1. Linked Data in Practice:
Building Standards, Building Communities
rsanderson@lanl.gov
Robert Sanderson
// azaroth42@gmail.com
// @azaroth42
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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2. Overview
• Standards
• Linked Data: Advantages and Challenges
• Graph Structure
• Open World
• Ontologies and Identities
• Serialization Formats
• Communities
WARNING: Packaged in a Factory Containing Controversy
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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3. Standards
Standards are essential: Infrastructure like Electricity
Like Electricity, there can be more than one but having
the adapters is always a pain
Or Standards like USB...
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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4. Building Standards
Standards are about agreement.
Technical side is easy compared to getting community
engagement and support.
(Much like herding cats)
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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5. Building Web Standards
The web has revolutionized communication,
especially scholarly communication.
Any modern communication standard
needs to be a web standard
Web Standards are about linking things together.
Web Standards are about data.
Linked Data is done using a Graph,
expressed in a technical framework called RDF
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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6. Graphs
ü Graphs are very powerful for modeling reality
ü Tree (like XML) is just a simple Graph
ü Don’t end up in semantic/syntactic hell (like XML)
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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7. Graphs: Structure and Data
Ø Working with graphs must take structure into
account
Graph: Structure and Data important,
but data currently treated as second class citizen
Other: Only Data important, so easier to work with
• Can’t think about “documents” as all nodes/edges
are stored together
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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8. Graphs: Structure and Data
Ø Visualization is difficult to get right
Ø … and hard to know when it is right
Ø Documents “easy” to visualize
Ø Graph visualization almost universally terrible
… because has to take structure into account
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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10. Not So Right
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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11. Graphs
Other structures don’t get as complicated
because they lack the expressiveness of a graph
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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12. The Open World
ü A Single Global Graph that everyone contributes to
ü
ü
ü
ü
ü
Great for data re-use
Global identities
Richness of data from multiple sources
Distributed: Can incrementally add to others descriptions
Fits with the WWW: The Data Web
Technically: If a statement is not asserted, then its truth-value is
unknown, rather than false.
Data:
Painting has X’s signature
Question:
Does the painting have Y’s signature?
Closed World: No
Open World:
I Don’t Know
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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13. The Open World: Global Identities
Jon publishes an Annotation about part of a web page.
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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14. The Open World: Global Identities
Brewster archives the page … and says where it is.
ü Without modifying
the annotation at all!
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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15. The Open World: Local Complexity
Ø Every assertion is considered true in all contexts
Q: How do we say that Canvas 2 comes after Canvas
1, and Canvas 3 comes after Canvas 2?
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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16. The Open World: Ordering
Did you think this?
Remember anyone can say anything, and it’s global…
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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17. The Open World: Ordering
Jane
Freya
Now there are two next links from Canvas 1, and our list is … a graph.
Use Case: Manuscript has different page order at different times
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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18. The Open World: Ordering
ORE introduces proxy nodes, as not just order is local.
Eg may wish to cite a resource in the context of a set of resources.
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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19. The Open World: Ordering
Shared Canvas uses multiple classes and the rdf:List construction.
Serializations hide the list’s anonymous nodes.
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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20. The Open World
Local identity for local context is good practice!
Think Globally
Identify Locally
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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21. Ontologies and Identities
ü Shared relationships increase interoperability
ü dc:title is ‘name’ or ‘label’, not property title or Dr.
ü Re-use of semantics makes it easier to build applications
ü Communities can develop own ontologies of relationships
independently
ü Shared Identity makes it possible for graph to merge
serendipitously
ü Everyone can mint own IDs using http URIs
ü By reusing ids, graphs will merge, creating new knowledge
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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22. Ontologies and Identities
Ø “The nice thing about … Ontologies … is that there’s
so many to choose from”
Ø Too many to choose from, hard to find the right one
Ø If almost right, do you reuse and hope for the best, or
specialize and create yet another ontology?
http://xkcd.com/927/
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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23. Ontologies and Identities
Ø “The nice thing about … Identities … is that there’s
so many to choose from”
Ø Far far too many to choose from, hard to find the right one
Ø As anyone can create identity for anything, they do
Ø Identity can have a contextual component – does LANL’s
identifier for Oppenheimer differ from DBPedia’s?
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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24. Ontologies and Identities
Standards! Communities!
House of Representatives from Huffington Post
http://www.flickr.com/photos/clydeorama/6693882429/
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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25. Serializations
ü The new JSON-LD format is pretty good
{!
"@context": "http://www.w3.org/ns/oa.json", !
"@id": "http://example.org/anno1", !
"@type": "oa:Annotation", !
"annotatedAt": "2012-11-10T09:08:07", !
"annotatedBy": {!
"@id": "http://public.lanl.gov/rsanderson#me", !
"@type": "foaf:Person", !
"name": "Rob Sanderson"!
}, !
“hasBody": {"chars": "This... is CNN.”}, !
“hasTarget": “http://www.cnn.com/”!
}!
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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26. Serializations
Ø The recommended RDF/XML is absolutely terrible
Ø “RDF/XML was the Semantic Web’s 3 Mile Island incident”
-- Manu Sporny, http://manu.sporny.org/2012/nuclear-rdf/
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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27. Communities
Building Community is hard!
• W3C Community Groups
• Funding
• Engagement not Argument
• Early Embedding
• Merge when possible
Path may be longer together, but it’s better
Linked Data in Practice: Building Standards and Communities
Yale Digital Collections Center, Nov 19 2013, New Haven CT, USA
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