XML Query Use Cases in Xcerpt
As part of the ongoing effort on XQuery, the W3C has released a set of use cases for XML query languages. Though the selection is, arguably, slightly tilted by the features of XQuery and expectations of the corresponding working group, it is nevertheless a very illuminating set of use cases for evaluating the adequacy of any XML query language. The remainder of this article describes our solutions for these use cases in Xcerpt. Actually, you can find two sets of solutions for these use cases. The first set is part of Sebastian Kraus' master thesis. Though there are some bugs left in the solutions and some solutions are missing, the solution set can actually be tested with the 2004 Xcerpt prototype. You can find the corresponding Xcerpt programs at http://svn.amachos.com/xcerpt/applications/2005/use-cases/w3c-xml-query/. More details on these solutions are described in Sebastian's master thesis.
A revision and extension of these solutions can be found in Deliverable D3 of the "reasoning-aware querying" working group in the REWERSE network. In that article we have focused on a side-by-side comparison with the XQuery solutions, pointing out strengths, peculiarities, and shortcomings of both Xcerpt and XQuery.
Notice, that in both sets the entire group of use cases on strongly typed data (section 1.9 in [XML Query Use Cases]) is omitted. This is due to the lack of type queries in current Xcerpt prototypes and specifications. However, Sacha Berger is working hard at providing both a static type system and type queries for Xcerpt.
We hope to provide a final revision of these use cases once the next generation prototype and the final Xcerpt syntax are finished. For more information, feedback, or questions please contact us at the xcerpt-devel mailing list.