Motivation

RDF is a graph data model:

• The best way to understand RDF data schemas (ontologies, application profiles, RDF shapes) is with a diagram.
• Many RDF visualization tools exist, but they either
  • Focus on large graphs (where the details are not easily visible), or
  • Visualization results are not satisfactory, or
  • Manual tweaking of the diagrams is required

Developed a tool rdfpuml that makes true diagrams directly from Turtle examples

• Uses PlantUML and GraphViz

Benefits:

• Guarantees consistency between said (triple statements) and shown (diagram)
• Lets you focus on domain modeling rather than diagram layouting/tweaking
• Enables efficient source control
• Saves you lots of effort

Simple Example: Getty CONA: Object Discovery

Source Turtle (puml: are diagram control triples, explained further)

cona:456-thing crm:P12i_was_present_at cona:456-discovery-123.
cona:456-discovery-123 a crmx:Discovery;
  crm:P2_has_type <cona/production/discovery>;
  crm:P4_has_time-span cona:456-discovery-123-date.
cona:456-discovery-123-date a crm:E52_Time-Span;
  crm:P82a_begin_of_the_begin "1800"^^xsd:gYear;
  crm:P82b_end_of_the_end "1850"^^xsd:gYear.
########################################
<cona/production/discovery> a puml:Inline.

Simple Example: Generated PlantUML

Takes care of many hairy details, eg node name sanitization, collecting property names & values, inlining, Reification/Association, replacing () with [] (puml quirk)…

@startuml
hide empty methods
hide empty attributes
hide circle
skinparam classAttributeIconSize 0
class cona_456_discovery_123 as "cona:456-discovery-123"
cona_456_discovery_123 : a crmx:Discovery
class cona_456_discovery_123_date as "cona:456-discovery-123-date"
cona_456_discovery_123 --> cona_456_discovery_123_date : crm:P4_has_time-span
cona_456_discovery_123 : crm:P2_has_type cona:production/discovery
cona_456_discovery_123_date : a crm:E52_Time-Span
cona_456_discovery_123_date : crm:P82a_begin_of_the_begin "1800"^^xsd:gYear
cona_456_discovery_123_date : crm:P82b_end_of_the_end "1850"^^xsd:gYear
class cona_456_thing as "cona:456-thing"
cona_456_thing --> cona_456_discovery_123 : crm:P12i_was_present_at
@enduml

Diagram Features

Diagram readability is a prime concern. Some measures:

• Shorten URLs aggressively. Some prefixed names you see in the diagram are not valid Turtle
• Sort properties by name (rdf:type comes first)
• Show literal types, use Turtle shortcuts (eg 1 instead of "1"^^xsd:integer)
• Collect property values together; collect "parallel" properties together
• Inlining: show object in the subject node, not as separate node
  • Types and literals are inlined automatically

  • Inline resource (optional label): used often for lookup values

    <cona/event/competition> a puml:Inline.
    cona_contrib:10000000 a puml:Inline; rdfs:label "VP".
    
    

  • Inline property: show all objects of a property inlined

    fn:annotationSetFrame a puml:InlineProperty. 
    
    

• Namespace puml: used for diagram control (usually written after ####)
  • Follows Dan Connolly's approach Circles and arrows diagrams using stylesheet rules (W3C 2005)

Collect "Parallel" Property Names

• Multiple property instances between nodes are collected in one arrow and shown as several labels
• Inverse arrows work fine

Arrow Customization

Customize arrow for one relation or all prop instances

<subj> puml:$dir-$head-$line <obj> .
<prop> puml:arrow puml:$dir-$head-$line .

• $dir: left, right, up, down (default)
• $head: none="", tri="|>", star="*", o="o" (default=normal arrow)
• $line: dashed (default is solid)
• Each part is optional. Example:

cona:456-production puml:left cona:456-motivation-123.

Stereotypes and Colored Circles

Stereotype: UML lingo for «guillemetted name» and colored circle.

