Coordination of ECA Rules by Verification and Control

International audienceEvent-Condition-Action (ECA) rules are a widely used language for the high level specification of controllers in adaptive systems, such as Cyber-Physical Systems and smart environments, where devices equipped with sensors and actuators are controlled according to a set of rules. The evaluation and execution of every ECA rule is considered to be independent from the others, but interactions of rule actions can cause the system behaviors to be unpredictable or unsafe. Typical problems are in redundancy of rules, inconsistencies, circularity, or application-dependent safety issues. Hence, there is a need for coordination of ECA rule-based systems in order to ensure safety objectives. We propose a tool-supported method for verifying and controlling the correct interactions of rules, relying on formal models related to reactive systems, and Discrete Controller Synthesis (DCS) to generate correct rule controllers

Towards Well-Founded and Richer Context-Awareness Conceptual Models

We observe that context-aware systems currently developed in one domain or another are mostly technology-driven, and not so much user-centric. They are often not based on a thorough analysis of the effects they produce when interacting with their context, especially regarding the contribution of these effects to user needs. We argue that a conceptual framework is needed to support such analyses. In this paper we identify the concepts necessary to define important structural aspects of a context-aware system and its context, and to formulate generalizations about effects of the interaction of the context-aware system and its context related to user needs. Using this conceptual framework, we classify context-aware systems in terms of the kinds of context assumptions that we can make at design time, and we discuss several threats to validity of a context-aware system. We believe that the proposed conceptual framework can help to better assess the utility concerning a context-aware system design. We use various examples of context-aware applications to illustrate our ideas.</p

Combining Transactional and Behavioural Reliability in Adaptive Middleware

International audienceAdaptive systems behaviours can be intuitively programmed, using rule based middleware, as a set of rules. The rules verify conditions and perform actions in order to achieve a set of objectives. However, this raises several problems. First, inconsistencies may result from the fact that an action is not actually performed due to a communication error or a hardware failure. Second, the rules may be conflicting and their sequential chaining may lead to undesirable behaviour. This paper proposes an approach that combines transactional and behavioural reliability (i.e. consistency and no conflict) in adaptive middleware. This approach is implemented using the middleware LINC and the automata based language Heptagon/BZR. A case study, in the field of building automation, is presented to illustrate the approach

Behavioral equivalences for AbU: Verifying security and safety in distributed IoT systems

Attribute-based memory Updates ([Formula presented]in short) is an interaction mechanism recently introduced for adapting the Event-Condition-Action (ECA) programming paradigm to distributed reactive systems, such as autonomic and smart IoT device ensembles. In this model, an event (e.g., an input from a sensor, or a device state update) can trigger an ECA rule, whose execution can cause the state update of (possibly) many remote devices at once; the latter are selected “on the fly” by means of predicates over their state, without the need of a central coordinating entity. However, the combination of different [Formula presented]systems may yield unexpected interactions, e.g., when a new device is added to an existing secure system, potentially hindering the security of the whole ensemble of devices. This can be critical in the IoT, where smart devices are more and more pervasive in our daily life. In this paper, we consider the problem of ensuring security and safety requirements for [Formula presented]systems (and, in turn, for IoT devices). The first are a form of noninterference, as they correspond to avoid forbidden information flows (e.g., information flows violating confidentiality); while the second are a form of non-interaction, as they correspond to avoid unintended executions (e.g., leading to erroneous/unsafe states). In order to formally model these requirements, we introduce suitable behavioral equivalences for [Formula presented]. These equivalences are generalizations of hiding bisimilarity, i.e., a kind of weak bisimilarity where we can compare systems up to actions at different levels of security. Leveraging these behavioral equivalences, we propose (syntactic) sufficient conditions guaranteeing the requirements and, then, effective algorithms for statically verifying such conditions

A configuration-based domain-specific rule generation framework for process model customization

In today’s changing world, there is an ever-increasing demand and need for software reuse in applications, where the process model needs to be reused in different applications in a domain-specific environment. The process model is required to adapt and implement changes promptly at run-time, in response of the end-user configuration requirements. Furthermore, reusability is emerging strongly as a necessary underlying capability, particularly for customization of business in a dynamic environment where end-users can select their requirements to achieve a specific goal. Such adaptations are in general, performed by non-technical end-users which can lead to losing a significant number of person-days and which can also open up possibilities to introduce errors into the system. These scenarios call for - indeed cry out for - a system with a configurable and customizable business process, operable by users with limited technical expertise. Research aims to provide a framework for generating the rule language and configuring domain constraints. This framework builds upon the core idea of Software Product Lines Engineering (SPLE) and Model-Driven Architecture (MDA). The SPLE provides a platform that includes the variability model. Variability models offer features where end-users can select features and customize possible changes in the domain template, which is the container for domain and process models. The user selects their requirements as a feature from feature models and generates rules from domain models using MDA. Then, the generated rules are translated from a high-level domain model, based on the requirements of the end-user. On the other hand, the weaving model is responsible for reflecting activation and de-activation of features of variabilities in the domain template. The usability of the proposed framework is evaluated with a user study in the area of Digital Content Technology. The results demonstrate that usability improvements can be achieved by using the proposed techniques. The framework can be used to support semi-automatic configuration that is efficient, effective and satisfactory