A formal dynamic schema evolution model for hypermedia databases

A hypermedia database schema is a meta-information which defines the structures of applications and objects. A dynamic schema evolution model is an abstract machine which describes changes of schemata. Unfortunately because of the lack of formal data structures of hypermedia databases, it is very difficult to describe the dynamic changes of a hypermedia schema. The research presented in this paper proposes a formal approach to define the model of dynamic schema information. That is, a complete formal structure of a hypermedia database on the basis of previous research[WH93, WH95, Wan96, Wan97], and the schema operations defined for the schema evolution. The significant features of this research are, firstly, a formalized model to define the dynamic schema structure, secondly, a theoretical approach to manage the global schema of a distributed system, and finally, a design strategy to integrate the Web databases to support a wide range of application areas.