Abstract:
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The BLOOM (BarceLona Object Oriented Model) data model was developed
to be the Canonical Data Model (CDM) of a Federated Database Management
System prototype. Its design satisfies the features that a data model
should have to be suitable as a CDM. The initial version of the model (BLOOM91)
has evolved into the present version, BLOOM99.
This report specifies the syntax of the schema definition language
of BLOOM99. In our model, a schema is a set of classes, related through two
dimensions: the generalization/specialization dimension, and the
aggregation/decomposition dimension. BLOOM supports several features in
each of these dimensions, through their corresponding metaclasses.
Even if users are supposed to define and modify schemas in an
interactive way, using a Graphical User Interface, a linear
schema definition language is clearly needed.
Syntax diagrams are used in this report to specify the language;
an alternative using grammar productions appears as Appendix
A. A possible graphical notation is given in Appendix B.
A comprehensive running example illustrates the model,
the language and its syntax, and the graphical notation. |