An extension of ontology based databases to handle preferences

1th International Conference on Enterprise Information Systems; Milan; Italy; 6 May 2009 through 10 May 2009Ontologies have been defined to make explicit the semantics of data. With the emergence of the SemanticWeb, the amount of ontological data (or instances) available has increased. To manage such data, Ontology Based DataBases (OBDBs), that store ontologies and their instance data in the same repository have been proposed. These databases are associated with exploitation languages supporting description, querying, etc. on both ontologies and data. However, usually queries return a big amount of data that may be sorted in order to find the relevant ones. Moreover, in the current, few approaches considering user preferences when querying have been developed. Yet this problem is fundamental for many applications especially in the e-commerce domain. In this paper, we first propose an extension of an existing OBDB, called OntoDB through extension of their ontology model in order to support semantic description of preferences. Secondly, an extension of an ontology based query language, called OntoQL defined on OntoDB for querying ontological data with preferences is presented. Finally, an implementation of the proposed extensions are described

A Semantic-Oriented Description Framework and Broker Architecture for Publication and Discovery in Cloud Based Conferencing

Cloud computing is an emerging paradigm for provisioning network, storage, and computing resources on demand using a pay-per-use model. Conferencing is the conversational exchange of media between several parties. Cloud-based conferencing services can provide benefits such as easy introduction of different types of conferences, resource usage efficiency and scalability. A business model has been recently proposed in a position paper for cloud-based conferencing with the following roles: conference substrate provider, conference infrastructure provider, conference platform provider, conference service provider, and broker. Conference substrates are generally atomic and served as elementary building blocks (e.g. signaling, mixing) of conferencing applications. They can be virtualized and shared for resource efficiency purposes. Multiple conferencing substrates can be combined to build a conferencing service (e.g. a dial-out audio signaling conference service composed from dial-out signaling and audio mixer substrates). The focus of this thesis is to design a semantic-oriented description framework for conferencing substrates and an architecture for their publication and discovery. The description framework is made up of a description language and a cloud-based conference ontology. The conference ontology is modeled on the basis of the interacting roles in the proposed cloud-based conferencing business model. The overall publication and discovery architecture for cloud-based conference substrates is made up of three brokers and the related publication and discovery interfaces. The publication and discovery interfaces are modelled using REpresentation State Transfer (REST) interfaces. A prototype is built to demonstrate the feasibility of this architecture. The effectiveness of the architecture is also proved using the performance measurements

Uma ontologia para expressão de preferências de utilizadores em sistemas OLAP

Dissertação de mestrado em Informática (área de especialização em Sistemas de Suporte à Decisão)Na maioria dos casos em que se submete uma query a um sistema, recebemos uma “enxurrada” de dados como resposta, que em grande parte não nos interessa. Na realidade, ao se obter um qualquer record set, fazemos frequentemente uma forte triagem para que fiquemos apenas com aquilo que realmente nos interessa no âmbito do problema que temos em mãos. De facto, era muito útil que, de algum modo, fosse possível expressar as nossas preferências em termos daquilo que queremos obter aquando do lançamento de uma dada query. Diversas pesquisas têm sido feitas com o objectivo de conseguir expressar as preferências dos utilizadores, no sentido de apresentar resultados mais satisfatórios nas suas consultas, mais próximos daquilo que o utilizador pretende. As preferências são utilizadas como filtragem nas consultas efectuadas, com o objetivo de reduzir o volume de dados que potencialmente poderá ser apresentado ao utilizador. Estas ajudam, também, na criação de políticas com base nos perfis dos utilizadores. Assim, neste trabalho de dissertação é proposto estudar a possibilidade de melhorar a interação dos utilizadores com os sistemas OLAP, recorrendo para isso à Web Semântica, nomeadamente à utilização de um modelo ontológico e a técnicas mais avançadas de expressão de preferências.In most cases in which a query is submitted to a system, the response is a “flood” of data which largely does not have any interest to us. Actually, to obtain any record set, we often do a strong triage to obtain what really interests us in the scope of the problem that we currently have. In fact, it would be very helpful that, somehow, we had the possibility to express our preferences in terms of what we want to get at the launch of a given query. Several researches have been done with the purpose of getting the user preferences expressed, in order to provide a more satisfactory result of the queries, closer to what the user pretends. User preferences are used as a filter in the result set, with the aim of reducing the data volume that could, potentially, be presented to the user. They help, also, in creating policies based on user profiles. Thus, in this dissertation work, it is proposed to study the possibility of improving the interaction of users with OLAP systems, resorting to Semantic Web, in particular the use of an ontological model and the most advanced techniques of expression of preferences

Handling domain knowledge in system design models. An ontology based approach.

Complex systems models are designed in heterogeneous domains and this heterogeneity is rarely considered explicitly when describing and validating processes. Moreover, these systems usually involve several domain experts and several design models corresponding to different analyses (views) of the same system. However, no explicit information regarding the characteristics neither of the domain nor of the performed system analyses is given. In our thesis, we propose a general framework offering first, the formalization of domain knowledge using ontologies and second, the capability to strengthen design models by making explicit references to the domain knowledgeformalized in these ontology. This framework also provides resources for making explicit the features of an analysis by formalizing them within models qualified as ‘’points of view ‘’. We have set up two deployments of our approach: a Model Driven Engineering (MDE) based deployment and a formal methods one based on proof and refinement. This general framework has been validated on several no trivial case studies issued from system engineering

Querying Ontology Based Database Using OntoQL (an Ontology Query Language

Nowadays, ontologies are used in several research domains by offering the means to describe and represent concepts of information sources. Therefore, several approaches and systems storing ontologies and their instances in the same repository (database) have been proposed. As a consequence, defining a query language to support ontology-based database (OBDB) becomes a challenge for the database community. In this paper, we present OntoQL, an ontology query language for OBDBs. Firstly, we present formally the OBDB data model supported by this language. Secondly, an overview of the algebra defining the semantics of operators used in OntoQL is described. Several query examples showing the interest of this language compared to traditional database query languages are given along this paper. Finally, we present a prototype of the implementation of OntoQL