By Mike Jackson, Software Architect.

Linked data is a way of representing and joining information from a variety of sources to allow it to be accessed, browsed, searched and used as easily as one would browse the web. One of the principles of linked data is that URIs are used to name things whether these be people, places, books, software, magazines, departments, machines and so on.

As anyone can develop their own linked data sets, and propose their own URIs, many URIs may be created for the same thing. sameAs.org is a service offered by Seme4 Limited that allows users to find out which URIs refer to the same thing. sameAs Lite is a refactored, open source, version of the software that powers sameAs.org. We are providing consultancy to Seme4 on how to improve sameAs Lite for deployers and developers and to promote community engagement.

Consider these URLs:

• http://sws.geonames.org/2650225/ from the GeoNames geographical database which covers all countries and contains over 8,000,000 place names.
• http://data.ordnancesurvey.co.uk/doc/50kGazetteer/81482, from the Ordnance Survey gazeteer.
• http://data.nytimes.com/N45752581330994625741, from The New York Times news vocabulary of 10,000 subject headings.
• http://dbpedia.org/resource/Auld_Reekie, from DBpedia, a crowd-sourced community effort to extract and publish structured information from Wikipedia.

These URIs all refer to the city of Edinburgh. As they refer to the same thing they are termed co-referent. Determining which URIs, produced by different authors for different purposes, refer to the same things, determining these co-references, is one way by which these distributed data sets can linked and explored as if they were one virtual data set.

sameAs.org is a search engine that, if given a URI, returns URIs that are co-referent, should any be known to it. The engine searches data harvested from a number of sources. Searches can be initiated via web form or via an HTTP-based API, such as this example.

sameAs.org is maintained by Seme4 Limited, who provide development, consultancy and education services around Semantic Web and linked data technologies. Seme4 have their origins within, and retain strong links with, the University of Southampton.

Apart from its own data stores, sameAs.org also hosts linked data stores for a number of organisations, including Freebase, which helps power Google Knowledge Graph, the British Library, other national libraries including those of Spain, France, Norway, Germany and Hungary, VIAF (Virtual International Authority File), and the Ordnance Survey. Many of these organisations may want to run their own data stores and Seme4 would like to help them do this. To this end, Seme4 has produced sameAs Lite, a refactored, free open source, version of the software that powers sameAs.org.

Seme4's chief architect, Hugh Glaser, applied to our Research Software Group for help as part of our Open Call. We will provide recommendations on how openness and community engagement can be improved, based upon a review of the sameAs Lite open source project infrastructure. Once complete, we will then review sameAs Lite from the perspective of a deployer who wishes to set up a local deployment of sameAs Lite, and a developer setting up a development/build/test environment, for maintaining, extending or bug fixing sameAs Lite. We will also provide recommendations as to how the sameAs Lite core library support for MySQL and SQLite can be refactored to be database agnostic without degrading performance.

It is hoped that together these will help to encourage the uptake of sameAs Lite, which, in turn, will both allow the ideas embodied within sameAs Lite to be exploited more widely, and for Seme4 Limited to market their value-added expertise in helping organisations exploit sameAs data stores and to work with systems that are "sameAs aware".

We look forward to reporting on our collaboration. For more details please see our who do we work with page.