MULTILEVEL DATA VERIFICATION ALERT SYSTEM FOR WRAPPER MAINTENANCE

Unfortunately, websites are continuously evolving and structural changes happen with no forewarning, which usually results in wrappers working incorrectly. Thus, wrappers maintenance is necessary for detecting whether wrapper is extracting erroneous data. Wrappers are pieces of software used to extract data from websites and structure them for further application processing. The solution consists of using verification models to detect whether wrapper output is statistically similar to the output produced by the wrapper itself when it was successfully invoked in the past. Current propos als present some weaknesses, as the data used to build these models are supposed to be homogeneous, independent or representative enough, or following a single predefined mathe matical model .