Periodic, On-Demand, and User-Specified Information Reconciliation

POUR is a framework that accepts periodic information updates, collects information on demand, and accepts user-specified information while presenting a single unified view to the user. The primary functionality of POUR is through its query interface. A query consists of any number of XPaths, where each XPath returns a list of XML strings that satisfies the query. Depending on the XPaths specified and the contents of the POUR database, query processing may be as simple as a database lookup, or as complex as a series of queries down a POUR hierarchy to a set of POUR repositories that compute the requested information on the fly before the appropriate results are returned.