Type-safe two-level data transformation

• Author(s): Cunha, Alcino ; Oliveira, José Nuno Fonseca ; Visser, J.
• Date: 2006
• Persistent ID: http://hdl.handle.net/1822/5618
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Two-level transformation; Program calculation; Refinement calculus; Strategic term rewriting; Generalized abstract datatypes; Generic programming; Coupled transformation; Format evolution; Data mappings
• Document Type: Conference Object
• Language: English

Description

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. 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. 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.