Extracting Key Value and Checking Structural Constraints for Validating XML Key Constraints

We propose an approach that can effectively validate key constrains over XML document by extracting key value and checking structural constraints. First we propose an XPath-based algorithm that can extract key values from the XML document and generate the corresponding key value document. Then we present how a key value document and its DTD can be designed to check whether predefined key constraints are satisfied. Last we draw an interesting conclusion that as long as XML keys can be expressed in XPath, the validation problem can be done by the XPath and the structural constraints checking.