User Demand Description and Optimization in Web Data Management.

Based on object deputy database, newly proposed web data management system (WDMS) provides user with personal data spaces to flexibly manage their various web data. Limited to database capacity, WDMS should gather data that user need from Web according to user demand implied in their personal data spaces. However, user demand that expressed in SQL sentences in data spaces can't be comprehended and executed by meta-search engine. Confronted with the problem, this paper proposed a user demand description method which is helpful to formalize user demand expression and bridge the gap between user demand and web data sources. Based on user demand description, this paper also proposed user demand set optimization method to eliminate the subset and intersection relationship among user demand set. The experimental results demonstrate that user demand description and its optimization method can well express complex user demand and reduce redundant query cost. This work can be widely used in various kinds of personal Web data service system.