This volume contains the refereed joint proceedings of two initiatives that have been devoted to the formal foundations of complex systems: the workshops WS-FM:FASOCC 2014 and WS-FM/BEAT 2015. The 11th International Workshop on Web Services and Formal Methods: Formal Aspects of Services-Oriented and Cloud Computing, WS-FM 2014, took place in Eindhoven, The Netherlands, in September 2014. The 12th International Workshop on Web Services, Formal Methods, and Behavioral Types, WS-FM 2015, took place in Madrid, Spain, in September 2015. The total of 8 papers presented in this volume was carefully reviewed and selected from 18 submissions. They were organized in topical sections named: expressiveness of behavioral models; service-oriented systems, and behavioral types.

This volume contains the papers presented at WS-FM 2007, the 4th International Workshop on Web Services and Formal Methods, held on September 28 and 29, 2007 in Brisbane, Australia. Web service technology aims at empowering providers of services, in the broad sense, with the ability to package and deliver their services by means of software applications available on the Web. Existing infrastructures for Web services - ready enable providers to describe services in terms of structure, access policy and behaviour, to locate services, to interact with them, and to bundle simpler services into more complex ones. However, innovations are needed to seamlessly extend this technology in order to deal with challenges such as managing int- actions with stateful and long-running Web services, managing large numbers of Web services each with multiple interfaces and versions, managing the quality of Web service delivery, etc. Formal methods have a fundamental role to play in shaping innovations in Web service technology. For instance, formal methods help to de?ne and to understand the semantics of languages and protocols that underpin existing infrastructures for Web services, and to formulate features that are found to be lacking. They also provide a basis for reasoning about Web service behaviour, for example to discover individual services that can ful?l a given goal, or even to compose multiple services that can collectively ful?l a goal. Finally, formal analysis of security properties and performance are relevant in many application areas of Web services such as e-commerce and e-business.

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.

This book presents papers from the lectures of leading researchers given at the Ninth International School on Formal Methods for the Design of Computer, Communication and Software Systems, SFM 2009, which was devoted to formal methods for web services.

This book constitutes the thoroughly refereed post-proceedings of the 8th International Workshop on Web Services and Formal Methods, WS-FM 2011, held in Clermont-Ferrand, France, in September 2011. The workshop was co-located with the 9th International Conference on Business Process Management, BPM 2011. The 9 full papers presented were carefully reviewed and selected from 14 submissions. They deal with service oriented computing (SOC), cloud computing and formal methods.

This book constitutes the thoroughly refereed post-workshop proceedings of the 7th International Workshop on Web Services and Formal Methods, WS-FM 2010, held in Hoboken, NJ, USA, in September 2010. The 11 revised full papers presented together with one invited paper were carefully reviewed and selected from 26 submissions. The papers feature topics such as web services; service oriented computing; cloud computing; formal methods; verification specification; testing; and business process management.

This book constitutes the thoroughly refereed post-workshop proceedings of the 5th International Workshop on Web Services and Formal Methods, WS-FM 2008, held in Milan, Italy, in September 2008 in conjunction with the 6th International Conference on Business Process Management, BPM 2008. The 13 revised full papers presented together with one invited paper were carefully reviewed and selected from 39 submissions. The papers feature topics such as analysis, test, and verification; choreographies and process calculi; transactions and interoperability; workflows and petri nets.