1. Let’s talk Linked Data session Open Belgium 2017
Brecht Van de Vyvere | @brechtvdv
Building a knowledge graph of the
Belgium War Press

2. Can I easily link historic papers with
other datasources?

3. Agenda
• hetarchief.be
• Knowledge graph
• 5-star Open Data plan
• Adding context
• Linked Data as a Service
• Future Work

4. Dataset

5. hetarchief.be
“News from the Great War”
• Newspapers 1914 - 1918
• 10+ Content Partners
• Begin 2015: site launched
• Functionality
• Search by keyword
• Map with place of publication
• Collections
1k titles
55k newspapers
300k pages

6. Human-readable interface

7. Policy
1. Metadata
• No restrictions → CC0
2. OCR, documents
• Pictures, short stories…
• Uncertain copyright status
• No license or “terms of use” that minimises restrictions
for re-use
• Disclaimer

8. hetarchief.be
• One of the biggest databases online
• No raw data?
• Title
• Description → OCR from ALTO
• Date created
• Owner
• IDs (carrier, Abraham, VIAA)
• URL image

9. 9
5-stars
Open Data Plan

10. First 3 Stars
• Open License
• Structured
• Non-proprietary
VIAA
DB
VIAA API NodeJS
→ github.com/viaacode/hetarchief2lod
IDs Metadata
CSV
Transform

11. Step 4: URIs for everything
• Map VIAAs internal ID to URI:
• http://data.viaa.be/noid/{id}
• Use ontologies
• BBC → Creative Work Ontology
• schema.org
• Hydra → collections

12. Knowledge graph
• Semantic network
• Concepts
• Relations
• Linked Data
• URIs
• RDF

13. <http://dbpedia.org/page
Albert_I_of_Belgium>
rdfs:type
<http://xmlns.com/
foaf/0.1/Person>
<http://data.viaa.be/
noid/example>
<http://www.bbc.co.uk/ontologies/
creativework#tag>

14. 5-star: link to other sources
• ABRAHAM: catalogue of newspapers in Belgium
<http://anet.be/record/abraham/opacbnc/c:bnc:26>
<http://data.viaa.be/noid/tm71v5c76q_191510XX>
owl:sameAs

15. L’illustration“1915-10-XX”
http://data.viaa.be/noid/
tm71v5c76q_191510XX
cwork:titlecwork:dateCreated
On dit que c'est
notre imagination
et….
cwork:content
cwork:CreativeWork
rdf:type
UGENT
schema:copyrightHolder
schema:inLanguage
en
Basic information triples

16. http://data.viaa.be/noid/
tm71v5c76q
http://data.viaa.be/noid/
tm71v5c76q_191804xx_0003
http://data.viaa.be/noid/
tm71v5c76q_191804xx_0002
http://data.viaa.be/noid/
tm71v5c76q_191804xx_0001
first
last
previous/next
first
memberOf
totalItemsHydra
last
3
first/last

17. Problems
• Node limited to 1.7 GB memory
• OCR too big
• Turtle file: 475 MB max (32k
newspapers)
• Compressed to HDT: 388 MB
• Basic triples with HDT:
• 54k newspapers → 8.2 MB

18. Adding context

19. Connect with other datasources
• Cfr. Europeana, delpher.nl, lab.kbresearch.nl

20. Stanford NER
• 4 types: Location, Organisation, Person and
Other
• Train your model: golden corpus
• Write code that fits your needs
• SPARQL query that matches strings
• REPERTOIRE des COMMUNES et des PRINCIPAUX
HAMEAUX de la ci-devant Belgique
• Difficult to find cultural APIs (cfr.
InFlandersField list of names, Abraham
catalogue)

21. DBpedia Spotlight
• Proof of concept
• Models for all languages (nl, en, fr, de)
NL/FR/EN/DE
trained model
DBpedia
matcher
Stanford NER

22. Results?
• Filter on OCR quality; e.g. <90% assurance
in ALTO
• Wrong time period, e.g. geonames
• Standard models, should be trained
• Use DBpedia knowledge later to filter
“impossible” tags

23. DBpedia Spotlight
• Running your own endpoint is easy:
• java -Xmx8G -jar dbpedia-
spotlight-0.7.1.jar nl http://localhost:2223/
nl/rest
• Or with Docker:
• docker build -f Dockerfile -t
dutch_spotlight .
• docker run -i -p 2223:80 dutch_spotlight
spotlight.sh

24. Linked Data as a Service
• Allow federated queries
• Low server cost
• Be reliable
• Triple Pattern Fragments: a Low-cost
Knowledge Graph Interface for the Web

25. Linked Data Fragments querying
• VIAA is part of the family!
http://data.viaa.be/
ldfhttps://query.wikidata.org/
bigdata/ldf
http://
data.linkeddatafragments.
org/linkedgeodata
http://
data.linkeddatafragments.
org/dbpedia2014
Your browser
Client-side algorithm
GET fragments

26. Demo time!

27. Demo
• Retrieve all newspaper titles:
SELECT DISTINCT ?title
WHERE {
?paper <http://www.bbc.co.uk/ontologies/creativework#title> ?title
}

28. Demo
• Retrieve more info from corresponding
DBpedia URI:
SELECT ?label ?comment
WHERE {
<http://data.viaa.be/noid/2z12n51476_19141120_0001> <http://
www.bbc.co.uk/ontologies/creativework#tag> ?tag .
?db owl:sameAs ?tag .
?db rdfs:label ?label .
?db rdfs:comment ?comment
}

29. Battle of the Somme
• Pages with military leaders from the Battle
of the Somme mentioned + thumbnail:
SELECT ?paper ?o ?thumbnail
WHERE {
<http://dbpedia.org/resource/Battle_of_the_Somme> <http://dbpedia.org/
ontology/commander> ?o .
?paper <http://www.bbc.co.uk/ontologies/creativework#tag> ?ctag .
?o owl:sameAs ?ctag .
?o <http://dbpedia.org/ontology/thumbnail> ?thumbnail .
}

30. Frontpainters
• Semi-automatic generation of collections,
e.g. about frontpainters
SELECT ?newspaper ?artist ?tag ?hetarchief
WHERE {
?artist dc:subject <http://dbpedia.org/resource/
Category:Belgian_war_artists> .
?artist owl:sameAs ?tag .
?newspaper <http://www.bbc.co.uk/ontologies/creativework#tag> ?
tag .
?newspaper <http://www.w3.org/2000/01/rdf-schema#seeAlso> ?
hetarchief
}

31. Conclusion
• Extra search method for our researchers
• NER versus OCR: enhanced findability
• Adding extra information (cfr. Abraham)
requires effort, we need more TPFs
interfaces

32. Future work
• Dereferencable URIs
• http://data.viaa.be/noid/{id}
• Content negotiation
• HTML
• JSON
• RDF
• Save location with OLR
• Suggestions are welcome!

33. Q&A
Brecht Van de Vyvere | @brechtvdv