An Approach to Assess the Quality of Web Pages in the Deep Web

Web pages contain a large number of structured data, which are useful for many advanced applications. Existing works mainly focused on extracting structured data from web pages by individual wrappers but ignored the quality for these underlying web pages, which in fact impact the extracting results seriously. Thus, we define the quality of a web page by the data quality a wrapper can achieve in extraction. This paper proposes a novel approach to assess the quality of web pages in the deep web. In our approach, we first define the schema of web data with a hierarchical model. Then web pages are dealt with as XML documents and parsed into a DOM tree. The data units and attribute values in the web page are annotated with the schema semantics and the XPATH of position in the DOM tree. Based on the annotation, we build an assessment model for the quality of web pages with two dimensions: the structure complexity and the text complexity of node in the DOM tree. The quality is partitioned into three quality levels in our model, and the quality of web pages in the same quality level is compared by the proposed formulas. Moreover, we design an XQuery-based wrapper to extract the web page and validate our quality model since most of existing wrappers can not handle the data with hierarchical structure. The wrapper generates XQuery statements to extract web data with the annotation information. The experimental results demonstrated our approach is accurate for assessing the data quality of web pages. It is very helpful for data quality control in the deep web related applications.