The Topology Map in OpenNMS has some architectural problems. Mainly that there is no "service layer" implemented, which causes mostly performance issues. Besides this no API or persistence model is enforced. This prevents easy integration with 3rd party applications or even provide a new UI implementation. Therefore I started playing around with a new Topology implementation (See issue HZN-1452) for more details). In order to not confuse it with existing implementations, it is called Graph Service or Graph Engine here.