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26
A Concurrent Logical Framework II: Examples and Applications
, 2002
"... CLF is a new logical framework with an intrinsic notion of concurrency. It is designed as a conservative extension of the linear logical framework LLF with the synchronous connectives # of intuitionistic linear logic, encapsulated in a monad. LLF is itself a conservative extension of LF with the ..."
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Cited by 46 (30 self)
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CLF is a new logical framework with an intrinsic notion of concurrency. It is designed as a conservative extension of the linear logical framework LLF with the synchronous connectives # of intuitionistic linear logic, encapsulated in a monad. LLF is itself a conservative extension of LF with the asynchronous connectives #.
Orchestrating Transactions in Join Calculus
, 2002
"... We discuss the principles of distributed transactions, then we define an operational model which meets the basic requirements and we give a prototyping implementation for it in joincalculus. In particular, our model: (1) extends BizTalk's short transactions; (2) it exploits an original commit alg ..."
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Cited by 34 (12 self)
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We discuss the principles of distributed transactions, then we define an operational model which meets the basic requirements and we give a prototyping implementation for it in joincalculus. In particular, our model: (1) extends BizTalk's short transactions; (2) it exploits an original commit algorithm, which is distributed; (3) it can deal with dynamically changing communication topology; (4) it is almost languageindependent. In fact, the model is simply based on a twolevel classification of resources, which should be easily conveyed to distributed calculi and languages, providing them with a powerful transactional mechanism.
A Concurrent Logical Framework: The Propositional Fragment
, 2003
"... We present the propositional fragment CLF0 of the Concurrent Logical Framework (CLF). CLF extends the Linear Logical Framework to allow the natural representation of concurrent computations in an object language. The underlying type theory uses monadic types to segregate values from computations ..."
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Cited by 31 (3 self)
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We present the propositional fragment CLF0 of the Concurrent Logical Framework (CLF). CLF extends the Linear Logical Framework to allow the natural representation of concurrent computations in an object language. The underlying type theory uses monadic types to segregate values from computations. This separation leads to a tractable notion of definitional equality that identifies computations di#ering only in the order of execution of independent steps. From a logical point of view our type theory can be seen as a novel combination of lax logic and dual intuitionistic linear logic. An encoding of a small Petri net exemplifies the representation methodology, which can be summarized as "concurrent computations as monadic expressions ".
Comparing Petri Net and Activity Diagram Variants for Workflow Modelling  A Quest for Reactive Petri Nets
 In Weber et al
, 2002
"... Petri net variants are widely used as a workflow modelling technique. Recently, UML activity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets ..."
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Cited by 25 (4 self)
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Petri net variants are widely used as a workflow modelling technique. Recently, UML activity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets and on the surface, one may think that they are variants of each other. To substantiate or deny this claim, we need to formalise the intended semantics of activity diagrams and then compare this with various Petri net semantics. In previous papers we have defined two formal semantics for UML activity diagrams that are intended for workflow modelling. In this paper, we discuss the design choices that underlie these two semantics and investigate whether these design choices can be met in lowlevel and highlevel Petri net semantics. We argue that the main di#erence between the Petri net semantics and our semantics of UML activity diagrams is that the Petri net semantics models resource usage of closed, active systems that are nonreactive, whereas our semantics of UML activity diagrams models open, reactive systems.
Nested commits for mobile calculi: extending Join
, 2004
"... In global computing applications the availability of a mechanism for some form of committed choice can be useful, and sometimes necessary. It can conveniently handle, e.g., contract stipulation, distributed agreements, and negotiations with nested choice points to be carried out concurrently. We pro ..."
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Cited by 18 (6 self)
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In global computing applications the availability of a mechanism for some form of committed choice can be useful, and sometimes necessary. It can conveniently handle, e.g., contract stipulation, distributed agreements, and negotiations with nested choice points to be carried out concurrently. We propose a linguistic extension of the Join calculus for programming nested commits, called Committed Join (cJoin). It provides primitives for explicit abort, programmable compensations and interactions between ongoing negotiations. We give the operational semantics of cJoin in the reflexive CHAM style. Then we discuss its expressiveness on the basis of a few examples and of the cJoin encoding of other paradigms with similar aims but designed in different contexts, namely AKL and ZeroSafe nets. Finally, we provide a bigstep semantics for cJoin processes that can be typed as shallow. We show that shallow processes are serializable by proving the correspondence between CHAM and bigstep semantics.
Transactions and ZeroSafe Nets
 Advances in Petri Nets: Unifying Petri Nets, Lect. Notes in Comput. Sci. 2128
, 2001
"... When employing Petri nets to model distributed systems, one must be aware that the basic activities of each component can vary in duration and can involve smaller internal activities, i.e., that transitions are conceptually refined into transactions. We present an approach to the modeling of transac ..."
