Incremental adaptation of XPath access control views

Materialized XPath access-control views are commonly used for enforcing access control. When access control rules defining a materialized XML access-control view change, the view must be adapted to reflect these changes. The process of updating a materialized view after its definition changes is referred to as view adaptation. While XPath security views have been widely reported in literature, the problem of view adaptation for XPath security views has not been addressed. View adaptation results in view downtime during which users are denied access to security views to prevent unauthorized access. Thus, efficient view adaptation is important for making XPath security views pragmatic. In this work, we show how to adapt an XPath access-control view incrementally by re-using the existing view, which reduces computation and communication costs significantly, and results in less downtime for the end-user. Empirical evaluations confirm that the incremental view adaptation algorithms presented in this paper are efficient and scalable.