Preserving composition in XML object relational storage

XML data can be stored in different types of databases including object-relational databases (ORDB). Using ORDB, we get the benefit of relational maturity and the richness of object-oriented modeling. One modeling concept that can be captured is composition hierarchy, which is a special type of relationship that shows an exclusive existence-dependent "part-of" relationship. This type of relationship frequently occurs in XML data, yet very often when the data is stored in a database repository, the "part-of" relationship is either flattened or split into an entirely separate table. In this paper we propose a model to preserve composition type in XML data into ORDB using the concept of row types. We use the Semantic Network diagram to represent the composition hierarchy in XML data. The composition hierarchy is divided into three types, namely single row composition, multi rows composition, and multi level composition. Each of these composition types will then be transformed into storage in an ORDB environment.