Ontology¶

OWL ontology definitions for Blacklake semantic metadata.

Overview¶

The Blacklake ontology defines the semantic model for data objects, commits, and relationships using OWL (Web Ontology Language).

Namespace Definitions¶

@prefix bl: <https://sempervent.github.io/blacklake/ns#> .
@prefix dct: <http://purl.org/dc/terms/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

Core Classes¶

Object Class¶

bl:Object a owl:Class ;
  rdfs:subClassOf dct:Dataset ;
  rdfs:label "Blacklake Object" ;
  rdfs:comment "A content-addressable object in the Blacklake system" .

Commit Class¶

bl:Commit a owl:Class ;
  rdfs:label "Blacklake Commit" ;
  rdfs:comment "A commit in the Blacklake version control system" .

Repository Class¶

bl:Repository a owl:Class ;
  rdfs:label "Blacklake Repository" ;
  rdfs:comment "A Blacklake repository containing objects and commits" .

Object Properties¶

Content Properties¶

bl:checksum a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:string ;
  rdfs:label "Checksum" ;
  rdfs:comment "The cryptographic hash of the object content" .

bl:algo a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:string ;
  rdfs:label "Algorithm" ;
  rdfs:comment "The hash algorithm used to compute the checksum" .

Relationship Properties¶

bl:author a owl:ObjectProperty ;
  rdfs:domain bl:Object ;
  rdfs:range foaf:Agent ;
  rdfs:subPropertyOf dct:creator ;
  rdfs:label "Author" ;
  rdfs:comment "The author of the object" .

bl:hasObject a owl:ObjectProperty ;
  rdfs:domain bl:Repository ;
  rdfs:range bl:Object ;
  rdfs:label "Has Object" ;
  rdfs:comment "Relates a repository to its objects" .

bl:hasCommit a owl:ObjectProperty ;
  rdfs:domain bl:Repository ;
  rdfs:range bl:Commit ;
  rdfs:label "Has Commit" ;
  rdfs:comment "Relates a repository to its commits" .

Data Properties¶

Dublin Core Properties¶

bl:title a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:string ;
  rdfs:subPropertyOf dct:title ;
  rdfs:label "Title" ;
  rdfs:comment "The title of the object" .

bl:description a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:string ;
  rdfs:subPropertyOf dct:description ;
  rdfs:label "Description" ;
  rdfs:comment "A description of the object" .

bl:format a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:string ;
  rdfs:subPropertyOf dct:format ;
  rdfs:label "Format" ;
  rdfs:comment "The MIME type of the object" .

bl:size a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:integer ;
  rdfs:subPropertyOf dct:extent ;
  rdfs:label "Size" ;
  rdfs:comment "The size of the object in bytes" .

Temporal Properties¶

bl:created a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:dateTime ;
  rdfs:subPropertyOf dct:created ;
  rdfs:label "Created" ;
  rdfs:comment "The creation date of the object" .

bl:modified a owl:DatatypeProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:dateTime ;
  rdfs:subPropertyOf dct:modified ;
  rdfs:label "Modified" ;
  rdfs:comment "The last modification date of the object" .

Object Relationships¶

Inheritance Hierarchy¶

graph TD
    THING[owl:Thing] --> RESOURCE[dct:Resource]
    RESOURCE --> DATASET[dct:Dataset]
    DATASET --> OBJECT[bl:Object]

    THING --> AGENT[foaf:Agent]
    AGENT --> PERSON[foaf:Person]
    AGENT --> ORGANIZATION[foaf:Organization]

    THING --> COMMIT[bl:Commit]
    THING --> REPOSITORY[bl:Repository]

Object Relationships¶

graph TD
    REPO[Repository] --> OBJECT[Object]
    REPO --> COMMIT[Commit]
    OBJECT --> AUTHOR[Agent]
    COMMIT --> AUTHOR
    COMMIT --> TREE[Tree Object]
    TREE --> OBJECT

Property Restrictions¶

Functional Properties¶

bl:checksum a owl:FunctionalProperty ;
  rdfs:domain bl:Object ;
  rdfs:range xsd:string .

Inverse Properties¶

bl:hasObject a owl:ObjectProperty ;
  owl:inverseOf bl:isObjectOf .

bl:isObjectOf a owl:ObjectProperty ;
  rdfs:domain bl:Object ;
  rdfs:range bl:Repository ;
  rdfs:label "Is Object Of" ;
  rdfs:comment "Relates an object to its repository" .

