关键词: 验证, Pi-演算, WS-CDL, Web服务组合

Abstract: The Web Services Choreography Description Language（WS-CDL） provides a mode to describe peer-to-peer collaborations of parties by defining，from a global view，their common and complementary observable behavior；where ordered message exchanges result in accomplishing a common business goal.Though the WS-CDL is claimed to be based on pi-calculus，but little solid work have been done to prove the effectiveness of pi-calculus in modeling WS-CDL.This paper proposes a pi-calculus based approach to formalization and verification of the WS-CDL.The presented method will ensure the correctness of WS-CDL before executing it so that the cost induced by the failures of the web services executing will decrease.This approach increases efficiency during deployment and lowers the risk of implementing and activating noncompliant web services.The contribution of the work can be concluded in three points.First，the semantics of WS-CDL is fully formalized with Pi-calculus；Secondly，the soundness of the formalization is validated and important properties are proved to be preserved in the formalization；Third，a concrete scenario is illustrated to show how model checking is applied to verify the reliability of WS-CDL model designs.

Key words: verification, Pi-calculus, WS-CDL, Web services composition