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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jss.2009.09.031 Byline: Imen Loulou (a), Mohamed Jmaiel (a), Khalil Drira (b)(c), Ahmed Hadj Kacem (a) Keywords: Software architecture; Publish/Subscribe style; Event-based communication; Formal specification; Reconfiguration modeling; Graph rewriting Abstract: We present P/S-CoM, a formal approach supporting the correct modeling of Publish/Subscribe architectural styles and safe reconfiguration of dynamic architectures for event-based communication. We elaborate a set of patterns and we define the corresponding composition rules to build correct by design Publish/Subscribe styles. The defined patterns and rules respect the principle of information dissemination guaranteeing that the produced information reaches all the subscribed consumers. The patterns are modeled as graphs and the semantics of each pattern and each rule is specified formally in Z notations. We implement these specifications under the Z-Eves theorem prover which we use to prove specification consistency. The Z specification of the designed architectural style is also built by composition by applying the composition rules coded in Z. We consider the interconnection topology between event dispatchers as well as the subscription model using elementary refinements of the style specification. Moreover, we model the reconfiguration of Publish/Subscribe architecture via guarded graph-rewriting rules whose body specifies the structural constraints and whose guards define the pre- and post-conditions ensuring in this way the preservation of stylistic constraints. Similarly, we interpret reconfiguration rules in Z notations, and we implement these rules under Z-Eves for proving that all reconfigurations are style preserving. This results in a unified formal approach which handles both the static and the dynamic aspects of Publish/Subscribe software architectures. Author Affiliation: (a) National Engineering School of Sfax, Research Unit ReDCAD, B.P.W., 3038 Sfax, Tunisia (b) CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse, France (c) Universite de Toulouse, UPS, INSA, INP, ISAE, LAAS, F-31077 Toulouse, France Article History: Received 25 September 2008; Revised 2 June 2009; Accepted 12 September 2009

In this paper, we present a multi-scale modeling methodology for software System of Systems (SoS) using the formal technique of bigraphical reactive system. This methodology provides a correct by design approach ensuring the correctness of the SoS architectures. A first scale is defined by the designer. Then, it is refined by successively adding lower scale details. The transition between scales is implemented following a rule-oriented refinement process. The executed rules respect the system constraints ensuring, in this way, the correctness of the obtained scale architectures. Moreover, we address the dynamic aspect of SoS by providing model-based rules of reconfiguration actions. We illustrate our approach with a Smart Buildings case study. [ABSTRACT FROM AUTHOR]