12. The article of manufacture of claim 11 wherein the database mapping language construct comprises: a keyword indicating a beginning of the database mapping language construct; a datastore type; a datastore name; and a keyword indicating an end of the database mapping language construct, wherein the class mapping language construct comprises: a keyword indicating a beginning of the class mapping language construct; a class name; a join condition; an attribute; and a keyword indicating an end of the class mapping language construct, and wherein the reference mapping language construct comprises: a keyword indicating a beginning of the reference mapping language construct; a reference name; a cardinality; a to table name and column name, and a from table name and column name; and a keyword indicating an end of the reference mapping language construct.
11. An article of manufacture for use in a computer system for mapping objects to a data store and for mapping the data store to the objects, said article of manufacture comprising a computer-readable storage medium having a computer program embodied in said medium which causes the computer system to: store in the computer system a schema mapping definition language construct; store in the computer system a database mapping language construct; store in the computer system a class mapping language construct; and store in the computer system a reference mapping language construct.