• Set on individual node or whole class

iso:ThesaurusArray puml:stereotype "(A,red)".
gvp:GuideTerm      puml:stereotype "(G,green)".
gvp:Concept        puml:stereotype "(C,lightblue)".

Reification

• <s> <p> <o> represented as node with 3 addressing props plus extra data

<node> a <ReificationClass>;
  <subjectProp>  <s>;
  <shortcutProp> <p>;
  <objectProp>   <o>;
  # extra data, eg dct:created, dct:creator

• RDF Reification is used most often (rdf:Statement)
• CIDOC CRM (with extension crmx:property or bmo:PX_property)
• Property Reification Vocabulary allows us to express this data formally:

Reification Nodes

• Automatically discover reifications as per the previous table and make PlantUML Association Class
• Show addressing properties with arrows (← : →) pointing to the subject, shortcut, object
• Limit: no more than 2 reifications per relation (and the second one is ugly). So use puml:noReify to avoid making reification

Examples: Getty CONA: Contribs and Sources

Aggressive URL shortening, collecting multiple values, value comments

Getty CONA: Iconographic Authority

Arrow direction, reification

American Art Collaborative: Mapping Museum Data to CIDOC CRM

One option how to map "cast after" (from the same mold)

FRBRoo: Don Quixote Example (Europeana EFAP Task Force)

EHRI: Person Network

Jewish social networks: CIDOC CRM and AgRelOn

Multisensor: Video Annotation & Text Annotation (NIF)

Multisensor: Social Network Analysis

Global influence and reachability

Multisensor: Image Annotation with OpenAnnotation+FISE

FISE (Stanbol) is used to express Confidence

Multisensor: News Item and its Translation

Stereotypes (circle, «italic»), arrow direction

Multisensor: FrameNet Embedded in NIF

Made with PlantUML "by hand", not rdfpuml. Uses PlantUML Packages

Multisensor: FrameNet+NIF (Part 1)

Multisensor: FrameNet+NIF (Part 2)

OpenAnnotation: Example 44

Blank nodes, RDF lists

Duraspace PCDM Metadata

• Portland Common Data Model for diglib metadata (Fedora, Islandora..)
• Reference Diagrams made by hand, takes a lot of time (eg Postcard)
• Proposed diagrams with rdfpuml (tracked as duraspace/pcdm#46)

Video Annotation: LinkedTV NISV Use Case

Video Annotation: Generated Diagram

ICIJ Offshore Leaks (RDF by Ontotext)

Offshore Leaks Evolution

Model is evolving as we unravel more of the data (github "image diff")

R2RML Generation

R2RML is the W3C standard for RDBMS->RDF conversion

• It is quite verbose and requires semantic experience to write
• What if we could describe RDBMS mapping in our examples?
• We can: include SQL queries and embedded field names

rdf2rdb generates R2RML transformations from examples:

• Saves about 15x in complexity
• Ensures consistency of model and actual conversion

Getty Museum: Exhibitions Model

Getty Exhibitions: Generated R2RML

Getty Exhibitions: Relational Data

constituents

exhibitions

exhvenuesxrefs

exhvenobjxrefs

Getty Exhibitions: Converted RDF Data

Getty Museum: Museum Object

Future Work

R2RML works great for RDBMS, but how about other sources?

Working to extend rdf2rml to generate:

• RML: extends R2RML to handle RDB, XML, JSON, CSV
• XSPARQL: extends XQuery with SPARQL construct and JSON input
• tarql: handles TSV/CSV with SPARQL construct

ClinicalTrials.gov: Clinical Study Results (XML)

Dun & Bradstreet (Fix-Width) to Fin. Ind. Business Ontology

Global Legal Entity Indentifier (XML) to FIBO

Farther Future

• Modularize & package better
• Integrate in Emacs org-mode: write Turtle, see diagram
• Extend RDF by Example to describe & generate RDF Shapes
• Another tool to visualize RDF Shapes (SHACL and Shex)