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Images

The following documents the way Prov4ITData modelled the resources from different service providers (i.e. Flickr, Imgur, Google).

Their toolchain is extensible to a wide variety of services. They opted to initially support Flickr and Imgur. Both services share a common purpose: uploading and sharing image-content. However, despite this commonality, they differ in various aspects such as the underlying data model and how the resources should be accessed. Additionally, we support the Google People API. This latter connector has a similar access method to Imgur (JSON Web API via OAuth 2.0), but contains data in a very different data model.

There are four different resources to model

  • A single Image resource
  • An Image Gallery that contains Image resources
  • A Collection that contains Image Gallery resources
  • A contact person

Schema.org

Image

Images can be mapped to schema:ImageObject-resources, which inherits properties from schema:MediaObject that can be used for describing the height, width, and more.

Image Gallery

An Image Gallery can be represented using schema:ImageGallery. Furthermore, the images it contains can be linked using the schema:hasPart property.

Collection

A Collection can be modeled through a schema:Collection, which can be linked to its Image Gallery resources through the schema:hasPart property.

DCAT

Image

We can model an Image as a dcat:Distribution.

dcat:Distribution A specific representation of a dataset. A dataset might be available in multiple serializations that may differ in various ways, including natural language, media-type or format, schematic organization, temporal and spatial resolution, level of detail or profiles (which might specify any or all of the above).

The dcat:Distribution class has the following properties

  • title
  • description
  • issued: date of issuance (e.g publication)
  • dcat:accessURL SHOULD be used for the URL of a service or location that can provide access to this distribution, typically through a Web form, query or API call.
  • dcat:downloadURL is preferred for direct links to downloadable resources.
  • dcat:mediaType: The media type of the distribution as defined by IANA
  • dct:format: The file format of the distribution.
  • dcat:accessService, pointing to a dcat:DataService
Image gallery

We can model an Image Gallery as a dcat:Dataset, which can point to zero or more dcat:Distributions.

Collection

[DCAT] contains a dcat:Catalog class, a curated collection of metadata about resources (e.g., datasets and data services in the context of a data catalog). A dcat:Catalog can be linked to zero or more dcat:Datasets.

Flickr

Flickr is an online photo management and sharing application. Its resources are made available through the [Flickr API][Flickr-API]. Flickr follows the [OAuth1.0a] protocol which requires that requests to protected resources are signed using the Consumer Secret and Token Secret. By specifying the protocol in the [RML Mapping][RML-mapping] the [RMLMapper-JAVA] takes care of the necessary steps for creating requests to protected resources. This also contributes to the extensibility of our solution: when a service decides to change to another protocol, only changes to the [RML Mapping][RML-mapping] must be made. Hence, avoiding the need for rebuilding code.

Using Schema.org

  • A Flickr Photo resource can be mapped to a schema:ImageObject.
  • A Flickr Photoset resource can be mapped to instances of schema:ImageGallery. The table below shows how its properties are mapped.
  • A Flickr Collection, which can contain Albums/Photosets, can be mapped using the schema:Collection class. The table below shows how its properties are mapped.
Flickr Photoset resource schema:ImageGallery
id schema:identifier
title._content schema:name
description._content schema:description
Flickr Collection resource schema:Collection
id schema:identifier
title schema:name
description schema:description

Using DCAT

  • An image resource can be modeled by a dcat:Distribution
  • A Flickr Album can contain image resources
  • A Flickr Collection can contain Flickr Albums, which contain image resources. Therefore, a Flickr Collection can be modeled by a dcat:Catalog which can be linked to zero or more dcat:Datasets (Albums)

Imgur

Imgur, an image hosting and sharing website, enables its users to quickly upload and share images and GIFs on social media platforms (e.g. Reddit, Twitter, etc.). Unlike the Flickr API, the [Imgur API][Imgur-API] uses OAuth 2.0. When making requests for protected resources it suffices to add a bearer token to the HTTP headers.

The data fields mapped from the Imgur image resources are

  • id: a unique identifier for that image
  • link: the URL to the image
  • description: the description of the image
  • views: the number of views
  • height: height of the image
  • width: width of the image

Using Schema.org

An Imgur image can be mapped to a schema:ImageObject, along with the following properties:

Imgur image resource schema:ImageObject
id schema:identifier
title schema:name
description schema:description
link schema:url *
schema:image *
type schema:encodingFormat
height schema:height
width schema:width
views schema:interactionStatistic

*Multiple properties are suitable for mapping the link property.

Using DCAT

  • An image resource can be modeled by a dcat:Distribution.
  • A Imgur Album can contain image resources, and can be modeled by dcat:Dataset.
  • An Imgur Gallery can contain Imgur Albums, which contain image resources. Therefore, an Imgur Gallery can be modeled by a dcat:Catalog which can be linked to zero or more dcat:Datasets (Albums).