Database Reference
In-Depth Information
Figure 6-4.
Possible Scenarios for User Interface
It must be emphasized that user interface design and development can and often occur
independent of database design and development. This is one of the potent results of data
independence (review sections 1.2 and 2.9): the user interface applications are immune
to structural and/or physical changes in the database. In fact, as mentioned in section 2.9,
the user interface (which is part of the front-end system) may reside on a different machine
(with a different operating system) from the actual database (which is part of the back-end
system). So in addition to data independence, we can have
platform independence
.
Two prominent protocols that facilitate platform independence between
database and user interface are
open database connectivity
(ODBC) and
Java database
connectivity
(JDBC).
Open Database Connectivity:
ODBC is an open standard
application programming
interface
(API) for accessing a database. A software product that desires to access an
external database must include in its suite, an ODBC driver for that database. The ODBC
driver converts the database objects into a generic format that is understood by the
software. The target DBMS must also support ODBC. This facilitates communication
and transfer of data among heterogeneous databases, irrespective of the platform that
they reside on. Microsoft is a strong proponent of ODBC; in fact, the ODBC software is
typically bundled with the Windows operating system (under Control Panel Ȥ
Administrative Tools). ODBC is also supported by other leading operating systems (Unix,
Linux, Windows, System i, etc.).
Java Database Connectivity:
JDBC is a Sun Microsystems product that allows Java
programs to access heterogeneous databases, irrespective of their platforms. This API is
included in J2SE and J2EE releases. JDBC cooperates with the ODBC protocol; as such, a
program running JDBC can reach ODBC-accessible databases.
ODBC and JDBC may be considered as subsets of the wider set of protocols
described as Common Object Request Broker Architecture (CORBA). CORBA will be
further discussed in chapter 22 (section 22.6). For the purpose of illustration, Figure
6-5
provides a summary of the steps you would take in order to configure an Oracle database
server to be accessed from Delphi 7.0 (or some later version) through ODBC (assuming a
Windows environment).
