A design-by-contract approach to recover the architectural style from run-time misbehaviour

• We propose to control the reconfigurations of applications leading to an erroneous state by exploiting its architectural model.
• Our work relies on ADR which is a rule-based formal framework for evolving software architectures.
• We add pre- and post-conditions to ADR rules so to constraint their applicability and resulting graphs.
• We give an algorithm to compute the weakest pre-condition out of a rule and its post-condition.
• A methodology uses our algorithm to reconfigure systems' architecture and regain its style when compromised at run-time.

We propose to control the reconfigurations of applications leading to an erroneous state by exploiting its architectural model. Our work relies on Architectural Design Rewriting (ADR, for short) which is a rule-based formal framework for modelling (the evolution of) software architectures. We equip the reconfiguration rules of an ADR architecture with pre- and post-conditions expressed in a simple logic; a pre-condition constraints the applicability of a rule while a post-condition specifies the properties expected of the resulting graphs. We give an algorithm to compute the weakest pre-condition out of a rule and its post-condition. On top of this algorithm, we design a simple methodology that allows us to select which rules can be applied at the architectural level to reconfigure a system so to regain its architectural style when it becomes compromised by unexpected run-time reconfigurations.