1. Publishing with
Triple Pattern Fragments
Ruben Taelman - @rubensworks
imec - Ghent University
1

2. Publishing with Triple Pattern Fragments
TPF server software
TPF client-side querying
Quad Pattern Fragments
Demo
2

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
4

5. Requires Node.js ≥ 4.0
Installing and running the LDF server with Node
5
[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
6
docker pull linkeddatafragments/server.js
docker run -p <port>:3000 -it --rm
-v $(pwd)/config.json:/tmp/config.json
ldf-server /tmp/config.json

7. Preconfigured LDF server with NGINX cache and web-client
Setting up a full stack with Docker (Compose)
7
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
8

9. {
"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
9

10. {
"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
10

11. {
"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
11

12. HDT
N-Triples
Turtle
JSON-LD
SPARQL-endpoint
Different data sources are possible
12

13. by extending lib/datasources/Datasource.js
Return triple stream given triple pattern, offset and limit
...or write your own datasource implementation
13

14. 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
16

17. No installation required at all!
http://client.linkeddatafragments.org/
Use the web client
17

18. Requires Node.js ≥ 4.0
Run from command line or include in your source code
Installing and running the LDF client with Node
18
[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
19
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
20

21. Quads are triples extended with a fourth element, the graph
<s> <p> <o> <g>.
Triples sometimes need some context
21

22. Quad Pattern Fragments (QPF)
Adding the fourth element to the interface
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23. 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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24. 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%

28. 28

29. 29

30. 30
Some query types are very slow
~1 hour!

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