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Abstract

Future network environments are likely to be used by cooperative applications. Indeed, the recent advent of peer to peer systems motivates this assumption. In this paper, we present a method that relies on graphs and graph grammar productions to automatically refine a high level service interactions representation of an activity into a deployment topology at the Middleware and the Transport level. At both levels, algorithms for service optimization are presented. The different models and algorithms are implemented in a case study of CMS-like operations for crisis management.

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Abstract

Handling context-aware dynamically adaptable architectures contributes to the design of self-configuring software systems. Dealing with such a problem for communicating system is even more challenging since adaptation should address simultaneously the different communication levels. This is necessary for handling both unpredictable changes in the low level constraints and predictable evolutions in the high level requirements. In this paper, we address this problem by providing a model-based, ruleoriented approach that supports the adaptation process. An architecture may represent the different possible service compositions and the associated architectural configurations. We consider the multi-level models of the communicating system architecture. We consider the intra-level architecture transformations as the elementary adaptation actions. We handle consistently the related inter-level adaptation actions by considering additional architectural relationships viewing the lower level architecture as a refinement or a mapping of the upper level. We provide the algorithm characterizing the multi-level architecture-based adaptation process. We then develop a rule-oriented implementation using graph grammar and handling architectural transformations as graph rewriting rules.

Abstract

Handling context-aware dynamically adaptable architectures contributes to the design of self-configuring software systems. Dealing with such a problem for communicating systems is even more challenging since adaptation should address simultaneously the different communication levels. This is necessary for handling both unpredictable changes in the low level constraints and predictable evolutions in the high level requirements. In this paper, we address this problem by providing a model-based, rule-oriented approach that supports the adaptation process based on a run-time transformation of the system architecture. Such architecture may represent the different possible service compositions and the associated architectural configurations. We consider the multi-level models of the communicating system architecture. We consider the intra-level architecture transformations as the elementary adaptation actions. We handle consistently the related inter-level adaptation actions by considering additional architectural relationships viewing the lower level architecture as a refinement or a mapping of the upper level.We provide the algorithms characterizing the multi-level architecture-based adaptation process. We then develop a rule-oriented implementation using graph grammar and handling architectural transformations as graph rewriting rules. We consider Crisis Management Systems (CMS) as a case study from the more general group communication systems to which our results apply.

Abstract

Architectural adaptation is important for handling self- configuring properties of autonomic distributed systems. It can be achieved by model-based management of dynamic architectures. Describing dynamic architectures includes defining rules for reconfiguration management. Within this research context, several works have been conducted using formal specification to handle this complexity. Graph and graph rewriting-based approaches showed, through many studies, their appropriateness to tackle architectural adaptation problems. However, scalability of such approaches remains an open issue and has been rarely explored. In this paper, we investigate this issue. We, introduce a graph- based general approach for handling of dynamic architectures, and we illustrate it within a scenario of collaboration support in crisis manage- ment systems. We elaborate the formal models for dynamic architecture management. Using the French Grid GRID5000, we conducted an experimental study to assess the scalability of the elaborated models.

Abstract

Architectural adaptation requires complex mechanisms for its management and is important for handling self-configuring properties of autonomic distributed systems. Describing dynamic architectures includes both characterizing conformance of an architecture to a given style description as well as defining rules for architecture evolving through reconfiguration management. Within this research context, several works have been conducted using formal specification to handle this complexity. Graph and graph rewriting-based approaches showed, through many studies, their appropriateness to tackle architectural adaptation problems. However, scalability of these approaches remains an open issue and has been rarely explored. In this paper, we investigate this issue.We, first, introduce a graph-based general approach for handling both aspects of dynamic architecture description, and we illustrate it within a scenario of communication and collaboration support in crisis management systems. We elaborate formal models for style and architecture description and management while considering multiple architectural levels. Using the French Grid GRID5000, we expose an experimental study to validate the elaborated models and give results for the related execution times of implemented architecture management protocols.

Abstract

In this paper, we propose a refinement-based adaptation approach for the architecture of distributed group communication support applications. Unlike most of previous works, our approach reaches implementable, context-aware and dynamically adaptable architectures. To model the context, we manage simultaneously four parameters that influence Qos provided by the application. These parameters are: the available bandwidth, the exchanged data communication priority, the energy level and the available memory for processing. These parameters make it possible to refine the choice between the various architectural configurations when passing from a given abstraction level to the lower level which implements it. Our approach allows the importance degree associated with each parameter to be adapted dynamically. To implement adaptation, we switch between the various configurations of the same level, and we modify the state of the entities of a given configuration when necessary. We adopt the direct and mediated Producer-Consumer architectural styles and graphs for architecture modelling. In order to validate our approach we elaborate a simulation model.

Mots-Clés / Keywords

Abstract

In this paper, we propose a refinement-based adaptation approach for the architecture of distributed group communication support applications. Unlike most of previous works, our approach reaches implementable, context-aware and dynamically adaptable architectures. To model the context, we manage simultaneously four parameters that influence Qos provided by the application. These parameters are: the available bandwidth, the exchanged data communication priority, the energy level and the available memory for processing. These parameters make it possible to refine the choice between the various architectural configurations when passing from a given abstraction level to the lower level which implements it. Our approach allows the importance degree associated with each parameter to be adapted dynamically. To implement adaptation, we switch between the various configurations of the same level, and we modify the state of the entities of a given configuration when necessary. We adopt the direct and mediated Producer-Consumer architectural styles and graphs for architecture modelling. In order to validate our approach we elaborate a simulation model.

Mots-Clés / Keywords

Résumé

Cet article présente une approche d'adaptation pour des applications de communication groupe sensibles au contexte et caractérisées par une architecture dynamique. Nous nous appuyons sur une modélisation par les graphes et un style architectural de type Publish/Subscribe. Nous proposons une démarche de raffinement qui permet de garantir un degré d'adaptabilité en faisant un compromis entre les différents paramètres du contexte.

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