Solving the Problem of Semantic Heterogeneity in Defining Mediator Update Translators

Mediator is a facility that supports an integrated view over multiple information sources, and allows for queries to be made against the integrated view. In this paper, we extend the mediator architecture to support updates against the integrated view. Updates expressed against the mediator's integrated view need to be translated into updates of the underlying local databases. We developed algorithms to generate translators for the basic types of mediator update operations. The novel aspects of our algorithms are that the translators are generated based on the correspondence assertions that formally specify the relationships between the mediator schema and the local databases schemas. Our formalism allows us to identify, precisely, the situations where the ambiguities can be solved at mediator definition time and the criteria for choosing the most appropriate translator. In this paper, we show that, by using our formalism, it is possible to define rigorously the correct translation for mediator update operations for cases where concepts in the mediator schema are represented differently in the local databases schemas.