Transitive Properties¶

bl:partOf a owl:ObjectProperty ;
  rdfs:domain bl:Object ;
  rdfs:range bl:Object ;
  owl:TransitiveProperty ;
  rdfs:label "Part Of" ;
  rdfs:comment "Relates an object to its parent object" .

Data Type Definitions¶

Custom Data Types¶

bl:SHA256Hash a owl:Datatype ;
  rdfs:subClassOf xsd:string ;
  rdfs:label "SHA-256 Hash" ;
  rdfs:comment "A SHA-256 hash value" .

bl:MIMEType a owl:Datatype ;
  rdfs:subClassOf xsd:string ;
  rdfs:label "MIME Type" ;
  rdfs:comment "A MIME type identifier" .

Enumeration Values¶

bl:HashAlgorithm a owl:Class ;
  rdfs:label "Hash Algorithm" ;
  rdfs:comment "Supported hash algorithms" .

bl:sha256 a bl:HashAlgorithm ;
  rdfs:label "SHA-256" ;
  rdfs:comment "SHA-256 hash algorithm" .

bl:sha1 a bl:HashAlgorithm ;
  rdfs:label "SHA-1" ;
  rdfs:comment "SHA-1 hash algorithm" .

Axioms and Rules¶

Object Axioms¶

bl:Object a owl:Class ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:checksum ;
    owl:cardinality 1
  ] ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:algo ;
    owl:cardinality 1
  ] .

Commit Axioms¶

bl:Commit a owl:Class ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:hasTree ;
    owl:cardinality 1
  ] ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:hasParent ;
    owl:minCardinality 0
  ] .

Ontology Diagram¶

graph TB
    subgraph "Blacklake Ontology"
        OBJECT[bl:Object]
        COMMIT[bl:Commit]
        REPO[bl:Repository]
        AGENT[foaf:Agent]
        PERSON[foaf:Person]
        ORG[foaf:Organization]
    end

    subgraph "Dublin Core"
        DATASET[dct:Dataset]
        RESOURCE[dct:Resource]
    end

    subgraph "Properties"
        CHECKSUM[bl:checksum]
        ALGO[bl:algo]
        AUTHOR[bl:author]
        HAS_OBJECT[bl:hasObject]
        HAS_COMMIT[bl:hasCommit]
    end

    OBJECT --> DATASET
    DATASET --> RESOURCE

    AGENT --> PERSON
    AGENT --> ORG

    OBJECT --> CHECKSUM
    OBJECT --> ALGO
    OBJECT --> AUTHOR

    REPO --> HAS_OBJECT
    REPO --> HAS_COMMIT

    HAS_OBJECT --> OBJECT
    HAS_COMMIT --> COMMIT

    AUTHOR --> AGENT

Usage Examples¶

Object Definition¶

bl:obj:sha256:abc123... a bl:Object ;
  bl:checksum "abc123..." ;
  bl:algo "sha256" ;
  bl:title "Sales Data 2024" ;
  bl:description "Q1-Q4 sales data" ;
  bl:format "text/csv" ;
  bl:size 1024000 ;
  bl:created "2024-01-15T10:30:00Z"^^xsd:dateTime ;
  bl:author [
    a foaf:Person ;
    foaf:name "Data Team" ;
    foaf:mbox <mailto:data@company.com>
  ] .

Commit Definition¶

bl:commit:sha256:def456... a bl:Commit ;
  bl:title "Add sales data" ;
  bl:description "Added Q1-Q4 sales data with metadata" ;
  bl:created "2024-01-15T10:30:00Z"^^xsd:dateTime ;
  bl:author [
    a foaf:Person ;
    foaf:name "Data Team" ;
    foaf:mbox <mailto:data@company.com>
  ] ;
  bl:hasTree bl:tree:sha256:ghi789... ;
  bl:hasParent bl:commit:sha256:jkl012... .

Validation Rules¶

Object Validation¶

bl:Object a owl:Class ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:checksum ;
    owl:cardinality 1
  ] ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:algo ;
    owl:cardinality 1
  ] ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty dct:title ;
    owl:cardinality 1
  ] .

Commit Validation¶

bl:Commit a owl:Class ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:hasTree ;
    owl:cardinality 1
  ] ;
  owl:equivalentClass [
    a owl:Restriction ;
    owl:onProperty bl:author ;
    owl:cardinality 1
  ] .

Next Steps¶

Metadata Model - Understanding the metadata model
JSON-LD - JSON-LD processing
SHACL - Data validation