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Relational Databases and the World Wide Web:
Automatic Generation of Hypertext based on
Reverse-engineered Meta Information
Richard Pönighaus, Johann Mitlöhner
Vienna University of Economics/Department of Applied Computer Science
A-1090 Augasse 2--6, Vienna, Austria
Email: poenigh@wu-wien.ac.at, mitloehn@wu-wien.ac.at
Abstract: In this work we describe an approach to the generation of HTML code based on meta information contained
in typical relational database systems. In principle reverse engineering methods can automatically produce web pages
from any database without the need for additional user input. Additional information can be supplied in order to
improve the structure of the resulting web pages. We successfully applied our approach to several databases from
different domains; in this paper, we use a database on classical records and its corresponding meta model to illustrate the
method and point out problems which arise in automatic code generation from databases.
1 Motivation
With the ever-growing popularity of the World Wide Web people become used to exploring data in new ways.
Navigating through hypertexts is becoming more and more common for users in diverse domains of application. The
presentation of data in HTML format allows for plattform-independence and easy access for non-technical users.
Recently there has been growing reserach interest in meta-data [Metadata 1996] in diverse areas. Relational databases
are capable of storing data in a highly structured way; when attempting to generate hypertexts from database records, the
system catalog of the database can provide information on relationships between database tables on the meta-level. On
the instance-level this allows for automatic creation of hypertext links between documents.
Among other things, database systems offer the advantage of being able to store large amounts of data in a consistent
way. Today, many database applications exist in a variety of application domains. Several reasons exist for making data
stored in these applications accessible via the web:
Non-technical users typically only have restricted or no access to RDBMS (Relational Database Management
System) data, since the interface provided often requires database knowledge the average user does not have.
Therefore, making available the huge amounts of data which exist in database applications in a way all users can
instantly grasp offers large benefits to organizations. By simplifying the access to the data users who lack skill or
time to use databases directly can still apply information systems in their work.
Generating hypertext from different RDBMS allows for a unified view of information: material from diverse
database systems can be combined into a single hypertext, eliminating the need for users to switch between
systems when accessing data.
Hypertext generated from database systems which do not support multiple users can be placed on web servers
and then be viewed by many users at once, resulting in effectively turning the application into multi-user mode
(at least for browsing).
Those points are valid not only for Intranets (within an organization), but also for Internet users distributed all over the
world. In the next sections we demonstrate the process of automatic hypertext generation by using the example of a
database of classical records.
2 The Music Database
In our model a piece of music is composed by exactly one composer. Several artists may take part in the recording of a
piece, optionally performing in a role specific to the piece (such as singers in opera). The record may be of a part of the