Database Reference
In-Depth Information
helped to spread the idea and potential of database management from the mainframe-dom-
inated domain of information systems departments to the desktop of the common end user.
The need to share data became apparent as more and more users worked with databases
throughout the late 1980s and early 1990s. The concept of a centrally located database that
could be made available to multiple users seemed a very promising idea. This would cer-
tainly make data management and database security much easier to implement. Database
vendors such as Microsoft and Oracle responded to this need by developing client/server
RDBMS programs.
In a client/server environment, the data resides on a computer acting as a database server,
and users interact with the data through applications residing on their own computers, or
database client. The database developer uses the client/server RDBMS program to create
and maintain the database and attendant end-user application programs. She implements
data integrity and data security on the database server, giving her the ability to base a vari-
ety of user applications on the same set of data without affecting the data's integrity or se-
curity.
Beyond the Relational Model
AlthoughRDBMSshavebeenwidelyacceptedforuseintypicalbusinessapplicationssuch
as inventory control, patient management, banking, order processing, and event schedul-
ing, they proved to be somewhat lacking for such applications as computer-aided design
(CAD), geographic information systems (GIS), and multimedia storage systems. Two new
database models eventually emerged in response to this problem: the
object-oriented
data-
base and the
object-relational
database.
The object-oriented model incorporates all of the characteristics of an object-oriented pro-
gramming language and essentially relegates the relational database to the status of a data
store. The fundamental idea here is that the database developer handles every aspect of
the database, including the sets of operations that manipulate the data in the database from
within the object-oriented database programming software. No longer is there a clear sep-
arationbetweenthedatabasesoftwareandtheapplicationprogrammingsoftware.(Aswith
any other model, there are pros and cons to this approach.) Versant Corporation and IBM
are two vendors that produce object-oriented database software.
Unlike the relational model, which has a solid theoretical basis in two distinct branches of
mathematics, theobject-oriented database modelhasnospecific theoretical foundation.As
such, there is no singular, cohesive consensus as to its definition. There is, however, a ver-
sion of the model defined by the Object Management Group (OMG) that is somewhat of a
de facto standard for object-oriented database management systems.
