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...tore, provided that other interactions that took place in the meantime do not lead to inconsistency (which, anyway, is not the case in our scenario). Otherwise, if the timeout expires, the constraint cannot be added to the store. 6. Related work We have already pointed out, mainly in Section 3.1.1, main relationships of CWS with other process calculi. By summing up, CWS borrows, e.g., global scoping and non-binding input from update calculus [33] and fusion calculus [34], distinction between variables and values from value-passing CCS [51], Applied π-calculus [52] and Distributed π-calculus [53], patternmatching from KLAIM [54], prioritised activities from variants of CCS with priority [55, 56, 57], and forced termination and protection from StAC [58]. Many works put forward enrichments of some well-known process calculus with constructs inspired by those of WS-BPEL. Most of them deal with issues of web transactions such as interruptible processes, failure handlers and time. This is, for example, the case of [4, 5, 59, 60] that present timed and untimed extensions of the π-calculus, called webπ and webπ∞, tailored to study a simplified version of the scope construct of WS-BPEL. Other...

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... static and dynamic type-checking. We show how the semantics can be extended to allow trust between sites, improving performance and expressiveness without compromising type-safety. 1 Introduction In =-=[12-=-] we presented a type system for controlling the use of resources in a distributed system, or network. The type system guarantees two properties: resource access is always safe, e.g. integer resource...

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...here can be seen as an instantiation on Klaim of a general framework, based on a specific notion of type, that could be applied to other distributed and mobile languages like, e.g., Ambit [15] or D�=-=� [29]-=-. The rest of the paper is organized as follows. Section 2 introduces the syntax and the informal semantics of Klaim processes, types and nets. Section 3 defines type equality and the subtyping relati...

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... However, this is proved at a very high level of abstraction, modelling migrations as context changes not controlled by agents; (ii) we thus consider a more concrete model, inspired from Dpi-calculus =-=[26]-=-, and obtained by adding explicit process mobility to the language. We formally prove that P BNDC implies the natural extension of Non-Interference in this new concrete model of mobile agents. At the ...

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... behaviour of incoming code – a coinductive characterisation of a natural contextual equivalence, based on the notion of typed actions. This is developed in terms of an extension of the language Dpi, =-=[11, 8, 20, 14]-=-, a version of the Picalculus, [21], in which processes may migrate between locations, which in turn can be dynamically created. In this paper we make ⋆ Partially supported by EPSRC grant GR/R31485, a...

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...l notion of contextual equivalence for distributed systems. The labelled transitions rely upon a type discipline for the language which can control resource access and mobility. As in [8,2], the use of a type environment representing the tester’s knowledge of the system plays an important role in characterising the contextual equivalences. In particular it aided us in defining a labelled transition system which accounts for information flow in a distributed setting with restricted mobility. There has been a great deal of interest in modelling distributed systems using calculi in recent years, [14,6,1,4,16,9,3]. The emphasis so far has largely been on design of the languages to give succinct descriptions of mobile processes with type systems given to constrain behaviour in a safe manner. Where equivalence has been used it has typically been introduced as some sort of contextual equivalence very similar to the one found in the present paper [6,1,11]. Proofs of correctness of protocols or language translations have been carried out with respect to these contextual equivalences. Recently in [5] a form of bisimulation has been suggested as a proof method for establishing contextual equivalence in the Se...

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... such as e-cash and SIMs. The calculus MR is inspired by the Mobile Ambient calculus [5, 16], bears relationships to Boxed Ambients [3] and the Seal calculus [23], and to distributed process algebras =-=[13, 22, 10]-=-, but differs from all these in important ways, motivated by our specific goals. Building upon a CCS-like calculus [18] with prefix, restriction, parallel composition, replication, no summation nor re...

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...uding process terms, can be exchanged along communication channels [3, 41, 50]. We believe that our typing system can be readily adapted to related location-based distributed calculi such as those in =-=[6, 12, 28, 17, 40, 47]-=-. Higher-Order Processes. The language we consider, lp v , is essentially a call-byvaluesl-calculus [39] augmented with the p-calculus primitives [33]. Values may be sent and received along communicat...

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...we did not discuss extensions of the type systems for distributed and open environments, where one needs to introduce location-dependent types and some combination of static typing and dynamic typing =-=[9, 27]-=-. Other applications of type systems include formal reasoning about program behavior through process equivalence theories [14, 22, 23, 28, 33], analysis of security properties [1, 8, 10] and optimizat...