ToMAS: A system for adapting mappings while schemas evolve

The use of Toronto mapping adaptation system (ToMas) for automatically detecting and adapting invalid mappings was discussed. It detect mappings that were affected by a schema constraint change and generates rewritings that were guaranteed to conform to the modified schema structure and constraints. It exploits the user choices embodied in the existing mappings to generate the right rewritings. The supported changes were not restricted to atomic type schema elements but could be applied to more complex schema structures.