Linked Data Overview - AGI Technical SIG

Linked Data – An Overview Chris Ewing 22 nd November 2011 http://www.flickr.com/photos/reedsturtevant/4288406572/sizes/l/in/set-72157623118237295/

Summary
What is Linked Data?
Why is it useful?
Geo Examples
http://www.w3.org/DesignIssues/diagrams/lod/480759174v0_350x350_Back.jpg

What is Linked Data?
A method of publishing structured data so that it can be interlinked and become more useful
Builds upon existing web technologies (HTTP, URI)

The semantic web
Linked Data is part of the semantic web (also nicknamed the Giant Global Graph (GGG))
Semantic Web describes:
Relationships between things
Properties of things
http://upload.wikimedia.org/wikipedia/en/3/37/Semantic-web-stack.png The Semantic Web Stack

Linked Data - Timeline
Basics have been around since birth of internet
Tim Berners-Lee paper in 2006
TED talk by TB-L in 2009
TB-L appointed UK Gov advisor to opening up Government data – Spring 2009
Data.gov.uk launches 2010
UK Location Linked Data workshop – Sep 2010
This workshop today!

Why is it useful?
Linked Data allows you to discover, connect to, describe, and re-use all kinds of data
Better answers to searches etc.
http://rww.readwriteweb.netdna-cdn.com/images/linked_data_graph.jpg

Why is it useful?
Can combine ALL kinds of data in a similar environment , share ACROSS organisations & reuse data and links
Faster access to data
More relevant data returned

Linked Data - Rules
Rule 1 – put something on the web
Not just docs, but people, places too
Rule 2 – get information back
Data in a useful format
Rule 3 – data is relationships
e.g. I was born in Liverpool, Liverpool is in Merseyside

Rule 1 - on the web
In the beginning only documents on the web
Now also music, video, maps, people, places etc.

Rule 2 – get information back
Ask a question and get a useful response
Show me all railways from OS 50k gazetteer
1. Search 2. Results 3. Items

Rule 3 – Data is Relationships
Postcode SO16 4GU is within SO16 4
SO16 4 is within SO16
SO16 is within SO
SO is within City of Southampton
Etc.

Linked Data “Rating” 2010 -http://www.w3.org/DesignIssues/LinkedData.html ★ Available on the web (whatever format), but with an open licence ★★ Available as machine-readable structured data (e.g. excel instead of image scan of a table) ★★★ as (2) plus non-proprietary format (e.g. CSV instead of excel) ★★★★ All the above plus, Use open standards from W3C (RDF and SPARQL) to identify things, so that people can point at your stuff ★★★★★ All the above, plus: Link your data to other people’s data to provide context

Linked Data Acronyms http://www.clir.org/pubs/archives/linked-data-survey/part00_b_acronyms.html

URI
Uniform Resource Identifier
String of characters used to reference a name or a resource on the Internet
Names for things!
http://example.org/absolute/URI/with/absolute/path/to/resource.txt
//example.org/scheme-relative/URI/with/absolute/path/to/resource.txt
relative/path/to/resource.txt
../../../resource.txt
./resource.txt#frag01
resource.txt
#frag01

RDF
Resource Description Framework
RDF uses URI references to identify resources and properties
“ The sky has the colour blue" in RDF is as the triple:
a subject denoting "the sky"
a predicate denoting "has the colour"
an object denoting "blue“
* http://www.w3.org/TR/rdf-concepts/#section-SimpleFacts RDF Triple

OWL
OWL Web Ontology Language
describes the meaning of terminology in web documents
http://www.w3.org/TR/owl-features/

SPARQL
SPARQL - SPARQL Protocol and RDF Query Language
Query the resources
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?email
WHERE {
?person a foaf:Person.
?person foaf:name ?name.
?person foaf:mbox ?email.
}
e.g. Returns Name and Email of everyone in a dataset

GeoSPARQL
Geospatial version of SPARQL
Created by an OGC working group
Goal is to “ support representing and querying geospatial data on the Semantic Web ”
Standardisation vote at end of 2011
Example – Select Airports near London

Some examples
GeoNames
Data.gov.uk
Ordnance Survey
DNF
INSPIRE
UK Location

GeoNames
makes it possible to add geospatial semantic information to the Word Wide Web.
Features in the GeoNames Semantic Web are interlinked with each other
All starts with Mother Earth
RDF dump with 7857409 features with 145919822 RDF triples (2011 08 24)

Data.gov.uk
http://data.gov.uk/linked-data
A series of SPARQL end points let you query the different data sources

Ordnance Survey Linked Data
http://data.ordnancesurvey.co.uk/.html
3 Linked Data datasets so far:
Postcodes
50k Gazeetter
Administrative boundaries
Free Text Search - http://api.talis.com/stores/ordnance-survey/items

DNF / UK Location
Digital National Framework
Oct 2011 – new Linked Data subgroup at BCS
EA bathing waters example from BSI Geographic Standards Committee*
UKLocation / BCS Linked Data business benefits – this Thursday 24 th Nov at BCS offices
*http://www.agi.org.uk/storage/GeoCommunity/AGI2011/Presentations/RichardDuffield.pdf

*http://www.agi.org.uk/storage/GeoCommunity/AGI2011/Presentations/RichardDuffield.pdf

INSPIRE and Linked Data *http://inspire.jrc.ec.europa.eu/documents/Network_Services/Linked_Data_&_INSPIRE_v101.pdf

http://www.flickr.com/photos/fenng/3199355352/sizes/o/in/photostream/

Chris Ewing Impact Forecasting Aon Benfield Analytics t: +44 (0)207 522 8305 e: [email_address] twitter: @web_gis

References
Linked Data
http://www.w3.org/DesignIssues/LinkedData.html
http://www.readwriteweb.com/archives/linked_data_is_blooming_why_you_should_care.php
http://en.wikipedia.org/wiki/Semantic_Web
RDF
http://www.w3.org/TR/rdf-concepts/#section-SimpleFacts
SPARQL
http://openuplabs.tso.co.uk/datasets
GeoSPARQL
http://www.geosparql.org
Ordnance Survey Linked Data
http://data.ordnancesurvey.co.uk/.html
http://johngoodwin225.wordpress.com/2010/10/25/location-location-location-%E2%80%93-exploring-ordnance-survey-linked-data-part-2/
Data.gov.uk LinkedData
http://data.gov.uk/linked-data
Linked Data and INSPIRE
http://inspire.jrc.ec.europa.eu/documents/Network_Services/Linked_Data_&_INSPIRE_v101.pdf
http://www.dnf.org/images/uploads/guides/20100915_-_Linked_Data_Workshop_Summary_v100.pdf

Linked Data Overview - AGI Technical SIG

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