The problem of extracting data that resides in the deep Web has become the center of many research efforts in the recent few years. The challenges in this research area are spanning from online databases discovery and forms extraction from query interfaces, to receiving structured queries from the user, submitting them automatically and retrieving accurate results back to the user. Therefore, the main task is to build an integrated system that connects this variety of missions. In this paper we give an overview of this area of research. We start by surveying previous deep Web systems. After that we define the basic components of a typical deep Web integrated system. Finally, we highlight the current challenges along with possible future research directions.
B. R. El-Gamil, W. Winiwarter, B. Božić, H. Wahl; "Deep Web Integrated Systems: Current Achievements and Open Issues"; 13th Conference on Information Integration and Web-based Applications & Services (iiWAS’11), 447-450; Vietnam, 2011