Modelling Constrained Dynamic Software Architecture with Attributed Graph Rewriting Systems

Dynamic software architectures are studied for handling adap- tation in distributed systems, coping with new requirements, new envi- ronments, and failures. Graph rewriting systems have shown their ap- propriateness to model such architectures, particularly while considering the consistency of theirs reconfigurations. They provide generic formal means to specify structural properties, but imply a poor description of specific issues like behavioural properties. This paper lifts this limita- tion by proposing a formal approach for integrating the consideration of constraints, non-trivial attributes, and their propagation within the framework of graph rewriting systems

Correctness by Construction and Style Preserving Reconfigurations of Distributed Systems.

In distributed systems and dynamic environments, software architectures may evolve. A crucial issue when conducting system evolutions is to maintain the system in a consistent and functional state. Based on formal proofs in design-time, correctness by construction has recently emerged to efficiently guarantee system coherency. This article proposes a new method for the construction and specification of correct by construction system reconfigurations. Such transformations are characterized by graph rewriting rules that necessarily preserve the coherency of a system. We firstly propose operators on graph transformations and show that they conserve their correctness. Given a system specified by a graph grammar, these operators then serve to construct and characterize a set of correct transformations. We show in particular that any correct configuration can be reached starting from any other one without inconsistent intermediate step, using these transformations only

Self-management of machine-to-machine communications: a multi-models approach

International audienceMachine-to-Machine (M2M) paradigm apply to systems composed by numerous devices sharing information and making cooperative decisions with little or no human intervention. The M2M standard defined by the European Telecommunications Standards Institute (ETSI) is the only one providing an end-to-end view of the global M2M architecture. Noticeably, it furnishes a standardised framework for inter-operable M2M services that satisfies most of M2M modelling requirements. However, and even though M2M systems usually operate in highly evolving contexts, this standard does not address the issue of system adaptations. It is furthermore unsuitable for building self-managed systems. This paper introduces a multi-model approach for modelling manageable M2M systems. Said approach consists in a formal graph-based model on top of the ETSI M2M standard, alongside bi-directional updates that ensure layer coherency. Its fitness for enforcing self-management properties is demonstrated by designing high-level reconfiguration rules. Finally, its applicability is illustrated and evaluated using a smart-metering application

Graph-based formalism for Machine-to-Machine self-managed communications

International audienceMachine-to-Machine communications comprise a large number of intelligent devices sharing information and making cooperative decisions without any human intervention. To support M2M requirements and applications which are in perpetual evolution, many standards are designed, updated and rendered obsolete. Among these, arise from The European Telecommunications Standards Institute (ETSI) a promising standard for M2M communications. The ETSI M2M provides in particular a standardized framework for interoperable M2M Services. As most of its peer, this standard does not, however, address the issue of dynamic reconfiguration or provide a suitable model for the reasoning required to build self-managed M2M architectures. In our paper, we propose a graph-based approach built on top of the ETSI standard, including rules for reconfiguration management, to enforce self-management properties of M2M communications

Enhanced Graph Rewriting Systems for Complex Software Domains (SoSyM Abstract)

International audienceMethodologies for correct by construction reconfigu-rations can efficiently solve consistency issues in dynamic software architecture. Graph-based models are appropriate for designing such architectures and methods. At the same time, they may be unfit to characterize a system from a non functional perspective. This stems from efficiency and applicability limitations in handling time-varying characteristics and their related dependencies. In order to lift these restrictions, an extension to graph rewriting systems is proposed herein. The suitability of this approach, as well as the restraints of currently available ones, are illustrated, analysed and experimentally evaluated with reference to a concrete example. This investigation demonstrates that the conceived solution can: (i) express any kind of algebraic dependencies between evolving requirements and properties; (ii) significantly ameliorate the efficiency and scalability of system modifications with respect to classic methodologies; (iii) provide an efficient access to attribute values; (iv) be fruitfully exploited in software management systems; (v) guarantee theoretical properties of a grammar, like its termination. This is an extended abstract for the Models 2015 Conference of the journal paper of the same name [1]. I. MOTIVATION Dynamic software architectures enable adaptation in evolving distributed systems. A crucial undesirable implication of such adaptations is a potential loss of correctness, the system withdrawing from its scope of consistency. Besides correctness, the system has evolving non-functional requirements, which are tightly linked to its appropriateness or efficiency. The satisfaction of these objectives depends on the properties of the system, its components, and their relations. On one hand, graph-based models are appropriate for the design of adaptation rules that necessarily preserve the system's consistency. On the other, currently available graph based methods exhibit limitations with regard to the description of system properties, in particular regarding their evolution and inter-dependencies

