Triannon

Store Open Annotation RDF in Fedora4 to support the Linked Data for Libraries use cases.

Installation into Your Existing Rails Application

Add this line to your Rails application's Gemfile

gem 'triannon'

Then install the gems:

$ bundle install

Then run the triannon generator:

$ rails g triannon:install

Edit the config/triannon.yml file:

• ldp: Properties of LDP server
  • url: the baseurl of LDP server
  • uber_container: name of an LDP Basic Container holding specific anno containers
  • anno_containers: (the names of LDP Basic Containers holding individual annos)
• solr_url: Points to the baseurl of Solr instance configured for Triannon
• triannon_base_url: Used as the base url for all annotations hosted by your Triannon server. Identifiers from the LDP server will be appended to this base-url. Generally something like "https://your-triannon-rails-box/annotations", as "/annotations" is added to the path by the Triannon gem

Generate the root annotations containers on your LDP server:

$ rake triannon:create_root_containers

This will generate the uber_container and the anno_containers (aka 'root containers') under the uber_container.

NOTE: you MUST create the root containers before creating any annotations. All annotation MUST be created as a child of a root container.

Set up caching for jsonld context documents:

• by using Rack::Cache for RestClient:

  • add to Gemfile:

gem 'rest-client'
gem 'rack-cache'
gem 'rest-client-components'

• bundle install

• create config/initializers/rest_client.rb

require 'restclient/components'
require 'rack/cache'
RestClient.enable Rack::Cache,
  metastore: "file:#{Rails.root}/tmp/rack-cache/meta",
  entitystore: "file:#{Rails.root}/tmp/rack-cache/body",
  default_ttl:  86400, # when to recheck, in seconds (daily = 60 x 60 x 24)
  verbose: false

Client Interactions with Triannon

Get a list of annos

as a IIIF Annotation List (see http://iiif.io/api/presentation/2.0/#other-content-resources)

• GET: http://(host)/annotations/search?targetUri=some.url.org

Search Parameters:

• targetUri - matches URI for target, with or without http or https scheme prefix
• bodyUri - matches URI for target, with or without http or https scheme prefix
• bodyExact - matches body characters exactly
• bodyKeyword - matches terms in body characters

• motivatedBy - matches fragment part of motivation predicate URI, e.g. commenting, tagging, painting

• use HTTP Accept header with mime type to indicate desired format

  • default: jsonld
  • Accept: application/ld+json
  • also supports turtle, rdfxml, json, html
  • Accept: application/x-turtle

Get a list of annos in a particular root container

as a IIIF Annotation List (see http://iiif.io/api/presentation/2.0/#other-content-resources)

• GET: http://(host)/annotations/(root container name)/search?targetUri=some.url.org

Search Parameters as above.

• use HTTP Accept header with mime type to indicate desired format
  • default: jsonld
  • Accept: application/ld+json
  • also supports turtle, rdfxml, json, html
  • Accept: application/x-turtle

Get a particular anno

GET: http://(host)/annotations/(root container)/(anno_id)

NOTE: you may need to URL encode the anno_id (e.g. "6f%2F0e%2F79%2F92%2F6f0e7992-83f5-4f31-8bb7-94a23465fdfb" instead of "6f/0e/79/92/6f0e7992-83f5-4f31-8bb7-94a23465fdfb"), particularly from a web browser.

• use HTTP Accept header with mime type to indicate desired format
  • default: jsonld
  • indicate desired context url in the HTTP Accept header thus:
    • Accept: application/ld+json; profile="http://www.w3.org/ns/oa-context-20130208.json"
    • Accept: application/ld+json; profile="http://iiif.io/api/presentation/2/context.json"
  • also supports turtle, rdfxml, json, html
  • indicated desired context url for jsonld as json in the HTTP Link header thus:
    • Accept: application/json
    • Link: http://www.w3.org/ns/oa.json; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"
    • note that the "type" part is optional and refers to the type of the rel, which is the reference for all json-ld contexts.
  • see https://github.com/sul-dlss/triannon/blob/master/app/controllers/triannon/annotations_controller.rb #show method for mime formats accepted

JSON-LD context

You can request IIIF or OA context for jsonld.

