Schema Change Operations for Full Support of Schema Versioning in the tauXSchema Framework

tauXSchema (Currim et al., 2004) is a framework (a language and a suite of tools) for the creation and validation of time-varying XML documents. A tauXSchema schema is composed of a conventional XML Schema annotated with physical and logical annotations. All components of a tauXSchema schema can evolve over time to reflect changes in the real-world. Since many applications need to keep track of both data and schema evolution, schema versioning has been long advocated to be the best solution to do this. In this paper, we propose an approach for schema versioning in the tauXSchema framework, allowing a complete and safe management of schema changes. It supports both versioning of conventional schema and versioning of annotations, in an integrated manner. For each component of a tauXSchema schema, our approach provides a complete set of low-level change primitives for the maintenance of such a component and defines their operational semantics.