Databases Reference
In-Depth Information
definition does not exclude other, different domains, such as a vehicle, the
atmosphere, or a chess game. According to that definition, a fax machine is
not an IS. A fax does not consider the documents it sends as information
about the state of some domain. To a fax, documents are just uninter-
preted data.
Thus, we define an IS as a designed system that collects, stores,
processes, and distributes information about the state of a domain. It is easy
to agree on those functions, but the problem is that they are too general and
are not related to the purpose for which the IS exists. For those reasons, many
authors prefer a more specific definition of the functions, one that captures
more neatly the nature of ISs.
To that end, it is considered that an IS has three main functions
(Figure 2.1) [3]:
1.
Memory function, to maintain a representation of the state of a
domain;
2.
Informative function, to provide information about the state of a
domain;
3.
Active function, to perform actions that change the state of a
domain.
Domain
Action
Represents
Changes
Query
Information
system
Answer
Figure 2.1
The functions of an IS.
