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A calculus of mobile processes, I
, 1992
"... We present the a-calculus, a calculus of communicating systems in which one can naturally express processes which have changing structure. Not only may the component agents of a system be arbitrarily linked, but a communication between neighbours may carry information which changes that linkage. The ..."
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Cited by 1184 (31 self)
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We present the a-calculus, a calculus of communicating systems in which one can naturally express processes which have changing structure. Not only may the component agents of a system be arbitrarily linked, but a communication between neighbours may carry information which changes that linkage. The calculus is an extension of the process algebra CCS, following work by Engberg and Nielsen, who added mobility to CCS while preserving its algebraic properties. The rr-calculus gains simplicity by removing all distinction between variables and constants; communication links are identified by names, and computation is represented purely as the communication of names across links. After an illustrated description of how the n-calculus generalises conventional process algebras in treating mobility, several examples exploiting mobility are given in some detail. The important examples are the encoding into the n-calculus of higher-order functions (the I-calculus and com-binatory algebra), the transmission of processes as values, and the representation of data structures as processes. The paper continues by presenting the algebraic theory of strong bisimilarity and strong equivalence, including a new notion of equivalence indexed by distinctions-i.e., assumptions of inequality among names. These theories are based upon a semantics in terms of a labeled transition system and a notion of strong bisimulation, both of which are expounded in detail in a companion paper. We also report briefly on work-in-progress based upon the corresponding notion of weak bisimulation, in which internal actions cannot be observed.
Bigraphs and Mobile Processes (revised)
, 2004
"... A bigraphical reactive system (BRS) involves bigraphs, in which the nesting of nodes represents locality, independently of the edges connecting them; it also allows bigraphs to reconfigure themselves. BRSs aim to provide a uniform way to model spatially distributed systems that both compute and comm ..."
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Cited by 66 (7 self)
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A bigraphical reactive system (BRS) involves bigraphs, in which the nesting of nodes represents locality, independently of the edges connecting them; it also allows bigraphs to reconfigure themselves. BRSs aim to provide a uniform way to model spatially distributed systems that both compute and communicate. In this memorandum we develop their static and dynamic theory. In Part I we illustrate...
Pure bigraphs: structure and dynamics
, 2005
"... Bigraphs are graphs whose nodes may be nested, representing locality, independently of the edges connecting them. They may be equipped with reaction rules, forming a bigraphical reactive system (Brs) in which bigraphs can reconfigure themselves. Following an earlier paper describing link graphs, a c ..."
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Cited by 62 (5 self)
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Bigraphs are graphs whose nodes may be nested, representing locality, independently of the edges connecting them. They may be equipped with reaction rules, forming a bigraphical reactive system (Brs) in which bigraphs can reconfigure themselves. Following an earlier paper describing link graphs, a constituent of bigraphs, this paper is a devoted to pure bigraphs, which in turn underlie various more refined forms. Elsewhere it is shown that behavioural analysis for Petri nets, π-calculus and mobile ambients can all be recovered in the uniform framework of bigraphs. The paper first develops the dynamic theory of an abstract structure, a wide reactive system (Wrs), of which a Brs is an instance. In this context, labelled transitions are defined in such a way that the induced bisimilarity is a congruence. This work is then specialised to Brss, whose graphical structure allows many refinements of the theory. The latter part of the paper emphasizes bigraphical theory that is relevant to the treatment of dynamics via labelled transitions. As a running example, the theory is applied to finite pure CCS, whose resulting transition system and bisimilarity are analysed in detail. The paper also mentions briefly the use of bigraphs to model pervasive computing and
Modeling and Validation of Service-Oriented Architectures: Application vs. Style
"... Most applications developed today rely on a given middleware platform which governs the interaction between components, the access to resources, etc. To decide, which platform is suitable for a given application (or more generally, to understand the interaction between application and platform) , we ..."
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Cited by 56 (11 self)
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Most applications developed today rely on a given middleware platform which governs the interaction between components, the access to resources, etc. To decide, which platform is suitable for a given application (or more generally, to understand the interaction between application and platform) , we propose UML models of both the architectural style of the platform and the application scenario. Based on a formal interpretation of these as graphs and graph transformation systems, we are able to validate the consistency between platform and application.
Style-Based Refinement of Dynamic Software Architectures
- In Proc. 4 th Working IEEE/IFIP Conference on Software Architecture, WICSA4
, 2004
"... In this paper, we address the correct refinement of abstract architectural models into more platformspecific representations. We consider the challenging case of dynamic architectures which can perform runtime reconfigurations. For this purpose, the underlying platform has to provide the necessary r ..."
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Cited by 28 (8 self)
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In this paper, we address the correct refinement of abstract architectural models into more platformspecific representations. We consider the challenging case of dynamic architectures which can perform runtime reconfigurations. For this purpose, the underlying platform has to provide the necessary reconfiguration mechanisms. To conceptually model such platforms including provided reconfiguration mechanisms, we use architectural styles formalized by graph transformation rules. Based on formal refinement relations between abstract and platform-specific styles, we can then investigate how to realize business-specific scenarios on a certain platform by automatically deriving refined, platform-specific reconfiguration scenarios.
