Strictly speaking, meta-data is data about data. That is, a way to describe data (specify its semantics, relationships with other data, and so on).
Archipelago uses 3 types of metadata :
- the database schema, that describes the structure of some existing database and the way it can be accessed.
- that meta model, that describes the structure of the data the user wants to handle. That is, the structure of the view through which concrete data are to be viewed.
- the database mapping, that describes the mapping between the 2.
The reference implementation of the Archipelago project will provide :
- databases schemas for several known databases
- a sample meta-model
- mappings from those known databases to this meta model