K. Kahn and V. Saraswat, "Actors as a Special Case of Concurrent Constraint Programming", ECOOP/OOPSLA 90 Proceedings, October 1990, pp. 57-66.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....one stream which is consumed by the receiver. ffl Languages with atomic test and unify allow multiple writers to a single stream. Both approaches suffer efficiency problems as pointed out in [5] Attempts to overcome these insufficiencies include mutual references [9] channels [15] and bags [6]. For the ccp language AKL [4] which combines Prolog style searchoriented nondeterministic computation with process oriented committedchoice and ccp, Haridi, Janson and Montelius [5] propose the concept of ports. A port is a connection between a bag of messages which serves as the object ....

K. M. Kahn and V. A. Saraswat. Actors as a Special Case of Concurrent Constraint Programming. In Proceedings of the European Conference on Object Oriented Programming, pages 57--66. ACM, October 1990.

....universe) As a prerequisite to this, we will first cover the formal background to concurrent constraint languages and discuss methods of disjunctive and hypothetical reasoning already investigated in logic languages. CHAPTER 1. INTRODUCTION 4 1. 1 Background Concurrent constraint languages [58, 32, 61, 60, 62] grew out of a formalization of concurrent logic languages 2 [46, 65, 72, 66] The concept of programming with constraints is taken from the work on constraint logic programming [30, 31, 39, 29, 12, 13, 22] which itself is a generalization of Prolog [36, 9, 69] 1.1.1 Terminology For the sake ....

....how our addition example could be programmed in a simple constraint system. If the store is limited to containing uninterpreted functions and constants, but one may ask more complex constraints which will suspend until the necessary variables become ground (such a system is offered by FCP( [76, 35, 32]) then the solution is the following CHAPTER 1. INTRODUCTION 25 Program 1.9 add(X,Y,Z) 9(Sum) Sum = X Y)# : Z = Sum , stop 2 9(Diff) Diff = Z Gamma X)# : Y = Diff , stop 2 9(Diff) Diff = Z Gamma Y)# : X = Diff , stop If one or both of the variables to the right of the equality in ....

Kenneth M. Kahn and Vijay A. Saraswat. Actors as a special case of concurrent constraint programming. In Meyrowitz [48], pages 57--66.

.... that an instance of a subtype can always be used in any context in which an instance of a supertype is expected [16] Syntax and semantics of the language model used in this paper resemble that of concurrent logic languages [14] relationships of these languages to the objectbased actor model [4] and to process algebra are widely known. An example of a process definition for a simple buffer with a capacity of one element shows the basic constructions of our language model: Buffer1(q) q . put(e) Delta get(a) Delta r; a got(e) Buffer1(r) The parameter q is the read port of a ....

Kenneth M. Kahn and Vijay A. Saraswat. Actors as a special case of concurrent constraint programming. ACM SIGPLAN Notices 25:10 (October 1990) 57--65. Proceedings OOPSLA/ECOOP'90.

....in 4.4. Our classification is far from exhaustive. In particular, we have emphasized imperative approaches to COOPL design, whereas declarative approaches based on logics appear to offer certain advantages with respect to abstraction of interface and implicit vs. explicit concurrency [3] [18], 21] We have also been rather abstract in the presentation of our example. We feel that requirements for reusability should ultimately be based on practical experience in the development of reusable frameworks for concurrent applications. A standard set of test cases illustrating both ....

K.M. Kahn and V.A. Saraswat, "Actors as a Special Case of Concurrent Constraint Programming," ACM SIGPLAN Notices, Proceedings OOPSLA/ECOOP '90, vol. 25, no. 10, pp. 57-65, Oct 1990.

.... seen several works in attempting to establishing it as a formal model of concurrent computation[31, 1] Recently, there have been other works that attempts to understand the Actor model in terms of other models of concurrent computation, such as the calculus[48, 47] Rewriting Logic[77] and CC[57]. In addition, there have been other works that explored the semantics of particular OOCP languages[6, 130, 99] The ultimate goal of these models can be regarded as establishing the foundations of concurrent computations in general, just as the Lambda Calculus is intended to give the foundations ....

Kenneth M. Kahn and Vijay A. Saraswat. Actors as a special case of concurrent constraint programming. In Proceedings of OOPSLA'90, volume 25, pages 57--65. SIGPLAN Notices, ACM Press, October 1990.

....stored in some other data structure, the new end of stream variable has to be stored in the data structure after one round of sending is completed. Usually this means copying parts of the data structure (but if some form of single reference optimisation is employed by the language implementation [2, 10, 4], this would not necessarily be the case) Even worse, to enable sharing of this data structure with another process object, where the possibility of the other object sending messages on the embedded streams cannot be excluded, two copies of the data structure have to be created (allocating new ....

....it. An inactive sender causes the same problem. Closing is just as explicit and problematic. The multiple readers ability can be achieved by other means. For example, a process can arbitrate requests for messages from a stream conceptually shared by several readers. 2.2. 5 Bags Kahn and Saraswat [10] introduced bags for the languages Lucy and Janus. Bags are multi sets of messages. They are like streams in that subsequent messages are sent on subsequent bags, but there is no need for user defined merging, as this is taken care of by the Tell constraint bag union B = B1 [ Delta Delta Delta ....

Kenneth M. Kahn and Vijay A. Saraswat. Actors as a special case of concurrent constraint programming. In Norman Meyrowitz, editor, OOPSLA/ECOOP '90 Conference Proceedings. ACM/SIGPPLAN, 1990.

....in which messages (here, p) are delivered to methods (here, p Gammaffi r, and p Gammaffi q) Indeed linear asks and tells allow for a direct, powerful form of communication. An example should suffice to convey the flavor. A natural way to model Actor style languages within the cc framework (see [SKL90,KS90]) is to represent actor mailboxes as logical variables equated to bags of values. Sending a message, say 5, to an actor with associated channel X , then, corresponds to posting the constraint 5 2 X . The actor suspends, asking whether there is a message on X; when activated, it pops a message off ....

.... we have presened hitherto (without any built in constraint system) is the basis of the programming language Linear Janus [Tse92] Linear Janus is a cleaned up and considerably simplified version of Lucy, the missing link between concurrent logic programming and actor languages described in [KS90]. As such it is in a long tradition of languages arising from the connection between concurrent logic programming languages and Actor languages. From a computational perspective, the system is very close to the asynchronous fragment of the calculus [MPW89] and one can also show that it is ....

Kenneth Kahn and Vijay Saraswat. Actors as a special case of concurrent constraint programming. In Proceedings of the Joint Conference on Object-Oriented Programming: Systems, Languages, and Applications and the EuropeanConference on Object-Oriented Programming. ACM Press, October 1990.

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K. Kahn and V. Saraswat, "Actors as a Special Case of Concurrent Constraint Programming", ECOOP/OOPSLA 90 Proceedings, October 1990, pp. 57-66.

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