Style-Based Modeling and Refinement of Service-Oriented Architectures -- A graph . . .
- SOFTWARE AND SYSTEMS MODELING
"... Service-oriented architectures (SOA) provide a flexible and dynamic platform for implementing business solutions. In this paper, we address the modeling of such architectures by refining business-oriented architectures, which abstract from technology aspects, into service-oriented ones, focusing on ..."
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Cited by 26 (4 self)
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Service-oriented architectures (SOA) provide a flexible and dynamic platform for implementing business solutions. In this paper, we address the modeling of such architectures by refining business-oriented architectures, which abstract from technology aspects, into service-oriented ones, focusing on the ability of dynamic reconfiguration (binding to new services at runtime) typical for SOA. The refinement is based on conceptual models of the platforms involved as architectural styles, formalized by graph transformation systems. Based on a refinement relation between abstract and platform-specific styles we investigate how to realize business-specific scenarios on the SOA platform by automatically deriving refined, SOA-specific reconfiguration scenarios.
Bigraphical Reactive Systems: Basic Theory
- PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF MATHEMATICIANS
, 2001
"... A notion of bigraph is proposed as the basis for a model of mobile interaction. A bigraph consists of two independent structures: a topograph representing locality and a monograph representing connectivity. Bigraphs are equipped with reaction rules to form bigraphical reactive systems (BRSs), which ..."
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Cited by 26 (7 self)
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A notion of bigraph is proposed as the basis for a model of mobile interaction. A bigraph consists of two independent structures: a topograph representing locality and a monograph representing connectivity. Bigraphs are equipped with reaction rules to form bigraphical reactive systems (BRSs), which include versions of the -calculus and the ambient calculus. Bigraphs are shown to be a special case of a more abstract notion, wide reactive systems (WRSs), not assuming any particular graphical or other structure but equipped with a notion of width, which expresses that agents, contexts and reactions may all be widely distributed entities. A behavioural theory is established for WRSs using the categorical notion of relative pushout; it allows labelled transition systems to be derived uniformly, in such a way that familiar behavioural preorders and equivalences, in particular bisimilarity, are congruential under certain conditions. Then the theory of bigraphs is developed, and they are shown to meet these conditions. It is shown that, using certain functors, other WRSs which meet the conditions may also be derived; these may, for example, be forms of BRS with additional structure. Simple examples of bigraphical systems are discussed; the theory is developed in a number of ways in preparation for deeper application studies.
Synchronised Hyperedge Replacement as a Model For Service Oriented Computing
, 2006
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Non-Functional Aspects of Wide Area Network Programming
, 2003
"... Wide-Area Network (WAN) applications have become one of the most popular ap-plications in current distributed computing. Internet and the World Wide Web are now the primary environment for designing, developing and distributing appli-cations. This scenario imposes different programming metaphors wit ..."
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Cited by 13 (13 self)
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Wide-Area Network (WAN) applications have become one of the most popular ap-plications in current distributed computing. Internet and the World Wide Web are now the primary environment for designing, developing and distributing appli-cations. This scenario imposes different programming metaphors with respect to traditional applications. Theoretical models for formally reasoning on WAN applications must consider many crucial aspects and their mutual relationships, e.g. mobility, network aware-ness, security, service level agreement, etc. This dissertation attempts to formally define declarative approaches for dealing with various facets of actual WAN programming and verification issues. We propose a declarative approach based on hypergraphs that provide founda-tional framework for “declaring ” components ’ behaviours of a distributed system. It is exercised with two well-known models for distributed computations as Ambient and Klaim. Moreover, we extend Klaim with constructs for specifying, at applica-
AGILE: Software architecture for mobility
- In Recent Trends in Algebraic Develeopment, 16th Intl. Workshop (WADT 2002), volume 2755 of LNCS, Frauenchiemsee
, 2003
"... Abstract. Architecture-based approaches have been promoted as a means of controlling the complexity of system construction and evolution, in particular for providing systems with the agility required to operate in turbulent environments and to adapt very quickly to changes in the enterprise world. R ..."
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Cited by 12 (2 self)
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Abstract. Architecture-based approaches have been promoted as a means of controlling the complexity of system construction and evolution, in particular for providing systems with the agility required to operate in turbulent environments and to adapt very quickly to changes in the enterprise world. Recent technological advances in communication and distribution have made mobility an additional factor of complexity, one for which current architectural concepts and techniques can be hardly used. The AGILE project is developing an architectural approach in which mobility aspects can be modelled explicitly and mapped on the distribution and communication topology made available at physical levels. The whole approach is developed over a uniform mathematical framework based on graph-oriented techniques that support sound methodological principles, formal analysis, and refinement. This paper describes the AGILE project and some of the results gained during the first project year. 1
