R. J. R. Back and K. Sere. Action systems with synchronous communication. In E.--R. Olderog, editor, Programming Concepts, Methods and Calculi (PROCOMET'94), IFIP Transactions A--56, pp. 107--126, North--Holland 1994.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... a delayed taking of the fixpoint of [27, 14] The action system model for parallel, distributed, and reactive systems was proposed by Back and Kurki Suonio [6, 7] The same basic approach has later been used in other models for distributed computing, notably UNITY [12] and TLA [19] Back and Sere [8] have added procedures to action systems. They, as well as Sere and Wald en [26] and Bonsangue et al. [11] have also studied input output refinement of action systems with methods, which is similar to our classes after self and super references have been resolved. Using trace refinement, we ....

....and grd (S #T) grd S# grd T for any S,T #i # 1, m . R[trm C.m i # trm CX# grd C.m i ] # grd D.m i # grd DX) The last line follows from (d) Condition (4) follows from (f) by monotonicity. ## 16 A related theorem has first been given for action systems with remote procedures in [8] and in a revised form in [26] which is similar to the corresponding theorem for OO action systems in [11] The theorem given here generalizes those in four ways. First, we consider trace refinement and not just input output refinement. Thus, class refinement also preserves reactive behavior and ....

Ralph Back and Kaisa Sere. Action systems with synchronous communication. In E.-R. Olderog, editor, IFIP Working Conference on Programming Concepts, Methods, Calculi, pages 107--126, San Miniato, Italy, 1994. NorthHolland.

....[Bac93] which was originally built for preservation of total correctness, i.e. all pre and postcondition pairs of programs. By modeling reactive systems as sequential programs and by using data refinement, the Refinement Calculus can be used for the refinement of reactive systems [Bac90] In [BS94], remote) procedures are added to this framework to increase the ability to split programs into modules. Refinement corresponds This research has been supported by the Foundation for Computer Science in the Netherlands SION under project 612 317 107. to the reduction of behaviours of a ....

....which corresponds to closed systems. This subset corresponds to normal UNITY programs. The ImpUNITY programming language is an extension of the standard UNITY programming language with new sections for hiding parts of the statespace and sections for (remote) procedure calls (like Action Systems [BS94]) An ImpUNITY program F consists of the following sections: ffl A shared section declaring the set of shared variables of the program, i.e. the variables that can be read and written by both the program and its environment. The set is denoted by shared(F ) and must be a subset of V . ffl A ....

R.J.R. Back and K. Sere. Action systems with synchronous communication. In E.- R. Olderog, editor, Programming Concepts, Methods and Calculi, volume A-56 of IFIP Transactions, pages 107--126. IFIP, Elsevier Science Publishers B.V. (North Holland), June 1994.

....reactive systems as sequential programs and by using data refinement, the Refinement Calculus can also be used for the refinement of reactive systems [Bac90] The programming language supports local variables and nondeterminism. Remote procedures can be added to split programs into modules [BS94]. Refinement corresponds to the reduction of possible behaviours (sequences of states) of a program and preserves all temporal properties. However, the framework does not support temporal reasoning about programs. The ImpUNITY framework combines UNITY and Action Systems in such a way that it ....

R.J.R. Back and K. Sere. Action systems with synchronous communication. In E.-R. Olderog, editor, Programming Concepts, Methods and Calculi, volume A-56 of IFIP Transactions, pages 107--126. IFIP, Elsevier Science Publishers B.V. (North Holland), June 1994.

.... The algorithms by Hofstee et al. are written in Dijkstra s guarded command language [5] They perform the synchronization and communication by message passing [10] The action systems framework that we are working in has recently been extended by adding procedure declarations to the action systems [2]. In the extended framework a procedure declaration can model the receiving of a message, while a procedure call in an action can be seen as sending a message. When an action calls a procedure, the calling action and the procedure are executed as a single atomic entity, i.e. they are ....

