Coupled schema transformation and data conversion for XML and SQL

• Author(s): Berdaguer, Pablo ; Cunha, Alcino ; Pacheco, Hugo ; Visser, J.
• Date: 2007
• Persistent ID: http://hdl.handle.net/1822/6621
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Haskell; Transformation; SQL; XML
• 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. We have implemented a system for performing two-level transformations on XML schemas and their corresponding documents, and on SQL schemas and the databases that they describe. The core of the system consists of a combinator library for composing type-changing rewrite rules that preserve structural information and referential constraints. We discuss the implementation of the system’s core library, and of its SQL and XML front-ends in the functional language Haskell. We show how the system can be used to tackle various two-level transformation scenarios, such as XML schema evolution coupled with document migration, and hierarchical-relational data mappings that convert between XML documents and SQL databases.