Schema Evolution publication categorizer

In order to formulate a meaningful XML query, a user must have some knowledge of the schema of the XML documents to be queried. The query will succeed only if the schema of the actual documents is consistent with the user's information. When a user queries a collection of documents collected from heterogeneous XML data sources, there is a high possibility that these documents do not all conform to the same schema assumed by the user, thus causing the query to fail. In this paper, we try to solve this query and data schema mismatching problem by proposing a query translation scheme.

As XML schemas evolve over time or as applications are integrated,
it is sometimes necessary to validate an XML document known
to conform to one schema with respect to another schema. More generally,
XML documents known to conform to a schema may be modified,
and then, require validation with respect to another schema. Recently,
solutions have been proposed for incremental validation of XML documents.
These solutions assume that the initial schema to which a document
conforms and the final schema with which it must be validated

Clio, the IBM Research system for expressing declarative schema mappings, has progressed in the past few years from a research prototype into a technology that is behind some of IBM's mapping technology. Clio provides a declarative way of specifying schema mappings between either XML or relational schemas. Mappings are compiled into an abstract query graph representation that captures the transformation semantics of the mappings. The query graph can then be serialized into different query languages, depending on the kind of schemas and systems involved in the mapping.