A Knowledge-Based Approach to overcome Structural Differences in Object Oriented Database Integration

Database integration comprises all activities to provide integrated access to autonomous databases. One of its most important tasks is to overcome representation anomalies which occur between independently created systems. Due to different perceptions of the reality even data-model-homogeneous schemes disagree on names, scales and logical database structures.

This paper discusses the resolution of structural differences in the framework of object-oriented systems. Two main concepts are introduced: message forwarding and context coloring. Message forwarding comes in if some object can not answer a message by itself because of structural differences. In order to find an answer the object forwards the message to semantically related objects which can handle the message. The plan how the message is to be forwarded at the instance level is developed and specified at the class level. Context coloring is used to remember with an object the environment through which it has been retrieved. Then an object which is returned by a forwarded message can reflect in its subsequent behavior the environment(s) which the message has passed.