Agha, G., Mason, I.A., Smith, S., Talcott, C. Towards a Theory of Actor Computation. In Cleaveland, R. (ed.), Proc of CONCUR '92. LNCS, Vol. 630, SpringerVerlag, Berlin Heidelberg (1992) 565--579.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Visualization Action: A visualization action corresponds to some rendering or animation activity which updates the current display of an algorithm. Typically, a visualization action is parameterized by the visualization event which invokes it. 1 Formally, actor events are only receive events [3]. However, for the sake of clarity we abuse terminology here. 14 Visualization Mechanism: The visualization mechanism specifies the relationship between visualization events and visualization actions. In particular, the visualization mechanism is responsible for detecting visualization events and ....

G. Agha, I. Mason, S. Smith, and C. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), pages 565-- 579, Stony Brook, NY, August 1992. Springer Verlag. Lecture Notes in Computer Science No. 630.

....decided to represent communication structures as abstract and directly as possible. Thus, we do not introduce new objects serving as buffers for messages. There are also some object based approaches. 3] proposes declarative rules for expressing coordination and synchronisation between objects. [2, 11] propose a process calculi based on the notion of actor like objects with asynchronous communication. In Sect. 2 we briefly introduce the object oriented specification language Troll by example and define the basic notions for the model theory. In Sect. 3 we construct a new model for object ....

G. Agha, I. Mason, S. Smith, and C. Talcott. Towards a Theory of Actor Computations. In Proceedings of CONCUR'92, pages 565--578. Springer, August 1992. LNCS 630.

....the style of CCS [12] We define a static algebra of actors (SAA for short) which is is described by means of structured operational semantics. The innovative aspect of the algebra we are proposing is that it is not defined over actor configurations (including also incoming messages as in [3]) but over actors only. This allows to reason on a particular actor system independently of the context, i.e. the multiset of incoming messages. Thus, as an example, equivalence between actor terms can be defined considering only actor programs, thus, abstracting from the multiset of pending ....

.... and the receiving object; this is the communication mechanism adopted by agents in CCS [12] The asynchronous mechanisms assumes that the buffering of messages is possible, thus it is not required an agreement with the receiving object to send a message; this is the approach adopted by actors [3] and by asynchronous process algebras [7] Since our goal is to select a set of primitive interaction mechanisms, we need to specify which kind of message passing should be considered as primitive in this context. We claim that asynchronous message passing is the most suitable basic interaction ....

[Article contains additional citation context not shown here]

G. Agha, I. Mason, S. Smith, and C. Talcott. Towards a Theory of Actor Computation. In Proc. of CONCUR'92, volume 630 of Lecture Notes in Computer Science, pages 564--579. Springer Verlag, 1992.

....to the most restrictive r p2p model. We showed that each model is obtained from the previous one by strengthening the privacy constraints. The exact relationship between our model and more operational models for mobile systems like for instance the calculus [Mil91] and the actor based approaches [AMST92] is an interesting area for future research. For example, we believe that our model can be used to give a denotational semantics for the asynchronous calculus. We also believe that the actor languages can be smoothly integrated within our formalism. Our approach is related to the work of Kok ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Springer LNCS, pages 565--579. Springer Verlag, aug 1992.

....its communication partners on the basis of computation and interaction. The formal modeling of mobility has been a very popular research direction in recent years. However, most models published so far have been formalized mainly in operational terms. Examples of such models are the Actor Model [HBS73, AMST92], the Calculus [EN86, MPW92a, MPW92b] the Chemical Abstract Machine [BB90] the Rewriting Logic [Mes91] and the Higher Order CCS [Tho89] On the contrary, our model gives a denotational formalization of mobility. As in the above models, this formalization is based on two assumptions. Firstly, ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In Proc. CONCUR'92, Lecture Notes in Computer Science 630, pages 565--579, 1992. 12

....pattern, etc. 8, 22] However, the notion of behavioral patterns still lack precise definitions and notational semantics which makes it hard to formalize and automate their usage. Similarly, the complexity of interactive modeling have also been addressed by paradigms like actors and roles [1]. Actors are autonomous objects of the information system, whose behavior at 10 any given instance, is determined by the role that they have adopted. This paradigm has also been used by the Artificial Intelligence (AI) community [2] The evolution in AI from logic and search to agent oriented ....

