=Paper=
{{Paper
|id=Vol-2180/paper-75
|storemode=property
|title=WebVOWL Editor: Device-Independent Visual Ontology Modeling
|pdfUrl=https://ceur-ws.org/Vol-2180/paper-75.pdf
|volume=Vol-2180
|authors=Vitalis Wiens,Steffen Lohmann,Sören Auer
|dblpUrl=https://dblp.org/rec/conf/semweb/WiensLA18
}}
==WebVOWL Editor: Device-Independent Visual Ontology Modeling==
https://ceur-ws.org/Vol-2180/paper-75.pdf
WebVOWL Editor: Device-Independent
Visual Ontology Modeling
Vitalis Wiens1,3 , Steffen Lohmann1 , and Sören Auer2,3
1
Fraunhofer IAIS, Sankt Augustin, Germany
vitalis.wiens@iais.fraunhofer.de
steffen.lohmann@iais.fraunhofer.de
2
L3S Research Center, University of Hannover, Germany
auer@l3s.eu
3
TIB Leibniz Information Center for Science and Technology, Hannover, Germany
Abstract. 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 different
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 device-
independence is achieved by considering different modes of operation,
including mouse and touch interactions. The visual modeling provides
an intuitive interaction mode for creating and editing ontologies. Guid-
ance during the ontology modeling and editing process reduces common
pitfalls and ensures that valid ontologies are created. From discussions
with domain experts, we identified a subset of OWL constructs that are
considered most relevant in ontology modeling and are supported by the
current implementation of the software.
Keywords: Visual Modeling, Device-Independence, OWL, WebVOWL
1 Introduction
A fundamental aspect of the Semantic Web is to create and communicate con-
ceptualizations of information and data in various domains. Ontologies serve
this purpose by providing a formal, machine-readable representation of the do-
main knowledge. The modeling of ontologies is often done collaboratively in joint
efforts of knowledge engineers and domain experts. On the one hand, domain
experts, who provide the conceptualization of the knowledge domain, are typi-
cally not familiar with semantic formalism and conceptual modeling techniques.
They often find it hard to follow logical notations in OWL representation [1].
On the other hand, ontology engineers, who provide the necessary know-how for
ontology modeling and logical notations in OWL, usually lack the expertise in
the domain to create ontologies of sufficient quality.
Fig. 1. GUI overview: 1) collapsible sidebar for default element selection; 2) message
box; 3) editing elements for a selected object property; 4) editing elements for a selected
class; 5) tool menu; 6) zooming controls; 7) collapsible sidebar for editing options.
Visualizations are often used to support ontology development, exploration,
verification, and sensemaking [3]. They can enable domain experts to get more
directly involved in ontology modeling. Many ontology visualization tools have
been developed in recent years, however, only few of them support direct editing
of the ontology [2]. The available tools are currently mainly used for illustrating
and exploring ontologies but not as an entry point for modeling. Nowadays,
knowledge workers often use more than one device for their daily tasks in a
myriad of interaction contexts, ranging from classical desktop settings to mobile
scenarios in meetings, workshops, and on business trips. Also, digital devices
for creativity techniques, such as interactive whiteboards, idea walls, and touch
tables, are increasingly available and used for idea generation and conceptual
modeling. This development shows the increasing need for device independent
solutions for ontology modeling.
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-specified
visual language for the user-oriented representation of OWL ontologies [3]. We
achieve a high device-independence by considering different input and output
modalities of common computing devices. Additional built-in guidance func-
tionalities help to avoid common pitfalls and the creation of syntactically valid
ontologies. The current implementation of WebVOWL Editor already supports
a large share of OWL constructs, and runs in most modern web browsers. An
overview of the graphical user interface is illustrated in Figure 1. Limited by
device resources and web-based technologies, WebVOWL Editor is designed for
visualizing and editing small and medium sized ontologies. Additionally, target-
ing domain experts and other user groups, it does not include any inference nor
reasoning for visualization and creation of OWL ontologies and RDF(S) graphs.
2 WebVOWL Editor
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 different user groups by using the
VOWL notation [3] for visual ontology modeling. Visual modeling is realized
by device-independent modes of operation for mouse and touch interactions.
The current implementation of WebVOWL Editor supports a subset of OWL
constructs that were identified from discussions with domain experts and which
are considered most relevant in ontology modeling.
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 define 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 first 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 cre-
ated, 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 inter-
relations between classes, are created by dragging the arrow head from a source
class to a target class, defining the domain and range of the corresponding prop-
erty 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 rep-
resentation (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 corre-
sponding 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 Protégé [4]),
allowing the user to set the label and the IRI of an element simultaneously.
Further Editing Options and Refinement — The right sidebar provides
further editing options for the meta information of ontology itself and the se-
lected element in the graphical representation. Additional characteristics options
are presented in the right sidebar for a selected element. Based on its type, these
are filtered 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 Demonstration Overview
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 mod-
eling 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 fill out a SUS-Questionnaire in order to gain
feedback and insights for improvement of WebVOWL Editor. This tools aims
for a direct involvement of different 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”.
References
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Anthony G Cohn. Involving domain experts in authoring OWL ontologies. In
International Semantic Web Conference, pages 1–16. Springer, 2008.
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genia Giannopoulou. Ontology visualization methods – a survey. ACM Computing
Surveys, 39(4), November 2007.
3. Steffen Lohmann, Stefan Negru, Florian Haag, and Thomas Ertl. Visualizing on-
tologies with VOWL. Semantic Web, 7(4):399–419, 2016.
4. Stanford. Protégé. http://protege.stanford.edu.