Evo-Path: Querying Data Evolution through Complex Changes

Evo-graph is a model for data evolution that captures data versions and treats changes as first-class citizens. A change in evo-graph can be compound, comprising disparate changes, and is associated with the data items it affects. In previous work, we specified how an evo-graph can be reduced to a snapshot holding under a specific time instance, we presented an XML representation of evo-graph called evoXML, we defined how evo-graph is constructed as the current snapshot evolves, as well as presented and evaluated the C2D framework that implements these concepts using XML technologies. In this paper, we formally define evo-path, an XPath extension for querying the data history and change structure in a uniform way over evograph. We specify the evo-path syntax, semantics and implementation, and present several query categories.