ActiveAnnotations

ActiveAnnotations is a gem for modeling simple OpenAnnotation-compatible annotations to Rails. It is ActiveRecord compatible, but is backed by an RDF graph that serializes (by default) to JSON-LD.

• The source_uri and the serialized annotation are stored in ActiveRecord; other methods access the underlying graph.
• All attributes are optional.
• Target selectors are currently limited to time-based media fragments, but will be generalized in future iterations.
• If using v1.x of the rdf gem, all DateTime values must be in UTC to ensure proper serialization. This restriction does not apply to rdf >= 2.0.

Installation

Add this line to your application's Gemfile:

gem 'active_annotations'

And then execute:

$ bundle install

Run the install generator which will copy over the required migrations and run them:

$ rails generate active_annotations:install

Usage

note = ActiveAnnotations::Annotation.create
note.label = 'This is the annotation label'
note.annotated_by = 'https://github.com/mbklein/'
note.annotated_at = DateTime.now
note.content = 'The five boxing wizards jump quickly.'
note.source = thing # thing is expected to respond to :rdf_uri and :rdf_type
note.start_time = 3.5
note.end_time = 10.75
note.save

puts note.pretty_annotation

Output:

{
  "@context": "http://www.w3.org/ns/oa.jsonld",
  "@id": "urn:uuid:cac68351-a920-47d5-8c7c-9820e2f4d3bd",
  "@type": "oa:Annotation",
  "dcterms:creator": {
    "@id": "https://github.com/mbklein/",
    "@type": "foaf:Person"
  },
  "hasBody": {
    "@id": "urn:uuid:55cb5e7e-19bf-406c-9e4c-cc0ff9fd0689",
    "@type": [
      "dctypes:Text",
      "cnt:ContentAsText"
    ],
    "chars": "The five boxing wizards jump quickly."
  },
  "hasTarget": {
    "@id": "urn:uuid:7a5adf37-7bf2-45d4-ab0d-5a6b9aa2c6ad",
    "@type": "oa:SpecificResource",
    "hasSelector": {
      "@id": "urn:uuid:21331f24-e065-4c06-8c7f-b42a95c53721",
      "@type": "oa:FragmentSelector",
      "conformsTo": "http://www.w3.org/TR/media-frags/",
      "value": "t=3.5,10.75"
    },
    "hasSource": {
      "@id": "http://www.example.edu/thing/being/annotated",
      "@type": "dctypes:MovingImage"
    }
  },
  "label": "This is the annotation label",
  "dcterms:modified": {
    "@value": "2016-04-22T12:59:31Z",
    "@type": "xsd:dateTime"
  }
}

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/avalonmediasystem/active_annotations.

License

The gem is available as open source under the terms of the Apache License.