SaGe: the 2019 February Release

Published: Feb 28, 2019 by GDD Team

We are proud to announce the release of Sage 1.1.

Sage is a SPARQL query engine designed for public Linked Data providers. Thanks to web preemption, the server can run without quotas on query execution time and consequently process arbitrary long-running queries with complete results.

The software and an online demo are freely available at:

http://sage.univ-nantes.fr/

The paper explaining the Sage approach [1] is accepted at WWW’19 and available as a postprint on HAL: https://hal.archives-ouvertes.fr/hal-02017155

Changes from version 1.0:

Sage Server:

SPARQL Unions are supported natively.
Some SPARQL Filters are supported natively. For now, only logical expression (<, =, &&, …) are allowed.
The Sage server API now supports plain text SPARQL queries: you can send a SPARQL query using a GET/POST request. See http://sage.univ-nantes.fr/documentation for details.
For example, you can now call http://sage.univ-nantes.fr/sparql?query=SELECT+%3Fcc+WHERE+%7B+++%3Chttp%3A%2F%2Fdbpedia.org%2Fresource%2FBarack_Obama%3E+%3Chttp%3A%2F%2Fwww.w3.org%2F2002%2F07%2Fowl%23sameAs%3E+%3Fcc+.+%7D+&default-graph-uri=http://sage.univ-nantes.fr/sparql/sameAs

Sage JS Client

Updated to take advantage of new server features
Uses parallelized Bound joins, as in FedX.

Sage Java Client:

Updated to take advantage of new server features
Uses parallelized Bound joins, as in FedX.
Some UNIONs and FILTERs are now evaluated server-side.
OptJoin implementation as described in the WWW’19 paper [1]. The OptJoin algorithm speeds up the evaluation of some OPTIONAL clauses.
Federated query processing using the FedX model: ASK-based source selection, exclusive groups optimization, extended with the OptJoin support. See the README of the java client https://github.com/sage-org/sage-jena.

Sage Website:

New preset queries selection UI, highlighting supported SPARQL features.
GraphQL support (see the GraphQL tab). GraphQL queries are translated into SPARQL queries, thanks to [4].
Automatic VOID description generation: http://sage.univ-nantes.fr/void/
http://sage.univ-nantes.fr/.well-known/void
New rendering engine based on Mithril.js. *Monitoring of the progression of query execution. Run the preset query http://sage.univ-nantes.fr/#query=prefix+dbo%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fontology%2F%3E%0Aprefix+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0A%0ASELECT+%3Fcity+%3Fperson+%3Fname%0AWHERE+%7B%0A++%3Fcity+a+dbo%3ACity%3B%0A++++++++rdfs%3Alabel+%3Fname.%0A++%3Fperson+a+dbo%3APerson%3B%0A++++++++rdfs%3Alabel+%3Fname.%0A%7D%0A&dataset=http%3A%2F%2Fsage.univ-nantes.fr%2Fsparql%2Fdbpedia-2016-04 on “Famous people with the same name as a city” to see it in action.

We appreciate your feedback/comments/questions to be sent to our mailing list [2] or our issue tracker on github [3].

On behalf of the Sage team,

Pascal Molli, Hala-Skaf-Molli, Thomas Minier - GDD Team https://sites.google.com/site/gddlina/home, LS2N https://www.ls2n.fr/?lang=en, University of Nantes http://www.univ-nantes.fr/.

[1] Thomas Minier, Hala Skaf-Molli and Pascal Molli. “SaGe: Web Preemption for Public SPARQL Query services” in Proceedings of the 2019 World Wide Web Conference (WWW’19), San Francisco, USA, May 13-17, 2019 https://hal.archives-ouvertes.fr/hal-02017155

[2] sage@univ-nantes.fr

[3] https://github.com/sage-org/sage-engine/issues

[4] https://www.npmjs.com/package/graphql-to-sparql

Positionning

Compared to public SPARQL endpoints, SAGE is stable and responsive without quotas. SAGE is able to deliver complete results for any SPARQL query. The Sage engine outperforms a Virtuoso server in term of execution time when the server load increases.

Compared to the Linked Data Fragment approach, SAGE outperforms a TPF server in term of execution time, communication costs and data transfers by several order of magnitude by processing BGP on the server side.

Experimental results and more details are available in [1].

We encourage you to run complex queries on RDF datasets available on the demo server and check performance (many presets queries are available).

We appreciate your feedback/comments/questions to be sent to our mailing list [2] or our issue tracker on github [3].

On behalf of the Sage team,

Pascal Molli, Hala-Skaf-Molli, Thomas Minier - GDD Team https://sites.google.com/site/gddlina/home, LS2N https://www.ls2n.fr/?lang=en, University of Nantes http://www.univ-nantes.fr/.

[1] Thomas Minier, Hala Skaf-Molli, Pascal Molli. SaGe: Preemptive Query Execution for High Data Availability on the Web. 2018. https://hal.archives-ouvertes.fr/hal-01806486v1

[2] sage@univ-nantes.fr

[3] https://github.com/sage-org/sage-engine/issues