Connectivity

Databases
Overview | ODBC | IDAPI | ODBA

Overview

The ability of a database to connect to other applications is a key feature of data independence.

Several ways to connect exist

Open Database Connectivity (ODBC)

Developed by Microsoft, ODBC enables an application to issue a request to retrieve or modify data, using SQL (Standard Query Language) to a wide variety of databases.

ODBC works in a similar way to Printer drivers in Windows.

The Application issues a request, say to retrieve a customers telephone number.
SELECT phone FROM customer_table FOR customer = "110123"

This request is passed to the Driver Manager (ODBC.DLL), It is a specific program provided by Microsoft and acts as an intermediary, routeing requests for data from the application to a specific driver. It doesn't alter the request in any way, though it does perform some limited checking.

The driver does all the processing related to the specific database. It interprets the requests from applications, and either interprets them itself or passes it onto the database engine. It does the basic nuts and bolts of the particular database, which it is supporting.

Finally the "data source" is accessed. This may be;

A full Data Base Management system (DBMS) running on a database server, such as, Oracle or SQL Server.
A gateway providing access to one or more DBMSs
A collection of datafiles, such as dBase or Paradox tables, stored on a network drive or local hard disk
Data contained in an application, such as an MS-Excel Spreadsheet.

SQL was developed by IBM around 1975

Independent Database Application Programming Interface (IDAPI)

The main rival to ODBC is Independent Database Application Programming Interface (IDAPI) under development by IBM, Borland, Novell. As at Apr 1994, no software development kits had been issued, and no drivers were available.

[Ref 50]Windows User Apr 94

Online database access (ODBA)

The process where people can access a wide variety of in-house or external databases from their browsers.

Strengths:

Most relational database vendors are

Web-enabling their databases (eg. Progress - Webspeed).

Developing API's (application programming interfaces)

Developing "browser plug-ins" enabling users to tap into various data formats using object-oriented technology (eg. Informix - datablades)

Functions across the Internet, Intranet or virtual private network.

Weakness

Still labour intensive particularly management issues (security, maintenance, access and expense of keeping the database).
Many organsations still do not have a co-ordinated database strategy.

Opportunities

Better use of database investment on TCP/IP-based networks. (Costs mostly in development since hardware/software mostly in place).
Object orientation allows disparate database to be integrated.

Threats

Giving users access to an overwhelming amount of information.
Wrong people accessing the wrong data.

(Parent,P 1997, Mar 24)