Search

Change-based persistence has the potential to support faster and more accurate model comparison, merging, as well as a range of analytics activities. However, reconstructing the state of a model by replaying its editing history every time the model needs to be queried or modified can get increasingly expensive as the model grows in size. In this work, we integrate change-based and state-based persistence mechanisms in a hybrid model persistence approach that delivers the best of both worlds. In this paper, we present the design of our hybrid model persistence approach and report on its impact on time and memory footprint for model loading, saving, and storage space usage.

Local search based meta-heuristics such as variable neighbourhood search have achieved remarkable success in solving complex combinatorial problems. Local search techniques are becoming increasingly popular and are used in a wide variety of meta-heuristics, such as genetic algorithms. Typically, local search iteratively improves a solution by making a series of small moves. Traditionally these methods do not employ any learning mechanism. We treat the selection of a local search neighbourhood as a dynamic multi- armed bandit (D-MAB) problem where learning techniques for solving the D-MAB can be used to guide the local search process. We present a D-MAB neighbourhood search (D-MABNS) which can be embedded within any meta- heuristic or hyperheuristic framework. Given a set of neighbourhoods, the aim of D-MABNS is to adapt the search sequence, testing promising solutions rst. We demonstrate the eectiveness of D-MABNS on two vehicle routing and scheduling problems, the real-world geographically distributed mainte- nance problem (GDMP) and the periodic vehicle routing problem (PVRP). We present comparisons to benchmark instances and give a detailed analysis of parameters, performance and behaviour. Keywords Meta-heuristic Local search Vehicle routing

When building simulations of complex systems the task of validation is often overlooked. Validation helps provide confidence in the simulation by exploring the link between the models that we build and the real complex system. We investigate software engineering validation techniques from outside the area of complex systems to assess their applicability for the types of simulation we build. We then provide an example of how such techniques can be applied to a complex systems simulation of cells migrating from blood vessels into lymph nodes through the walls of the blood vessels. We suggest that explicitly stating the modelling and simulation assumptions we make is key to the process of validation. Concluding, we highlight a possible process for validating complex systems that explicitly incorporates environmental aspects.

International audience; The relation between individuality and aggregation is an important topic in complex systems sciences, both aspects being facets of emergence. This topic has frequently been addressed by adopting a classical, individual versus population level perspective. Here, however, the frontiers that emerge in segregated communities are the focus; segregation is synonymous with the existence of frontiers that delineate and interface aggregates. A generic agent-based model is defined, with which we simulate communities located on grid and scale-free networked environments. Emerging frontiers are analyzed in terms of their relative occupancy, porosity, and permeability. Results emphasize that the frontier is highly sensitive to the topology of the environment, not only to the agent tolerance. These relations are clarified while addressing the topics of frontier robustness and the trade-off between its capacity to separate and allow exchange.

International audience; Modelling languages and thus their metamodels are subject to change. When a metamodel evolves, existing models may no longer conform to the evolved metamodel. To avoid rebuilding them from scratch, existing models must be migrated to conform to the evolved metamodel. Manually migrating existing models is tedious and errorprone. To alleviate this, several tools have been proposed to build a migration strategy that automates the migration of existing models. Little is known about the advantages and disadvantages of the tools in different situations. In this paper, we thus compare a representative sample of migration tools - AML, COPE, Ecore2Ecore and Epsilon Flock - using common migration examples. The criteria used in the comparison aim to support users in selecting the most appropriate tool for their situation.

International audience

The Object Constraint Language (OCL) provides a set of powerful facilities for navigating and querying models in the MOF metamodelling architecture. Currently, OCL queries can be expressed only in the context of MOF metamodels and UML models. This adds an additional burden to the development and use of Domain Specific Languages, which can also benefit from an instance-level querying mechanism. In an effort to address this issue, we report on ongoing work on defining a rigorous approach for aligning the OCL querying and navigation facilities with arbitrary Domain Specific Languages to support instance-level queries. We present a case-study that demonstrates the usefulness and practicality of this approach., Electronic Communications of the EASST, Volume 5: OCL for (Meta-)Models in Multiple Application Domains 2006

We grow increasingly dependent on the appropriate operation of computer-based systems. One aspect of such systems is security. As systems become more complex current means of analysis will probably prove ineffective. In the safety domain a variety of analysis techniques has emerged over many years. These have proved surprisingly effective. Since the safety and security domains share many similarities, various authors have suggested that safety techniques might usefully find application in security. This report takes one such technique, HAZOPs, and applies it to one widely used informal design component – UML’s use cases.

International audience; no abstract

Volume LNCS 2068, Springer-Verlag

National audience; Our project is combining UML with the B formal method for the domain of data intensive information systems. It consists in extracting a subset of UML concepts suitable for the analysis of such systems, producing derivation rules from UML diagrams to B specifications and developping a prototype support tool. A preliminary step is to precisely define the syntax and semantics of the required UML notations. This is achieved using a metamodelling technique. In this article we present the specialised metamodels, in UML and B notations, for structural (class diagrams) and behavioural (state transition and collaboration diagrams) elements. Then we outline how the formal metamodel is used in the development of the tool.