17. A method comprising: receiving an object data document and an operation to perform on the object data document from an application program; determining a class in a referential integrity metadata framework for the object data document, the referential integrity metadata framework specifying at least an identifying attribute and a relationship attribute from the object data document for the class; and calling a class-specific stored procedure based on the class, the class-specific stored procedure being configured to: extract a first value for the identifying attribute from the object data document, extract a second value for the relationship attribute from the object data document, build a data manipulation language statement using the first value and the second value that performs the operation on a table in a relational database system, the table corresponding to the class in the referential integrity metadata framework and including a column for the identifying attribute, a column for the relationship attribute, and a column that stores the object data document, and issue the data manipulation language statement for the relational database system to execute, the relational database system enforcing referential integrity constraints based on the relationship attribute.
17. A method comprising: receiving an object data document and an operation to perform on the object data document from an application program; determining a class in a referential integrity metadata framework for the object data document, the referential integrity metadata framework specifying at least an identifying attribute and a relationship attribute from the object data document for the class; and calling a class-specific stored procedure based on the class, the class-specific stored procedure being configured to: extract a first value for the identifying attribute from the object data document, extract a second value for the relationship attribute from the object data document, build a data manipulation language statement using the first value and the second value that performs the operation on a table in a relational database system, the table corresponding to the class in the referential integrity metadata framework and including a column for the identifying attribute, a column for the relationship attribute, and a column that stores the object data document, and issue the data manipulation language statement for the relational database system to execute, the relational database system enforcing referential integrity constraints based on the relationship attribute. 18. The method of claim 17 , wherein the class-specific stored procedure is generated by an initialization module, the initialization module being configured to: use the referential integrity metadata framework to automatically create the table in the relational database system, the table including a column for the identifying attribute, a column for the relationship attribute, and a column for the object data document; and use the referential integrity metadata framework to automatically create referential integrity structures for the table in the relational database system.