ABSTRACT

Metadata is a term that has been defined rather loosely. It originates from data management. Initially it was called the data dictionary or the catalog that described the data in the databases [DATE90]. As discussed in Chapter 2, in a relational database the data dictionary will have information about the relations and their attributes. Soon data diction­ aries included other information such as access control rules, integrity constraints, and information about data distribution. Subsequently, this information came to be known as metadata. With data warehousing, multimedia, and web information management, the definition of metadata started expanding. Finally, with integration of heterogeneous databases, applications, and systems, metadata is now used synony­ mously with repository technology.