Querying over Federated SPARQL Endpoints : A State of the Art Survey

Querying over Federated SPARQL Endpoints : A State of the Art Survey
Querying over Federated SPARQL Endpoints : A State of the Art Survey
Bibliographical Metadata
Subject:	Querying Distributed RDF Data Sources
Keywords:	Federation, SPARQL, RDF, Linked Data.
Year:	2013
Authors:	Nur Aini Rakhmawati, J. Umbrich, Marcel Karnstedt, Ali Hasnain, Michael Hausenblas
Venue	arXiv

Abstract

The increasing amount of Linked Data and its inherent distributed nature have attracted significant attention throughout the research community and amongst practitioners to search data, in the past years. Inspired by research results from traditional distributed databases, different approaches for managing federation over SPARQL Endpoints have been introduced. SPARQL is the standardised query language for RDF, the default data model used in Linked Data deployments and SPARQL Endpoints are a popular access mechanism provided by many Linked Open Data (LOD) repositories. In this paper, we initially give an overview of the federation framework infrastructure and then proceed with a comparison of existing SPARQL federation frameworks. Finally, we highlight shortcomings in existing frameworks, which we hope helps spawning new research directions.

Conclusion

Federation query over SPARQL Endpoints made a significant progress in the recent years. Although a number of federation frameworks have already been developed, the field is still relatively far from maturity. Based on our experience with the existing federation frameworks, the frameworks mostly focus on source selection and join optimization during query execution. In this work, we have presented a list of federation frameworks over SPARQL Endpoints along with their features. According to this list, the user can have considerations to choose the suitable federation framework for their case. We have classied those framework into three categories: i) framework interprets SPARQL 1.1 query to execute federation SPARQL query covering VALUES and SERVICE operator; ii) framework handles SPARQL 1.0 query and has responsibility to find relevant source for a query and join incoming result from SPARQL Endpoints; and iii) framework accepts SPARQL 1.0 and translate the incoming query to SPARQL 1.1 format. Based on the current generation of federation frameworks surveyed in this paper, it still requires further improvements to make frameworks more effective in a broader range of applications. We suggested several features that could be included in the future developments. Finally, we point out challenges for future research directions.

Future work

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Approach

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Implementations

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