M.J. Butler. An approach to the design of distributed systems with B AMN. In J.P. Bowen, M.G. Hinchey, and D. Till, editors, 10th International Conference of Z Users (ZUM'97), volume LNCS 1212, pages 223 -- 241. Springer--Verlag, April 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....discusses issues of liveness and fairness in dynamic specifications. Internal operations are specified as in [WD96] and he also considers the refinement relations needed for Z specifications of concurrent systems. Similar work has appeared in other state based formalisms. For example, Butler [But97] considers the specification and refinement of internal actions in the B method Specifying and Refining internal operations in Z 5 [Abr96] There, internal actions are specified explicitly in an abstract machine. Additional work in this area also includes the work of Lano, e.g. Lan97] In each ....

....occurrence of an internal operation in the abstract specification by zero or more internal actions (using I ) in the concrete specification. To prevent divergence being introduced upon refinement we introduce two divergence refinement rules. The criteria these rules embody are based upon those in [But97]. We use a well founded set WF with a partial order , and a variant which is an expression in the state variables. The variant, E , should Specifying and Refining internal operations in Z 17 always be an element of the set WF, and it should be decreased by each internal operation in the concrete ....

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M. Butler. An approach to the design of distributed systems with B AMN. In J. P. Bowen, M. G. Hinchey, and D. Till, editors, ZUM'97: The Z formal specification notation, LNCS 1212, pages 223--241, Reading, April 1997. Springer-Verlag.

....but this is not yet the case for software. We do have a selection of tools and methods available which could be used for this type of work from simple diagramming notations and system description languages [15] to complete systems for the construction, execution and evaluation of proposed systems [16]. These tools come from two areas: Formal methods and other design techniques and notations. Design notations and techniques either suffer from a lack of a suitable formal underpinning or where this exists, it is not enforced. As a consequence, where appropriate simulation tools are available, ....

M. J. Butler, "An Approach to the Design of Distributed Systems with B AMN," presented at 10th International Conference of Z Users (ZUM'97), Reading, 1997.

....for u 2 USR action UserGotKey u in k : KEY : ustatus = needkey key : k Fig. 1. Action System speci cation for part of secure database system A detailed understanding of Action Systems is not required here, and the interested reader is directed to the work of Morgan [17] and that of Butler [5,6]. It is worth noting that status, ustatus and key are examples of state variables characteristic of this style of formalism. At this point, we wish to hand over to a suitable protocol, very possibly developed using a di erent notation, in this case, CSP. 3 Combining speci cations an overview ....

....section provide the mechanisms to integrate separate views using our relational conditions. How most e ectively to check that component speci cations satisfy these conditions is a challenging problem under research. 9 Relation to other work and conclusions Butler has developed a tool csp2b [5,6] which provides a means of combining CSP with standard B speci cations. The technique builds on weakestprecondition formulations for Action Systems given by Morgan [17] and Butler [4] CSP like descriptions are translated into machine readable B speci cations, which can then be veri ed by a ....

M.J. Butler. An approach to the design of distributed systems with B AMN. In D. Till J. Bowen, M. Hinchey, editor, ZUM'97, pages 223-241. Springer, 1998.

.... as PVS and HOL will be important for our proposed research on automated test case generation [21, 22, 12] Some of this work was part of the EPSRC funded Tool Integration for Applied Formal Methods project (GR K83014) Compositionality Our existing work on modelling distributed systems in B [8], feature interaction [39] and the theory of refinement [4] is important for modelling and reasoning about component composition and decomposition. Refinement and Abstraction Our existing work on stepwise refinement [9] is the foundation for our proposed research on multi level simulation while ....

M. J. Butler. An approach to the design of distributed systems with B AMN (extended version). Declarative Systems & Software Engineering Technical Reports DSSE-TR-96-6, Univ. of Southampton, 1996.

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M.J. Butler. An approach to the design of distributed systems with B AMN. In J.P. Bowen, M.G. Hinchey, and D. Till, editors, 10th International Conference of Z Users (ZUM'97), volume LNCS 1212, pages 223 -- 241. Springer--Verlag, April 1997.

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M.J. Butler. An approach to the design of distributed systems with B AMN. In J.P. Bowen and M.G. Hinchey, editors, 10th International Conference of Z Users (ZUM'97), volume LNCS 1212, pages 223-241. Springer{Verlag, 1997.

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M.J. Butler. An Approach to the Design of Distributed Systems with B AMN (extended version). Technical Report DSSE-TR-96-6 (http://www.dsse.ecs.soton.ac.uk/techreports/96-6.html), University of Southampton, 1996. Shorter version appears in proceedings of 10th International Conference of Z Users (ZUM'97), 3-4th April

....of event traces. Event trace properties model safety properties of a system and are MACHINE M SETS SS CONSTANTS C VARIABLES v INITIALISATION init OPERATIONS : Figure 1: Abstract machine outline. preserved by refinement. This extra ingredient is based on previous work by the author [3, 4] which helps to bridge the gap between state based formal methods, such as B, with event based methods such as CSP. In this paper we apply the approach to the Needham Schroeder Authentication Protocol [13] The aim of this protocol is to provide authenticated exchange of secrets (nonces) The ....

M.J. Butler. An approach to the design of distributed systems with B AMN. In J.P. Bowen and M.G. Hinchey, editors, 10th International Conference of Z Users (ZUM'97), volume LNCS 1212, pages 223--241. Springer-- Verlag, 1997.

....C VARIABLES v INITIALISATION init OPERATIONS : Figure 1: Abstract machine outline. security properties in terms of event traces. Event trace properties model safety properties of a system and are preserved by refinement. This extra ingredient is based on previous work by the author [3, 4] which helps to bridge the gap between state based formal methods, such as B, with event based methods such as CSP. In this paper, we apply the approach to the Needham Schroeder Public Key Authentication Protocol [13] The aim of this protocol is to provide authenticated exchange of secrets ....

M.J. Butler. An approach to the design of distributed systems with B AMN. In J.P. Bowen and M.G. Hinchey, editors, 10th International Conference of Z Users (ZUM'97), volume LNCS 1212, pages 223--241. Springer--Verlag, 1997.

....may be refined in a stepwise manner relying on an extension of this weakest precondition calculus. Di#erent views as to what constitutes the observable behaviour of an action system may be taken. We have here considered a state based view of action systems. An event based view is studied in [10]. In the statebased view action systems have a local and a global state. The environment interacts with an action system via its global state. It is, thus, only the global state that is visible to and accessible to the environment. In this paper we show how refinement of action systems and, hence, ....

M. J. Butler. An approach to the design of distributed systems with B AMN. University of Southampton, Declarative Systems & Software Engineering Technical Reports, DSSE-TR-96-6, September 1996.

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M. J. Butler. An approach to the design of distributed systems with B AMN. In the Proc. of the 10th International Conference of Z Users (ZUM'97), University of Reading, UK, April 1997.

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Butler M. J.: An Approach to the Design of Distributed Systems with B AMN. In J. Bowen, M. Hinchey D. Till, editors, ZUM'97, Springer (1998), pp 223-241.

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