OptiqueVQS: A visual query system over ontologies for industry

An important application of semantic technologies in industry has been the formalisation of information models using OWL 2 ontologies and the use of RDF for storing and exchanging application data. Moreover, legacy data can be virtualised as RDF using ontologies following the ontology-based data access (OBDA) approach. In all these applications, it is important to provide domain experts with query formulation tools for expressing their information needs in terms of queries over ontologies. In this work, we present such a tool, OptiqueVQS, which is designed based on our experience with OBDA applications in Statoil and Siemens and on best HCI practices for interdisciplinary engineering environments. OptiqueVQS implements a number of unique techniques distinguishing it from analogous query formulation systems. In particular, it exploits ontology projection techniques to enable graph-based navigation over an ontology during query construction. Secondly, while OptiqueVQS is primarily ontology driven, it exploits sampled data to enhance selection of data values for some data attributes. Finally, OptiqueVQS is built on well-grounded requirements, design rationale, and quality attributes. We evaluated OptiqueVQS with both domain experts and casual users and qualitatively compared our system against prominent visual systems for ontology-driven query formulation and exploration of semantic data. OptiqueVQS is available online and can be downloaded together with an example OBDA scenario

Making linked-data accessible: A review

Linked-Data (LD) is a paradigm that utilises the RDF triplestore to describe numerous pieces of knowledge linked together. When an entity is retrieved in LD, its associated data becomes instantly obtainable. SPARQL is the query language that allows users to access LD. On the other hand, SPARQL has a complicated syntax that necessitates previous knowledge. Thus, in order to encourage the end-users to use LD, it is crucial to allow them to obtain the data efficiently, in addition to improving their overall experience. Instead of manually constructing SPARQL queries, this paper investigates and reviews existing methods in which LD can be accessed using various tools and techniques, including query builders, visualisation approaches, and several LD applications. We then identify gaps within the literature and highlight future research directions

ForestQB: Enhancing linked data exploration through graphical and conversational UIs integration

This paper introduces the Forest Query Builder (ForestQB), an innovative toolkit designed to enhance the exploration and application of observational Linked Data (LD) within the field of wildlife research and conservation. Addressing the challenges faced by non-experts in navigating Resource Description Framework (RDF) triplestores and executing SPARQL queries, ForestQB employs a novel integrated approach. This approach combines a graphical user interface (GUI) with a conversational user interface (CUI), thereby greatly simplifying the process of query formulation and making observational LD accessible to users without expertise in RDF or SPARQL. Developed through insights derived from a comprehensive ethnographic study involving wildlife researchers, ForestQB is specifically designed to improve the accessibility of SPARQL endpoints and facilitate the exploration of observational LD in wildlife research contexts. To evaluate the effectiveness of our approach, we conducted a user experiment. The results of this evaluation affirm that ForestQB is not only efficient and user-friendly but also plays a crucial role in eliminating barriers for users, facilitating the effective use of observational LD in wildlife conservation and extending its benefits to wider domains

Querying industrial stream-temporal data: An ontology-based visual approach

An increasing number of sensors are being deployed in business-critical environments, systems, and equipment; and stream a vast amount of data. The operational efficiency and effectiveness of business processes rely on domain experts’ agility in interpreting data into actionable business information. A domain expert has extensive domain knowledge but not necessarily skills and knowledge on databases and formal query languages. Therefore, centralised approaches are often preferred. These require IT experts to translate the information needs of domain experts into extract-transform-load (ETL) processes in order to extract and integrate data and then let domain experts apply predefined analytics. Since such a workflow is too time intensive, heavy-weight and inflexible given the high volume and velocity of data, domain experts need to extract and analyse the data of interest directly. Ontologies, i.e., semantically rich conceptual domain models, present an intelligible solution by describing the domain of interest on a higher level of abstraction closer to the reality. Moreover, recent ontology-based data access (OBDA) technologies enable end users to formulate their information needs into queries using a set of terms defined in an ontology. Ontological queries could then be translated into SQL or some other database query languages, and executed over the data in its original place and format automatically. To this end, this article reports an ontology-based visual query system (VQS), namely OptiqueVQS, how it is extended for a stream-temporal query language called STARQL, a user experiment with the domain experts at Siemens AG, and STARQL’s query answering performance over a proof of concept implementation for PostgreSQL

Filter (Dials | ...)

