NeT and CoT: inferring XML schemas from relational world

Abstract

Two conversion algorithms, called NeT and COT, to translate relational schemas to XML schemas using various semantic constraints are presented. We first present a language-independent formalism named XSchema so that our algorithms are able to generate output schema in various XML schema language proposals. The benefits of such a formalism are that it is both precise and concise. Based on the XSchema formalism, our proposed algorithms have the following characteristics: (1) NeT derives a nested structure from a flat relational model by repeatedly applying the nest operator so that the resulting XML schema becomes hierarchical, and (2) COT considers not only the structure of relational schemas, but also inclusion dependencies during the translation so that relational schemas where multiple tables are interconnected through inclusion dependencies can also be handled.