Efficient Querying of XML Data Through Arbitrary Security Views

International audienceWe study the problem of querying virtual security views of XML data that has received a great attention during the past years. A major concern here is that user XPath queries posed on recursive views cannot be rewritten to be evaluated on the underlying XML data. Existing rewriting solutions are based on the non-standard language, “Regular XPath”, which makes rewriting possible under recursion. However, query rewriting under Regular XPath can be of exponential size. We show that query rewriting is always possible for arbitrary security views (recursive or not) by using only the expressive power of the standard XPath. We propose a more expressive language to specify XML access control policies as well as an efficient algorithm to enforce such policies. Finally, we present our system, called SVMAX, that implements our solutions and we show that it scales well through an extensive experimental study based on real-life DTD