A set of slides that provides a high-level overview of the W3C Linked Data Platform specification presented at the 4th Linked Data in Architecture and Construction Workshop. For more detailed and technical version of the presentation, please refer to http://www.slideshare.net/nandana/learning-w3c-linked-data-platform-with-examples LDAC 2016 programme http://smartcity.linkeddata.es/LDAC2016/#programme

1. Introduction
to
W3C Linked Data Platform (LDP)
Nandana Mihindukulasooriya,
W3C Linked Data Platform WG,
Ontology Engineering Group,
Universidad Politécnica de Madrid,
Spain.
@nandanamihindu
LDAC 2016 - June 21st, 2016 – Madrid, Spain

2. From static web pages …
2
1991

3. To Web 2.0, Web APIs, etc …
3
2004

4. Linked Data
4
Linked Data principles
• Use URIs as names for things
• Use HTTP URIs so that people can look up
those names
• When someone looks up a URI, provide
useful information, using the standards
(RDF*, SPARQL)
• Include links to other URIs, so that they can
discover more things
Tim Berners-Lee. Linked data-design issues (2006) http://www. w3.org/DesignIssues/LinkedData.html
Leo Sauermann and Richard Cyganiak. Cool URIs for the Semantic Web (2008) http://www.w3.org/TR/cooluris/
Tom Heath and Christian Bizer. Linked Data: Evolving the Web into a Global Data Space (2011) http://linkeddatabook.com/
2006

5. Let’s see an example
5
FI - UPM
Bloque 5
GET /data/building/bloque3#it HTTP/1.1
Host: fi.upm.es
HTTP/1.1 200 OK
Content-Type: text/turtle; charset=UTF-8
Content-Length: 250
@prefix dc: <http://purl.org/dc/terms/> .
@prefix dbo: <http://dbpedia.org/ontology/> .
@prefix geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
@prefix ifc: <http://ifcowl.openbimstandards.org/IFC4#> .
<http://fi.upm.es/data/bloque3#it> a ifc:IfcBuilding;
ifc:buildingAddress_IfcBuilding _:address;
geo:long "-116.175869655195683"^^xsd:decimal ;
geo:lat "43.544840771226816"^^xsd:decimal ;
dbo:city <http://dbpedia.org/resource/Madrid>;
dbo:owningOrganisation <http://fi.upm.es> .
(1)
(3)
(4)
(2) http://fi.upm.es/data/bloque3#it

6. Linked Data Platform 1.0 http://www.w3.org/2012/ldp/
6
• RESTful protocol for Read / Write Linked Data
• Extensions to HTTP protocol
• Pagination, ordering, partial updates, introspection, creation factories,
collections
• Standardization focused of interoperability
• Developed by W3C Linked Data Platform Working Group
• 54 participants from 32 organizations
• Industry: IBM, Oracle, EMC, Fujitsu, OpenLink Software, Base22, …
• Academia: Universidad Politécnica de Madrid, MIT, University of
Oxford, DERI, Université de Lyon, INRIA, …
• Progress:
• W3C LDP WG created, 18 June 2012,
• W3C Candidate Recommendation 19 June 2014,
• W3C Proposed Recommendation 18 November 2014
• W3C Recomendation, 26 February 2015 2012

7. Outcomes
7

8. LDP Implementations
8
• 22 implementations
• https://www.w3.org/wiki/LDP_Implementations
• https://www.w3.org/2012/ldp/hg/tests/reports/ldp.html

9. LDP4j
9
• Java-based framework for the development of read-write Linked
Data applications
• Motto: Focus on your business logic, we will take care of the rest
• License: Apache License, v2.0
• Features:
• Simplified business object handling:
• Lifting from and lowering to an intermediate representation that can be
automatically unmarshalled from or marshalled to RDF, respectively.
• LDP support
• Protocol conversation control
• Transparent metadata management
• REST aware
• Transparent publication of RDF URIRefs.
• HTTP compliant
• The framework takes care of fulfilling the requirements prescribed by the
HTTP related RFCs (i.e., conditional requests processing, content
negotiation, entity tag handling,…)
www.ldp4j.org
https://github.com/ldp4j/ldp4j @LDP4j
contact@ldp4j.org

10. Other related initiatives
10
• W3C Hydra Community Group
• https://www.w3.org/community/hydra/
• W3C Read Write Web Community Group
• https://www.w3.org/community/rww/
• W3C RDF Shapes Working Group
• https://www.w3.org/2014/data-shapes/charter
• W3C Permissions & Obligations Expression Working
Group
• https://www.w3.org/2016/poe/charter
• WebID Community Group
• https://www.w3.org/community/webid/

11. What’s next?
LDAC2016 11

12. LDP IN USE
LDP high-level overview
12

13. LDP Terminology
13

14. Common LDP scenarios
14
• Looking up a Linked Data resource
• Paging
• Modifying a Linked Data resource
• Creating Linked Data resources
• Basic Container / Direct Containers / Indirect
containers
• Creating Linked Data Platform containers
• Deleting a Linked Data resource

15. Looking up a Linked Data resource
15
• a simple HTTP GET with
• additional guarantees
• LDP mandates some features that are optional in HTTP
• e.g., e-tags, HEAD, OPTIONS
GET
200 OK
GET

16. LDP Paging
16
• Some resources are too large
• Clients may not be able to handle the complete resource
• Alternatives
• Server-driven
• Client-driven
• Client preferences
• max-triple-count, max-kbyte-count, max-member-count
• Page links
• next, canonical, first, last,

17. Modifying a Linked Data resource
17
200 OK
PUT/PATCH
ETag: “123456789”
If-Match: W/'123456789'
GET
204 No Content
GET
Modify
• uses HTTP PUT or PATCH operations
• encourages conditional requests to avoid “lost update”
problem

