Friedman, vice president of e-business strategies at Meta Group Inc. in Toronto, described WSCI as “an XML-based language to describe the flow of messages exchanged by a Web service, but in the context of a higher-level business process.”

WSCI is critical to collaboration in applications such as e-business, Friedman said. The technology would be used to look at the behavioural patterns of messages and the expectations of senders and receivers.

“Right now, you have the Web services flow language, but it doesn’t address a higher level of how this Web service interacts with other Web services,” Friedman said.

“Basically, what (WSCI) does is it allows you to design and create elaborate business processes,” she said.

For example, in an e-commerce transaction, WSCI would enable a buyer or merchant conducting a transaction to query the Web for a set of carriers to deliver the merchandise, she said. WSCI enables collaboration between more than two parties, said Friedman.

“It’s the missing dimension to the Web services stack,” she said.

Business process frameworks such as ebXML (e-business XML) or others could be used with WSCI, Friedman said.

WSCI works in conjunction the WSDL (Web Services Description Language) or with another service definition language that exhibits the same characteristics as WSDL, Sun said.

Sun is currently accepting feedback on the specification, but company officials declined to comment.