Patent ID: 7254577

Claim:
A method to extract data from a plurality of semi-structured data sources, said method comprising: parsing a semi-structured data source to produce a well-formed document that is mapped to a Document Object Model (DOM) tree; generating a respective representative label for each of a set of identified instances of a data element within said semi-structured data source; generating a generalized representative label that matches each of the representative labels generated for the identified, instances; evaluating a resilience of the generalized representative label to structural changes of the semi-structured data source by estimating, for a set of possible structural changes to the semi-structured data source, a probability of the generalized representative label satisfying a set of resilience criteria; and storing the evaluated resilience of the generalized representative label, wherein the resilience of a label is evaluated with respect to a known change model that is learned from a history of previous changes to said semi-structured data source, wherein said evaluating comprises evaluating the resilience against a selection criterion by: comparing a calculated degree of resilience for the generalized representative label with a calculated degree of resilience of another generalized representative label; and selecting the generalized representative label having a highest calculated degree of resilience, wherein said estimating occurs by determining a probability that said respective representative label will match nodes of interest in said DOM tree and determining a probability that said respective representative label will match nodes not of interest in said DOM tree, and wherein said resilience of the generalized representative label is used as a measure to extract data from said plurality of semi-structured data sources.