Slide 26 of 52
Notes:
In migrating from a relational application to OO, the semantics of the applications using the data becomes merged with the object structures.
In migrating from an OO application to relational, applications to access and manage the database would be separated from the data. An issue which will be partially addressed by SQL3 is the difficulty of converting a class hierarchy or lattice into flat tables. Not all forms of direct object relationships will be supported by SQL3 (e.g., circular relationships).
Some commercial ODBMSs and nearly all OO GIS products support direct interfaces to commercial RDBMS, so that OO applications can use the RDBMS as part or all of the repository. The emerging Open GIS standards (to be discussed shortly) are focussed on allowing any compliant GIS to work with geo-spatial data held in either RDBMS or ODBMS.
