Best of Marketing

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LDP inApache Marmotta
http//marmotta.apache.org/events/iswc2014
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Who Am I
Sergio Fernández
_at_wikier http//linkedin.com/in/sergiofernandez htt
p//www.wikier.org

• Committer at the Apache Software Foundation
• also
• Member of the LDP working group at W3CSenior
  Researcher at Salzburg Research
• Partner Technology Manager at Redlink GmbH

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What is LDP?
a set of best practices and simple approach for a
read-write Linked Data architecture, based on
HTTP access to web resources that describe their
state using the RDF data model
Linked Data Platform 1.0http//www.w3.org/TR/ldp/
W3C Last Call Working Draft 16 Sep 2014
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A bit of history.
2007 Linked Data Design Issues http//www.w3.org/DesignIssues/LinkedData.html
2010 Linked Media Principleshttps//code.google.com/p/lmf/wiki/PrinciplesLinkedMedia
2011 Linked Data Basic Profile 1.0 http//www.w3.org/Submission/ldbp/
2012 Linked Data Platform 1.0http//www.w3.org/2012/ldp/
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Linked Data

1. Use URIs as names for things
2. Use HTTP URIs so that people can look up those
   names
3. When someone looks up a URI, provide useful
   information, using the standards (RDF, SPARQL)
4. Include links to other URIs, so that they can
   discover more things

LDP provides clarifications and extensions of the
rules of Linked Data principles, providing a
specification that describes the use of HTTP for
accessing, updating, creating and deleting
resources from servers that expose their
resources as Linked Data
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Terminology

• Linked Data Platform Resource (LDPR)
• an HTTP resource
• Linked Data Platform RDF Source (LDP-RS)
• an LDPR whose state is fully represented in RDF,
  corresponding to an RDF graph
• Linked Data Platform Non-RDF Source (LDP-NR)
• an LDPR whose state is not represented in RDF
• Linked Data Platform Container (LDPC)
• a LDP-RS representing a collection of LDPR
• Linked Data Platform Basic Container (LDP-BC)
• an LDPC that defines a simple link to its
  contained resources
• Linked Data Platform Direct Container (LDP-DC)
• an LDPC that adds the concept of membership,
• allowing the flexibility of choosing what form
  takes
• Linked Data Platform Indirect Container (LDP-IC)
• an LDPC similar to a LDP-DC that is also capable
  of having members whose URIs are based on its
  contained documents rather than the URIs assigned
  to those documents

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LDP Hierarchy
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LDP server and resources

• a LDP server manages two kinds of resources
• those resources whose state is represented using
  RDF (LDP-RSs)
• and those using other formats (LDP-NRs)

Such servers do not impose any restriction on
LDPRs and generally act as storage systems
without any domain specific application logic and
vocabularies.
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LDP concepts in a glance

• LDP covers read and write interactions with
  resources
• Writable aspects include creation of new
  resources (using POST or PUT), updates (using PUT
  or PATCH), and deletion of resources.
• Resource creation is an essential feature
  providing structured creation of resources.
• During creation the created resource is added to
  its Container and a containment link between the
  Container and the new entry is made.

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LDP Containers
a LDPC is a specialization of a LDP-RS
representing a collection of links to other
resources responds to client requests for
creation, modification, and/or enumeration of its
members
The simplest container is the Basic Container
(LDP-BC). It defines the basic containment
described using a generic vocabulary. This can be
used in a generic storage service to manage a
containment hierarchy of arbitrary resources
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LDP Containers (II)
Containers can contain other containers. This can
be done by POSTing (a child) container
representation to a (parent) container.
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LDP Direct Containers
A Direct Container is a specialisation of a Basic
Container. Additional assertions called
membership triples which use a domain-specific
vocabulary are made by a Direct Container as part
of the creation process. The membership triples
augment the containment triples maintained by all
containers. LDP-DCs are used for the management
custom scenarios, where use of existing
vocabulary is preferable.
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LDP Containers applications
Direct Container membership triples can be about
subjects other than the Container resource.
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LDP Containers applications (II)
Also different facets of a Resource be managed
using multiple Containers.
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LDP protocol particularities

• LDP defines two interaction models
• LDPC by default, which creates a container
  accepting the creation of resources
• LDPR creates resources which does not accept
  creation of new resources.
• LDP reuses some things from Atom (RFC 5023)
• The Slug header is used for requesting naming
  resources on creation
• The Prefer header is used optionally by clients
  to supply a hint to help the server form a
  response that is most appropriate

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LDP in Apache Marmotta

• Since version 3.2.0 Marmotta is compatible with
  LDP 1.0 drafts
• Although not full support
• LDP-DC and LDP-IC are not (yet?) supported
• LDP support is provided under /ldp
• requests to /resource are still managed following
  the old Linked Media Principles

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References

• Linked Data Platform 1.0http//www.w3.org/TR/ldp/
  W3C Last Call Working Draft 16 September 2014
• Linked Data Platform 1.0 Primerhttp//www.w3.org/
  TR/ldp-primer/ W3C First Public Working Draft 26
  June 2014
• Linked Data Platform Best Practices and
  Guidelineshttp//www.w3.org/TR/ldp-bp/ W3C
  Working Group Note 28 August 2014
• Linked Data Platform Implementation Conformance
  Reporthttps//dvcs.w3.org/hg/ldpwg/raw-file/defau
  lt/tests/reports/ldp.html Unofficial Draft 15
  October 2014
• Linked Data Platform 1.0 Test Caseshttps//dvcs.w
  3.org/hg/ldpwg/raw-file/tip/tests/ldp-testsuite.ht
  ml Unofficial Draft 15 October 2014

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let's play!
butJakob -)
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grazie!
acknowledgments to the MICO FP7 project (grant
no. 610480)
http//marmotta.apache.org/events/iswc2014
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