....superposition method. In section 5 we derive a distributed load balancing algorithm from the specification given in section 3. Finally, we end with some concluding remarks in section 6. 2 Action systems with procedures We use the action systems formalism [1] extended with procedure declarations [2, 4] to construct the distributed load balancing algorithm with synchronous communication. We first give a brief overview of the action system formalism. An action system A is a statement of the form A def = j[ var z ; x : z0; x0; proc p 1 = P 1 ; p n = P n ; q 1 = Q 1 ; ....

[Article contains additional citation context not shown here]

R. J. R. Back and K. Sere. Action systems with synchronous communication. In E. R. Olderog, editor, Programming Concepts, Methods and Calculi, IFIP Transaction A-56. North-Holland, 1994.

....is usually treated UNITY style ( CM88] i.e. as the fair interleaved execution of an action system consisting of a fixed number of processes with communication through shared variables. Some results in the literature are established dealing with the superposition of action systems (e.g. [BS94]) In general, however, the underlying weakest precondition semantics is not tuned to a compositional treatment of concurrency. Several authors have proposed a predicate transformer semantics for concurrency. Recent references are, e.g. Bes89, Lam90, SZ92] Taking all together none of these ....

R.J.R. Back and K. Sere. Action Systems with Synchronous Communication. In E.-R. Olderog, editor, Proc. Programming Concepts, Methods and Calculi, pages 107--126. IFIP, North Holland, 1994.

....is usually treated UNITY style: the (fair) interleaved execution of an action system consisting of a fixed number of processes with communication through shared variables ( CM88, BKS88, Ser90, Luk91] Some results are established dealing with the superposition of action systems. e.g. BS92] and [BS94], where additionally procedures are incorporated. In general, however, the underlying weakest precondition semantics is not tuned to a compositional treatment of concurrency. For some programming languages this may not be an issue at all. For others, in particular those with dynamical object or ....

R.J.R. Back and K. Sere. Action Systems with Synchronous Communication. In E.- R. Olderog, editor, Programming Concepts, Methods and Calculi, volume A-56 of IFIP Transaction, pages 107--126. Elsevier Science Publishers B.V. North-Holland, 1994.

....reactive systems as sequential programs and by using data refinement, the Refinement Calculus can also be used for the refinement of reactive systems [Bac90] The programming language supports local variables and nondeterminism. Remote procedures can be added to split programs into modules [BS94]. Refinement corresponds to the reduction of possible behaviors (sequences of states) of a program and preserves all temporal properties. However, the framework does not support temporal reasoning about programs. The ImpUNITY framework combines UNITY and Action Systems in such a way that it ....

R.J.R. Back and K. Sere. Action systems with synchronous communication. In E.-R. Olderog, editor, Programming Concepts, Methods and Calculi, volume A-56 of IFIP Transactions, pages 107--126. IFIP, Elsevier Science Publishers B.V. (North Holland), June 1994.

....event based formalisms have been put forward by several other researchers, see for example the work of Chandy and Misra [12] who describe their UNITY framework and Francez [14] who develops his IPlanguage. Recently , Back and Sere introduced the idea of remote procedures for action systems [8]. It has also been shown how this mechanism is used in practical program development [6, 21] Furthermore, Kurki Suonio has studied remote procedure calls in action systems using an object oriented modeling formalism [15] The action systems approach supports the stepwise refinement paradigm for ....

....to the refinement calculus independently by Back [3] and Morgan [16] with slightly di#erent ways in which parameter passing is handled. We extend the data refinement of reactive action systems as described by Back [4] to handle remote procedures. We extend the preliminary work by Back and Sere [8] considerably by developing a more general rule for the refinement of remote procedures together with a number of useful special cases of it. We pay special attention to the compositionality of the developed rules thus supporting a modular way of program development. Moreover, as an example we ....

[Article contains additional citation context not shown here]

R. J. R. Back and K. Sere. Action systems with synchronous communication. In E.--R. Olderog, editor, Programming Concepts, Methods and Calculi (PROCOMET'94), IFIP Transactions A--56, pp. 107--126, North--Holland 1994.