Generic approach for graph-based description of dynamically reconfigurable architectures

Architectural adaptation is studied for handling adaptation in autonomic distributed systems. It is achieved by implementing a model-based approach for managing reconfiguration of dynamic architectures. Describing such architectures includes defining rules for describing both architectural styles and theirs reconfiguration mechanisms. Within this research context, the work presented in this paper is conducted using formal specification based on graphs and graph rewriting appropriately for tackling architectural adaptation problems. A graph-based general approach for describing architectures and handling their dynamic reconfiguration is introduced. Our approach is illustrated in the context of a distributed hierarchical application. The formal models that allow the generation of a graph grammar for dynamic architecture description and the automatic definition of transformation rules for achieving intern self-protecting during the adaptation are elaborated

Caractérisation de la reconfiguration dynamique des architectures logicielles par les grammaires de graphe

National audienceL'adaptabilité automatique d'une application est devenue impérative dans un contexte dynamique de syst emes complexes fortement distribués et contenant un grand nombre de composants. La résolution de cette problématique peut etre obtenue grâcè a l'adaptation structurelle impliquant une re-configuration de la structure architecturale de l'application. Nous présentons dans cet article un formalisme permettant, en utilisant les grammaires de graphes, de caractériser le style architectural d'une application et les transformations applicables lors de son exécution

Partitioning and Exocytosis of Secretory Granules during Division of PC12 Cells

The biogenesis, maturation, and exocytosis of secretory granules in interphase cells have been well documented, whereas the distribution and exocytosis of these hormone-storing organelles during cell division have received little attention. By combining ultrastructural analyses and time-lapse microscopy, we here show that, in dividing PC12 cells, the prominent peripheral localization of secretory granules is retained during prophase but clearly reduced during prometaphase, ending up with only few peripherally localized secretory granules in metaphase cells. During anaphase and telophase, secretory granules exhibited a pronounced movement towards the cell midzone and, evidently, their tracks colocalized with spindle microtubules. During cytokinesis, secretory granules were excluded from the midbody and accumulated at the bases of the intercellular bridge. Furthermore, by measuring exocytosis at the single granule level, we showed, that during all stages of cell division, secretory granules were competent for regulated exocytosis. In conclusion, our data shed new light on the complex molecular machinery of secretory granule redistribution during cell division, which facilitates their release from the F-actin-rich cortex and active transport along spindle microtubules

From Inception to Execution: Query Management for Complex Event Processing as a Service

International audienceComplex Event Processing (CEP) is a set of tools and techniques that can be used to obtain insights from high- volume, high-velocity continuous streams of events. CEP-based systems have been adopted in many situations that require prompt establishment of system diagnostics and execution of reaction plans, such as in monitoring of complex systems. This article describes the Query Analyzer and Manager (QAM) mod- ule, a first effort toward the development of a CEP as a Service (CEPaaS) system. This module is responsible for analyzing user-defined CEP queries and for managing their execution in distributed cloud-based environments. Using a language-agnostic internal query representation, QAM has a modular design that enables its adoption by virtually any CEP system

Query Analyzer and Manager for Complex Event Processing as a Service

Complex Event Processing (CEP) is a set of tools and techniques that can be used to obtain insights from high-volume, high-velocity continuous streams of events. CEP-based systems have been adopted in many situations that require prompt establishment of system diagnostics and execution of reaction plans, such as in monitoring of complex systems. This article describes the Query Analyzer and Manager (QAM) module, a first effort toward the development of a CEP as a Service (CEPaaS) system. This module is responsible for analyzing user-defined CEP queries and for managing their execution in distributed cloud-based environments. Using a language-agnostic internal query representation, QAM has a modular design that enables its adoption by virtually any CEP system