By imposing a single hierarchy on data, XML makes queries brittle in the sense that a query might fail to produce the desired result if it is executed on the same data organized in a different hierarchy, or if the hierarchy evolves during the lifetime of an application. This paper presents a new transformation language, called XMorph, which supports more flexible querying. XMorph is a shape polymorphic language, that is, a single XMorph query can extract and transform data from differently-shaped hierarchies. The XMorph data shredder distills XML data into a graph of closest relationships, which are exploited by the query evaluation engine to produce a result in the shape specified by an XMorph query.

XMorph is a new, shape polymorphic, domain-specific XML query language. A query in a shape polymorphic language adapts to the shape of the input, freeing the user from having to know the input's shape and making the query applicable to a wide variety of differently shaped inputs. An XMorph query specifies the shape of the output. The XMorph query engine transforms the input to the desired shape by shredding an XML document to a graph of closest relationships, and performing a closeness preserving transformation. We plan to demonstrate XMorph using a Java applet, which can also be used by the audience during the demonstration, to evaluate various XMorph queries. The applet will show the output, the shapes generated by the query, and report on potential data loss in a transformation.