.... Moreover, Abadi and Leino develop a Hoare style logic for reasoning about object oriented programs [AL97] Reasoning about DisCo specifications is carried out within TLA [Lam91] The way we define inheritance or sub typing as class refinement is based on data refinement for action systems [Bac90, BS94, SW97]. Class refinement in the data refinement framework has also been studied by Mikhajlova and Sekerinski [MS97] They construct new classes by inheritance and overriding, but do not consider the addition of new methods. Moreover, their objects are not active and distributed as ours are. Class ....

....of the procedures declared in C might change in the refinement step. Using this rule no new global methods are provided by the subclass C . The formal parameters of the methods are not to be changed in a refinement step. A special case of the rule for class refinement, the superposition rule [BS92, BS94], could be used instead of the above, more general data refinement rule. In superposition we do not remove old variables, only new variables are added into a class. Hence, a subclass would work with all variables declared in the superclass and with some new, added variables. Introducing new ....

R.J.R. Back and K. Sere. Action systems with synchronous communication. In E.-R. Olderog, editor, Proceedings of the IFIP Working Conference on Programming Concepts, Methods and Calculi, IFIP Transactions A-56, pages 107--126, North-Holland Publishing Company, 1994.

....event based formalisms have been put forward by several other researchers, see for example the work of Chandy and Misra [11] who describe their UNITY framework and Francez [13] who develops his IP language. Recently, Back and Sere introduced the idea of remote procedures for action systems [8]. It has also been shown how this mechanism is used in practical program development [6, 19] The action systems approach supports the stepwise refinement paradigm for the construction of parallel and distributed systems. The refinement calculus is a formalization of the stepwise refinement ....

....refinement calculus independently by Back [3] and Morgan [14] with slightly di#erent ways in which parameter passing is handled. We extend the data refinement of reactive action systems as described by Back [4] to handle remote procedures. Our paper is based on preliminary work by Back and Sere [8] who consider a more limited version of data refinement than we do here. We develop a very general rule for the refinement of remote procedures together with a number of useful special cases of it. We pay special attention to the compositionality of the developed rules thus supporting a modular ....

[Article contains additional citation context not shown here]

R. J. R. Back and K. Sere. Action systems with synchronous communication. In E.--R. Olderog, editor, Programming Concepts, Methods and Calculi 20 (PROCOMET'94), IFIP Transactions A--56, pp. 107--126, North--Holland 1994.

....our screen saver in the next version ManyFishes (Figure 2) The declaration ACTION MoveRight(i: 0. many 1) generates an action for each i between 0 and many 1. The replicator i can be used like a constant in the guard and body of the action. Like actions, procedures may be protected by a guard [6]. If the evaluation of the guard of an action or the execution of its body would lead to a call of a disabled procedure, the action is considered to be disabled. Note that no waiting for the guard to become true takes place, as is common with monitors or semaphores. 3 Type bound actions Being ....

R. Back and K. Sere. Action systems with synchronous communication. In IFIP TC 2 Working Conference on Programming Concepts, Methods and Calculi (PROCOMET '94), pages 107--126. Elsevier, 1994.

....parallel, as long as the actions do not share any variables. Atomicity guarantees that a parallel execution of an action system gives the same results as a sequential and nondeterministic execution. A recent extension of the action system framework, adding procedure declarations to action systems [6], gives us a very general mechanism for synchronized communication between action systems. When an action in one action system calls a procedure in another action system, the effect is that of a remote procedure call. The calling action and the procedure body involved in the call are executed as a ....

....could be derived in a stepwise manner within it relying heavily on the work done in data refinement. In both cases parallel and concurrent activity is modelled within a purely sequential framework. Procedures were added to the refinement calculus independently by Back [2] and Morgan [13] In [6] Back and Sere show how action systems with remote procedure calls can be derived within the refinement calculus for reactive systems. We will in this paper show how these results are applied to a non trivial case study, the formal derivation of a microprocessor. The initial specification of the ....

