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<!doctype html><html lang="en">
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta content="width=device-width, initial-scale=1, shrink-to-fit=no" name="viewport">
<title>FAIR Data Point</title>
<meta content="UD" name="w3c-status">
<link href="https://www.w3.org/StyleSheets/TR/2021/W3C-UD" rel="stylesheet">
<meta content="Bikeshed version 0ef803fdf, updated Tue Jan 6 11:59:39 2026 -0800" name="generator">
<link href="https://specs.fairdatapoint.org/" rel="canonical">
<link href="https://www.w3.org/2008/site/images/favicon.ico" rel="icon">
<meta content="0e0d42a8cf4807cb4dfc41e770244bcf12d9528f" name="revision">
<meta content="dark light" name="color-scheme">
<link href="https://www.w3.org/StyleSheets/TR/2021/dark.css" media="(prefers-color-scheme: dark)" rel="stylesheet" type="text/css">
<style>/* Boilerplate: style-autolinks */
.css.css, .property.property, .descriptor.descriptor {
color: var(--a-normal-text);
font-size: inherit;
font-family: inherit;
}
.css::before, .property::before, .descriptor::before {
content: "‘";
}
.css::after, .property::after, .descriptor::after {
content: "’";
}
.property, .descriptor {
/* Don't wrap property and descriptor names */
white-space: nowrap;
}
.type { /* CSS value <type> */
font-style: italic;
}
pre .property::before, pre .property::after {
content: "";
}
[data-link-type="property"]::before,
[data-link-type="propdesc"]::before,
[data-link-type="descriptor"]::before,
[data-link-type="value"]::before,
[data-link-type="function"]::before,
[data-link-type="at-rule"]::before,
[data-link-type="selector"]::before,
[data-link-type="maybe"]::before {
content: "‘";
}
[data-link-type="property"]::after,
[data-link-type="propdesc"]::after,
[data-link-type="descriptor"]::after,
[data-link-type="value"]::after,
[data-link-type="function"]::after,
[data-link-type="at-rule"]::after,
[data-link-type="selector"]::after,
[data-link-type="maybe"]::after {
content: "’";
}
[data-link-type].production::before,
[data-link-type].production::after,
.prod [data-link-type]::before,
.prod [data-link-type]::after {
content: "";
}
[data-link-type=element],
[data-link-type=element-attr] {
font-family: Menlo, Consolas, "DejaVu Sans Mono", monospace;
font-size: .9em;
}
[data-link-type=element]::before { content: "<" }
[data-link-type=element]::after { content: ">" }
[data-link-type=biblio] {
white-space: pre;
}
@media (prefers-color-scheme: dark) {
:root {
--selflink-text: black;
--selflink-bg: silver;
--selflink-hover-text: white;
}
}
</style>
<style>/* Boilerplate: style-colors */
/* Any --*-text not paired with a --*-bg is assumed to have a transparent bg */
:root {
color-scheme: light dark;
--text: black;
--bg: white;
--unofficial-watermark: url(https://www.w3.org/StyleSheets/TR/2016/logos/UD-watermark);
--logo-bg: #1a5e9a;
--logo-active-bg: #c00;
--logo-text: white;
--tocnav-normal-text: #707070;
--tocnav-normal-bg: var(--bg);
--tocnav-hover-text: var(--tocnav-normal-text);
--tocnav-hover-bg: #f8f8f8;
--tocnav-active-text: #c00;
--tocnav-active-bg: var(--tocnav-normal-bg);
--tocsidebar-text: var(--text);
--tocsidebar-bg: #f7f8f9;
--tocsidebar-shadow: rgba(0,0,0,.1);
--tocsidebar-heading-text: hsla(203,20%,40%,.7);
--toclink-text: var(--text);
--toclink-underline: #3980b5;
--toclink-visited-text: var(--toclink-text);
--toclink-visited-underline: #054572;
--heading-text: #005a9c;
--hr-text: var(--text);
--algo-border: #def;
--del-text: red;
--del-bg: transparent;
--ins-text: #080;
--ins-bg: transparent;
--a-normal-text: #034575;
--a-normal-underline: #bbb;
--a-visited-text: var(--a-normal-text);
--a-visited-underline: #707070;
--a-hover-bg: rgba(75%, 75%, 75%, .25);
--a-active-text: #c00;
--a-active-underline: #c00;
--blockquote-border: silver;
--blockquote-bg: transparent;
--blockquote-text: currentcolor;
--issue-border: #e05252;
--issue-bg: #fbe9e9;
--issue-text: var(--text);
--issueheading-text: #831616;
--example-border: #e0cb52;
--example-bg: #fcfaee;
--example-text: var(--text);
--exampleheading-text: #574b0f;
--note-border: #52e052;
