A language of formal proteins, the ¢-calculus, is introduced. Interactions are modeled at the domain level, bonds are represented by means of shared names, and reactions are required to satisfy a causality requirement of mono-tonicity. An example of a simplified signalling pathway is introduced to illustrate how standard biological events can be expressed in our protein language. A more comprehensive example, the lactose operon, is also developed, bringing some confidence in the formalism considered as a modeling language. Then a finer-grained concurrent model, the £ ¤ ¢-calculus, is considered, where interactions have to be at most binary. We show how to embed the coarser-grained language in the latter, a property which we call self-assembly. Finally we show how the finer-grained language can itself be encoded in ¥-calculus, a standard foundational language for concurrency theory.

Abstract. We define a formal contract language along with subcontract and compliance relations. We then extrapolate contracts out of processes, that are a recursion-free fragment of ccs. We finally demonstrate that a client completes its interactions with a service provided the corresponding contracts comply. Our contract language may be used as a foundation of Web services technologies, such as wsdl and wscl.

Abstract.A timed extension of π-calculus with a transaction construct -the calculus Webπ -is studied. The underlying model of Webπ relies on networks of processes; time proceeds asynchronously at the network level, while it is constrained by the local urgency at the process level. Namely process reductions cannot be delayed to favour idle steps. The extensional model -the timed bisimilarity -copes with time and asynchrony in a different way with respect to previous proposals. In particular, the discriminating power of timed bisimilarity is weaker when local urgency is dropped. A labelled characterization of timed bisimilarity is also discussed.

Abstract. We study long-running transactions in open componentbased distributed applications, such as Web Services platforms. Longrunning transactions describe time-extensive activities that involve several distributed components. Henceforth, in case of failure, it is usually not possible to restore the initial state, and firing a compensation process is preferable. Despite the interest of such transactional mechanisms, a formal modeling of them is still lacking. In this paper we address this issue by designing an extension of the asynchronous π-calculus with longrunning transactions (and sequences) -the πt-calculus. We study the practice of πt-calculus, by discussing few paradigmatic examples, and its theory, by defining a semantics and providing a correct encoding of πt-calculus into asynchronous π-calculus.

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