Higher-Order and Symbolic Computation, 11(3)281-343
Composable Semantic Models for Actor TheoriesCarolyn L. Talcott, Stanford University, Computer Science Departments, Stanford, CA 94305
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Abstract: We are interested in developing a semantic foundation
that supports specifying, composing, and reasoning about components of
open distributed systems. The actor model provides the basic elements
for open distributed computation: encapsulation of state; independent
concurrent units of computation; interaction; and dynamic creation and
interconnection. In order to provide for composability, and for
reasoning about properties at many different levels of abstraction we
introduce the notions of actor component, actor component algebra, and
actor component algebra morphism. Morphisms from syntactic to semantic
algebras give composable semantics. We first illustrate features of
the actor model and a variety of component algebras and morphisms
through a series of simple examples. We then define three semantic
models for actor computation starting with a generalization to open
systems of Clinger's event diagram model, and forming two
abstractions: interaction diagrams and interaction paths. An algebra
is defined on each semantic domain with operations for parallel
composition, hiding of internal actors, and renaming, and we show that
component algebra laws hold. We use these models to provide semantics
for descriptions of actor components based on actor theories and show
that the semantics is a component algebra homomorphism.
Keywords: actors, actor component algebra, morphism, event diagram, composable semantics |
This article can be downloaded [here].
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