Framing the Problem
In theory, we could discuss the mapping between XML and relational data without reference to the applications that will use such a mapping or how those applications might be implemented. However, these factors have implications for the type of mapping chosen—one may want or be constrained to choose a different mapping technique based on the actual requirements of a particular application. In particular, we consider XQuery as one particular type of application, one that places certain requirements on how to map between XML and relational data. We also consider other types of applications that have fewer or additional requirements.
We will begin by discussing at a high level the processing models that might ...