Designing Semistructured Databases: A Conceptual Approach

Semi-structured data has become prevalent with the growth of the Internet. The data is usually stored in a traditional database system or in a specialized repository. While many information providers have presented their databases on the web as semi-structured data, other information providers are developing repositories for new application. One such application is e-commerce, which is emerging as a major web-supported application assisting business transactions between multiple parties via the network and involving large amounts of data. Designing a \good" semi-structured database is increasingly crucial to prevent data redundancy, inconsistency and updating anomalies. In this paper, we propose a conceptual approach to design semi-structured databases. A conceptual layer which is based on the popular Entity-Relationship (ER) model is employed to remove anomalies and redundancies at the semantic level. An algorithm to map an ER diagram involving composite attributes weak entity types, recursive, n-ary and ISA relationship sets, and aggregations to a semi-structured schema graph (S3-Graph) used to represent semi-structured data is given. Our study reveals similarities between the S3-Graph and the hierarchical model and nested relations in that all have limitations in modeling situations with nonhierarchical relationships given their tree-like structures.