Data and Metadata Management

In this chapter we illustrate fundamental notions of Data Management. We start from the basic concepts of database schema and instance, illustrating how they are handled within dictionaries in relational databases. We then address, from a general point of view, the notion of data model as a means for the representation of information at different levels of details, and show how dictionaries can be used to manage schemas of different data models. A further level of abstraction, called metamodel, is then introduced with the aim of supporting the interoperability between model based applications. Finally, we discuss a methodology for schema translation that makes use of the metamodel as an intermediate level.