An increasing number of data providing organizations publish their unique information as Linked data which is available in the Semantic Web in RDF (Resource Distribution Framework) format. RDF is a standard model describing web information that is understandable to computer applications. For users without much technical knowledge, information visualization provides support to interpret the structure of underlying data in the web, understand their relationships, form queries and extract more interesting information. This thesis proposes a visual query technique focusing on the visualization of overall availability of data. The prototype visualization tool developed shows the available groups of data items and their size according to different filtering options. The thesis report starts with a clear description of the research problem and an analysis of the efforts made so far in the field for finding a solution. A survey of the the related work is presented to find the potential for the visualization. The Filter Dials, a novel visualization concept serves as the base work and a starting point and that the evolved new technique attempts to overcome some of the notable drawbacks of the Dials. The thesis also proposes a new visual query technique that aims to achieve the goal of visually presenting an overview of large and complex data available in the web. A prototypical implementation of the visualization tool is done and evaluated by users and conclusions are drawn with the applications, advantages, disadvantages and the possible future directions in the proposed method

Visuelle Suchanfragen auf graphbasierten Datenstrukturen

Die Menge an verfügbaren Daten nimmt stetig zu. Durch standardisierte Datenformate wird die Verknüpfung verschiedener Datenquellen und dadurch auch die Zusammenführung unterschiedlicher Datenelemente je nach Anwendungszweck ermöglicht. Dies führt wiederum zu noch umfassenderen Datenbeständen, in denen die eigentlich gewünschten Informationen teilweise nur schwer gefunden werden können. Handelt es sich bei den Daten um unstrukturierte oder gleichförmige Informationen, so beschränken sich Suchmöglichkeiten auf die Suche nach Übereinstimmungen von Mustern mit Datenelementen oder Teilen davon - beispielsweise Zeichenketten oder regulären Ausdrücken, die mit Teilen von textuellen Datenelementen übereinstimmen. In zunehmendem Maß stehen jedoch auch strukturierte Daten zur Verfügung. Bei diesen wird entweder von Anfang an zwischen unterschiedlichen Facetten pro Datenelement unterschieden, oder es wurden ursprünglich unstrukturierte Daten entsprechend angereichert. Da die einzelnen Facetten auch Verknüpfungen zu anderen Datenelementen darstellen können, entstehen hierbei Graphstrukturen, welche sich für Ansätze der facettierten Suche eignen. Eine Interoperabilität zwischen Datenquellen wird hier unter anderem über die Konzepte und Techniken des Semantic Web erreicht. Zahlreiche Arbeiten haben sich mit der Darstellung der gesamten Datenmengen als Übersicht oder von festgelegten Ausschnitten der Datenmengen im Detail auseinandergesetzt. Jedoch ist das Auffinden bestimmter Daten nach wie vor ein Problem. Die Schwierigkeit liegt dabei darin, die Suchkriterien präzise auszudrücken. Da sich zwischen den einzelnen Kriterien komplexe Zusammenhänge ergeben können, bietet sich auch hier genau wie bei der Übersicht der Datenmengen eine visuelle Darstellung an. Eine Besonderheit dieses Einsatzszenarios für Visualisierungen besteht darin, dass nicht zwangsläufig Daten vorliegen. Statt dessen muss die Visualisierung auch ohne verfügbare Daten die konzeptuelle Idee einer Suchanfrage ausdrücken. Frühere Arbeiten zu diesem Problem befassen sich mit der visuellen Repräsentation von Suchanfragen und Filterausdrücken in Bezug auf relationale Datenbanken und Objektdatenbanken. Viele neuere Arbeiten gehen vermehrt auch auf den Kontext des Semantic Webs ein. Einige dieser Konzepte sind jedoch nicht auf abstrakte Weise klar definiert. Bei komplexeren Anfragen treten zum Teil auch Skalierungsprobleme auf. Zudem wurde bisher kaum betrachtet, wie sich unterschiedliche Konzepte miteinander in Verbindung bringen lassen, um die Vorteile aus unterschiedlichen Anfragevisualisierungen nutzen zu können. Diese Dissertation adressiert die beschriebenen Probleme und stellt sechs Konzepte für die visuelle Darstellung von Suchanfragen vor. Es wird sowohl auf Visualisierungen für allgemeine Einsatzzwecke - also für die Filterung beliebiger strukturierter Informationen -, als auch für spezielle Domänen oder Arten von Informationen eingegangen. Bestehende Ansätze wurden teilweise auf die Gegebenheiten