Sessions and Session Types: An Overview -- Choreography Rehearsal -- A Graph Syntax for Processes and Services -- A Formalisation of Adaptable Pervasive Flows -- Compliance Preorders for Web Services -- A Formal Semantics for the WS-BPEL Recovery Framework -- Realizability Is Controllability -- Specification and Verification of Multi-user Data-Driven Web Applications -- Automated Composition of Nondeterministic Stateful Services -- Towards Compensation Correctness in Interactive Systems -- Small Specifications for Tree Update.

This book constitutes the thoroughly refereed post-workshop proceedings of the 6th International Workshop on Web Services and Formal Methods, WS-FM 2009, held in Bologna, Italy, in September 2009. The 10 revised full papers presented together with one invited paper were carefully reviewed and selected from 18 submissions. The papers feature topics such as approaches to analyzing and designing systems based on Web Service technology, formal approaches to enterprise systems modeling in general, and business process modeling in particular.