Eetu Mäkelä

MuseumFinland-Finnish museums on the semantic web

This article presents the semantic portal MuseumFinland for publishing heterogeneous museum collections on the Semantic Web. It is shown how museums with their semantically rich and interrelated collection content can create a large, consolidated semantic collection portal together on the web. By sharing a set of ontologies, it is possible to make collections semantically interoperable, and provide the museum visitors with intelligent content-based search and browsing services to the global collection base. The architecture underlying MuseumFinland separates generic search and browsing services from the underlying application dependent schemas and metadata by a layer of logical rules. As a result, the portal creation framework and software developed has been applied successfully to other domains as well. MuseumFinland got the Semantic Web Challence Award (second prize) in 2004.

Semantic autocompletion

This paper generalizes the idea of traditional syntactic text autocompletion onto the semantic level The idea is to autocomplete typed text into ontological categories instead of words in a vocabulary The idea has been implemented and its application for semantic indexing and content-based information retrieval in multi-facet search is proposed Four operational semantic portals on the web using the implementation are presented as application cases.

Ontoviews: a tool for creating semantic web portals

This paper presents a semantic web portal tool OntoViews for publishing RDF content on the web. OntoViews provides the portal designer with a content-based search engine server, Ontogator, and a link recommendation system server, Ontodella. The user interface is created by combining these servers with the Apache Cocoon framework. From the end-users viewpoint, the key idea of OntoViews is to combine the multi-facet search paradigm, developed within the information retrieval research community, with semantic web RDFS ontologies, and extend the search service with a semantic browsing facility based on ontological reasoning. Onto Views is presented from the viewpoints of the end-user, architecture, and implementation. The implementation described is modular, easily modified and extended, and provides a good practical basis for creating semantic portals on the web. As a proof of concept, application of Onto Views to a deployed semantic web portal is discussed.

Ontogator — a semantic view-based search engine service for web applications

View-based search provides a promising paradigm for formulating complex semantic queries and representing results on the Semantic Web. A challenge for the application of the paradigm is the complexity of providing view-based search services through application programming interfaces (API) and web services. This paper presents a solution on how semantic view-based search can be provided efficiently through an API or as web service to external applications. The approach has been implemented as the open source tool Ontogator, that has been applied successfully in several practical semantic portals on the web.

How to deal with massively heterogeneous cultural heritage data: lessons learned in CultureSampo

This paper presents the CultureSampo system from the viewpoint of publishing heterogeneous linked data as a service. Discussed are the problems of converting legacy data into linked data, as well as the challenge of making the massively heterogeneous yet interlinked cultural heritage content interoperable on a semantic level. In the approach described, the data is published not only for human use, but also as intelligent services for other computer systems that can then provide interfaces of their own for the linked data. As a concrete use case of using CultureSampo as a service, the BookSampo system for publishing Finnish fiction literature on the semantic web is presented.

CultureSampo: A National Publication System of Cultural Heritage on the Semantic Web 2.0

CultureSampo is an application demonstration of a national level publication system of cultural heritage contents on the Web, based on ideas and technologies of the Semantic (Web and) Web 2.0. On the semantic side, the system presents new solutions to interoperability problems of dealing with multiple ontologies of different domains, and to problems of integrating multiple metadata schemas and cross-domain content into a homogeneous semantic portal. A novelty of the system is to use semantic models based on events and narrative process descriptions for modeling and visualizing cultural phenomena, and for semantic recommendations. On the Web 2.0 side, CultureSampo proposes and demonstrates a content creation process for collaborative, distributed ontology and content development including different memory organizations and citizens. The system provides the cultural heritage contents to end-users in a new way through multiple (nine) thematic perspectives, based on semantic visualizations. Furthermore, CultureSampo services are available for external web-applications to use through semantic AJAX widgets.

Elements of a National SemanticWeb Infrastructure--Case Study Finland on the Semantic Web

This article presents the vision and results of creating the basis for a national semantic Web content infrastructure in Finland in 2003-2007. The main elements of the infrastructure are shared and open metadata schemas, core ontologies, and public ontology services. Several practical applications testing and demonstrating the usefulness of the infrastructure are overviewed in the fields of eculture, ehealth, egovernment, elearning, and ecommerce.

Linked Data Finland: A 7-star Model and Platform for Publishing and Re-using Linked Datasets

The idea of Linked Data is to aggregate, harmonize, integrate, enrich, and publish data for re-use on the Web in a cost-efficient way using Semantic Web technologies. We concern two major hindrances for re-using Linked Data: It is often difficult for a re-user to (1) understand the characteristics of the dataset and (2) evaluate the quality the data for the intended purpose. This paper introduces the “Linked Data Finland” platform LDF.fi addressing these issues. We extend the famous 5-star model of Tim Berners-Lee, with the sixth star for providing the dataset with a schema that explains the dataset, and the seventh star for validating the data against the schema. LDF.fi also automates data publishing and provides data curation tools. The first prototype of the platform is available on the web as a service, hosting tens of datasets and supporting several applications.

Aether – Generating and viewing extended VoID statistical descriptions of RDF datasets

This paper presents the Aether web application for generating, viewing and comparing extended VoID statistical descriptions of RDF datasets. The tool is useful for example in getting to know a newly encountered dataset, in comparing datasets between versions and in detecting outliers and errors. Examples are given on how the tool has been used to shed light on multiple important datasets.

ONTODELLA -- A Projection and Linking Service for Semantic Web Applications

Content in semantic Web portals is often projected along application specific navigational taxonomies and linked semantically. This paper presents a logic-based method and a server Ontodella for these tasks. We argue that logic rules between the content layer and the application layer add flexibility and better architectural separation of content and functionality. The system has been implemented and applied succesfully in several semantic portals