10,545 research outputs found
Continuous client-side query evaluation over dynamic linked data
Existing solutions to query dynamic Linked Data sources extend the SPARQL language, and require continuous server processing for each query. Traditional SPARQL endpoints already accept highly expressive queries, so extending these endpoints for time-sensitive queries increases the server cost even further. To make continuous querying over dynamic Linked Data more affordable, we extend the low-cost Triple Pattern Fragments (TPF) interface with support for time-sensitive queries. In this paper, we introduce the TPF Query Streamer that allows clients to evaluate SPARQL queries with continuously updating results. Our experiments indicate that this extension significantly lowers the server complexity, at the expense of an increase in the execution time per query. We prove that by moving the complexity of continuously evaluating queries over dynamic Linked Data to the clients and thus increasing bandwidth usage, the cost at the server side is significantly reduced. Our results show that this solution makes real-time querying more scalable for a large amount of concurrent clients when compared to the alternatives
Knowledge Organization Systems (KOS) in the Semantic Web: A Multi-Dimensional Review
Since the Simple Knowledge Organization System (SKOS) specification and its
SKOS eXtension for Labels (SKOS-XL) became formal W3C recommendations in 2009 a
significant number of conventional knowledge organization systems (KOS)
(including thesauri, classification schemes, name authorities, and lists of
codes and terms, produced before the arrival of the ontology-wave) have made
their journeys to join the Semantic Web mainstream. This paper uses "LOD KOS"
as an umbrella term to refer to all of the value vocabularies and lightweight
ontologies within the Semantic Web framework. The paper provides an overview of
what the LOD KOS movement has brought to various communities and users. These
are not limited to the colonies of the value vocabulary constructors and
providers, nor the catalogers and indexers who have a long history of applying
the vocabularies to their products. The LOD dataset producers and LOD service
providers, the information architects and interface designers, and researchers
in sciences and humanities, are also direct beneficiaries of LOD KOS. The paper
examines a set of the collected cases (experimental or in real applications)
and aims to find the usages of LOD KOS in order to share the practices and
ideas among communities and users. Through the viewpoints of a number of
different user groups, the functions of LOD KOS are examined from multiple
dimensions. This paper focuses on the LOD dataset producers, vocabulary
producers, and researchers (as end-users of KOS).Comment: 31 pages, 12 figures, accepted paper in International Journal on
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