Olga De Troyer

Emergent semantics principles and issues

Information and communication infrastructures underwent a rapid and extreme decentralization process over the past decade: From a world of statically and partially connected central servers rose an intricate web of millions of information sources loosely connecting one to another. Today, we expect to witness the extension of this revolution with the wide adoption of meta-data standards like RDF or OWL underpinning the creation of a semantic web. Again, we hope for global properties to emerge from a multiplicity of pair-wise, local interactions, resulting eventually in a self-stabilizing semantic infrastructure. This paper represents an effort to summarize the conditions under which this revolution would take place as well as an attempt to underline its main properties, limitations and possible applications.

Understanding ontology evolution: A change detection approach

In this article, we propose a change detection approach in the context of an ontology evolution framework for OWL DL ontologies. The framework allows ontology engineers to request and apply changes to the ontology they manage. Furthermore, the framework assures that the ontology and its depending artifacts remain consistent after changes have been applied. Innovative is that the framework includes a change detection mechanism that allows generating automatically a detailed overview of changes that have occurred based on a set of change definitions. In addition, different users (such as maintainers of depending artifacts) may have their own set of change definitions, which results into different overviews of the changes, each providing a different view on how the ontology has been changed. Using these change definitions, also different levels of abstraction are supported. Both features will enhance the understanding of the evolution of an ontology for different users.

Accessibility: a Web engineering approach

Currently, the vast majority of web sites do not support accessibility for visually impaired users. Usually, these users have to rely on screen readers: applications that sequentially read the content of a web page in audio. Unfortunately, screen readers are not able to detect the meaning of the different page objects, and thus the implicit semantic knowledge conveyed in the presentation of the page is lost. One approach described in literature to tackle this problem, is the Dante approach, which allows semantic annotation of web pages to provide screen readers with extra (semantic) knowledge to better facilitate the audio presentation of a web page. Until now, such annotations were done manually, and failed for dynamic pages. In this paper, we combine the Dante approach with a web design method, WSDM, to fully automate the generation of the semantic annotation for visually impaired users. To do so, the semantic knowledge gathered during the design process is exploited, and the annotations are generated as a by-product of the design process, requiring no extra effort from the designer.

Applying semantic web technology to feature modeling

Feature models are models used to capture differences and commonalities between software features, enabling the representation of variability within software. There are many variations of feature models and different notations are often used to represent the same information. Currently support for validating or integrating feature models is missing. In this paper, we provide an ontology framework for feature modeling which consists of an ontology that formally provides a specification for feature models. In addition, we provide means to integrate segmented feature models and provide a rule based model consistency check and conflict detection. We use SWRL rules to implement the rules and a DL reasoner to evaluate the rules and infer extra interesting information regarding the variability of the software.

A survey on web modeling approaches for ubiquitous web applications

Purpose – Ubiquitous web applications (UWA) are a new type of web applications which are accessed in various contexts, i.e. through different devices, by users with various interests, at anytime from anyplace around the globe. For such full-fledged, complex software systems, a methodologically sound engineering approach in terms of model-driven engineering (MDE) is crucial. Several modeling approaches have already been proposed that capture the ubiquitous nature of web applications, each of them having different origins, pursuing different goals and providing a pantheon of concepts. This paper aims to give an in-depth comparison of seven modeling approaches supporting the development of UWAs. Design/methodology/approach – This methodology is conducted by applying a detailed set of evaluation criteria and by demonstrating its applicability on basis of an exemplary tourism web application. In particular, five commonly found ubiquitous scenarios are investigated, thus providing initial insight into the modeling concepts of each approach as well as to facilitate their comparability. Findings – The results gained indicate that many modeling approaches lack a proper MDE foundation in terms of meta-models and tool support. The proposed modeling mechanisms for ubiquity are often limited, since they neither cover all relevant context factors in an explicit, self-contained, and extensible way, nor allow for a wide spectrum of extensible adaptation operations. The provided modeling concepts frequently do not allow dealing with all different parts of a web application in terms of its content, hypertext, and presentation levels as well as their structural and behavioral features. Finally, current modeling approaches do not reflect the crosscutting nature of ubiquity but rather intermingle context and adaptation issues with the core parts of a web application, thus hampering maintainability and extensibility. Originality/value – Different from other surveys in the area of modeling web applications, this paper specifically considers modeling concepts for their ubiquitous nature, together with an investigation of available support for MDD in a comprehensive way, using a well-defined as well as fine-grained catalogue of more than 30 evaluation criteria.

