Producing interoperable queries for relational and object-oriented databases

In this paper, we develop techniques to produce interoperable queries with object and relational databases. A user poses a local query in a local quer y language, against a local object or relational schema. We transparently p roduce appropriate queries with respect to a remote target object or relati onal schema, corresponding to some remote database which contains data rele vant to the user's query. Mapping knowledge to resolve representational het erogeneities in local and remote schemas is expressed in a canonical repres entation, CRmapping, and is independent of the particular data model. A can onical representation CRquery is also used to resolve heterogeneities of qu ery languages. A set of heterogeneous transformation algorithms define the appropriate transformations from the local queries to the remote queries. T he use of canonical representations (CR) allows us to represent queries ind ependent of the particular query language, and to resolve representational conflicts in a uniform manner, independent of models and query languages.