A Three-Layered XML View Model: A Practical Approach

Since the early software models, abstraction and conceptual semantics have proven their importance in software engineering methodologies. For example, Object-Oriented conceptual modeling offers the power in describing and modeling real-world data semantics and their inter-relationships in a form that is precise and comprehensible to users. Conversely, XML is becoming the dominant standard for storing, describing and interchanging data among various Enterprises Information Systems and databases. With the increased reliance on such self-describing, schema-based, semi-structured data language/(s), there exists a requirement to model, design, and manipulate XML data and associated semantics at a higher level of abstraction than at the instance level. But, existing Object-Oriented conceptual modeling languages provide insufficient modeling constructs for utilizing XML schema like data descriptions and constraints, and most semi-structured schema languages lack the ability to provide higher levels of abstraction (such as conceptual models) that are easily understood by humans. To this end, it is interesting to investigate conceptual and schema formalisms as a means of providing higher level semantics in the context of XML-related data engineering. In this paper, we use XML view as a case in point and present a three-layered view model with illustrated examples taken from a real-world application domain. We focus on conceptual and schema view definitions, view constraints, and the conceptual query operators.