SEKE 2012 Proceedings - Knowledge Systems Institute

transformation of UML diagrams directly, but offer ontology
modeling utilizing UML profiles (compare [4][pg.2ff]). In this
alternative approach users have to explicitly specify OWL elements
using UML syntax[1], while conventional tools typically
try to extract implicit information from UML elements[2].
Only the latter approach is relevant for CDL-Flex, hence only
one representative, i. e., TwoUseToolkit 2 , will be outlined in
this paper. Other examples for hybrid tools are Altova Semantic
Works,UMLtoOWL by Gasevic et al. which is described in [3]
and VisioOWL.
Purebred transformation tools have been compared and
evaluated based on portability, traceability, their transformation
approach, up-to-dateness, availability of documentation,
support, usability and surplus value for CDL-Flex. The major
prerequisite was that the UML to OWL transformation feature
is executable or that, if the tool/feature is not available, it is
somehow justified, why the tool is capable to transform UML
into OWL.
A. Evaluation Results
None of the tools transformed VP XMI 1.2 or 2.1 into valid
OWL 2 DL. All scripts completed within a reasonable time
(in other words: none of the programs crashed), but also none
of the tools correctly transformed a single UML element into
its valid OWL counterpart. The tools either terminated before
an OWL file was created or the root element of the resulting
OWL XML/RDF file was empty.
Most of the tools passed their own reference model tests,
which means that they successfully translated the examples
(XMI files) they provided into valid OWL ontologies, which
has been validated using OWL Validator by University of
Manchester (ManchesterValidator) 3 . Transformation of Leinhos’
UML2OWL 4 reference models failed when the models
were opened in Poseidon for UML SE 6.0.2 and re-exported
into XMI 1.2. Dia 5 successfully imported MS Visio XSD
files, but crashed during OWL export, because the Visio file
could not be saved as a valid Dia file (tested with Ubuntu
11.04). OntoStudio 6 seemed quite interesting and provides
a pliable GUI (Eclipse based). However, UML 2 is only
available for ObjectLogics. NeOn Toolkit 7 , which is a derivate
of OntoStudio claims to provide transformation functionality
as well, but version 2.5.1 misses any feature. Eclipse offers
an entire UML modeling environment (EMF; ATL; UML2 or
Papyrus project) and ATL transformation performed well for
the distributed XMI 2.1 reference examples, but the flip side
of the coin is that most of the Eclipse modeling tools are still
in incubation. Detailed evaluation results and a comprehensive
comparison of available tools in tabular form are provided in
[4][p.2ff].
2 http://code.google.com/p/twouse
3 http://owl.cs.manchester.ac.uk/validator
4 http://diplom.ooyoo.de/index.php?page=download
5 http://projects.gnome.org/dia/
6 http://www.ontoprise.de/de/produkte/ontostudio/
7 http://neon-toolkit.org/wiki/Main Page
B. ODM-ATL Implementation (Bridging UML - OWL)
ATL 8 is an Eclipse-based model transformation language
that provides ways to produce a set of target models out of
a set of source models. It originally has been initiated by
Object Management Group (OMG) and is part of Eclipse’s
Model To Model Transformation (M2M) project. One of the
transformation use cases for ATL is the Ontology Defnition
Meta Model (ODM) implementation for bridging UML
and OWL. Hillairet 9 provides the most current project files
(including samples) as well as the source files for reverse
transformation (OWL2UML) of OWL. Evaluation showed
that the tool transforms XMI 2.1 UML models accurate, if
they have been designed using Eclipse’s UML2 plug-in or
Papyrus, which both implement OMG’s XMI 2.1 standard.
Transformation of VP XMI 2.1 caused exceptions and resulted
in an empty OWL file.
Eclipse ATL’s transformation approach is based on different
meta levels, as defined by OMG (compare [5]). ATL is used to
transform UML 2.0 (XMI 2.1) input files into OWL metadata,
based on OWL.ecore. Eclipse ecore is a meta language inspired
by MOF 1.4 and is used to define platform independent
models [6]. Once the XMI input file has been transformed into
OWL ecore format, the AM3 plugin serializes OWL resulting
in valid OWL RDF/XML output.
The ATL approach is elegant, though transformation rules
are defined in a single, transparent file. ATL supports syntax
highlighting and debugging. Transformation rules are intuitive
to interpret and may be easier to read than XSLT, because the
rules do not follow an XML sytanx. Helper functions can be
defined and allow more freedom for the developer. ATL is easy
adaptable. Drawbacks are that the Eclipse environment is hard
to setup. ATL UML2OWL project requires Eclipse Eclipse
Modeling Framework (EMF), UML2 and AM3. Some of those
components are still in incubation phase and incompatible
either among themselves or with some versions of Eclipse.
Furthermore, ecore/ATL training effort is high. Developers
have to dive into the EMF concept to gain a deeper understanding
and learn ATL, which can be time consuming.
C. TwoUse Toolkit
The TwoUse Toolkit originated from an European project. It
implements the current OMG and W3C standards for software
design, code generation and OWL ontology engineering.[7]
All components are implemented as Eclipse plug-ins. The
aim of TwoUse toolkit is to enable Semantic Web Software
Engineering and Model Driven Semantic Web. Thus, besides
extensive browsing and querying support (e.g. SPARQL), it
offers different graphically design tools for modeling of OWL
ontologies:
• UML editor for modelling and transformation of UML
profiles into OWL ontology functional syntax.
• TwoUse Graphical Editor for directly creating ontologies
(some design elements have been adopted from Protégé).
8 http://www.eclipse.org/atl
9 http://perso.univ-lr.fr/ghillair/projects.html
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