Basics of Open Data: what you need to know by Wouter Degadt & Pieter Colpaert

Data → open and linked
Wouter Degadt & Pieter Colpaert
wouter.degadt@leiedal.be & pieter.colpaert@okfn.org

Programme
1. The basics
Data → Open Data → Linked Data
1. Linked Open Data
How to publish data?

Data
Wikipedia says:
English (disambiguation): data is uninterpreted information
English (computing): is any sequence of symbols given meaning by specific acts of
interpretation.
Dutch: data is the plural of datum, which is an observation of a fact

process
legal
technical
syntactic
object
semantic
↓
Querying
Would the data governance be able
to be merged?
Are you legally allowed to merge 2 datasets?
Can you connect the communication channels?
e.g., merge a dataset published as a CD with a
dataset published using floppy disk
What’s the interoperability of the serialisation
formats? E.g., JSON vs. PDF?
What can you request to the server?
Do the words in the one dataset mean the same
as the words in the other?
How easy is it to ask certain questions over the
borders of the dataset?

Open Data
Because non-personal data increases in value when
others reuse it

reuse is allowed
Data on the web
reuse in a gray zone unauthorised reuse

How can we find open data?
It’s made available through open data portals
http://data.gov.uk,
http://datahub.io,
http://open-data.europa.eu,
http://data.gent.be,
…
Via links in existing datasets
e.g., http://dbpedia.org/resource/Ghent

Linked Data
Because it is impossible to store all the world’s
knowledge on one machine

name type same as location
iMinds company IBBT Gaston
Crommenlaan 8
{
“iMinds” : {
“type” : “company”,
“same as” : “IBBT,
“location” : “Gaston
Crommenlaan 8”
}
}
<iMinds>
<type>company</type>
<sameas>IBBT</sameas>
<location>
Gaston Crommenlaan 8
</location>
</iMinds>
Table / CSV / Spreadsheet
JSON XML

name type same as location
iMinds company IBBT Gaston
Crommenlaan 8
<iMinds> <type> <company> .
<iMinds> <sameas> <IBBT> .
<iMinds> <vestiging> “Gaston Crommenlaan 8” .
Table / CSV / Spreadsheet
triples
JSON XML
{
“iMinds” : {
“type” : “company”,
“same as” : “IBBT,
“location” : “Gaston
Crommenlaan 8”
}
}
<iMinds>
<type>company</type>
<sameas>IBBT</sameas>
<location>
</location>
</iMinds>

Machine 1 Machine 2 Machine 3
iMinds
same as
IBBT
World Wide Web
iMinds
is a
company
IBBT
located at

Probleem
semantic interoperability
The word company is ambiguous. How can we make
sure that machines understand each other?
What about “is a”?
and what about “iMinds”?

Solution
Uniform Resource Identifiers (URI’s)
iMinds → http://data.kbodata.be/organisation/0866_386_380#id
is a → http://www.w3.org/1999/02/22-rdf-syntax-ns#type
Company → http://www.w3.org/ns/regorg#RegisteredOrganization
een triple = is an atomary piece of data (a datum
or a fact) that cannot be misunderstood on
machine-level in a Web context

iMinds
compa
ny
is a
is een → http://www.w3.org/1999/02/22-rdf-syntax-ns#type
Company → http://www.w3.org/ns/regorg#RegisteredOrganization

Company register
iMinds
compa
ny
is a
Open
Knowledge
Belgium
TVH
Maes
…

company
register
address
database
…
Government
Service X

Linked Open Data cloud: de verzameling
van biljoenen triples gepubliceerd via het
Web

Summary
New terms: data quality, data interoperability, triples, open
data, linked open data cloud
Linked Open Data means: making your data more
interoperable with other datasets on the web by using URIs
as identifiers and triples as atomary building blocks

Data publishing
Bedrijf → http://www.w3.org/ns/regorg#RegisteredOrganization

Linked Data principles
1. Use a URI for every term
2. Dereference these URIs over HTTP
3. Return useful information
4. Add links towards useful sources

E.g., I’m launching a new company
{mynewcompany} → http://{mynewcompany}.be/#org
Een identifier voor jouw bedrijf en
jij bent baas over de betekenis.

E.g., I’m launching a new company
heeft een home page → http://xmlns.com/foaf/0.1/homepage
http://{mynewcompany}.be/

Publishing methods
1. Data dumps
2. Triples within HTML pages
3. JSON → JSON-LD web services
4. Triple pattern fragments

Data dumps
http://wiki.dbpedia.org/Downloads2014
→ all facts in 1 file

JSON API
http://{address to API document on Empire State}

Triple Pattern Fragments server
iMinds → is a → company
?subject → ?predicate → ?object

Triple Pattern Fragments clients

Basics of Open Data: what you need to know by Wouter Degadt & Pieter Colpaert

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