Overall Objectives
Scientific Foundations
Application Domains
New Results
Contracts and Grants with Industry
Other Grants and Activities

Section: New Results

Formal Model for Software Adaptation

SCeSAME: Formal Definition of Software Architecture Adaptation

Participants : Rubby Casallas, Anthony Cleve, Laurence Duchien, Gabriel Tamura.

In order to define properties on adaptation process, we need to formally model the architecture reconfiguration of a component-based (CB) system as an action performed by itself. These actions are performed in response to the disruption of Quality of Service (QoS) contracts, in the spirit of the Effeil's rescue clause in object-oriented programming. By doing this, we aim to develop on the vision of the CBSE as a sound base to produce software systems enabled to automatically and safely reconfigure themselves by reconfiguring their abstract (reflection) architectures at runtime. For such structural reconfigurations, a system architect may reuse design patterns from other disciplines with the purpose of restoring QoS contracts, thus preserving them.

Our approach, named SCeSAME for A Safe Contract-based Self-Adaptive Framework to Preserve QoS Properties on Mobile Devices is built on the theory of extended graph (e-graph) rewriting proposed in e-graph  [62] , as a formalism to represent QoS contracts on component. We have given a formal definition of component-based structure systems, QoS contracts, and architecture reconfiguration rules. Based on these definitions, we built a framework that enables a component-based system to preserve its QoS contracts through architecture self-reconfiguration as a responding action to QoS contract violations. Our approach extends a theory of graph rewriting and defines a process calculus as formalisms to model the structure and reconfiguration process of architecture reconfiguration. The reconfiguration process, once parameterized with reconfiguration rules, can be verified as safe, i.e., component structural-compliant, terminating and confluent. This result is a part of Gabriel Tamura's PhD and the first results have been published in [16] , [35] .

FracToy : Formal Methodology to Specify Self-Configurable Component-Based Systems

Participants : Philippe Merle, Lionel Seinturier.

One of the key research challenges in autonomic computing is to define rigorous mathematical models for specifying, analyzing, and verifying high-level self-* policies.  [36] presents the FracToy formal methodology to specify self-configurable component-based systems, and particularly both their component-based architectural description and their self-configuration policies. This rigorous methodology is based on the first-order relational logic, and is implemented with the Alloy formal specification language.  [36] presents the different steps of the FracToy methodology and illustrates them on a self-configurable component-based example.


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