Information Technology Reference
In-Depth Information
Object-Relational Database Management Systems
An
object-oriented database
uses the same overall approach of objected-oriented program-
ming that was discussed in Chapter 4. With this approach, both the data and the processing
instructions are stored in the database. For example, an object-oriented database could store
monthly expenses and the instructions needed to compute a monthly budget from those
expenses. A traditional DBMS might only store the monthly expenses. The King County
Metro Transit system in the state of Washington uses an object-oriented database in a system
supplied by German vendor Init to manage the routing and accounting of its bus line.
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Object-oriented databases are useful when a database contains complex data that needs to be
processed quickly and efficiently.
In an object-oriented database, a
method
is a procedure or action. A sales tax method, for
example, could be the procedure to compute the appropriate sales tax for an order or sale—
for example, multiplying the total amount of an order by five percent, if that is the local sales
tax. A
message
is a request to execute or run a method. For example, a sales clerk could issue
a message to the object-oriented database to compute sales tax for a new order. Many object-
oriented databases have their own query language, called
object query language (OQL)
, which
is similar to SQL, discussed previously.
An object-oriented database uses an
object-oriented database management system
(OODBMS)
to provide a user interface and connections to other programs. Computer ven-
dors who sell or lease OODBMSs include Versant and Objectivity. Many organizations are
selecting object-oriented databases for their processing power. Versant's OODBMS, for ex-
ample, is being used by companies in the telecommunications, defense, online gaming, and
healthcare industries, and by government agencies. The
Object Data Standard
is a design
standard created by the
Object Database Management Group
(www.odmg.org)
for developing
object-oriented database systems.
An
object-relational database management system (ORDBMS)
provides a complete set
of relational database capabilities plus the ability for third parties to add new data types and
operations to the database. These new data types can be audio, images, unstructured text,
spatial, or time series data that require new indexing, optimization, and retrieval features.
Each of the vendors offering ORDBMS facilities provides a set of application programming
interfaces to allow users to attach external data definitions and methods associated with those
definitions to the database system. They are essentially offering a standard socket into which
users can plug special instructions. DataBlades, Cartridges, and Extenders are the names
applied by Oracle and IBM to describe the plug-ins to their respective products. Other plug-
ins serve as interfaces to Web servers.
object-oriented database
A database that stores both data and
its processing instructions.
object-oriented database
management system
(OODBMS)
A group of programs that manipu-
late an object-oriented database
and provide a user interface and
connections to other application
programs.
object-relational database
management system
(ORDBMS)
A DBMS capable of manipulating
audio, video, and graphical data.
Visual, Audio, and Other Database Systems
In addition to raw data, organizations are increasingly finding a need to store large amounts
of visual and audio signals in an organized fashion. Credit card companies, for example, enter
pictures of charge slips into an image database using a scanner. The images can be stored in
the database and later sorted by customer name, printed, and sent to customers along with
their monthly statements. Image databases are also used by physicians to store x-rays and
transmit them to clinics away from the main hospital. Financial services, insurance compa-
nies, and government branches are using image databases to store vital records and replace
paper documents. Drug companies often need to analyze many visual images from labora-
tories. Chesapeake Energy maintains a database filled with scanned images of terrain and
special-purpose database systems. Many relational databases can also store graphic content.
Combining and analyzing data from different databases is an increasingly important
challenge. Global businesses, for example, sometimes need to analyze sales and accounting
data stored around the world in different database systems. Companies such as IBM are
developing
virtual database systems
to allow different databases to work together as a unified
database system. Banc of America Securities Prime Brokerage, for example, turned to database
virtualization to address management and performance problems. Since its implementation,
