![](bg3.png)
logic. Obligation formulates that the proposition is
true in all acceptable worlds. Permission formulates
that the proposition is true in some acceptable world.
Structural rules can be expressed using alethic
logic. Necessity formulates that the proposition is
true in all possible worlds. Possibility formulates
that the proposition is true in some possible world.
2.2 Design
Three main design approaches have been
distinguished: object-oriented approaches, fact-
oriented approaches and ontologies.
The object-oriented approach is the most
traditional approach and the most widely used of the
three. The most often used object-oriented modelling
language is UML complemented by OCL for
modelling constraints.
The fact-oriented approach considers the real
world as objects playing roles in events. The ORM
language illustrates this approach.
The ontology approach is illustrated by the
ontology languages from the W3C consortium: RDF
(Resource Description Framework), RDFS (RDF
Schema) and OWL (Web Ontology Language).
2.2.1 Object-Oriented Approach
Nowadays, it is undoubtedly the most widely used
design approach and is illustrated by the UML
standard.
UML allows structural and behavioral design of
Information Systems. UML is extended by OCL that
is a declarative language for expressing constraints.
This is a deliberately simple access language and has
an elementary grammar based on predicate logic and
set theory. It can be interpreted by tools.
2.2.2 Fact-Oriented Approach
The second approach considered is the approach
based on the facts and illustrated by the ORM
solution. ORM is a logical modelling method based
on the facts. It is so called because it sees the world
in terms of objects that play roles. This approach has
been proposed to counter the lack of extensibility of
the object-oriented modelling approach.
There are therefore no more notions of classes
and attributes. This approach relies on a graphical
notation that is complemented with textual
formulations. The graphical notation for modelling
data allows a visual representation variety of
constraints.
ORM has been specially designed to provide
models that can be validated, which are semantically
stable, expressive and orthogonal. To do this, ORM
is based on two principles: the principle of
validation and the principle of semantic stability.
The principle of validation is to ensure that the
models provided should facilitate validation by
domain experts. This is achieved via the principles
of population and verbalization. The principle of
population specifies that all structures must be easily
filled with concrete examples. The principle of
verbalization states that all aspects of the model can
be verbalized in a language that is understandable by
business experts.
The principle of semantic stability requires that
the representation of a fact in the model should not
be affected unless the meaning of the fact has been
changed. This requires avoiding structures based on
attributes and offers extensibility.
2.2.3 Ontology-based Approach
The third approach considered is that based on
ontologies. In computer science, an ontology is a
structured set of terms and concepts representing the
meaning of an information field, either by metadata
namespace or by the elements of a knowledge
domain.
The ontology is itself a model representative of a
set of data concepts in a domain and the
relationships between these concepts. It is used to
reason about the objects in the field. The primary
purpose of an ontology is to represent a body of
knowledge in a given field. Ontologies are closely
related to the Semantic Web.
RDF (Resource Description Framework) is a data
model for the description of objects (resources)
and relations between them. It provides for the
concept of semantic data model. Data models can
be represented in XML syntax.
RDFS (RDF Schema) provides a vocabulary for
describing properties and classes of RDF
resources, and semantics for generalization of
properties and classes.
OWL (Web Ontology Language) adds more
capabilities to describe properties and classes:
relations between classes (e.g. disjunction),
cardinality (e.g. "only one"), equality, properties
and characteristics (e.g. symmetry).
2.2.4 Discussion
Table 1 synthesizes and compares the three
approaches to designing business rules together.
Thus, the three approaches can express the
SBVR vocabulary and business rules. But only the
MODELSWARD2014-InternationalConferenceonModel-DrivenEngineeringandSoftwareDevelopment
350