A 068 Ozone : Integrating Structured and Semistructured Data ?

Applications have an increasing need to manage semistructured data (such as XML) along with conventional structured data. We extend the structured object database model ODMG and its query language OQL with the ability to handle semistructured data based on the OEM model and Lorel language, and we implement our extensions in a system called Ozone. In our approach, structured data, such as typed objects or relations, may contain entry points to semi-structured data, and vice-versa. The uniied representation and querying of such \hybrid" data is the main contribution of our work. We retain strong typing and access to all properties of structured portions of the data while still allowing untyped access to semistructured portions of the data. Ozone also enhances both ODMG/OQL and OEM/Lorel by virtue of their combination. For example, ordering in ODMG allows Ozone to provide ordering in OEM (enabling correct modeling of XML). Furthermore, untyped OEM semantics can optionally be applied to suspend type-checking on ODMG data, allowing Ozone to support semistructured-style navigation of structured data. Ozone is implemented as a wrapper on top of the ODMG-compliant O 2 database system, and it fully supports our extensions to the ODMG model and OQL.