1.
Publishing with
Triple Pattern Fragments
Ruben Taelman - @rubensworks
imec - Ghent University
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2.
Publishing with Triple Pattern Fragments
TPF server software
TPF client-side querying
Quad Pattern Fragments
Demo
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3.
Publishing with Triple Pattern Fragments
TPF server software
TPF client-side querying
Quad Pattern Fragments
Demo
3

4.
http://linkeddatafragments.org/software/
JavaScript LDF server
Python
Perl
Ruby
PHP
Java
...
TPF server implementations in different languages
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5.
Requires Node.js ≥ 4.0
Installing and running the LDF server with Node
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[sudo] npm install -g ldf-server
ldf-server config.json <port> <workers>
Documentation: https://github.com/LinkedDataFragments/Server.js

6.
Requires Docker
Installing and running the LDF server with Docker
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docker pull linkeddatafragments/server.js
docker run -p <port>:3000 -it --rm
-v $(pwd)/config.json:/tmp/config.json
ldf-server /tmp/config.json

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Preconfigured LDF server with NGINX cache and web-client
Setting up a full stack with Docker (Compose)
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docker-compose up
https://github.com/LinkedDataFragments/FullStackServer

8.
{
"title": "My Linked Data Fragments server",
"datasources": {
"dbpedia": {
"title": "DBpedia 2014",
"type": "HdtDatasource",
"description": "DBpedia 2014 with an HDT back-end",
"settings": { "file": "data/dbpedia2014.hdt" }
},
"dbpedia-sparql": {
"title": "DBpedia 3.9 (Virtuoso)",
"type": "SparqlDatasource",
"description": "DBpedia 3.9 with a Virtuoso back-end",
"settings": { "endpoint": "http://dbpedia.restdesc.org/",
"defaultGraph": "http://dbpedia.org" }
}
}
}
LDF server is configured with config.json
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{
"title": "My Linked Data Fragments server",
"datasources": {
"dbpedia": {
"title": "DBpedia 2014",
"type": "HdtDatasource",
"description": "DBpedia 2014 with an HDT back-end",
"settings": { "file": "data/dbpedia2014.hdt" }
},
"dbpedia-sparql": {
"title": "DBpedia 3.9 (Virtuoso)",
"type": "SparqlDatasource",
"description": "DBpedia 3.9 with a Virtuoso back-end",
"settings": { "endpoint": "http://dbpedia.restdesc.org/",
"defaultGraph": "http://dbpedia.org" }
}
}
}
Configure list of datasources
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{
"title": "My Linked Data Fragments server",
"datasources": {
"dbpedia": {
"title": "DBpedia 2014",
"type": "HdtDatasource",
"description": "DBpedia 2014 with an HDT back-end",
"settings": { "file": "data/dbpedia2014.hdt" }
},
"dbpedia-sparql": {
"title": "DBpedia 3.9 (Virtuoso)",
"type": "SparqlDatasource",
"description": "DBpedia 3.9 with a Virtuoso back-end",
"settings": { "endpoint": "http://dbpedia.restdesc.org/",
"defaultGraph": "http://dbpedia.org" }
}
}
}
Load an HDT file
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{
"title": "My Linked Data Fragments server",
"datasources": {
"dbpedia": {
"title": "DBpedia 2014",
"type": "HdtDatasource",
"description": "DBpedia 2014 with an HDT back-end",
"settings": { "file": "data/dbpedia2014.hdt" }
},
"dbpedia-sparql": {
"title": "DBpedia 3.9 (Virtuoso)",
"type": "SparqlDatasource",
"description": "DBpedia 3.9 with a Virtuoso back-end",
"settings": { "endpoint": "http://dbpedia.restdesc.org/",
"defaultGraph": "http://dbpedia.org" }
}
}
}
Act as a proxy to a SPARQL endpoint
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HDT
N-Triples
Turtle
JSON-LD
SPARQL-endpoint
Different data sources are possible
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by extending lib/datasources/Datasource.js
Return triple stream given triple pattern, offset and limit
...or write your own datasource implementation
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Exposing multiple datasources as if it was one
Useful for fragmented datasets that can’t be merged
Compose multiple datasources
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https://github.com/LinkedDataFragments/Server.js/blob/master/config/config-composite.json

15.
Publishing with Triple Pattern Fragments
TPF server software
TPF client-side querying
Quad Pattern Fragments
Demo
15

16.
http://linkeddatafragments.org/software/
JavaScript LDF client
Python
Perl
Java
...
Different client implementations exist as well
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No installation required at all!
http://client.linkeddatafragments.org/
Use the web client
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Requires Node.js ≥ 4.0
Run from command line or include in your source code
Installing and running the LDF client with Node
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[sudo] npm install -g ldf-client
ldf-client <tpf-endpoint-url> <sparql-query-path>
Documentation: https://github.com/LinkedDataFragments/Client.js

19.
Requires Docker
Installing and running the LDF client with Docker
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docker pull linkeddatafragments/client.js
docker run -it --rm
-v <sparql-query-path>:/tmp/query.sparql
linkeddatafragments/client.js
<tpf-endpoint-url> /tmp/query.sparql

20.
Publishing with Triple Pattern Fragments
TPF server software
TPF client-side querying
Quad Pattern Fragments
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Quads are triples extended with a fourth element, the graph
<s> <p> <o> <g>.
Triples sometimes need some context
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Quad Pattern Fragments (QPF)
Adding the fourth element to the interface
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SELECT *
FROM <http://example.org/graph0>
FROM NAMED <http://example.org/graph1>
WHERE {
GRAPH ?g {
?s ?p ?o.
}
}
QPF Clients are able to use quad features
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QPF is backwards-compatible with TPF
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TPF
QPF
TPF
QPF
Ignores graphs

25.
Quad Pattern Fragments (WIP)
https://github.com/LinkedDataFragments/Server.js/tree/feature-qpf-latest
https://github.com/LinkedDataFragments/Client.js/tree/feature-qpf-latest
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26.
Publishing with Triple Pattern Fragments
TPF server software
TPF client-side querying
Quad Pattern Fragments
Demo
26

27.
Let’s try overloading the DBpedia TPF endpoint!
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http://fragments.dbpedia.org/
Uptime of 99.9967%

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Some query types are very slow
~1 hour!

31.
Server running TPF server software with any dataset
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TPF server
software
RDF dataset
HDT dataset
SPARQL endpoint
...