Supporting Structural Evolution of Data in Web-Based Systems via Schema Versioning in the tauXSchema Framework

tauXSchema is a framework for creating and validating temporal XML documents, while using a temporal schema that consists of three components: a conventional XML Schema document annotated with a set of temporal logical and physical annotations. Each one of these components can evolve over time to reflect changes in the real-world. Besides, schema versioning has been long advocated to be the most efficient way to keep track of both data and schema evolution. Hence, in this chapter the authors complete tauXSchema, which is predisposed from the origin to support schema versioning, by defining the operations that are necessary to exploit such a feature and make schema versioning functionalities available to end users. Precisely, the authors’ approach provides a complete and sound set of change primitives and a set of high-level change operations, for the maintenance of each component of a tauXSchema schema, and defines their operational semantics. Furthermore, they propose a new technique for schema versioning in tauXSchema, allowing a complete, integrated and safe management of schema changes.