Gul Agha, Ian A. Mason, Scott Smith, Carolyn Talcott. Towards a Theory of Actor Computation. Proc of CONCUR '92, R. Cleaveland (Ed.), LNCS 630, pp. 565-579, Springer-Verlag, 1992.

....imperative functional languages. Dr. Talcott in collaboration with Professors Agha, Mason and Smith have developed a formal theory of components of open distributed systems based on the actor model of computation [74, 1, 2] The formal semantics of a higher order actor language is presented in [3, 4] and a rich equational theory for actor programs was developed. This provides a basis for establishing correctness of compiler optimizations and other operations on actor programs. In [187] two important notions are introduced: actor theories (called abstract actor structures in early papers) and ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Lecture Notes in Computer Science, pages 565--579. Springer Verlag, August 1992.

....; send Create message . END Figure 1: Process type Object. by actions, a process may perform stuttering steps where it does not change its state while the process environment performs a state transition. The cTLA process type Object describes safety properties. Liveness constraints (cf. [3]) are described by additional weak or strong fairness assumptions forcing the execution of an action if it would be enabled for an infinite period of time otherwise. Weak fair actions (denoted by WF : callAction) are only required to execute if the action would otherwise be incessantly enabled ....

....of time otherwise. Weak fair actions (denoted by WF : callAction) are only required to execute if the action would otherwise be incessantly enabled while execution of strong fair actions (denoted by SF : callAction) is guaranteed even if the action is sometimes disabled. Unlike the definition of [3] and TLA, cTLA provides for conditional fairness assumptions in order to keep the compositionality of systems. A fair action has to execute only if otherwise infinitely many states exist where the action is enabled as well as its execution is tolerated by the environment. Systems and subsystems ....

[Article contains additional citation context not shown here]

Gul Agha, Ian A. Mason, Scott Smith, and Carolyn Talcott. Towards a theory of actor computation. In Proceedings CONCUR'92, volume 630 of Lecture Notes in Computer Science, pages 565--579. Springer-Verlag, 1992.

....of object orientation settings) Most of the frameworks introduced auxiliary mechanisms: bu#ering, for example see [3, 7] However, these extensions are not always suitable to deal with computational aspects of process calculi. On the other hand, Honda and Tokoro in [10] and Agha et al. in [1] proposed process calculi based on the notion of actor like objects with asynchronous communication [9] In particular, the 14 Note that all the expressions in this example are sound. calculus in [10] is very similar to ours, in which it expresses asynchronous messages as newly created output ....

Agha, G., Mason, I., Smith, S., and Talcott, C., Towards a Theory of Actor Computations, Proceedings of CONCUR'92, LNCS 630, p???-???, August, 1992.

....interact exploiting the new CORBA asynchronous messaging service, the algebra of actors could also be used to provide a formal account of CORBA services. In the past few years, several advances have been achieved on the semantics of actors, dealing with aspects of communication and concurrency [4, 3, 30, 31, 21], but these papers do not investigate the relationships of the actor model with traditional process algebras, even though recently Robin Milner [24] suggested that it may be worthwhile to work in this direction. We believe that our approach is complementary to previous approaches to the semantics ....

G. Agha, I.A. Mason, S. Smith, and C. Talcott. Towards a Theory of Actor Computation. In Proc. of CONCUR'92, volume 630 of Lecture Notes in Computer Science, pages 564--579. Springer Verlag, 1992.

....create, to create new actors; send, to send messages to other actors; and become, to change the behaviour of an actor [1] Two interesting formalizations of actors have been proposed in the past few years dealing with aspects of communication and concurrency. In the approach of Agha et al. [4, 5] the operational semantics is defined by means of a reduction system, which allows one to define a notion of equivalence between actor configurations (set of actors) Unfortunately this approach is not adequate for our purposes. First, it does not follow a process algebra style, while our goal was ....