[Article contains additional citation context not shown here]

R. J. R. Back and K. Sere. Action systems with synchronous communication. To be presented at PROCOMETT'94, San Miniato, Italy, June 1994.

....in the next version ManyFishes (Fig. 2) The action declaration ACTION MoveRight(i: 0. many 1) generates an action for each i between 0 and many 1. The replicator i can be used like a constant in the guard and body of the action. Like actions, procedures may be protected by an optional guard [7]. If the evaluation of the guard of an action or the execution of its body would lead to a call of a disabled MODULE ManyFishes; CONST many=5; height=10; width=20; VAR x, y: ARRAY many OF INTEGER; right, up: ARRAY many OF BOOLEAN; k: INTEGER; ACTION MoveRight(i: 0. many 1) WHEN right[i] ....

R. Back and K. Sere. Action systems with synchronous communication. In IFIP TC 2 Working Conference on Programming Concepts, Methods and Calculi (PROCOMET '94), pages 107--126. Elsevier, 1994.

....the refinement calculus. We will not go any deeper into the methods by which modularity is used in program refinement, nor will we give specific refinement rules for modular components. These issues have been treated in other papers, and the interested reader can consult them for more details [9, 11, 7]. The features of our modular programming language have been chosen so that refinement of program modules is simple and straightforward. We want to show how a single framework can be used for both the specification of large systems, the modular decomposition of the system into smaller units and ....

R. J. R. Back and K. Sere. Action Systems with Synchronous Communication. To appear in E.--R. Olderog, editor, IFIP TC 2 Working Conference on Programming Concepts, Methods and Calculi (PROCOMET '94), pages 107--126. Elsevier, 1994.

....or distributed program where parallel activity is described in terms of events, so called actions. Several actions can be executed in parallel, as long as the actions do not share any variables. A recent extension of the action system framework, adding procedure declarations to action systems [5], gives us a very general mechanism for communication between action systems. The action systems formalism was proposed by Back and Kurki Suonio [3] The refinement calculus is a formalization of the stepwise refinement method of program construction. It was originally proposed by Back [1] and it ....

R. J. R. Back and K. Sere. Action systems with synchronous communication. In E.-R. Olderog, editor, Programming Concepts, Methods and Calculi. Proceedings of the IFIP TC2/WG2.1/WG2.2/WG2.3 Working Conference, pages 107--126, 1994.

....parallel, as long as the actions do not share any variables. Atomicity guarantees that a parallel execution of an action system gives the same results as a sequential and nondeterministic execution. A recent extension of the action system framework, adding procedure declarations to action systems [7], gives us a very general mechanism for synchronized communication between action systems. When an action in one action system calls a procedure in another action system, the effect is that of a remote procedure call. The calling action and the procedure body involved in the call are executed as a ....

....the calculus. Back [3] made yet another extension to the calculus showing how reactive programs could be derived in a stepwise manner within it relying heavily on the work done in data refinement. In both cases parallel and concurrent activity is modelled within a purely sequential framework. In [7] Back and Sere show how action systems with remote procedure calls can be derived within the refinement calculus for reactive systems. We will here show how this extention of the refinement calculus action system framework is applied to a non trivial case study, the formal derivation of an ....

[Article contains additional citation context not shown here]

R. J. R. Back and K. Sere. Action systems with synchronous communication. Proc. of PROCOMET'94, San Miniato, Italy, June 1994. E.-R. Olderog, editor, Programming Concepts, Methods and Calculi, IFIP Transactions A-56, pages 107-- 126, North--Holland 1994.

....event based formalisms have been put forward by several other researchers, see for example the work of Chandy and Misra [12] who describe their UNITY framework and Francez [14] who develops his IPlanguage. Recently , Back and Sere introduced the idea of remote procedures for action systems [8]. It has also been shown how this mechanism is used in practical program development [6, 21] Furthermore, Kurki Suonio has studied remote procedure calls in action systems using an object oriented modeling formalism [15] The action systems approach supports the stepwise refinement paradigm for ....

