Annotation API Documentation

Owned by Jolan Wuyts
Last updated: Mar 15, 2024 by Hugo Manguinhas
10 min read

The Annotation API is allows users to search, obtain and contribute annotations about items in Europeana. Annotations are user-contributed or software-generated enhancements, additions or corrections to (or a selection of) metadata or content resources. We adopted the Web Annotation Data Model as a base model for the representation of annotations and as a format for exchanging annotations between client applications and the API, but also the Web Annotation Protocol as base protocol for the API.

 

 

The Annotation Data Model

What are annotations?

Annotations (in the Europeana context) are user-contributed or software-generated enhancements to (a selection of) metadata or content resource. The Annotations API adopted the Web Annotation Data Model (WADM) as a base model for representing and exchanging annotations between client applications and the API. The WADM is a W3C recommendation that describes a model and format to share annotations across different platforms.

Please note that, even though we have adopted WADM as underlying data model for this API, it is not expected that we support the full extent of the model. We thus advise to look at the EDM Annotations Profile which describes the basics of our implementation and, in particular, the section on Annotation Scenarios for a comprehensive list of the different kinds of annotations that we support.

Basics of the model

In WADM, an annotation is essentially a reified relation between two or more resources, typically a body and a target, and conveys that the body reflects what is intended to be said about the target. A body can also be absent to describe situations where a target is simply bookmarked. A target can represent a resource or just a part of it that is being annotated.

Being reified as a class enables an annotation to be further described with a motivation which expresses the reason why the annotation was created but also some provenance information such as the user that created the annotation and the software application that was used, as well as the times when it was initially created and sent to the API.

 

Field

Datatype

Description

Field

Datatype

Description

Annotation

@context

String (URL)

The URL of the JSON-LD context. (always with value "http://www.w3.org/ns/anno.jsonld")

id

String (URI)

The identifier of the Annotation. It is automatically generated unless a local identifier is specified upon creation.

type

String

The type of the resource. Always set to "Annotation".

created

String (DateTime)

The time at which the Annotation was created by the client application. It must be expressed in ISO8601 format and should have a timezone specified.

creator

Object (Agent)

The agent responsible for creating the Annotation. This may be either a human or software agent.

generated

String (DateTime)

The time at which the annotation was sent to the server.

generator

Object (Software)

The agent responsible for generating the Annotation. Typically a client application used to create the annotation.

motivation

String

Expresses the reason why the annotation was created. The value can be either "tagging", "linking" or "transcribing".

body

String or Object (Semantic Resource or Textual Body)

A body conveying what is intended to be said about the target. If the value is provided as a string, then it is interpreted as the URI and must only be used for the semantic tagging scenario. See the application scenarios section for more information.

bodyValue

String

A string conveying the tag text. This field must only be used in combination with "tagging" as motivation and when the language of the tag is not known. Otherwise, it is recommended to use the body field as defined in the Application Scenarios section.

target

String, Media Resource or Array (String)

The URL of the resource that is being annotated, or a specific resource in the case of media annotations. An array of URLs may also be set (mostly used for the object linking).

via

String

The URL of the annotation, if available in an external service.

Agent

An Agent can be either a Person or a Software. Typically the Person corresponds to the user that created the annotation while the Software reflects the client application that was used to create it. A Software can also create annotations if they result from an automatic process.

type

String

Either "Person" or "Software".

name

String

The name of the agent. Either the name of the user that created the annotation, or the name of the client software that was used to create it.

homepage

String

The homepage of the user or client application, if available.

Semantic Resource

A Semantic Resource is used whenever an external resource needs to be referenced as the body of the annotation. It is mostly used for Semantic Tagging.

type

String

Always "SpecificResource".

source

String (URI)

The URI of the resource being referred as body.

language

String (ISO639)

The ISO639 language code corresponding to the language of the resource.

Media Resource

Annotations that refer to a media resource require that an oa:SpecificResource object is defined so that the context in which the annotation was made is captured by the annotation. Besides context, a Specific Resource can be used to capture any additional information about how a target is used in the Annotation. The following table lists the properties supported by this class.

type

String

Always "SpecificResource".

source

String (URL)

The URL that identifies the media resource which is the ultimate target of the annotation.

scope

String (URI)

The unique identifier of the Europeana item to which this media resource is associated. In more general terms, scope is used to define the context in which the annotation was made, in terms of the resources that the annotator was viewing or using at the time.

 

 

 

 

 

 

 

 

 

SHOW A DYNAMIC EXAMPLE

Annotation Scenarios

 

The Annotations API supports different types of annotations. This page explains the types of annotations that are currently supported, providing examples on how to represent them in the API.

The examples used in this Section are shortened versions of the Annotation Model, you can find an example of a complete Annotation Data Model implementation here.

Simple tags (without language)

A simple tag is a short textual description of a resource. This scenario only applies when the language of the tag is not known, otherwise see the scenario described in the next Section.

Examples:

church
blue
black and white

Requirement:

A maximum of 64 characters is allowed for a simple tag. A tag cannot be a URL.

In the API:

Set the "motivation" to "tagging" and set the tag within the "bodyValue" field.

Availability:

Since version 0.2.1.

{ "motivation": "tagging", "bodyValue": "painting", "target": "http://data.europeana.eu/item/92062/BibliographicResource_1000126189360" }

Simple tags (with language)

A simple tag is a short textual description of a resource.