--note-bg: #e9fbe9;
--note-text: var(--text);
--noteheading-text: hsl(120, 70%, 30%);
--notesummary-underline: silver;
--assertion-border: #aaa;
--assertion-bg: #eee;
--assertion-text: black;
--advisement-border: orange;
--advisement-bg: #fec;
--advisement-text: var(--text);
--advisementheading-text: #b35f00;
--warning-border: red;
--warning-bg: hsla(40,100%,50%,0.95);
--warning-text: var(--text);
--amendment-border: #330099;
--amendment-bg: #F5F0FF;
--amendment-text: var(--text);
--amendmentheading-text: #220066;
--def-border: #8ccbf2;
--def-bg: #def;
--def-text: var(--text);
--defrow-border: #bbd7e9;
--datacell-border: silver;
--indexinfo-text: #707070;
--indextable-hover-text: black;
--indextable-hover-bg: #f7f8f9;
--outdatedspec-bg: rgba(0, 0, 0, .5);
--outdatedspec-text: black;
--outdated-bg: maroon;
--outdated-text: white;
--outdated-shadow: red;
--editedrec-bg: darkorange;
}
@media (prefers-color-scheme: dark) {
:root {
--text: #ddd;
--bg: black;
--unofficial-watermark: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='400' height='400'%3E%3Cg fill='%23100808' transform='translate(200 200) rotate(-45) translate(-200 -200)' stroke='%23100808' stroke-width='3'%3E%3Ctext x='50%25' y='220' style='font: bold 70px sans-serif; text-anchor: middle; letter-spacing: 6px;'%3EUNOFFICIAL%3C/text%3E%3Ctext x='50%25' y='305' style='font: bold 70px sans-serif; text-anchor: middle; letter-spacing: 6px;'%3EDRAFT%3C/text%3E%3C/g%3E%3C/svg%3E");
--logo-bg: #1a5e9a;
--logo-active-bg: #c00;
--logo-text: white;
--tocnav-normal-text: #999;
--tocnav-normal-bg: var(--bg);
--tocnav-hover-text: var(--tocnav-normal-text);
--tocnav-hover-bg: #080808;
--tocnav-active-text: #f44;
--tocnav-active-bg: var(--tocnav-normal-bg);
--tocsidebar-text: var(--text);
--tocsidebar-bg: #080808;
--tocsidebar-shadow: rgba(255,255,255,.1);
--tocsidebar-heading-text: hsla(203,20%,40%,.7);
--toclink-text: var(--text);
--toclink-underline: #6af;
--toclink-visited-text: var(--toclink-text);
--toclink-visited-underline: #054572;
--heading-text: #8af;
--hr-text: var(--text);
--algo-border: #456;
--del-text: #f44;
--del-bg: transparent;
--ins-text: #4a4;
--ins-bg: transparent;
--a-normal-text: #6af;
--a-normal-underline: #555;
--a-visited-text: var(--a-normal-text);
--a-visited-underline: var(--a-normal-underline);
--a-hover-bg: rgba(25%, 25%, 25%, .2);
--a-active-text: #f44;
--a-active-underline: var(--a-active-text);
--borderedblock-bg: rgba(255, 255, 255, .05);
--blockquote-border: silver;
--blockquote-bg: var(--borderedblock-bg);
--blockquote-text: currentcolor;
--issue-border: #e05252;
--issue-bg: var(--borderedblock-bg);
--issue-text: var(--text);
--issueheading-text: hsl(0deg, 70%, 70%);
--example-border: hsl(50deg, 90%, 60%);
--example-bg: var(--borderedblock-bg);
--example-text: var(--text);
--exampleheading-text: hsl(50deg, 70%, 70%);
--note-border: hsl(120deg, 100%, 35%);
--note-bg: var(--borderedblock-bg);
--note-text: var(--text);
--noteheading-text: hsl(120, 70%, 70%);
--notesummary-underline: silver;
--assertion-border: #444;
--assertion-bg: var(--borderedblock-bg);
--assertion-text: var(--text);
--advisement-border: orange;
--advisement-bg: #222218;
--advisement-text: var(--text);
--advisementheading-text: #f84;
--warning-border: red;
--warning-bg: hsla(40,100%,20%,0.95);
--warning-text: var(--text);
--amendment-border: #330099;
--amendment-bg: #080010;
--amendment-text: var(--text);
--amendmentheading-text: #cc00ff;
--def-border: #8ccbf2;
--def-bg: #080818;
--def-text: var(--text);
--defrow-border: #136;
--datacell-border: silver;
--indexinfo-text: #aaa;
--indextable-hover-text: var(--text);
--indextable-hover-bg: #181818;
--outdatedspec-bg: rgba(255, 255, 255, .5);
--outdatedspec-text: black;
--outdated-bg: maroon;
--outdated-text: white;
--outdated-shadow: red;
--editedrec-bg: darkorange;
}
/* In case a transparent-bg image doesn't expect to be on a dark bg,
which is quite common in practice... */
img { background: white; }
}
</style>
<style>/* Boilerplate: style-counters */
body {
counter-reset: example figure issue;
}
.issue {
counter-increment: issue;
