=Paper=
{{Paper
|id=Vol-467/paper-2
|storemode=property
|title=UbisEditor 3.0: Collaborative Ontology Development on the Web
|pdfUrl=https://ceur-ws.org/Vol-467/paper2.pdf
|volume=Vol-467
}}
==UbisEditor 3.0: Collaborative Ontology Development on the Web==
https://ceur-ws.org/Vol-467/paper2.pdf
UbisEditor 3.0:
Collaborative Ontology Development on the Web
Matthias Loskyll Dominikus Heckmann Ichiro Kobayashi
Saarland University DFKI GmbH Ochanomizu University
66123 Saarbrücken, Germany 66123 Saarbrücken, Germany Ohtsuka Bunkyo-ku Tokyo
matthias@xantippe.cs.uni- heckmann@dfki.de 112-8610, Japan
sb.de koba@is.ocha.ac.jp
ABSTRACT methods.
Ontologies continuously become larger and more complex, With the increasing importance of ontologies, several on-
and therefore more and more difficult to maintain, to edit tology editors have been developed. Two of the currently
and to develop by one single person or a small group of most popular ones are Protégé [7] and Swoop [3]. However,
experts. The basic principle of Web 2.0, on the other hand, there are only few online editors for ontologies available.
is to use the willingness and knowledge of a huge community Recently, a web-based version of Protégé called WebProtégé
of users to create rich user-generated content. The obvious [11] was released. An evaluation of different tools for col-
idea that comes to mind is to combine the technologies of the laborative ontology development during the CKC challenge
Semantic Web with the trend of the Web 2.0. We present [6] showed that users prefer Web interfaces for editing tools.
UbisEditor 3.0, an easy-to-use web tool for the creation and Our prototype called UbisEditor uses Ajax technologies to
manipulation of structured collective knowledge represented load and send required data on demand such that it provides
as ontologies. This web ontology editor is realized as part of a lightweight and efficient way of performing ontology edit-
the UbisWorld project and already supports ontology editing ing on the Web. Other differences of our approach compared
techniques like adding new concepts, renaming and deleting, with related work are: our ontology is stored in a database
but also the creation of personalized ontology views. structure, editing can be performed using a context menu,
we already have a role-based rights management, and we
Categories and Subject Descriptors provide multilingual renaming of concepts.
M.1 [Knowledge Engineering Methodologies]
; H.5 [Information Interfaces and Presentation]: User
Interfaces
General Terms
Semantic Web, Web 2.0
Keywords
online ontology editing, collaborative ontology building, on-
tology views
1. INTRODUCTION
The characterization of Web 3.0 used in this paper is based
on [12], in which Wahlster and Dengel define Web 3.0 as the
Figure 1: The trend of Web 3.0 combining Web 2.0
integration of Semantic Web technologies with the princi-
and Semantic Web
ples of Web 2.0. UbisEditor 3.0 perfectly fits to this defini-
tion of Web 3.0 because it combines ontology development,
Ontology segmentation or the creation of ontology views
which forms the backbone of Semantic Web, together with
is an important issue. Since many ontologies constantly
the community approach of Web 2.0 (see Figure 1). Re-
grow in size and are therefore more and more difficult to
cently, the meaning of Web 3.0 has been extended to an
understand, maintain and edit, ontology segmentation shall
intelligent web by also adding further artificial intelligence
help to extract only those parts of a large ontology that are
relevant for a certain scenario and to create a stand-alone
ontology out of these concepts. Seidenberg and Rector com-
pare and evaluate several algorithms for extracting relevant
segments in [9]. The key approach is to let the user se-
lect some relevant concepts and to automatically add super-
classes, subclasses and other related concepts (e.g. classes
contained in axioms and restrictions) to the ontology view.
We implemented a similar, lightweight online approach as
part of the UbisEditor.
UbisEditor 3.0 uses the same graphical user interface as the
UbisWorld ontology browser, but with additional features
2. THE WEB ONTOLOGY EDITOR enabled like check boxes, a context menu and editable tree
The idea behind UbisEditor is the following (see Figure 2): node labels.
Our basic ontology is created and edited by an ontology
expert, who can use either a common ontology editor like
Protégé or UbisEditor to perform this task. Our ontology
community, on the other hand, extends the basic ontology
via UbisEditor with the possible issue of dublicated and con-
flicting concepts. Another feature of UbisEditor is to allow
an individual ontology user to create a personalized ontology
segment.
Figure 3: Part of the UbisEarth ontology tree
2.1 Architecture of UbisEditor 3.0
Figure 4 shows the basic architecture of the UbisEditor 3.0
Figure 2: Collaborative Ontology Engineering in the and the ontology browser. Both the developers of our group
Web 3.0 era with UbisEditor and our user community can use the UbisEditor to manip-
ulate the different ontologies. When committing changes,
The UbisEditor 3.0 itself is part of the UbisWorld project, a script stores the appropriate data in the database and a
which focuses its research on ubiquitous user modeling [1] script for building the ontology trees sends the updated in-
and Web 3.0. The latest tool set version UbisWorld 3.0 inte- formation back to the client. With this technology, we are
grates Web 2.0-like services and Semantic Web technologies. able to overcome the performance issues that appeared in
The knowledge base of the system is built out of two on- the context of web ontology editors so far.
tologies: GUMO (General User Modeling Ontology) [2] and
UbisOntology. These ontologies are represented as foldable
trees whose nodes consist of classes and instances whereby
the conversion from ontologies usually represented as graphs
to ontology trees is performed by using multiple heritage. In
addition, several external ontologies (e.g. SUMO, DOLCE,
OpenCyc) and taxonomies (e.g. the Amazon.com category
tree) have been parsed and integrated into the UbisWorld.
