%0 Book Section
%B FM 2006: Formal Methods
%D 2006
%T Type-safe two-level data transformation
%A Alcino Cunha
%A José Nuno Oliveira
%A Joost Visser
%C Hamilton, Ontario, Canada
%I Springer-Verlag
%P 284-299
%R 10.1007/11813040_20
%S LNCS
%U http://link.springer.com/chapter/10.1007%2F11813040_20
%V 4085
%X <p>A two-level data transformation consists of a type-level transformation of a data format coupled with value-level transformations of data instances corresponding to that format. Examples of two-level data transformations include XML schema evolution coupled with document migration, and data mappings used for interoperability and persistence.<br /> We provide a formal treatment of two-level data transformations that is type-safe in the sense that the well-formedness of the value-level transformations with respect to the type-level transformation is guarded by a strong type system. We rely on various techniques for generic functional programming to implement the formalization in Haskell.<br /> The formalization addresses various two-level transformation scenarios, covering fully automated as well as user-driven transformations, and allowing transformations that are information-preserving or not. In each case, two-level transformations are disciplined by one-step transformation rules and type-level transformations induce value-level transformations. We demonstrate an example hierarchical-relational mapping and subsequent migration of relational data induced by hierarchical format evolution.</p>
%8 Aug.