Resolving inconsistencies in evolving ontologies

Changing a consistent ontology may turn the ontology into an inconsistent state. It is the task of an approach supporting ontology evolution to ensure an ontology evolves from one consistent state into another consistent state. In this paper, we focus on checking consistency of OWL DL ontologies. While existing reasoners allow detecting inconsistencies, determining why the ontology is inconsistent and offering solutions for these inconsistencies is far from trivial. We therefore propose an algorithm to select the axioms from an ontology causing the inconsistency, as well as a set of rules that ontology engineers can use to resolve the detected inconsistency.

Designing Localized Web Sites

The term World Wide Web (WWW) emphasizes that the Web is global and many companies realize that this creates new opportunities. A considerable amount of literature on web site development stresses that, in order to attract and retain more customers, it is vital to create different versions of a web site and adapt those versions to the local communities they target. This process is usually called globalization and the different web site versions are called localized web sites. Although content management systems (CMS) for web sites provide support for multinational web sites, current web site design methodologies do not consider the issue of globalization. In general, the globalization effort is done after the web site is designed and implemented. This makes globalization much harder. In this paper, we show how to extend an existing web site design method, WSDM, to support the design of localized web sites.

Design time support for adaptive behavior in Web sites

Adaptive web sites are sites that automatically improve their internal organization and/or presentation by observing user-browsing behavior. In this paper we argue that adaptive behavior of websites should be controlled in order to keep the website manageable. We believe that adaptive behavior may be a useful complement to a good website design method on the condition that the adaptations are limited and according to the modeling approach followed during design. Therefore, we allow a website designer to specify at design time the adaptive behavior that will be allowed at runtime. To accomplish this goal, an Adaptation Specification Language is defined that allows designers to specify at the level of the navigational model, which adaptations could be performed at runtime. The language is event based, i.e. a collection of rules is used to specify the adaptation operations to be carried out if certain conditions are satisfied. The approach proposed is elaborated in the context of WSDM, an audience driven website design method, but is generally applicable to other design methodologies.

A Framework for Decentralized, Context-Aware Mobile Applications Using Semantic Web Technology

The recent evolution in mobile devices, combined with rapid advancements in identification techniques, has lead to new opportunities for mobile application developers: mobile applications that can be made aware of their environment and the objects in it. Additionally, by combining mobile devices and identification technology with the Web, mobile applications can be developed that exploit services and information associated with nearby objects. In this paper, we present an application framework that supports the development of such mobile applications, without having to rely on a central service to provide information on the users environment. Furthermore, by deploying Semantic Web technology, the integration of information from various information sources is facilitated, allowing for expressive and powerful personalized information delivery.

Adding semantic annotations, navigation paths and tour guides to existing virtual environments

Nowadays, more Virtual Environments (VEs) are becoming available on the Web. This means that VEs are becoming accessible to a larger and more diverse audience. It also means that it is more likely that the use of these VEs (i.e. how to interact with the virtual environment and the meanings of the associated virtual objects) may be different for different groups of persons. In order for a VE to be a success on the Web, end-users should easily get familiar with the VE and understand the meanings of its virtual objects. Otherwise, the end-user may be tempted to quit the VE. Therefore, annotations and the creation of navigation paths for virtual tour guides become important to ease the use of VEs. Most of the time, this is done by VR-experts and the annotations are very poor and often only text based. This paper describes an approach and associated tool that allows a layman to add or update annotations to existing VEs. In addition, annotations are not limited to text but may also be multimedia elements, i.e. images, videos, sounds. Furthermore, the approach (and the tool) also allows easy creation of navigation paths and tour guides, which can be used to adapt a VE to the needs of a user. The paper illustrates the results by means of a real case, which is a reconstruction of a coalmine site for a museum.