Validation has been an important part of XML processing from the initial conception of XML. As XML reaches maturity in the enterprise, users are rapidly realising that validation using schema languages such as W3C XML Schema or RELAX NG provide only a partial solution. Common real-world requirements such as the ability to relate elements in distant parts of documents, to validate multiple documents against each other, and to make use of reference information in external data sources are not provided by these languages.

In this town hall meeting we will explore current solutions to validation that can address the requirements elicited above. We will consider tools such as xlinkit and Schematron that can be used as part of a validation pipeline for post-schema validation, extension to the schema languages themselves, and explore the view that validation in XML Schema is redundant as most processing code will perform the same checks anyway.