Ontology-based end-user visual query formulation: Why, what, who, how, and which?

Value creation in an organisation is a time-sensitive and data-intensive process, yet it is often delayed and bounded by the reliance on IT experts extracting data for domain experts. Hence, there is a need for providing people who are not professional developers with the flexibility to pose relatively complex and ad hoc queries in an easy and intuitive way. In this respect, visual methods for query formulation undertake the challenge of making querying independent of users’ technical skills and the knowledge of the underlying textual query language and the structure of data. An ontology is more promising than the logical schema of the underlying data for guiding users in formulating queries, since it provides a richer vocabulary closer to the users’ understanding. However, on the one hand, today the most of world’s enterprise data reside in relational databases rather than triple stores, and on the other, visual query formulation has become more compelling due to ever-increasing data size and complexity—known as Big Data. This article presents and argues for ontology-based visual query formulation for end-users; discusses its feasibility in terms of ontology-based data access, which virtualises legacy relational databases as RDF, and the dimensions of Big Data; presents key conceptual aspects and dimensions, challenges, and requirements; and reviews, categorises, and discusses notable approaches and systems

Querying Multimedia Presentations Based on Content

In this paper, we consider the problem of querying multimedia presentations based on content information. We believe that presentations should become an integral part of multimedia database systems, and users should be able to store, query, and possibly manipulate multimedia presentations using a single database management system software. Multimedia presentations are modeled as presentation graphs, which are directed acyclic graphs that visually specify multimedia presentations. Each node of a presentation graph represents a media stream. Edges depict sequential or concurrent playout of streams during the presentation. Information captured in each individual stream and the presentation order of this information during the multimedia presentation constitute the content information of the presentation. Querying multimedia presentation graphs based on content is important for the retrieval of information from a database. We present a graph data model for the specification of multimedia p..