graphbasierter Datenstrukturen angepasst. Ebenso werden neue Ansätze präsentiert, die gezielt auf diese Art von Datenstrukturen ausgelegt sind. Dazu wird jeweils erörtert, inwiefern sich die Anfragevisualisierungen auch ohne Vorhandensein einer zu filternden Datensammlung einsetzen lassen. Zudem wird erklärt, wie bei Vorhandensein einer solchen eine Vorschau auf die Ergebnisse des Filtervorgangs gewährt werden kann. Abschließend werden Verbindungsmöglichkeiten der unterschiedlichen Visualisierungskonzepte präsentiert. Dieser Verbindungsansatz eignet sich dazu, beliebige Anfragevisualisierungen systematisch miteinander zu kombinieren. Mit dem Verbindungskonzept können Benutzer verschiedene Bestandteile einer Anfrage mittels unterschiedlicher Visualisierungskonzepte ausdrücken, um gleichzeitig von den Stärken unterschiedlicher Anfragevisualisierungen zu profitieren. Auf diese Weise können nun Anfragen visuell definiert und dargestellt werden, die sowohl komplexe Bedingungen als auch komplexe Zusammenhänge zwischen den Bedingungen aufweisen, ohne die visuelle Übersicht über einen dieser Aspekte zu verlieren.The total amount of available data is steadily increasing. Standardized data formats allow for connecting different data sources, which can include merging of different data items depending on the use case. This creates even more comprehensive datasets that render finding a particular piece of information difficult. If the data consist of unstructured of homogenous information, searching can only be done by matching patterns with data items or parts thereof - for instance, character strings or regular expressions that match parts of textual data items. However, the availability of structured data is increasing. This kind of data is either stored as distinct facets of each data item from the outset, or originally unstructured data has been enriched to form a structure. As each facet can indicate a link to another data item, the entire dataset forms a graph that is suitable for faceted search conepts. At this point, some interoperability across data sources can be achieved by employing Semantic Web approaches and techniques. Numerous works have attempted to visualize an overview of the entire dataset, or details of a particular excerpt of the dataset. Finding specific data remains a problem, however, as the precise specification of search criteria is difficult. As these criteria can be connected in complex ways, just like the overview of datasets, this issue lends itself to using visual representations. A special trait of this application of visualization is the possible absence of any data. Instead, the visualization must be capable of conveying the conceptual idea of a search query without displaying any data. Former works related to this problem focused on the visual representation of search queries and filter expressions for relational and object-oriented databases. More recent works increasingly address a Semantic Web context. Various of these concepts, however, lack a clear abstract definition. Also, scalability issues appear in the case of complex queries. Furthermore, little attention was paid to how to connect several concepts in order to combine advantages of different query visualizations. This dissertation considers the described problems and presents six concepts for query visualization. Both generic visualizations - that is, for filtering any kind of structured data - and domain-specific or type-specific visualizations are addressed. In part, existing approaches have been adapted to the particularities of graph-based data structures. Likewise, several new approaches specifically designed for this kind of data are presented. For each of these concepts, the necessity of a dataset is discussed. Moreover, options for providing a preview on query results from such a dataset, if available, are considered. Finally, ways for connecting the query visualization concepts are presented. This connection approach is suitable for systematically linking together arbitrary query visualizations. By means of the connection approach, users can express different parts of a query using different visualization concepts, in order to benefit from the advantages of several query visualizations at a time. Like this, queries that include complex criteria as well as complex relations between criteria can now be defined and displayed visually without losing the visual overview of any of these aspects

Semantically en enhanced information retrieval: an ontology-based aprroach

Tesis doctoral inédita. Universidad Autónoma de Madrid, Escuela Politécnica Superior, enero de 2009Bibliogr.: [227]-240 p