RDF by Example: rdfpuml for True RDF Diagrams, rdf2rml for R2RML Generation

Motivation
- Simple Example: Getty CONA: Object Discovery
- Simple Example: Generated PlantUML
Diagram Features
Examples: Getty CONA: Contribs and Sources
R2RML Generation
- Getty Museum: Exhibitions Model
- Getty Museum: Museum Object
Future Work

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:

ReificationClass	subjectProp	shortcutProp	objectProp	prop (shortcut)
rdf:Statement	rdf:subject	rdf:predicate	rdf:object	any prop
crm:E13_Attribute _Assignment	crm:P140_assigned _attribute_to	crmx:property	crm:P141_assigned	any CRM prop
crm:E14_Condition _Assessment	crm:P34_concerned	crmx:property	crm:P35_has_identified	crm:P44_has_condition
crm:E15_Identifier _Assignment	crm:P140_assigned _attribute_to	crmx:property	crm:P37_assigned, crm:P38_deassigned	crm:P1_is_identified_by, crm:P102_has_title
crm:E16_Measurement	crm:P39_measured	crmx:property	crm:P40_observed _dimension	crm:P43_has_dimension
crm:E17_Type _Assignment	crm:P41_classified	crmx:property	crm:P42_assigned	crm:P2_has_type or subprop

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

exhibitions.r2rml.png

Getty Exhibitions: Relational Data

constituents

constituentid	constituent
1	'Getty Museum'
2	'MoMA'
3	'LACMA'

exhibitions

exhibitionid	exhdepartment	exhtitle	displaydate	beginisodate	endisodate
123	53	'Getty through the ages'	'October 2016'	'2016-10-01'	'2016-10-30'

exhvenuesxrefs

exhvenxref	exhid	conid	conaddrid	approved	dispord	displaydate	beginisodate	endisodate
202	123	2	102	1	1	'Early Oct 2016'	'2016-10-01'	'2016-10-15'
203	123	3	103	1	2	'Late Oct 2016'	'2016-10-16'	'2016-10-30'

exhvenobjxrefs

exhvenuexrefid	objectid	catalognumber	begindispldateiso	enddispldateiso	displayed
202	1001	'cat 1001'	'2016-10-01'	'2016-10-15'	1
203	1001	'cat 1001'	'2016-10-16'	'2016-10-30'	1
202	1002	'cat 1002'	'2016-10-01'	'2016-10-15'	1