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Cited by 15 (8 self)
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When employing Petri nets to model distributed systems, one must be aware that the basic activities of each component can vary in duration and can involve smaller internal activities, i.e., that transitions are conceptually refined into transactions. We present an approach to the modeling of transactions based on zerosafe nets. They extend ordinary pt nets with a simple mechanism for transition synchronization. We show that the net theory developed under the two most diffused semantic interpretations (collective token and individual token philosophies) can be uniformly adapted to zerosafe nets. In particular, we show that each zerosafe net has associated two pt nets which represent the abstract counterparts of the modeled system according to the two philosophies. We show several applications of the framework, a distributed interpreter for zs nets based on classical net unfolding (here extended with a commit rule) and discuss some extensions to other net flavours.
Transactions in RCCS
 In Proc. of CONCUR, LNCS 3653
, 2005
"... Abstract. We propose a formalisation of the notion of transaction, using a variant of CCS, RCCS, that distinguishes reversible and irreversible actions, and incorporates a distributed backtrack mechanism. Any weakly correct implementation of a given transaction in CCS, once embedded in RCCS, automat ..."
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Cited by 14 (1 self)
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Abstract. We propose a formalisation of the notion of transaction, using a variant of CCS, RCCS, that distinguishes reversible and irreversible actions, and incorporates a distributed backtrack mechanism. Any weakly correct implementation of a given transaction in CCS, once embedded in RCCS, automatically obtains a correct one. We show examples where this method allows for a more concise implementation and a simpler proof of correctness. 1
Comparing Logics for Rewriting: Rewriting logic, action calculi and tile logic
 Theoretical Computer Science
, 2002
"... The large diffusion of concurrent and distributed systems has spawned in recent years a variety of new formalisms, equipped with features for supporting an easy specification of such systems. The aim of our paper is to analyze three proposals, namely rewriting logic, action calculi and tile logic, c ..."
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Cited by 13 (3 self)
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The large diffusion of concurrent and distributed systems has spawned in recent years a variety of new formalisms, equipped with features for supporting an easy specification of such systems. The aim of our paper is to analyze three proposals, namely rewriting logic, action calculi and tile logic, chosen among those formalisms designed for the description of rulebased systems. For each of these logics we first try to understand their foundations, then we briefly sketch some applications. The overall goal of our work is to find out a common layout where these logics can be recast, thus allowing for a comparison and an evaluation of their specific features.
Executable Tile Specifications for Process Calculi
, 1999
"... . Tile logic extends rewriting logic by taking into account sideeffects and rewriting synchronization. These aspects are very important when we model process calculi, because they allow us to express the dynamic interaction between processes and "the rest of the world". Since rewriting logic is the ..."
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Cited by 13 (10 self)
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. Tile logic extends rewriting logic by taking into account sideeffects and rewriting synchronization. These aspects are very important when we model process calculi, because they allow us to express the dynamic interaction between processes and "the rest of the world". Since rewriting logic is the semantic basis of several language implementation efforts, an executable specification of tile systems can be obtained by mapping tile logic back into rewriting logic, in a conservative way. However, a correct rewriting implementation of tile logic requires the development of a metalayer to control rewritings, i.e., to discard computations that do not correspond to any deduction in tile logic. We show how such methodology can be applied to term tile systems that cover and extend a wideclass of SOS formats for the specification of process calculi. The wellknown casestudy of full CCS, where the term tile format is needed to deal with recursion (in the form of the replicator operator), is di...
Symmetric Monoidal and Cartesian Double Categories as a Semantic Framework for Tile Logic
 MATHEMATICAL STRUCTURES IN COMPUTER SCIENCE
, 2002
"... Tile systems offer a general paradigm for modular descriptions of concurrent systems, based on a set of rewriting rules with sideeffects. Monoidal double categories are a natural semantic framework for tile systems, because the mathematical structures describing system states and synchronizing acti ..."
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Cited by 13 (9 self)
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Tile systems offer a general paradigm for modular descriptions of concurrent systems, based on a set of rewriting rules with sideeffects. Monoidal double categories are a natural semantic framework for tile systems, because the mathematical structures describing system states and synchronizing actions (called configurations and observations, respectively, in our terminology) are monoidal categories having the same objects (the interfaces of the system). In particular, configurations and observations based on netprocesslike and term structures are usually described in terms of symmetric monoidal and cartesian categories, where the auxiliary structures for the rearrangement of interfaces correspond to suitable natural transformations. In this paper we discuss the lifting of these auxiliary structures to double categories. We notice that the internal construction of double categories produces a pathological asymmetric notion of natural transformation, which is fully exploited in one dimension only (for example, for configurations or for observations, but not for both). Following Ehresmann (1963), we overcome this biased definition, introducing the notion of generalized natural transformation between four double functors (rather than two). As a consequence, the concepts of symmetric monoidal and cartesian (with consistently chosen products) double categories arise in a natural way from the corresponding ordinary versions, giving a very good relationship between the auxiliary structures of configurations and observations. Moreover, the Kelly–Mac Lane coherence axioms can be lifted to our setting without effort, thanks to the characterization of two suitable diagonal categories that are always present in a double category. Then, symmetric monoidal and cartesian double categories are shown to offer an adequate semantic setting for process and term tile systems.