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Linked Data Fragments: Web-scale querying

From: Ruben Verborgh <ruben.verborgh@ugent.be>
Date: Tue, 11 Mar 2014 12:06:05 +0000
Message-Id: <EF33FF64-0ABF-4882-8661-84AB4B90F4DC@ugent.be>
To: public-lod Data <public-lod@w3.org>, "semantic-web@w3.org Web" <semantic-web@w3.org>
Dear Semantic Web and Linked Data enthusiasts,

If you're curious about new ways to query Linked Data,
you might like our Linked Data Fragments client.
It lets your browser execute SPARQL queries over Web data
in a scalable way: http://client.linkeddatafragments.org/

Today's answer to Web querying consists of SPARQL endpoints.
Publishers of data sets offer a public endpoint, which
answers highly specific questions for any client. Unfortunately,
the availability of public SPARQL endpoints is problematic [1] –
and thus so is the availability of publicly queryable datasets.
We cannot rely on them for building applications, and that's a pity.

It is not an issue of performance but an inherent architectural issue:
making a public server responsible for arbitrarily complex requests
doesn't work on a Web scale. We have to create more simple servers,
only answering simple questions that don't endanger availability.
Yet at the same time, the dataset should remain easily queryable.

This is the goal of the Linked Data Fragments project [2].
“Linked Data Fragments” is a term for all ways to offer parts of a dataset:
 - SPARQL results are (precise but expensive) Linked Data Fragments.
 - Data dumps are (huge but straightforward) Linked Data Fragments.
Between those two extremes, an underexplored range of fragments exists.

We propose a new type called “basic Linked Data Fragments”,
which partitions a dataset in all its basic triple patterns.
This reconciles the need for queryable public datasets
with the availability demands of Web applications.
A basic Linked Data Fragments server with well-known datasets
is available online [3] (and so is its source code [4]).

Try our online client [5] that answers SPARQL queries
using only basic Linked Data Fragments (source code [6]).
It works up to two magnitudes faster than Linked Data Querying [7]
because servers offers those fragments that assist client-side querying –
without needing to solve expensive queries at the server side.

Basic Linked Data Fragments are not a definitive answer;
there are many other types of fragments to explore.
However, you might be surprised to see quite acceptable query times,
and – most importantly – high availability and scalability.

Read more on Linked Data Fragments on the website
http://linkeddatafragments.org/ and discover all details
in our forthcoming LDOW2014 publication [8].

Looking forward to your feedback!

Best regards,

Ruben Verborgh
Ghent University – iMinds, Belgium

[1] http://sw.deri.org/~aidanh/docs/epmonitorISWC.pdf
[2] http://linkeddatafragments.org/
[3] http://data.linkeddatafragments.org/
[4] https://github.com/LinkedDataFragments/Server
[5] http://client.linkeddatafragments.org/
[6] https://github.com/LinkedDataFragments/Client
[7] https://cs.uwaterloo.ca/~ohartig/files/Hartig_LDQueryExec_DBSpektrum2013_Preprint.pdf
[8] http://linkeddatafragments.org/publications/ldow2014.pdf
Received on Tuesday, 11 March 2014 12:06:41 UTC

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