8. An article of manufacture comprising a storage device storing executable code, the executable code executed by a processor to perform a method for defining a metadata schema to facilitate passing data between an eXtensible Markup Language (XML) document and a hierarchical database, the method comprising: accessing a database schema indicative of database field names and a hierarchical structure for a hierarchical database; accessing a document schema that defines the hierarchical structure, content data syntax, and semantics of valid, well-formed, XML documents that can be passed into and out of the hierarchical database, the document schema comprising an XML element name that maps to a database field name in the database schema, the document schema comprising at least one directive metadata element not interfering with third-party applications using the document schema and facilitating passing data between the XML document and the hierarchical database; and relating the database schema and the document schema to provide a metadata schema that enables data to be passed between an XML document and the hierarchical database.
12. The article of manufacture of claim 8 , wherein the database schema comprises a database field type identifier and the document schema comprises an XML element data type identifier that maps to the database field type identifier to facilitate converting content data between the XML element data type and the database field type based on the database field type identifier and the XML element data type identifier.