Databases Reference
In-Depth Information
For our purposes, the main problem with that kind of definition is that
it does not give a clear characterization of ISs. The wider system of which an
IS is part may require means that are not ISs to achieve its objectives. Fur-
thermore, other things can provide the same type of contribution, without
being an IS. For example, there are various ways to facilitate communication
among users, including working physically close to each other or participat-
ing in meetings.
Even if it is difficult to define ISs in terms of the contribution they pro-
vide, it is important to realize that this perspective is essential during their
development. The requirements of an IS are determined from the objectives
of the organization for which the system is designed and built.
From the second perspective, definitions emphasize the structure and
the behavior of the physical and abstract elements that make up an IS. Both
structure and behavior can be characterized at different levels of detail.
For the purposes of conceptual modeling, the most useful definitions
are those based on the functions performed by ISs, that is, definitions that
emphasize what ISs do, abstracting from why and how they do it.
Within this third perspective, the classical definition says that an IS is
a system that collects, stores, processes, and distributes information. That
definition is commonly accepted for both its simplicity and its generality.
However, some comments may be in order to make it more precise.
First, in IS engineering, we should restrict the definition to designed
systems, that is, systems an engineer designs and builds [2]. The restriction is
needed because natural systems that perform information-processing func-
tions are beyond the scope of our study. For example, in cognitive science the
human mind is viewed as a complex system that receives, stores, processes,
and distributes information.
Second, the definition is too general with respect to the kind of infor-
mation an IS may deal with. In fact, the definition poses no constraint on the
kind of information, with the result that it encompasses systems that many
people would not consider ISs. For example, a fax could be considered an IS
according to that definition, because it can be seen as a system that receives
documents (which contain data representing some information), stores them
(even if only for a short time), translates them (i.e., changes the representa-
tion of the information), and sends the result through the phone.
The usual constraint on the kind of information handled by an IS is
that it must be about the state of some domain (also called object system
or universe of discourse). The nature of this domain is irrelevant to the defi-
nition of IS. For many systems, its domain is an organization, but the
