This volume contains the proceedings of two international workshops EPEW and WS-FM held atthe Universit ede VersaillesSaint-Quentin-en-Yvelines,V- sailles, France, 1 3 September 2005. EPEW (European Performance Engineering Workshop) and WS-FM (Int- national Workshop on Web Services and Formal Methods) were colocated to gather the researchers working across the spectrum of techniques for modelling, speci?cation, analysis and veri?cation of the behavior of computer systems and business processes. This proceedings contains a selection of 20 research contributions, out of 59 submissions, which went through a rigorous review process by international reviewers. We therefore owe special thanks to all members of both program committees of EPEW and WS-FM and their sub-referees for the excellent work they did in the short time they had. Additionally, this proceedings includes four invited papers, by Gianfranco Ciardo (University of California at Riverside), Peter G. Harrison (Imperial C- lege London), Cosimo Laneve (University of Bologna) and Wil van der Aalst (Eindhoven University of Technology). These contributions brought an ad- tional dimension to the technical and the scienti?c merit of these workshops. Finally,ourthanksgototheUniversityofVersaillesSaint-Quentin-en-Yvelines, its Laboratoire PRiSM and the CNRS for hosting the workshops and providing technicaland?nancialsupport.

Inhalt
Invited Speakers.- Performance Engineering and Stochastic Modelling.- Implicit Representations and Algorithms for the Logic and Stochastic Analysis of DiscreteState Systems.- PiDuce: A Process Calculus with Native XML Datatypes.- Life After BPEL?.- EPEW.- On Moments of Discrete Phase-Type Distributions.- Zero-Automatic Queues.- A Unified Approach to the Moments Based Distribution Estimation Unbounded Support.- Bounds for Point and Steady-State Availability: An Algorithmic Approach Based on Lumpability and Stochastic Ordering.- Stochastic Model Checking with Stochastic Comparison.- Delay Analysis of the Go-Back-N ARQ Protocol over a Time-Varying Channel.- Performance Tuning of Failure Detectors in Wireless Ad-hoc Networks: Modelling and Experiments.- Hypergraph Partitioning for Faster Parallel PageRank Computation.- Prediction of Communication Latency over Complex Network Behaviors on SMP Clusters.- A Diffusion Approximation Model of an Electronic-Optical Node.- WS-FM.- Choreographing Security and Performance Analysis for Web Services.- Application of Formal Methods to the Analysis of Web Services Security.- Automatic Translation of WS-CDL Choreographies to Timed Automata.- Executable Semantics for Compensating CSP.- Verifying the Conformance of Web Services to Global Interaction Protocols: A First Step.- From Theory to Practice in Transactional Composition of Web Services.- Timing Issues in Web Services Composition.- A Compositional Operational Semantics for OWL-S.- A Parametric Communication Model for the Verification of BPEL4WS Compositions.- Reasoning About Interaction Patterns in Choreography.