On Integrating Data in the Internet Era
With the development of networking infrastructures came the need to exchange digital information across distributed organizations. While various efforts focused on standardizing the computer-to-computer exchange of structured messages, e.g. in the context of the Electronic Data Interchange EDI format,
(1) others tackled the difficult problem of relat-
ing heterogeneous data sources designed independently. Data integration aims at combining data residing at heterogeneous sources and providing the user with a unified view over those data.