10. A computer program product comprising a physical computer usable medium having computer usable program code for extensible markup language (XML) path (XPATH) expression debugging, the computer program product including: computer usable program code for receiving an XPATH input expression; computer usable program code for parsing the XPATH input expression to produce a plurality of sub-expressions; computer usable program code for ordering the sub-expressions in a model for the XPATH input expression comprising: computer usable program code for associating each sub-expression with a node in the model; computer usable program code for, responsive to a selection of one of the sub-expressions in the model, producing a result set for the sub-expression comprising: computer usable program code for computing a result set for a sub-expression associated with a selected node in the model in a user interface; and computer usable program code for if the result set does not isolate a point of failure in the XPATH input expression, recursively selecting another sub-expression and computing another result set for said another sub-expression until a point of failure in the XPATH input expression is isolated.
10. A computer program product comprising a physical computer usable medium having computer usable program code for extensible markup language (XML) path (XPATH) expression debugging, the computer program product including: computer usable program code for receiving an XPATH input expression; computer usable program code for parsing the XPATH input expression to produce a plurality of sub-expressions; computer usable program code for ordering the sub-expressions in a model for the XPATH input expression comprising: computer usable program code for associating each sub-expression with a node in the model; computer usable program code for, responsive to a selection of one of the sub-expressions in the model, producing a result set for the sub-expression comprising: computer usable program code for computing a result set for a sub-expression associated with a selected node in the model in a user interface; and computer usable program code for if the result set does not isolate a point of failure in the XPATH input expression, recursively selecting another sub-expression and computing another result set for said another sub-expression until a point of failure in the XPATH input expression is isolated. 13. The computer program product of claim 10 , wherein the computer usable program code for ordering the sub-expressions in a model for the XPATH input expression, comprises: computer usable program code for rendering a visual representation of the model in a user interface for an integrated development environment (IDE).