Caromel, Henrio, and Serpette take a deterministic sequential object calculus, inspired by Abadi and Cardelli [1], and build a parallel calculus on top of it, by assuming that the objects are distributed into activities (single threads). A method call to an active object is asynchronous, and is queued until it is serviced. The caller can continue until it needs the result of a method call, a so-called future. At this point, the caller might be blocked. The paper gives operational semantics for this model. The authors prove a confluence theorem; under conditions for interference freedom, some of which can be checked statically, they prove a determinism theorem.

A section describes other models, and a detailed comparison can be found in a book-length exposition by two of the authors [2]. The authors develop Java middleware as a test implementation [3].

The proposed programming model is interesting. This paper is likely to be of interest to programming language theorists.