A Study of Conventional Schema Versioning in the τXSchema Framework

Schema versioning is an indispensable feature for applications using temporal databases and requiring an entire history of data and schema. τXSchema [6] is an infrastructure for constructing and validating temporal XML documents; but any explicit support for XML schema versioning is offered. A τXSchema schema is composed of a conventional XML Schema document annotated with physical and logical annotations. All components of a τXSchema schema (i.e., conventional schema, logical annotations, and physical annotations) can change over time to reflect changes in user requirements or in reference world of the database. In a previous work [9], we deal with versioning of logical and physical annotations. In this work, we study τXSchema conventional schema versioning: we propose a complete set of low-level primitives for changing such a schema and define their operational semantics.