....to the refinement calculus independently by Back [3] and Morgan [16] with slightly di#erent ways in which parameter passing is handled. We extend the data refinement of reactive action systems as described by Back [4] to handle remote procedures. We extend the preliminary work by Back and Sere [8] considerably by developing a more general rule for the refinement of remote procedures together with a number of useful special cases of it. We pay special attention to the compositionality of the developed rules thus supporting a modular way of program development. Moreover, as an example we ....

[Article contains additional citation context not shown here]

R. J. R. Back and K. Sere. Action systems with synchronous communication. In E.--R. Olderog, editor, Programming Concepts, Methods and Calculi (PROCOMET'94), IFIP Transactions A--56, pp. 107--126, North--Holland 1994.

....can be seen as a mixture between UNITY and the language of the action system formalism. It has an associated temporal logic similar to the logic of UNITY [3] and it has formal refinement notions and the structuring mechanisms (procedures, local variables) of the the action system formalism [1]. As an example of an ImpUNITY program, consider the program Buf given in Figure 1. This program models a buffer that communicates with its environment by a procedure interface. Messages are put in the buffer by calling the procedure flushin and the buffer outputs messages by calling the ....

R. J. R. Back and K. Sere. Action systems with synchronous communication. In E.-R. Olderog, editor, Programming Concepts, Methods and Calculi, volume A-56 of IFIP Transactions, pages 107--126. Elsevier, June 1994.

.... Moreover, Abadi and Leino develop a Hoare style logic for reasoning about object oriented programs [AL97] Reasoning about DisCo specifications is carried out within TLA [Lam91] The way we define inheritance or sub typing as class refinement is based on data refinement for action systems [Bac90, BS94, SW97]. Class refinement in the data refinement framework has also been studied by Mikhajlova and Sekerinski [MS97] They construct new classes by inheritance and overriding, but do not consider the addition of new methods. Moreover, their objects are not active and distributed as ours are. Class ....

....of the procedures declared in C might change in the refinement step. Using this rule no new global methods are provided by the subclass C 0 . The formal parameters of the methods are not to be changed in a refinement step. A special case of the rule for class refinement, the superposition rule [BS92, BS94], could be used instead of the above, more general data refinement rule. In superposition we do not remove old variables, only new variables are added into a class. Hence, a subclass would work with all variables declared in the superclass and with some new, added variables. Introducing new ....

R.J.R. Back and K. Sere. Action systems with synchronous communication. In E.-R. Olderog, editor, Proceedings of the IFIP Working Conference on Programming Concepts, Methods and Calculi, IFIP Transactions A-56, pages 107--126, North-Holland Publishing Company, 1994.

....do not have any variables in common. The actions are atomic: if an action is chosen for execution, it is executed to completion without any interference from the other actions in the system. Recently the action system framework has been extended with procedure mechanism and remote procedure calls [7]. In this paper we de ne a return statement for procedures of an action system. The intention for this new statement is to allow early return from a procedure call so that the caller and the callee can proceed with their respective code concurrently. The de nition is based on the atomicity ....

....parameters and y the formal call by result parameters. Then a call on p with the actual parameters a; b is removed by the substitution S = S [P 0 =p(a; b) where P 0 is the statement j[ var x ; y ; x : a; P ; b : y ]j: The de nition of procedures is studied in more detail in [2, 7]. Enabledness of an action Let p = b T ) be a procedure and let a S ; p be an action that calls on p. Then the enabledness of this action is determined by the value of the action guard g(a S ; p) a g(S ; p) where g(S ; p) is calculated as follows: g(S ; p) g(S ; b T ) wp(S ; ....

[Article contains additional citation context not shown here]

R. J. R. Back and K. Sere. Action systems with synchronous communication. Proc. of PROCOMET'94, San Miniato, Italy, June 1994. E.-R. Olderog, editor, Programming Concepts, Methods and Calculi, IFIP Transactions A-56, pages 107 126, NorthHolland 1994.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC