8. A non-transitory computer-readable medium storing program code, the program code comprising: code to call a constructor to register an interface to a description of a persistent class; code to access the registered interface to determine an internal structure of the persistent class; code to process an instance of the persistent class based on the determined internal structure, wherein the instance of the persistent class is a persistent database object; code to determine, based on the determined internal structure, members of the persistent database object that are filled with default values; code to store the persistent database object in a database; and code to reduce storage demands on the database by removing the default values from the persistent database object before the storing of the persistent database object in the database; code to read the persistent database object from the database after the storing of the persistent database object in the database; and code to, after the reading of the persistent database object from the database, populate the determined members of the persistent database object with the default values of the persistent database object that were removed from the persistent database object before the storing of the persistent database object to reduce storage demands on the database.
8. A non-transitory computer-readable medium storing program code, the program code comprising: code to call a constructor to register an interface to a description of a persistent class; code to access the registered interface to determine an internal structure of the persistent class; code to process an instance of the persistent class based on the determined internal structure, wherein the instance of the persistent class is a persistent database object; code to determine, based on the determined internal structure, members of the persistent database object that are filled with default values; code to store the persistent database object in a database; and code to reduce storage demands on the database by removing the default values from the persistent database object before the storing of the persistent database object in the database; code to read the persistent database object from the database after the storing of the persistent database object in the database; and code to, after the reading of the persistent database object from the database, populate the determined members of the persistent database object with the default values of the persistent database object that were removed from the persistent database object before the storing of the persistent database object to reduce storage demands on the database. 12. The medium according to claim 8 , the program code further comprising: code to verify referential integrity of the instance.