The correct way:

• use HTTP Accept header with mime type and context url:
  • Accept: application/ld+json; profile="http://www.w3.org/ns/oa-context-20130208.json"
  • Accept: application/ld+json; profile="http://iiif.io/api/presentation/2/context.json"

You can also use either of these methods (with the correct HTTP Accept header):

• GET: http://(host)/annotations/iiif/(anno_id)

• GET: http://(host)/annotations/(anno_id)?jsonld_context=iiif

• GET:http://(host)/annotations/oa/(anno_id)

• GET: http://(host)/annotations/(anno_id)?jsonld_context=oa

Note that OA (Open Annotation) is the default context if none is specified.

Create an anno

POST: http://(host)/annotations/(root container)

• the body of the HTTP request should contain the annotation, as jsonld, turtle, or rdfxml
  • Wrap the annotation in an object, as such:
  • { "commit" => "Create Annotation", "annotation" => { "data" => oa_jsonld } }
• the Content-Type header should be the mime type matching the body
• the anno to be created should NOT already have an assigned @id
• to get a particular format back, use the HTTP Accept header
  • to get a particular context for jsonld, do one of the following:
  • Accept: application/ld+json; profile="http://www.w3.org/ns/oa-context-20130208.json"
  • Accept: application/ld+json; profile="http://iiif.io/api/presentation/2/context.json"
  • to get a particular jsonld context for jsonld as json, specify it in the HTTP Link header thus:
  • Accept: application/json
  • Link: http://www.w3.org/ns/oa.json; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"
    • note that the "type" part is optional and refers to the type of the rel, which is the reference for all json-ld contexts.

Delete an anno

DELETE: http://(host)/annotations/(root container)/(anno_id)

NOTE: you may need to URL encode the anno_id (e.g. "6f%2F0e%2F79%2F92%2F6f0e7992-83f5-4f31-8bb7-94a23465fdfb" instead of "6f/0e/79/92/6f0e7992-83f5-4f31-8bb7-94a23465fdfb")

Running This Code in Development

There is a bundled rake task for running triannon in a test rails application, but there is some one-time set up.

One time setup

Set up the testing Rails app that uses triannon gem

$ rake engine_cart:generate # (first run only)

Set up a local instance of Fedora4 and Solr

$ rake jetty:download
$ rake jetty:unzip
$ rake jetty:environment
$ rake triannon:jetty_config

triannon:jetty_config task does the following:

• turns off basic authorization in Fedora4
• sets up a Triannon flavored Solr core

Start jetty

$ rake jetty:start

Note that jetty can be very sloooooooow (a couple of minutes) to start up with Fedora and Solr.

Check if Solr and Fedora are up

Go to

• http://localhost:8983/solr/#/triannon - Solr admin GUI page, you should not see any error text in your browser
• http://localhost:8983/solr/triannon/select - actual Solr query; should give http status other than 200 if there is a problem

Go to

• http://localhost:8983/fedora/rest/ - you should see a fedora object.

If all is not well for Fedora or Solr, try:

$ rake triannon:jetty_reset

This stops jetty, cleans out the jetty directory, recreates it anew from the download, configures jetty for Triannon, and starts jetty. It may take a long time (a couple of minutes) for jetty to restart.

Then check the Solr and Fedora urls again.

Generate root annotations containers in Fedora

After you ensure that Fedora is running, you need to create the root anno containers using the configuration of test rails app created by engine_cart:

$ cd spec/internal
$ rake triannon:create_root_containers
$ cd ../..

Configure spec/internal/config/triannon.yml as specified above

NOTE: You probably won't need to change this file - it will work with the jetty setup provided.

$ vi spec/internal/config/triannon.yml

Run the testing Rails application

$ rake jetty:start  # if it isn't still running
$ rake triannon:server
$ <cntl + C> # to stop Rails application
$ rake jetty:stop # to stop Fedora and Solr

The app will be running at localhost:3000, with root containers "foo" and "blah" available (and empty).

Running the Tests

Run tests:

$ rake spec