Trend Report of Search Sites with Complex Search

General search engines provide a search facility to reach Web pages with a single query keyword. Besides these general search engines, there are many Web sites that provide Web interface to access their database with complex query, most of which are realized by multiple text inputs. Dnavi (Database Navigation Service of the National Diet Library) contains a list of 2,800 such searchable databases. Metasearch engines that integrate these specialized databases are good candidates for the search engines of next generation. One of the key issues in realizing metasearch engines is to discover schema of databases behind Web interface. This paper reports on the current situation of complex query forms and possibility to infer data schema by analyzing forms of HTML.