At the moment, further OWL ontologies can only be im-
ported by our team, but we plan to provide a functionality
to allow users to import and edit their own ontologies any-
time soon.
All the trees can be browsed in a very efficient way by using
Ajax technologies [5]. This means that the data needed to
display the layer of a tree is sent to the client not before
the user has opened the corresponding parent node. Using
this visualization technique we are basically able to display
arbitrary large trees.
In the UbisEarth ontology tree (our largest ontology with
about 28 million nodes), depicted in Figure 3, we are already
able to display roles and properties as tree nodes, too. This
very useful feature shall also be implemented for the rest
of the UbisWorld. Furthermore, this tree emphasizes the
strength of our visualization by displaying limitation nodes,
which subsume large numbers of nodes in ten thousand or
hundred packets, respectively. These nodes add additional
structure to the tree hierarchy and facilitate an easy-to-use Figure 4: Abstract architecture of the UbisEditor
tree browsing. 3.0 and visualization system
2.2 Editing Process and Quality Control label according to a situation-aware strategy.
The UbisEditor 3.0 already supports the most important In order to make a multilingual labeling of the concepts of
functionalities for editing an ontology: creating new classes the different ontologies possible, we provide an additional
or instances, renaming and deleting objects as well as chang- method to edit the UbisLabel of an object. When selecting
ing a node’s parent via drag&drop. By using a context a node of an ontology tree, a grid appears on the right hand
menu, we provide an efficient and easy to use way of perform- side of the UbisWorld webpage (Fig. 6). This grid has two
ing these editor actions. Right mouse button click opens the columns (Language and Label) where the different labels
context menu and highlights the selected node in the tree that already exist for this concept are shown together with
(Fig. 5). This context menu is adaptive to the rights of the corresponding language. Further translations of the con-
the user, which depend on the user’s role. This means that cept’s name can be added by first selecting a language out of
only users belonging to a certain role can delete objects, for a combo box containing the different iso 639 language codes
example. and entering the appropriate name into a text editor field
afterwards. This feature facilitates a collective generation of
multilingual ontology concepts.
Figure 5: The Context Menu Before Inserting a New Figure 6: Grid for Multilingual Label Editing
Class
When the editing process is finished, the user has to push 2.4 Aspects of Collaborative Ontology Devel-
a button to commit those changes to the server. Then a opment
script executes the actions corresponding to the type of the The idea to facilitate a collaborative ontology editing raises
changes. By changing only those values in the database that several issues. One important task is the implementation of
really have changed, the updated tree can be reloaded and a transaction management to avoid problems when multiple
displayed immediately to the user. users edit the ontologies and commit their changes simul-
For each editing process performed with UbisEditor we store taneously. However, since our system stores the different
the identifier of the registered user who is responsible for the ontologies in a database back end, the concurrency control
appropriate changes. By doing so, we are able to find out will probably be solved on the database level. In addition,
whether a user constantly inserts low quality content. In we think about implementing a locking mechanism on the
addition, UbisWorld already has a five-star rating system subtree or ontology module level to avoid inconsistencies.
available, with which our user community can help to en- When different members of a community collectively extend
sure the quality and integrity of our content [8]. A possible an ontology, different opinions inevitably can cause conflicts
extension could be to make it possible to rate the raters, to occur. Consequently, a conflicts resolution is an essen-
too. tial functionality. We plan to solve this problem using a
combined approach consisting of a community-based and a
2.3 Multilingual Editing of Labels role-based conflicts resolution strategy similar to the one
UbisLabel is our approach to define multilingual labels in proposed by Li et al. in [4].
identifiers for semantic web and ubiquitous computing. We In order to avoid dublicated concepts, we already imple-
use UbisLabels to denote concepts in our ontologies. The mented a search engine for the UbisWorld system, which
basic idea is to use only ASCII characters in names, even if can be used to find classes, instances and properties of the
selected special characters are allowed. The syntax of the UbisOntology. This is a very important feature with regard
UbisLabel approach is described below. to the editing process using UbisEditor. When a user plans
to insert a new element into the UbisWorld ontology, but is
[D] UbisLabel ::= SimpleLabel | LanguageLabel | MultiLabel
not sure whether an appropriate concept already exists, the
[D] SimpleLabel ::= UbisToken UbisSearch can be used to remove ambiguity.
[D] LanguageLabel ::= (LanguageCode)+ ".." UbisToken
[D] MultiLabel ::= UbisLabel ("..." UbisLabel)+ In the near future we plan to develop a change management
[D]
[D]
LanguageCode ::= ISO_639_1 | "ME"
ISO_639_1 ::= "EN" | "DE" | "IT" | "JP" | "YI" | ...
system for UbisEditor and to extend the rating system such
that performed ontology editing operations can be rated. By
doing so, the change history and versioning information of
So this approach not only enables multiple labels for any each ontology concept can be displayed on the right side of
concept from the knowledge representation point of view, the website helping the user to understand the evolution of
but also allows the adaptive selection and presentation of a the ontology. Our user community can help do discuss and
decide whether performed changes to the ontology should be gumo revisited for future web 2.0 extensions. In
kept or reverted. In this context, the availability of tagging P. Bouquet, J. Euzenat, C. Ghidini, D. L.
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UbisEditor 3.0 in order to support the definition of ontolog-
ical axioms, the creation of properties and the user-driven
merging of ontologies. Concerning the support of collabo-
rative ontology development, mechanisms for concurrency
control, conflicts resolution and change management are es-
sential. Additionally, we are going to perform an extensive
evaluation of the editor features and of our ontology visual-
ization techniques.
Acknowledgments
This work has partly been supported by the EU funded FP7
project GRAPPLE (215434).
Special thanks to Francesca Carmagnola.
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