Semantic Data Modeling Using XML Schemas

Most research on XML has so far largely neglected the data modeling aspects of XML schemas. In this paper, we attempt to make a systematic approach to data modeling capabilities of XML schemas. We first formalize a core set of features among a dozen competing XML schema language proposals and introduce a new notion of XGrammar. The benefits of such formal description is that it is both concise and precise. We then compare the features of XGrammar with those of the Entity-Relationship (ER) model. We especially focus on three data modeling capabilities of XGrammar: (a) the ability to represent ordered binary relationships, (b) the ability to represent a set of semantically equivalent but structurally different types as "one" type using the closure properties, and (c) the ability to represent recursive relationships.