....delivered to an actor in b 62 A (event av in the Deliver rule of Table 1) All the other actions are silent, i.e. labelled with . We provide an example to illustrate this notion of equivalence; the reader interested to more complete treatment of equivalence issues in actor systems can refer to [4, 5, 18, 40]. Example 6.2 Since for actors there is arrival order non determinism in message delivery, it is expected that the equivalence does not depend on the order in which send operations are performed. To illustrate this we consider a simple example of two actor terms: A = a BreakP air1 and B = a ....

[Article contains additional citation context not shown here]

G. Agha, I. Mason, S. Smith, and C. Talcott. Towards a Theory of Actor Computation. In Proc. of CONCUR'92, volume 630 of Lecture Notes in Computer Science, pages 564--579. Springer Verlag, 1992.

....our work. An interesting point could be to analyse if their proposal for modelling quality of service can be successfully used in an asynchronous context. In the past few years, several advances have been achieved on the semantics of actors, dealing with aspects of communication and concurrency [4, 3, 27, 28, 18], but these papers do not investigate the relationships of the actor model with traditional process algebras, even though recently Robin Milner [21] suggested that it may be worthwhile to work in this direction. We believe that our approach is complementary to previous approaches to the semantics ....

G. Agha, I.A. Mason, S. Smith, and C. Talcott. Towards a Theory of Actor Computation. In Proc. of CONCUR'92, volume 630 of Lecture Notes in Computer Science, pages 564--579. Springer Verlag, 1992.

....are established using bisimulations as well as the beta value rule. The authors point out that establishing expression equivalence using bisimulations is much more complicated than establishing process algebra equations. An early version of actor semantics presented in this paper appeared in (Agha et al. 1992). There we defined a notion of operational bisimulation that incorporated fairness. Operational bisimulations were intended to serve as tools for establishing observational equivalence, not as equivalence relations per se. We also found that operational bisimulations were not an effective tool for ....

Agha, G., Mason, I. A., Smith, S. F., and Talcott, C. L. (1992). Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Lecture Notes in Computer Science, pages 565--579.

....and runtime activities in a uniform framework. This model establishes a formal basis for specifying and reasoning about resource management activities, dynamic system modifications, and properties such as noninterference and composability. The application level of the model refines the model of [2, 3], explicitly representing runtime structures, location, and allocation of resources. It also abstracts from the choice of specific programming language, providing a framework for reasoning about heterogeneous systems. Applications of this architecture include formal verification of a distributed ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Lecture Notes in Computer Science, pages 565--579. Springer Verlag, August 1992.

....in a distributed system by allowing locality to be directly expressed and optimized. The locality property of Actors states that there is no way for an actor to contact other actors whose name it has not received in a previous communication. This simplifies the task of reasoning about actors (cf. [AMST92]) Furthermore, communication in Actors is secure: for example, it is not possible to steal messages by creating an actor with the same name as an existing actor. Finally, actors do not have to commit to a single type of message when waiting for a message to arrive. Linda is decoupled in both ....

....ActorSpace In this section we present the ActorSpace paradigm and describe the new operations that extend an Actor language. The primitives of the Actor model that we refer to are the fundamental primitives of Actor based languages. A formal semantics describing these primitives has been given in [AMST92]. ActorSpace adds three new concepts to Actors, namely: patterns as an abstract specification of a group of receivers, actorspaces as a scoping mechanism for pattern resolution, and capabilities as a security mechanism. The new paradigm will support programs that use both the perspective of Actors ....

