When integrating information systems (especially when integrating legacy systems into the infrastructure of a next generation information system), one approach which is taken is to publish the relevant interfaces of the legacy system as Web Services to be used by the new system. This is often a performance bottleneck – it can be sufficient for accessing single data records or a small set of data records, but it might not be a proper solution when a large number of records or even structures in the legacy system need to be accessed from the new system. In these cases, it might be better to look for a solution on a lower level, ideally on the database level. The Oracle database provides the possibility to create database links for such purposes.

Lets see how to create and use such database links.