Topology Data Model

Topology involves the mathematical study of spatial relationships. It describes characteristics of a geometric figure that do not change under continuous transformation. In a graph, the number of edges, nodes and faces, and their relationship to each other are constant, even if their features are stretched or distorted. In geospatial applications, topology is the means to describe, manage, and retrieve these relationships explicitly without resorting to time-consuming spatial comparisons.

The Oracle documentation provides details on Oracle's implementation of topology. See http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14256/sdo_topo_concepts.htm#sthref20.

There are two types of topology in Bentley products:

Session topology in the topology information is built on-the-fly each time as necessary, like in MicroStation GeoGraphics 8.5.
Persistent topology in which topological primitives are created only once. Topological primitive (node, edge, face) information is in the DGN.

These modes are supported with or without Oracle. When working with Oracle Spatial topology, Bentley persistent topology is created and maintained in Bentley Map.

Oracle topology can be versioned in Oracle, but only the pessimistic locking mode can be used to edit data. Oracle does not support optimistic locking in this release.

Oracle supports hierarchical topology models where top features are composed of other features, but this is not yet supported in Bentley.

Oracle currently does not support 3D topology so neither does Bentley.

Oracle valid time support is not supported by Oracle topology in the current version, so only history mode is supported.

Oracle Patches needed for using topology:

For 10.2.0.3 on Windows - PATCH 6215383 and 6430380
For 10.2.0.3 on platforms other than Windows - generic patch, PATCH 6330165. The topology patch does not need to be applied for 10.2.0.4.
For 10.2.0.3 - Patch 6415621 - WORKSPACE MANAGER RELEASE 10.2.0.4.2 PATCHSET. This WM patch does not need to be applied for 10.2.0.4.