We introduce the idea of utilizing ontologies as a service for query expansion, based on an AJAX widget. This ONKI Query Expansion Widget can be integrated into the search input eld of a traditional keyword-based legacy system by one line of JavaScript code, making the search system semantic. For example, when searching for \tools", also \hammers", \axes" etc. can be found based on the underlying hyponymy. In the same vein, the spatial relations of a geo-ontology or temporal relations can be utilized. Application of the widget in legacy search systems on the web is discussed by examples. The widget makes it possible to utilize the ontologies of the Finnish Ontology Library Service ONKI in a very cost-e cient way.
(rdfs:subClassOf ) for expanding the query concepts with their subclasses. In case of the Finnish Spatio-temporal ontology SAPO4 the place names in the query are expanded to regionally overlapping current and historical places. Also other relations could be used for query expansion by adjusting the ontology-speci c con guration les of the ONKI Ontology Service as desired.
To integrate the ONKI widget into an application the following code is added to the HTML source of the web page. First, the ONKI JavaScript library is loaded into the browser: <script type="text/javascript" src="http://www.yso.fi/onki.js"></script>
Then the input elds on the HTML page can be changed into ONKI widgets by using a parametrized method call in the onkeyup-attribute: <input id="searchField" onkeyup="onki['koko'].search({'queryExpansion' : true})" />
The functionalities of the widget can be customized by parametrizing the method call. By default the selected query concepts and the concepts expanding them are stored in hidden input elds to be sent to the application along with the search form. A JavaScript callback method can be used, too. The form of the query expression can be de ned by providing a JavaScript method. For example, in a Google query, disjunctive query terms term1 and term2 are expressed in the form \term1 " OR \term2 ".
For a demonstration we have used the Kantapuu. museum collection search form5, and created a copy of it with three integrated ONKI widgets for the elds keywords, place of use, and material6. Also a demonstration page consisting of a Google search eld with integrated ONKI widget is available7.
Acknowledgements This work has been funded by Lusto The Finnish Forest Museum8. Partial funding was given by the FinnONTO project9, funded by the National Technology and Innovation Agency (Tekes) and 38 private and public organizations, and the EU FP7 project SmartMuseum10. 4 http://www.seco.tkk.fi/ontologies/sapo/ 5 http://www.kantapuu.fi/ 6 http://www.yso.fi/kantapuu-qe/. 7 http://www.yso.fi/google-qe/ 8 http://www.lusto.fi/ 9 http://www.seco.tkk.fi/projects/finnonto/ 10 http://www.smartmuseum.eu/