Exploring Validation in an End-to-end XML Architecture

An application architecture that uses XML for data storage and message
passing throughout the life cycle of the data can leverage powerful
data validation techniques early and often. It can identify problems
with the data quickly and greatly increase the overall assurance of the
correctness of that data. XForms fits naturally into such an architecture,
as it requires users to enter their data as XML. As a result, XForms
provides a direct interface to the power of XML validation tools for
immediate and meaningful feedback to the user about any problems in
the data. Further, the use of validation components enables and
encourages the reuse of these components at other points of entry into
the system, or at other system boundaries. This article sketches the
uses of validation in an architecture that operates over XML data that
is at least partly entered through human-computer interaction. At the
data entry end, the architecture validates data produced from XForms
by re-purposing Schematron validation rules for different approaches
to helping the user understand problems that might exist in the data.
The article also briefly mentions an orthogonal use of the same
Schematron rules for validating mappings from legacy data formats such
as relational databases to a local XML schema. Multiplexing validation
components for multiple uses allows a pervasive level of quality of
XML content at the point of entry and retrospectively.