Extracting Objects from the Web

There are various kinds of objects embedded in static Web pages and online Web databases. Extracting and integrating these objects from the Web is of great significance for Web data management. The existing Web information extraction (IE) techniques cannot provide satisfactory solution to the Web object extraction task since objects of the same type are distributed in diverse Web sources, whose structures are highly heterogeneous. The classic information extraction (IE) methods, which are designed for processing plain text documents, also fail to meet our requirements. In this paper, we propose a novel approach called Object-Level Information Extraction (OLIE) to extract Web objects. This approach extends a classic IE algorithm, Conditional Random Fields (CRF), by adding Web-specific information. It is essentially a combination of Web IE and classic IE. Specifically, visual information on the Web pages is used to select appropriate atomic elements for extraction and also to distinguish attributes, and structured information from external Web databases is applied to assist the extraction process. The experimental results show OLIE can significantly improve the Web object extraction accuracy.