In more detail, such a migration process consists of three
steps which are (1) the schema migration process which
maps a relational schema to an equivalent1 object oriented
schema, (2) the data migration process which converts
extensions of the relational schema to equivalent2 extensions
of the object oriented schema and (3) the application
migration process which creates a new application program
using the object oriented database for every application program
that uses the legacy database such that the input/output
behaviours of the corresponding application programs
are identical for equivalent database extensions