Chapter 3 . 24 XWRAPComposer : A Multi - Page Data Extraction Service

We present a service-oriented architecture and a set of techniques for developing wrapper code generators, including the methodology of designing an effective wrapper program construction facility and a concrete implementation, called XWRAPComposer. Our wrapper generation framework has two unique design goals. First, we explicitly separate tasks of building wrappers that are specific to a Web service from the tasks that are repetitive for any service, thus the code can be generated as a wrapper library component and reused automatically by the wrapper generator system. Second, we use inductive learning algorithms that derive information flow and data extraction patterns by reasoning about sample pages or sample specifications. More impor-