OntologyConnector is a base class which provides abstract methods to connect with the external ontology systems. Its sub classes implements the abstract methods specific for a particular ontology system.
The queries made to the external systems via OntologyConnector is as:
u1 subClassOf u2
u1 partOf u2
u2 hasPart u1
The OntologyConnector class also maintains a cache for all the inference computations queries made to the external ontology systems for the future use to search locally for before sending requests to the external ontology systems.
If the OntologyConnector specialize class fails to report the inference computations result made to the external ontology systems, then, the ontology connector assumes that the assertion query such as (Left thumb partOf Left hand) is false, and store the false assertion in the cache.
In such case where the specialize fails to get results from the external systems then the ontology connector should not store those queries in the cache.