Mobile Objects as Mobile Processes

Abstract

Obliq is a lexically-scoped, distributed, object-based programming language. In Obliq, the migration of an object is proposed as creating a clone of the object at the target site, whereafter the original object is turned into an alias for the clone. Obliq has only an informal semantics, so there is no proof that this style of migration is safe, i.e., transparent to object clients. In previous work, we introduced Øjeblik, an abstraction of Obliq, where, by lexical scoping, sites have been abstracted away. We used Øjeblik in order to exhibit how the semantics behind Obliq's implementation renders migration unsafe. We also suggested a modified semantics that we conjectured instead to be safe. In this paper, we rewrite our modified semantics of Øjeblik in terms of the π-calculus, and we use it to formally prove the correctness of object surrogation, the abstraction of object migration in Øjeblik.

Towards a behavioural theory of access and mobility control in distributed systems

“…The emphasis so far has largely been on design of the languages to give succinct descriptions of mobile processes with type systems given to constrain behaviour in a safe manner. Where equivalence has been used it has typically been introduced as some sort of contextual equivalence very similar to the one found in the present paper [1,7,14]. Proofs of correctness of protocols or language translations have been carried out with respect to these contextual equivalences.…”

A framework for mobile Java applications

“…Obliq [4] and Pict [8] are both programming languages with semantics founded in the π calculus, while Nomadic Pict [10] takes this further, introducing distribution not usually present in the π calculus. Within research related to the ambient calculus, a machine framework (PAN citesangiorgi:safeambientsmachine) has been developed and implemented.…”

“…American usage: doorman/woman 4. Names may be of any length, but we prefer single letters for formal representations to maintain brevity.…”