Examples:

church
blue
black and white

Requirement:

A maximum of 64 characters is allowed for a simple tag. A tag cannot be a URL and the language information must be specified.

In the API:

Set the "motivation" to "tagging" and set the tag within the "body" field as a Textual Body.

Availability:

Since version 0.2.1.

{ "motivation": "tagging", "body": { "type": "TextualBody", "value": "painting", "language": "en" }, "target": "http://data.europeana.eu/item/92062/BibliographicResource_1000126189360" }

Semantic tags

A semantic tag is a tag to a resource from a controlled vocabulary, making it machine-interpretable.

Example:

This object in Europeana is somehow related to France (http://sws.geonames.org/2988507).

Requirement:

Any URI is accepted as semantic resource. In the future, it will be limited to a controlled list of acceptable domains.

In the API:

Set the "motivation" to "tagging" and set as body the URI for the semantic resource taken from a contolled vocabulary.

Availability:

Since version 0.2.1.

{ "motivation": "tagging", "body": "http://sws.geonames.org/2988507", "target": "http://data.europeana.eu/item/09102/_UEDIN_214" }

An object link is a relationship between two (Europeana) objects. This relationship can be any.

Example:

This object in Europeana is (in some way) similar to this object.

Requirement:

An object link can only be made between two Europeana objects.

In the API:

Set the "motivation" to "linking" and set as target an array containing the URIs of both objects.

Availability:

Since version 0.2.1.

Geo Tags

A geo-tag adds a geographical location to an item.

Example:

This object in Europeana was located at latitude 52.081131 and longitude 4.324053. .

In the API:

Set the "motivation" to "tagging" and include the "type", "lat" and "long" attributes in the body as per the example below.

Availability:

Since version 0.2.2.

Annotating media resources

Annotating a media resource means that the target of the annotation is not the Europeana item but instead a specific media resource within that item.

In the API:

Set the "target" of the annotation to a JSON object with the "scope" holding the unique identifier of the Europeana item and the "source" field the URL of the actual media resource being annotated.

Availability:

Since version 0.2.8.

Transcriptions

A transcription is typically an annotation expressing a relation between an image and the text that is represented on that image. Besides the text, the annotation can also refer to a page where the text is displayed, like in the example below.

In the API:

Set the "motivation" to "transcribing" and apply the same criteria as for media resources.

Availability:

Since version 0.2.8.

Getting Started

Access keys

While this API is in an Alpha state you will need to use a separate API key (other than for the main Europeana REST API) to start using it. You can use the following keys:

Environment

Details

Environment

Details

Test

API key apidemo with user token tester1 (allows to create, update & remove annotations on behalf of a test user in the Annotations API test environment).

Production

API key apidemo (allows to search and retrieve annotations in the Annotations API production (live) environment).

Creating annotations in the production (live) environment is currently limited to only selected partners, this will be opened up as part of the Beta release.

Request

Every Annotations API call is an HTTP request in a specified format that is sent to the Annotations API service. The API root URLs for the two environments are located at:

https://test-annotations.europeana.eu/annotation (test)
https://www.europeana.eu/api/annotations (production)

Response

This API only supports the JSON-LD format, which is the Linked Open Data version of JSON (with the same syntax as JSON). The request and response format does not need to be passed along to the API, if not provided it will fallback to the default. You can provide the format either via the URL (extension) or via the "Accept" header. To specify the request and response format you can either do:

/search.jsonld?wskey=xxxxx&query=*:*

Or:

Request header: "Accept: application/ld+json"
/search?wskey=xxxxx&query=*:*

Retrieving annotations

Retrieve annotations by their identifier.

GET /{provider}/{identifier}

Response

See data model for more information on the representation of an annotation.

Discovery

Search for annotations.

GET /search

Request

Search and Facet fields

The following table shows the fields that can be used for searching annotations and the ones that can be used for faceting:

Response

Provision

Using the PUT/POST/DELETE methods for this API is currently not publicly available.. You can request access to the write methods by emailing us with your use case.

Create

The API has a generic method available for the creation of annotations. The creation method expects a body payload in the request with the full annotation. Alternatively you can provide this information as part of the body parameter.

POST http://annotations.europeana.eu/annotation/

Request

Response

For more examples and information on the data model for an annotation, see data model.

Update

Update the contents of an annotation. For this you can send a PUT request to the ID of the annotation. You can only update the annotations you have created yourself.

PUT /base/1

Request

You can provide the same content in the Update method as you’d provide for the Create method. Note that you have to provide the full annotation body, you currently cannot update parts of the annotation.

Response

Delete

Delete an annotation. You can send a DELETE HTTP request using the ID of the annotation. You can only delete the annotations you have created yourself. Deletion means the annotation will not be available anymore for search, and only available for retrieval based on the ID of the annotation.

DELETE /base/1

Request

Response

Console

Roadmap and Changelog

The current version of the Annotations API is 0.3.3 (August 2022). It is currently available as a Public Alpha, which is the first public version released primarily to get feedback from you. Do note that this means that changes can be introduced which could break backwards compatibility. It also means that to use this API you need a separate API key than for the other Europeana APIs. To see the changes made for the current version and also all previous releases, see the API changelog in the project GitHub.

Credits

This API was initially developed as part of the Europeana Sounds project. It's development has been carried out by the AIT Austrian Institute of Technology in cooperation with the Europeana Foundation.