A calculus for attribute-based communication

Abstract

The notion of attribute-based communication seems promising to model and analyse systems with huge numbers of interacting components that dynamically adjust and combine their behaviour to achieve specific goals. A basic process calculus, named AbC, is introduced that has as primitive construct exactly attribute-based communication and its impact on the above mentioned kind of systems is considered. An AbC system consists of a set of parallel components each of which is equipped with a set of attributes. Communication takes place in a broadcast fashion and communication links among components are dynamically established by taking into account interdependences determined by predicates over attributes. First, the syntax and the reduction semantics of AbC are presented, then its expressiveness and effectiveness is demonstrated by modelling two scenarios from the realm of TV streaming channels. An example of how well-established process calculi could be encoded into AbC is given by considering the translation into AbC of a prototypical π-calculus process

Efficient compensation handling via subjective updates

“…Intuitively, S is a subjective variant of S: using two reductions, S emulates the movement induced by objective updates in S (see (1)):…”

“…Transactions t[P , Q], where t is a name and P, Q are processes; 1 The terminology 'subjective' and 'objective' updates is inspired by the distinction between subjective and objective mobility, as in calculi such as Ambients [3] and Seal [4]. As explained in [4], Ambients use subjective mobility (an agent moves itself), while Seal uses objective mobility (an agent is moved by its context).…”

“…Our prior work [7] encoded the six calculi in [9] into adaptable processes with objective update as in Rule (1). These encodings, however, are not as efficient as one may like: objective updates turn out to be inconvenient when "collecting" protected blocks scattered within nested transactions.…”

“…Since the located process "updates itself", subjective updates offer a more autonomous adaptation semantics than objective updates. 1 In this paper, we carefully revisit the encodings of compensation handling in [7] using subjective update (as in Rule (2)) rather than objective update (as in Rule (1)). The main contribution of the paper are therefore new, efficient encodings of the calculi in [9].…”

Modelling Ambulance Deployment with CarmaCARMA

“…The development of CARMA has been influenced by a number of previous process algebra including the Markovian process algebra PEPA [12], the location-focussed PALOMA [9] and SCEL [8] which uses attribute-based communication. Attribute-based communcation is explored further in the process calculus AbC [2].…”