On Adding Some Mobility Primitives to an Architecture Description Language

In mobile software systems specification, we focus on the movement of software elements across a network of locations and on how their execution environment may change without altering or changing their internal structure or behavior. It seems evident that we are more interested on the topology of the system and its possible evolutions; by means of components movement; rather than the detailed code of each component. Consequentely, it is necessary that the global structure, of the system under specification, emerges at an early stage. Architecture Description Languages (ADLs for short) seem to be the adequate framework. However, most of the existing ADLs define system structure statiquely, i.e. these ADLs do not support mobility of components, and/or their semantics is not well defined. In this work, we attempt to extend an ADL, the CBabel language, by defining a new notion of components location-mobility space of components- and a set of primitives governing components mobility. CBabel language is chosen for its simple syntax and rigorous semantics, based on rewriting logic, allowing formal verification of system properties

A BRS-Based Approach to Model and Verify Cloud Systems Elasticity

AbstractElasticity is actually one major and important asset for cloud-based systems. This property grants this kind of systems the ability to dynamically adjust their resources allocation by scaling up/down when needed in autonomic manner, allowing them to capitalize resource utilization, and maintain a suitable quality of service. In this paper, we lean on formal methods to give a precise and sufficient semantics to cloud system elasticity. We propose a unique semantic framework based on bigraphical reactive systems (BRS) for modeling both structural and behavioral aspects of cloud-based systems. Besides, Maude system serves to simulate and verify the elasticity property inherent to these systems using many model-checking techniques as the model-checking invariants one

Towards a Tile Based Semantic Model for Reconfigurable Distributed Systems

The paper deals with the definition of a formal semantic framework for the specification of hierarchical and dynamically reconfigurable component based distributed systems. Based on tile logic (an extension of rewriting logic), the proposed model allows hierarchical and compositional construction of system state and behavior by incrementally composing subcomponents states and behaviors respectively. We do not need to flatten its hierarchical structure. Thus, the semantic meta-model associated to a given system is given by a tile system (or more precisely a double category) defining its structural and behavioral aspects in a modular manner. Besides, computation in such system is guided by subcomponents interactions. Hence, local change effects are propagated to the environment via input/output interfaces of tiles, that may be composed in space or time, for eventual synchronizations or sequential evolution respectively

Verifying Cloud Systems using a Bigraphical Maude-based Model Checker

Formal methods are system design techniques based on rigorous mathematical models to build software systems. Our aim in this paper is to define formal specifications of cloud systems and offer analysis support to formally model check their inherent properties. Hence, we define a formal semantic framework, based on Bigraphical Reactive Systems (BRS), for specifying cloud architectures and their shape shifting to ensure service availability and quick scalability. Then, we propose a Bigraphical Maude-based Model Checker to formally verify some properties.31

An Event Structure Based Coordination Model for Collaborative Sessions

Distributed collaborative applications are characterized by supporting groups’ collaborative activities. This kind of applications is branded by physically distributed user groups, who cooperate by interactions and are gathered in work sessions. The effective result of collaboration in a session is the production of simultaneous and concurrent actions. Interactions are fundamental actions of a collaborative session and require being coordinated (synchronized) to avoid inconsistencies. We propose in the present work an event structure based model for coordination in a collaborative session, making possible interactions between participants and applications in a consistent way. The proposed model describes interdependencies, in the form of coordination rules, between different actions of the collaborative session actors

A Theoretical Approach for Modelling Cloud Services Composition

International audienceCloud services are designed to provide remote and scalable access to applications and resources. They are inclined to be composed for creating more complex value-added services. Cloud Services Composition (CSC) has become an increasingly active area in both research topics and technological fields. An important and challenging issue in this area is how to model Cloud services for supporting services composition with all its facets. Relying heavily on mathematical definitions, formal methods may be applied in this context to provide a precise model of Cloud Services Composition. This paper investigates the use of Milner's bigraphs for modelling Cloud Services Composition. As its main result, we first present a meta-model for Cloud Services Composition. Then, we define a Bigraph model for Cloud Services Composition (BiG-CSC), which associates a formal semantic to the meta-model. Finally, a graphical environment based on the Eclipse Modelling Framework is proposed to validate our modelling methodology for Cloud Services Composition. \textcopyright 2016 IEEE