Annotation API Documentation

Owned by Jolan Wuyts
Last updated: Oct 02, 2024 by Hugo Manguinhas
11 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 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 is expressed in ISO8601 format with a timezone specified.

creator

Object (Agent)

The agent responsible for creating the Annotation. This may be either a human or software agent and is always determined by the user information present in the JWT token used upon creation.

generated

String (DateTime)

The time at which the annotation was sent to the server. It is expressed in ISO8601 format with a timezone specified.

generator

Object (Software)

The agent responsible for generating the Annotation. The client application used to submit the annotation to the server and is always determined by the client information present in the JWT token used upon creation.

motivation

String

Expresses the reason why the annotation was created. Depending on the application scenario, the value can one of the following: "tagging", "linking", "describing", “highlighting“, “transcribing“, “translating“, “captioning“, “subtitling“, “linkForContributing“

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, Array (String), Media Resource or Array (Media Resource)

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).

User Agent

A user agent typically responsible for creating the annotation.

id

String

The unique identifier of the user. This identififer is obained from the JWT token used upon creation.

type

String

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

Software Agent

A client application or software typically responsible for generating the annotation on behalf of the user. A software can also create annotations if they result from an automatic process.

id

String

The identifier of the client application. This identififer is obained from the JWT token used upon creation.

type

String

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

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

Application Scenarios

Because annotations are a very flexible construct, in theory, any kind of information could be represented as an annotation. However, to guarantee consistency of the annotations and their proper display or reuse, a range of “use cases” for annotations were identified, modelled and implemented which we call application scenarios. This list can grow as new and relevant use cases are identified and proposed for adoption.

This section explains all the application scenarios that are presently supported with examples on how they are represented in the API.

The examples used in this Section are shortened versions of the Annotation Model which exclude administrative fields such as created, creator, generated, generator, you can find an example of a complete Annotation Data Model implementation here.

1. Tagging (without language)

A tag is a short textual label for a resource. It can be used to e.g. classify or name a resource. This scenario only applies when the language of the tag is not known, otherwise see the scenario described in the next Section.

Annotation

motivation

tagging

bodyValue

The short text of the tag. It typically contains a single word or expression

target

The URL of the Item

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

2. Tagging (with language)

A language tag is a short textual label for a resource that is qualified with a language. Similarly as the previous scenario, language qualified tags can be used to name or classify a resource.

Annotation

motivation

tagging

body

A TextualBody as the body of the annotation with the tag as the value of value field and the respective language indicated in language field

target

The URL of the Item

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

3. Semantic tagging

An annotation of a CHO with a semantic tag. A semantic tag is a tag from a controlled (linked data) vocabulary such as VIAF or AAT. As any other tag, semantic tags are typically used to classify a resource with the benefit of bring extra information to the annotation as the result of being a linked data resource.

Annotation

motivation

tagging

body

The URL of the semantic resource being used to tag the item

target

The URL of the Item

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

4. Geospatial tagging witch coordinates

An annotation of a CHO with a location given in geospatial coordinates (latitude, longitude, and optionally altitude). In addition, there can be a label expressing the name or address of the location.

Annotation

motivation

tagging

body

A resource of type Place that follows the EDM guidelines for Places. Some of the properties that may be present are: latitude, longitude, altitude, prefLabel or altLabel when appropriate.

target

The URL of the Item

5. Geospatial tagging with an address

An annotation of a CHO with a location given in geospatial coordinates (latitude, longitude, and optionally altitude). In addition, there can be a label expressing the name or address of the location.

Annotation

motivation

tagging

body

A resource of type Place that follows the EDM guidelines for Places. Some of the properties that may be present are: latitude, longitude, altitude, prefLabel or altLabel when appropriate.

target

The URL of the Item

Object links

Object links

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.

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

Roadmap and Changelog

We deploy new versions of this API quite regularly. 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. 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.