Efficient compensation handling via subjective updates

Abstract

Programming abstractions for compensation handling and dynamic update are crucial in specifying reliable interacting systems, such as Collective Adaptive Systems (CAS). Compensations and updates both specify how a system reacts in response to exceptional events. Prior work showed that different semantics for compensation handling can be encoded into a calculus of adaptable processes with objective updates, in which a process is reconfigured by its context. This paper goes further by considering subjective updates, in which, intuitively, a process reconfigures itself. A calculus of adaptable processes with subjective update its introduced, and its expressivity is assessed by encoding two semantics for compensation handling. The resulting encodings are more efficient than those using objective updates: they require less computational steps.

On primitives for compensation handling as adaptable processes

“…Origin of the results. This paper distills, improves, and collects preliminary results from our papers [9] and [10]. While in [9] we studied encodings into adaptable processes with objective updates, in [10] we studied encodings into adaptable processes with subjective updates, and compared them against those in [9].…”

“…This paper distills, improves, and collects preliminary results from our papers [9] and [10]. While in [9] we studied encodings into adaptable processes with objective updates, in [10] we studied encodings into adaptable processes with subjective updates, and compared them against those in [9]. A main difference between [9,10] and the current paper is that here we concentrate on a specific source calculus, namely the calculus in [15] with static recovery and discarding semantics.…”

“…While in [9] we studied encodings into adaptable processes with objective updates, in [10] we studied encodings into adaptable processes with subjective updates, and compared them against those in [9]. A main difference between [9,10] and the current paper is that here we concentrate on a specific source calculus, namely the calculus in [15] with static recovery and discarding semantics. Indeed, the developments in [9,10] consider also source calculi with dynamic recovery and/or preserving and aborting semantics.…”

“…A main difference between [9,10] and the current paper is that here we concentrate on a specific source calculus, namely the calculus in [15] with static recovery and discarding semantics. Indeed, the developments in [9,10] consider also source calculi with dynamic recovery and/or preserving and aborting semantics. The calculus with static recovery and discarding semantics arguably defines the simplest setting for both encodings, one in which the key differences between compensable and adaptable processes can be more sharply presented.…”

“…Also, this focus allows us to have a concise presentation. As we discuss in § 8, the (efficient) encoding in § 5 extends to source calculi with the semantics we considered in [9] and [10].…”