W3C Publishes First Draft of WS-CDL


The World Wide Web Consortium has published the first draft of the Web services Choreography Description Language (WS-CDL). WS-CDL is targeted at coordinating interactions among Web services and their users. WS-CDL promises to be a necessary component for BPEL or other programming languages used to model business processes.

The WS-CDL specification defines peer-to-peer collaboration between Web service participants. A user of a Web service, automated or otherwise, is a "client" of that service. Users may be other Web services, applications and human beings. In WS-CDL, a set of client interactions may be related over time in a "collaboration group." A collaboration group could be for example, a set of components that make up a business transaction or a database transaction.

The future of e-business applications is in the loosely coupled, decentralized environment of the World Wide Web. This environment requires the ability to perform long-lived, peer-to-peer collaborations between the participating services, within or across the trusted domains of an organization. Applications that implement WS-CDL can accomplish this shared business goal, as the Working Group developed its requirements document to consider both broad practical business needs and sound theories.

Interestingly enough, WS-CDL is based on Pi Calculus. I used to be a formal methods guys and have studied Pi Calculus and its predecessor, CCS before. Never imagined that they'd show up in Web services.

I believe that there is hope that WS-CDL and BPEL will be complimentary. We'll see.