18. LDP Containers
18
• a special type of Linked Data resource that acts as
• an enumeration of a collection of linked documents
• a creation factory
• Handles resource management and clean up
• Flexible and configurable
• Three types of LDP containers
• Direct container
• Direct container
• Indirect container

19. LDP Basic Container - Creating an LDPR
19
Contact List
<<Basic Container>>
Raul’s
Contact
Miguel’s
Contact
ldp:contains
ldp:contains
Fernando’s
Contact
POST

20. LDP Basic Container - Creating an LDPR
20
Raul’s
Contact
Miguel’s
Contact
ldp:contains
ldp:contains
Fernando’s
Contact
POST
Fernando’s
Contact
ldp:contains
Contact List
<<Basic Container>>

21. LDP IN USE
LDP4j in practice
21

22. morph-LDP
22
• Exposes relational databases as read-write Linked Data
Oegmembers Table
id fname lname
asun Asunción Gómez Pérez
fpriyatna Freddy Priyatna
mesteban Miguel Estebam
nmihindu Nandana Mihindukulas
ocorcho Oscar Corcho
rgarcia Raul Garcia Castro
@prefix rr: <http://www.w3.org/ns/r2rml#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
<TriplesMapPerson>
a rr:TriplesMap;
rr:logicalTable [ rr:tableName "oegmembers" ];
rr:subjectMap [ a rr:Subject; rr:class foaf:Person;
rr:template “http://example.org/oeg/members/{id}";
rr:termType rr:IRI; ];
rr:predicateObjectMap [
rr:predicateMap [ rr:constant foaf:firstName ];
rr:objectMap [ rr:column “fname"; rr:termType rr:Literal; ];
];
rr:predicateObjectMap [
rr:predicateMap [ rr:constant foaf:lastName ];
rr:objectMap [ rr:column “lname"; rr:termType rr:Literal; ];
];
…
http://example.org/oeg/members/fpriyatna
Registration
Office
morph-LDP
Web App
Relational
Database
Library
Legacy Applications
configures
exposes
Tabulator
OpenLink Data Explorer
ldspider LDIF
Freddy
Priyatna
dereferences to
GET /oeg/members/ HTTP/1.1
Host: example.org
Accept: text/turtle
200 OK
HTTP/1.1 200 OK
Content-Type: text/turtle; charset=UTF-8
Link: <http://www.w3.org/ns/ldp#BasicContainer>; rel="type"
ETag: W/"195482449"
@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.
<> a ldp:BasicContainer;
dcterms:title "Members of OEG, UPM";
ldp:contains <http://example.org/oeg/members/asun> ;
ldp:contains <http://example.org/oeg/members/fpriyatna> ;
ldp:contains <http://example.org/oeg/members/mesteban>;
ldp:contains <http://example.org/oeg/members/nmihindu>;
ldp:contains <http://example.org/oeg/members/ocorcho> ;
ldp:contains <http://example.org/oeg/members/rgarcia> .
Read-write LDMorph-LDPDatabase + R2RML
mappings
Mihindukulasooriya, N., Priyatna, F., Corcho, O., Garcıa-Castro, R., Esteban-
Gutiérrez, M.: morph-LDP: An R2RML-based Linked Data Platform implementation.
Demo at the 11th Extended Semantic Web Conference, Crete, Greece (May 2014)

23. The Bugzilla LDP adapter
23
• Exposes Bugzilla as an LDP-enabled application
 RDF
 HTTP
Headers
LDP Clients
Bugzilla
LDP Adapter
 XML-RPC
 Native data
model
ALM iStack ontology
POST /ita/containers/bugs HTTP/1.1
Host: localhost
Content-Type: text/turtle
@prefix ai: <http://delicias.dia.fi.upm.es/ontologies/alm-istack#> .
…rest of the namespace declarations are omitted for brevity.
<> a ai:ClientDefect;
dcterms:creator <http://localhost/ita/ldp/resources/users/9> ;
dcterms:title "Bugzilla adapter build is broken"^^xsd:string;
dcterms:description "Bugzilla adapter build fails due to a
test failure"^^xsd:string;
oslc_asset:relatedAsset <http://localhost/ita/ldp/resources/versions/16> ;
ai:relatedIncident <https://bugzilla.mozilla.org/show_bug.cgi?id=730698> .
HTTP/1.1 201 Created
Location: http://localhost/ita/ldp/resources/bugs/12
Link: <http://www.w3.org/ns/ldp#Resource>; rel='type'
Content-Length: 0
An example of bug creation
Mihindukulasooriya, N., Esteban-Gutiérrez, M., García-Castro, R.: A Linked Data
Platform adapter for the Bugzilla issue tracker. Demo at the 13th International
Semantic Web Conference, Riva del Garda, Italy (Oct 2014)

24. Smart Developer Hub
24
• integration of heterogeneous ALM tools and the
provision of tool-independent metrics

25. References
25
• Linked Data Platform 1.0
• http://www.w3.org/TR/ldp/
• Linked Data Platform 1.0 Primer
• http://www.w3.org/TR/ldp-primer/
• Linked Data Platform Best Practices and Guidelines
• http://www.w3.org/TR/ldp-bp/
• Linked Data Platform Paging 1.0
• http://www.w3.org/TR/ldp-paging/
• Linked Data Patch Format
• http://www.w3.org/TR/ldpatch/

26. Questions?
Nandana Mihindukulasooriya,
W3C Linked Data Platform WG,
Ontology Engineering Group,
Universidad Politécnica de Madrid,
Spain.
@nandanamihindu