Lambda the Ultimate

Nested commits for mobile calculi: extending Join
by Roberto Bruni, Hernan Melgratti, Ugo Montanari

In global computing applications the availability of a mechanism for some form of committed choice can be useful, and sometimes necessary. It can conveniently handle, e.g., contract stipulation, distributed agreements, and negotiations with nested choice points to be carried out concurrently. We propose a linguistic extension of the Join calculus for programming nested commits, called Committed Join (cJoin).
It provides primitives for explicit abort, programmable compensations and interactions between ongoing negotiations. We give the operational semantics of cJoin in the reflexive CHAM style. Then we discuss its expressiveness on the basis of a few examples and of the cJoin encoding of other paradigms with similar aims but designed in different contexts, namely AKL and Zero-Safe nets.

To me the main interest lies in section 4.2, which shows an encoding of a subset of AKL in cJoin.
More references to relationships between logic/constraint and "pi-family" approaches to concurrency are welcome!