Based on the current GPS position of a mobile device, DBpedia Mobile renders a map containing information about nearby locations from the DBpedia dataset. Geographic locations are currently available for 300,000 of DBpedia's 2.18 million “things”. It uses the Marbles Linked Data Browser to render Fresnel-based views for selected resources, as well as its SPARQL capabilities to build the map view. Starting from the map, users can explore background information about locations and can navigate into DBpedia and other interlinked datasets such as GeoNames, Revyu, EuroStat and Flickr.
DBpedia Mobile's initial view is a browser-based area map that indicates the user's position and nearby DBpedia resources with appropriate labels and icons. The user's position is provided to the application in the query string by a supplemental launcher application that runs natively on the device (see section Positioning).
Selected YAGO categories are mapped to icons, and the display may be limited to specific resource types such as Museums or Train Stations from within a settings pane. Here, the preferred language for labels and abstracts may also be selected from the 14 languages supported by DBpedia.
Clicking on a resource brings up a summary view of the selected item generated by the Marbles Linked Data Browser. This view includes a short text describing the resource and optionally an image, a link to the resource's foaf:homepage and reviews from the Revyu rating site if existent. If the displayed data contains RDF links into other datasets, the user may click them to obtain a full details view of the referenced resource. In this manner, the user can navigate from the DBpedia dataset into other interlinked datasets. For instance, he could traverse GeoNames' parentFeature link hierarchy to find out more about the city, state and country in which a resource is located.
On mobile devices
On a mobile device, the map view can be panned by dragging it on the touch screen, or zoomed using the provided controls. It is designed for displays with at least QVGA (320x240 pixels) resolution. Currently, only Opera Mobile 8 is known to work, as most other mobile browsers don't have adequate Document Object Model (DOM) Level 1 and 2 support to host the underlying Google Maps API. It does work on the iPhone, but is currently not really usable, as iPhone specifics haven't been implemented yet (notably, dragging and screen size parameters).
The application may also be accessed on desktop computers. While GPS-based positioning is likely of limited concern in this scenario, the desktop view can be used to explore DBpedia resources around the world. The application has been successfully tested with Firefox 2, Internet Explorer 7, Safari 3 and Opera 9.
2 Positioning client for Windows Mobile
The GPS Launcher application has located the user A supplemental launcher application may be used to initialize the Map View with the user's current location as retrieved from a built-in or externally connected GPS receiver on Windows Mobile devices.
Once the position is found, the user may launch the Map View in his web browser using the Go button. His position is thereby passed in the URL's query string.
Download the positioning client: DBpediaMobile.cab
As the Map View currently only works with Opera Mobile, Opera Mobile 8 should be installed and configured as the default browser.
DBpedia Mobile's Map View uses the following components:
- Core DBpedia datasets (labels, geo-coordinates and categories) are pre-loaded into Marbles' Sesame 2.1 MySQL store
- Map tiles provided by OpenStreetMap
- Jibbering RDF Parser to parse RDFXML map data results
- GeoLite City for IP Lookup
- Google Maps API
- GxMarker V2
Christian Becker, Christian Bizer: DBpedia Mobile: A Location-Enabled Linked Data Browser. 1st Workshop about Linked Data on the Web (LDOW2008), Beijing, China, April 2008. [PDF] Paper [PDF] Slides