The role of user requirements in data repository design

International Journal on Software Tools for Technology Transfer - Requirements engineering plays a crucial role in the development process of an information system as it aims at providing a...     

Correction to: On Formal Modeling and Validation of Wireless Sensor Network Protocols

Wireless Personal Communications -     

Algorithms and Support for Horizontal Class Partitioning in Object-Oriented Databases

Horizontal partitioning is a logical database design technique which facilitates efficient execution of queries by reducing the irrelevant objects accessed. Given a set of most frequently executed queries on a class, the horizontal partitioning generates horizontal class fragments (each of which is a subset of object instances of the class), that meet the queries requirements. There are two types of horizontal class partitioning, namely, primary and derived. Primary horizontal partitioning of a class is performed using predicates of queries accessing the class. Derived horizontal partitioning of a class is the partitioning of a class based on the horizontal partitioning of another class. We present algorithms for both primary and derived horizontal partitioning and discuss some issues in derived horizontal partitioning and present their solutions. There are two important aspects for supporting database operations on a partitioned database, namely, fragment localization for queries and object migration for updates. Fragment localization deals with identifying the horizontal fragments that contribute to the result of the query, and object migration deals with migrating objects from one class fragment to another due to updates. We provide novel solutions to these two problems, and finally we show the utility of horizontal partitioning for query processing.     

Requirement-driven Architecture for Learning Analytics: The Case of AT41 Project

Digital technologies are becoming present and essential in all sectors of our lives. In education, the intensive usage of digital learning devices contributes to generating a large amount of trace data from digital learning activities. Intelligent exploitation of these traces represents a valuable asset for both device producers (to improve the design of the devices) and consumers (learners and teachers). In this paper, we first share our vision for better exploitation by teachers, of traces from middle schoolers' digital activities generated by their use of tools and digital learning services during different classes. This vision is a part of the AT41 project funded by the French Ministry of Education. This exploitation has to meet the requirements of the different teachers. Conducting such a project is not an easy task, because it has to consider the following issues: the lack of comprehensive and clear methodology to design and exploit these traces; ②heterogeneity of teacher requirements that complicates their elicitation and analysis; ③the diversity of trace sources. Secondly, we propose a requirement-driven architecture for Learning Analytics composed of a well-identified life cycle. This architecture is augmented by learner traces. It offers a repository storing both teacher requirements and traces to facilitate the Learning Analytics in generating relevant and valuable indicators.     

On Formal Modeling and Validation of Wireless Sensor Network Protocols

Formal verification is becoming more and more important in the field of wireless networks (WSN). The general purpose formal method called Event-B is the latest incarnation of the B Method: it is a proof based approach with a formal notation and refinement technique for modeling and verifying systems. Refinement enables implementation level features to be proven correct with respect to an abstract specification of the system. This paper proposes an initial attempt to model and verify consistency and correctness of a WSN operation in its different layers. Several formal models are introduced for this type of networks. In the first time, coloured Petri net are used to elaborate network layer models, then each one will be detailed by an Event-B formalism, while proofs are carried out using the RODIN platform which is an integrated development framework for Event-B.