Gul Agha, Ian Mason, Scott Smith, and Carolyn Talcott. Towards a Theory of Actor Computation. In R. Cleaveland, editor, The Third International Conference on Concurrency Theory (CONCUR '92). Springer--Verlag, 1992. LNCS (forthcoming). 12 ActorSpaces: An Open Distributed Programming Paradigm

....features of actor computation such as the acquaintance relation and ordering of events are given in [7] Will Clinger [12] developed a powerdomain semantics of actor systems, showing the consistency of these axioms. An interleaving transition system semantics for an actor language is given in [6, 5]. This work builds on the formulation in [2] and develops methods for reasoning about equivalence of actor programs. 1.2 The Two Level Approach Open distributed systems should provide strong support for customization and adaptation. Non reflective systems which support customization do so only ....

....distributed over a network of processing nodes. Base level actors carry out application level computation, while meta actors are part of the runtime system which manages system resources and controls the runtime behavior of the base level. The application level of the model refines the model of [6], explicitly representing more of the runtime structures and resources. It also abstracts from the choice of a specific programming language, providing a framework for reasoning about heterogeneous systems. Meta actors communicate with each other via message passing as do base level actors, but ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Lecture Notes in Computer Science, pages 565--579. Springer Verlag, August 1992.

....communicate via message passing which is asynchronous and fair. The communication topology of an actor system is called the acquaintance relation and can change dynamically. Semantics of actor interactions are relatively well understood and reasoning about systems of actors has been formalized [2, 12]. Specifying QoS in the Actor based model is essentially a problem of specifying coordination constraints between distributed objects. Synchronizers [4] allow us to express these coordination constraints, i.e. local synchronization constraints or multi actor coordination constraints.Synchronizers ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Lecture Notes in Computer Science, pages 565--579. Springer Verlag, August 1992.

....and runtime activities in a uniform framework. This model establishes a formal basis for specifying and reasoning about resource management activities, dynamic system modifications, and properties such as non interference and composability. The application level of the model refines the model of [3, 4], explicitly representing runtime structures, location, and allocation of resources. It also abstracts from the choice of specific programming language, providing a framework for reasoning about heterogeneous systems. Applications of this architecture include formal verification of a distributed ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Lecture Notes in Computer Science, pages 565--579. Springer Verlag, August 1992.

....distributed over a network of processing nodes. Base level actors carry out application level computation, while meta actors are part of the runtime system which manages system resources and controls the runtime semantics of the base level. The application level of the model refines the model of [5, 39], explicitly representing more of the runtime structures and resources. It also abstracts from the choice of a specific programming language or system architecture, providing a framework for reasoning about heterogeneous systems. Meta actors communicate with each other via message passing as do ....

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92), volume 630 of Lecture Notes in Computer Science, pages 565--579. Springer Verlag, August 1992.

No context found.

Agha, G., Mason, I.A., Smith, S., Talcott, C. Towards a Theory of Actor Computation. In Cleaveland, R. (ed.), Proc of CONCUR '92. LNCS, Vol. 630, SpringerVerlag, Berlin Heidelberg (1992) 565--579.

No context found.

Gul Agha, Ian A. Mason, Scott Smith, Carolyn Talcott. Towards a Theory of Actor Computation. Proc of CONCUR '92, R. Cleaveland (Ed.), LNCS 630, pp. 565-579, Springer-Verlag, 1992.

No context found.

G. Agha, I. Mason, S. Smith, and C. Talcott. Towards a Theory of Actor Computations. In Proceedings of CONCUR'92, pages 565--578. Springer-Verlag, LNCS 630, August 1992.

No context found.

G. Agha, I. A. Mason, S. Smith, and C. Talcott. Towards a theory of actor computation (extended abstract). In W. R. Cleaveland, editor, CONCUR'92: Proc. of the Third International Conference on Concurrency Theory, pages 565--579. Springer, Berlin, Heidelberg, 1992.

No context found.

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In The Third International Conference on Concurrency Theory (CONCUR '92),volume 630 of Springer LNCS, pages565-- Springer Verlag, aug 1992.

No context found.

G. Agha, I. A. Mason, S. F. Smith, and C. L. Talcott. Towards a theory of actor computation. In Proc. CONCUR'92, Lecture Notes in Computer Science 630, pages 565--579, 1992. 12

First 50 documents  Next 50

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