Actalk is a testbed for modeling, classifying and experimenting with object-oriented concurrent programming languages.
A Squeak implementation of Actalk, conducted by Serge Stinckwich, is here.
Object-oriented concurrent programming (OOCP) is a programming paradigm based on the concept of community of active and autonomous entities (called active objects or also actors) which communicate and coordinate by exchanging messages. Object-oriented concurrent programming unifies objects with processes, and message passing with synchronization. This methodology helps decomposing programs in a modular way and exploiting parallel computers to run them efficiently.
The Actalk testbed is designed to help understanding, classifying, designing, combining, and experimenting with various OOCP languages and constructs. Actalk is implemented and integrated within Smalltalk-80 environment. The testbed includes the kernel which models basic OOCP model (that is serialized active objects and asynchronous message passing), and various extensions in order to simulate various OOCP languages and constructs. They implement various models of activity (serial, quasi-concurrent, concurrent...), communication (asynchronous, synchronous, eager, express...), and synchronization (to control/delay acceptance of messages).
Actalk stands for active objects, or also actors, in Smalltalk.
Current version 3 (implemented in Objectworks then VisualWorks\Smalltalk) has been completed and documented.
Previous versions were archived within Manchester Smalltalk Archive Library (link is down) which was an invaluable resource of (free) Smalltalk software.
(File VERSION_3.* provides a general info on previous and current versions of Actalk, including how they differ).
You can move to the Actalk directory (access problem) to retrieve the system and its documentation. (You may have a quick look at the README file.)
You can download the most recent version: Version 6 archive and the associated information.
You can access to most of the various publications about Actalk, or some more general selection of my papers.