From Sustainable Information System with a Farandole of Models to Services - Intentional Perspectives on Information Systems Engineering - page 7

of integrity rules defined on a same class is another integrity rule defined on this
class. Hyper-role is a combination of several roles, which can be assumed by a same
person at the same time. Hyper-event is a combination of several events, which can
occur at the same time.
Since all conceptual models have to be implemented, they must be written by
means of a conceptual meta-model, which is interoperable with the informatics
meta-model. In the IS infancy, the most appropriate informatics for IS was the
database management system, and therefore, most of the concepts of the concep-
tual world were extracted of concepts of informatics and stripped of their technical
aspects.
3.2 Overlap Between the IS Conceptual World
and the IS Informatics World
As mentioned before, the stakes of the conceptual world and the informatics world
are not the same: the first ones are centred on the concept of information when the
second ones are focused around performance, reliability, distribution, concurrency,
etc. Obviously, these worlds share concepts and, therefore, their interoperability can
be assured. But, they use them in different contexts [ 31] . For instance, a class is
used at the conceptual level to represent information when, at the informatics level,
it is used to store data with a homogeneous internal schema. Thus, a class at the
conceptual level can be decomposed into several classes at the informatics level in
order to improve performance, to assure security, to distribute its objects on several
internal layers.
The classic position is to consider that the conceptual meta-models must obey
the informatics meta-model. Even if this way of thinking has its part of relevance, it
becomes dogmatic if it argues that this is the only way of thinking. Another way of
thinking is to consider that the IS domain discovers new generic situations, which
have to be taken into account by systems. More generally, the creators of systems,
which are used to develop IS, must take care of the generic situations, which IS
developers face to, and these situations are described in the conceptual meta-model.
Let us consider some examples. At the time of the relational DBMS, the creators
of DBMS were interested only by the attributes of classes (named relations or tables
at this time). However, for some IS pioneers, it was obvious that the determina-
tion of methods obeys the same rules as the determination of attributes. And then
they discover that an important part of the IS dynamics can be described with these
methods and events (e.g. method Remora [ 8, 29] ). After some years, the object-
oriented approach “discovered” this relevant property and developed object-oriented
systems. Another example concerns the concept of specialization . This concept is
well known in several sciences such as botany for example. In the IS domain, the
static specialization defined as in botany - an object takes a permanent place in a
specialization hierarchy - is a particular case of the utility of specialization in the IS
domain, because the object can move in the specialization hierarchy: a person can
become a student and, after, can be no more a student. The dynamic specialization