The growing attention of ontologies in the industrial and the Semantic Web domain raises the need for approaches that are easy to use, immediately available, and independent of a particular device category and interaction context. In order to foster direct involvement of di erent user groups in ontology modeling, the complexity and learning processes of ontology engineering tools need to be reduced. We present WebVOWL Editor, an open source software that is 1) largely device independent, 2) uses visual modeling, and 3) provides modeling guidance. The deviceindependence is achieved by considering di erent modes of operation, including mouse and touch interactions. The visual modeling provides an intuitive interaction mode for creating and editing ontologies. Guidance during the ontology modeling and editing process reduces common pitfalls and ensures that valid ontologies are created. From discussions with domain experts, we identi ed a subset of OWL constructs that are considered most relevant in ontology modeling and are supported by the current implementation of the software.
A fundamental aspect of the Semantic Web is to create and communicate
conceptualizations of information and data in various domains. Ontologies serve
this purpose by providing a formal, machine-readable representation of the
domain knowledge. The modeling of ontologies is often done collaboratively in joint
e orts of knowledge engineers and domain experts. On the one hand, domain
experts, who provide the conceptualization of the knowledge domain, are
typically not familiar with semantic formalism and conceptual modeling techniques.
They often nd it hard to follow logical notations in OWL representation [
Visualizations are often used to support ontology development, exploration,
veri cation, and sensemaking [
We demonstrate WebVOWL Editor, a web-based visual ontology modeling
application that is independent of a particular device and interaction context.
Ontologies are visualized using the VOWL notation which is a well-speci ed
visual language for the user-oriented representation of OWL ontologies [
WebVOWL Editor is designed to serve the skills and needs of domain experts with limited knowledge of ontology modeling. Its most distinctive characteristic is the device-independent mode of operation for the visual modeling of ontologies. The implementation is available under a persistent URL4 and its source code is released on GitHub. The GitHub repository enables users to download and reuse the source code, open issues, and ask for help. Additionally, it is released under the MIT license in order to allow for wide-spread use and adoption.
We address the various backgrounds of di erent user groups by using the
VOWL notation [
Visual Modeling Elements | Visual modeling elements are provided for the nodes and links in the graphical representation of the ontology. In order to reduce visual clutter, these are presented to the user when an editing operation of a certain element is desired. With respect to device-independence, we de ne that the desire to do so arises when the user selects an element. Additionally, on point and click devices we show the visual modeling elements on mouse hovering in order to skip the interaction of rst having to select an element. Visual modeling elements provide functionalities for creating, editing, and deleting elements such as classes, object properties, datatype properties and datatypes.
Modeling of Classes | Classes are created by performing a double click or double tap interaction on the empty space of the canvas area. After a class is created, we assume that the user wants to change the default label (i.e., NewClass) to a proper name for the conceptualization. Thus, we trigger a label editing operation on the creation of an element.
Modeling of Object Properties | Object properties, describing interrelations between classes, are created by dragging the arrow head from a source class to a target class, de ning the domain and range of the corresponding property respectively. Additional visual elements are provided for properties on their selection in order to easily change domain and range of a property.
Modeling of Datatypes | Datatype properties are created with a visual modeling element that is provided only for classes (green plus button). The corresponding datatype is created based on the selection of the default element in the left sidebar. Additionally, according to VOWL notation, datatypes and datatype properties are bound together, thus datatype properties provide only an editing element for its domain.
Label and IRI Editing | Label editing is provided in the graphical
representation (double click or double tap on a visual element) and in the right
sidebar. IRI editing is provided only in the right sidebar. However, the
corresponding IRI is also synchronised during label editing when it was not changed
4 Tool and GitHub repository can be found at https://w3id.org/webvowl/editor
from the default initial value (as similar as how IRIs are handled in Protege [
Further Editing Options and Re nement | The right sidebar provides further editing options for the meta information of ontology itself and the selected element in the graphical representation. Additional characteristics options are presented in the right sidebar for a selected element. Based on its type, these are ltered to only those that can be applied without invalidating the ontology. For example, for object properties inverse functional among other characteristics is applicable, while for datatype properties only functional is allowed.
Guidance | Guidance during the modeling and editing process plays a key role in order to involve domain experts and other user groups directly in ontology modeling. WebVOWL Editor provides built-in constraints for the visual modeling elements and additional restrictions in order to ensure the creation of syntactically correct ontologies. A message box provides feedback to the user, explaining the reason of an enforced constraint or other hints and guidance. 3
In the demonstration scenario we will explain the need of WebVOWL Editor and its features. We want to provide a hands on experience for visual ontology modeling with WebVOWL Editor. A QR-Code (link) forwarding to the application will be provided, thus, allowing for independent testing of the tool. Additionally, we would like to invite the users to ll out a SUS-Questionnaire in order to gain feedback and insights for improvement of WebVOWL Editor. This tools aims for a direct involvement of di erent user groups by providing a software that is easy to learn, ready to use, and independent of a particular device category. Acknowledgments This work has partly been funded by the EU project GRACeFUL (grant no. 640954) as well as a scholarship from the German National Library of Science and Technology (TIB). In addition, parts of it evolved in the context of the Fraunhofer Cluster of Excellence \Cognitive Internet Technologies".