Reasoning about software reconfigurations: The behavioural and structural perspectives

Abstract

Software connectors encapsulate interaction patterns between services in complex, distributed service-oriented applications. Such patterns encode the interconnection between the architectural elements in a system, which is not necessarily fixed, but often evolves dynamically. This may happen in response to faults, degrading levels of QoS, new enforced requirements or the re-assessment of contextual conditions. To be able to characterise and reason about such changes became a major issue in the project of trustworthy software. This paper discusses what reconfiguration means within coordination-based models of software design. In these models computation and interaction are kept separate: components and services interact anonymously through specific connectors encoding the coordination protocols. In such a setting, of which Reo is a paradigmatic illustration, the paper introduces a model for connector reconfigurations, from both a structural and a behavioural perspective.

A Note on Reactive Transitions and Reo Connectors

“…This paper indicates that reactive transition systems may play an interesting role in the formal description of software connectors in Reo, either from a behavioural (semantic) or spatial (syntactic) point of view. In the later sense, we are currently enriching our previous work on connector reconfiguration [17] to handle such reactive spatial descriptions of coordination patterns.…”

“…Again such graphs can be regarded as Kripke frames expressing the spatial structure of coordination patterns. This perspective was introduced by N. Oliveira and L. S. Barbosa [17] when proposing an elementary framework for expressing reconfigurations of the interaction protocols, i.e. of the connector's structure, as discussed, for instance, by C. Krause [16].…”