XLANG

XLANG is an extension of WSDL, the Web Service Definition Language. It provides both the model of an orchestration of services as well as collaboration contracts between orchestrations. XLANG, like BPML, were designed with an explicit -calculus theory foundation.

XLANG - Technology Reports

XLANG is expected to serve as the basis for automated protocol engines that can track the state of process instances and help enforce protocol correctness in message flows.

XLANG - Web Services for Business Process Design

Automation of business processes based on web services requires a notation for the specification of message exchange behavior among participating web services. This document specifies such a notation. We call it XLANG.

XLANG - Web Services Primer
XLANG is a notation for expressing the compensatory actions for any request that needs to be undone. The web services infrastructure can leverage XLANG specifications to perform complex undo operations..