Sharing OWL/SWRL and UML/OCL Rules
Milan Milanović
1
, Dragan Gašević
2
, Adrian Giurca
3
, Gerd Wagner
3
, and Vladan
Devedžić
1

1
FON-School of Business Administration, University of Belgrade, Serbia
milan@milanovic.org, devedzic@etf.bg.ac.yu
2
School of Interactive Arts and Technology, Simon Fraser University Surrey, Canada
dgasevic@sfu.ca
3
Institute of Informatics, Brandenburg Technical University at Cottbus, Germany
Giurca@tu-cottbus.de, G.Wagner@tu-cottbus.de
Abstract. The paper presents a metamodel-driven model transformation
approach to sharing rules between the Semantic Web Rule Language along with
the Web Ontology Language (OWL/SWRL) and Object Constraint Language
(OCL) along with UML (UML/OCL). The solution is based on the REWERSE
Rule Markup Language (R2ML), a MOF-defined general rule language, as a
pivotal metamodel and the bi-directional transformations between OWL/SWRL
and R2ML and between UML/OCL and R2ML.
1. Introduction
In this paper, we further extend the research in approaching the Semantic Web and
MDA by proposing a solution to interchanging rules between two technologies. More
specifically, we address the problem of mapping between the Object Constraint
Language (OCL), a language for defining constrains and rules on UML and MOF
models and metamodels, and the Semantic Web Rule Language (SWRL), a language
complementing the OWL language with features for defining rules. In fact, our
proposal covers the mapping between OCL along with UML (i.e., UML/OCL) and
SWRL along with OWL (OWL/SWRL).
In our solution, we use R2ML [1], a MOF-defined general rule language capturing
integrity, derivation, production, and reaction rules, which covers almost all of the use
cases requirements of the W3C RIF WG [4]. R2ML is a pivotal metamodel for
interchanging between OWL/SWRL and UML/OCL. This means that we have to
provide a two way mappings for either of two rule languages with R2ML. The main
benefit of such an approach is that we can actually map UML/OCL rules into all other
rule languages (e.g., Jess, F-Logic, and Prolog) that have mappings defined with
R2ML. Since various abstract and concrete syntax are used for representing and
sharing all three metamodels (e.g., R2ML XMI, R2ML XML, OWL XML, OCL
XMI, UML XMI, OCL text-based syntax), the implementation is done by using Atlas
Transformation Language (ATL) and by applying the metamodel-driven model
transformation principle.

2 Milanović et al.
4. Transformations
Mapping between OWL/SWRL and R2ML. In a nutshell, this mapping consists of
two transformations. The first one is from OWL/SWRL rules represented in the
OWL/SWRL XML format into the models compliant to the RDM (Rule Definition
Metamodel) [2]. Second, such RDM-based models are transformed into R2ML
models, which are compliant to the R2ML metamodel and this represents the core of
the transformation between the OWL/SWRL and R2ML. The rationale for
introducing one more metamodel, i.e. RDM, is that it represents an abstract syntax of
the SWRL (with OWL) language in the MOF technical space.
Step 1. This step consists of injecting OWL/SWRL rules from the XML technical
space into the MOF technical space. Such a process is shown in detail for R2ML
XML and the R2ML metamodel in.
Step 2. In this step, we transform the XML model obtained in Step 1 into the
RDM-compliant model. This transformation is done by using the ATL transformation
named XML2RDM.atl. The output RDM model conforms to the RDM metamodel.
Step 3. The last step in this
transformation process is the most
important transformation where we
transforming RDM model to R2ML
model (Fig. 1). This means that this
step represents the transformation of
the OWL/SWRL abstract syntax into
the R2ML abstract syntax. In Table
1, we give an excerpt of mappings
between the SWRL XML schema,
XML metamodel, RDM metamodel
and R2ML metamodel.
An additional step is to transform
rules from R2ML into the R2ML
XML concrete syntax, which we have also implemented by using the ATL language.
Table 1. An excerpt of mappings between the OWL/SWRL XML schema, XML metamodel,
RDM metamodel, and the R2ML metamodel
OWL/SWRL XML metamodel RDM metamodel R2ML metamodel
individualPropertyAtom
Element name =
'swrlx:individualPropertyAtom'
Atom
UniversallyQuantified
Formula
OneOf Element name = 'owlx:OneOf' EnumeratedClass Disjunction
var Element name = 'ruleml:var' IndividualVariable ObjectVariable
sameIndividualAtom
Element name =
'swrlx:sameIndividualAtom'
Atom EqualityAtom
maxcardinality
Element name =
'owlx:maxcardinality'
MaxCardinality
Restriction
AtMostQuantifiedFormula
Mapping between UML/OCL and R2ML. Since the R2ML and OCL metamodels
are both located in the MOF technical space and there is an metamodel for OCL
defined in the OCL specification, the transformation by ATL is straightforward in
terms of technological requirements, i.e. we do not have to introduce an additional
metamodel like we have done with RDM.
Fig. 1. The transformation of the models compliant
to the RDM metamodel into the models compliant to
the R2ML metamodel