}
.issue:not(.no-marker)::before {
content: "Issue " counter(issue);
}
.example {
counter-increment: example;
}
.example:not(.no-marker)::before {
content: "Example " counter(example);
}
.invalid.example:not(.no-marker)::before,
.illegal.example:not(.no-marker)::before {
content: "Invalid Example " counter(example);
}
figcaption {
counter-increment: figure;
}
figcaption:not(.no-marker)::before {
content: "Figure " counter(figure) " ";
}
</style>
<style>/* Boilerplate: style-issues */
a[href].issue-return {
float: right;
float: inline-end;
color: var(--issueheading-text);
font-weight: bold;
text-decoration: none;
}
</style>
<style>/* Boilerplate: style-md-lists */
/* This is a weird hack for me not yet following the commonmark spec
regarding paragraph and lists. */
[data-md] > :first-child {
margin-top: 0;
}
[data-md] > :last-child {
margin-bottom: 0;
}
</style>
<style>/* Boilerplate: style-selflinks */
:root {
--selflink-text: white;
--selflink-bg: gray;
--selflink-hover-text: black;
}
.heading, .issue, .note, .example, li, dt {
position: relative;
}
a.self-link {
position: absolute;
top: 0;
left: calc(-1 * (3.5rem - 26px));
width: calc(3.5rem - 26px);
height: 2em;
text-align: center;
border: none;
transition: opacity .2s;
opacity: .5;
}
a.self-link:hover {
opacity: 1;
}
.heading > a.self-link {
font-size: 83%;
}
.example > a.self-link,
.note > a.self-link,
.issue > a.self-link {
/* These blocks are overflow:auto, so positioning outside
doesn't work. */
left: auto;
right: 0;
}
li > a.self-link {
left: calc(-1 * (3.5rem - 26px) - 2em);
}
dfn > a.self-link {
top: auto;
left: auto;
opacity: 0;
width: 1.5em;
height: 1.5em;
background: var(--selflink-bg);
color: var(--selflink-text);
font-style: normal;
transition: opacity .2s, background-color .2s, color .2s;
}
dfn:hover > a.self-link {
opacity: 1;
}
dfn > a.self-link:hover {
color: var(--selflink-hover-text);
}
a.self-link::before { content: "¶"; }
.heading > a.self-link::before { content: "§"; }
dfn > a.self-link::before { content: "#"; }
</style>
<style>/* Boilerplate: style-syntax-highlighting */
code.highlight { padding: .1em; border-radius: .3em; }
pre.highlight, pre > code.highlight { display: block; padding: 1em; margin: .5em 0; overflow: auto; border-radius: 0; }
.highlight:not(.idl) { background: rgba(0, 0, 0, .03); }
c-[a] { color: #990055 } /* Keyword.Declaration */
c-[b] { color: #990055 } /* Keyword.Type */
c-[c] { color: #708090 } /* Comment */
c-[d] { color: #708090 } /* Comment.Multiline */
c-[e] { color: #0077aa } /* Name.Attribute */
c-[f] { color: #669900 } /* Name.Tag */
c-[g] { color: #222222 } /* Name.Variable */
c-[k] { color: #990055 } /* Keyword */
c-[l] { color: #000000 } /* Literal */
c-[m] { color: #000000 } /* Literal.Number */
c-[n] { color: #0077aa } /* Name */
c-[o] { color: #999999 } /* Operator */
c-[p] { color: #999999 } /* Punctuation */
c-[s] { color: #a67f59 } /* Literal.String */
c-[t] { color: #a67f59 } /* Literal.String.Single */
c-[u] { color: #a67f59 } /* Literal.String.Double */
c-[cp] { color: #708090 } /* Comment.Preproc */
c-[c1] { color: #708090 } /* Comment.Single */
c-[cs] { color: #708090 } /* Comment.Special */
c-[kc] { color: #990055 } /* Keyword.Constant */
c-[kn] { color: #990055 } /* Keyword.Namespace */
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<h1 class="no-ref p-name" id="title">FAIR Data Point</h1>
<p id="w3c-state"><a href="https://www.w3.org/standards/types/#UD">Unofficial Proposal Draft</a>,
<time class="dt-updated" datetime="2026-03-12">12 March 2026</time></p>
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<summary>More details about this document</summary>
<div data-fill-with="spec-metadata">
<dl>
<dt>This version:
<dd><a class="u-url" href="https://specs.fairdatapoint.org/">https://specs.fairdatapoint.org/</a>
<dt>Previous Versions:
<dd><a href="https://specs.fairdatapoint.org/v1.2/fdp-specs-v1.2.html" rel="prev">https://specs.fairdatapoint.org/v1.2/fdp-specs-v1.2.html</a>
<dt>Issue Tracking:
<dd><a href="https://github.com/fdp-specs/fdp-specs.github.io/issues">Github</a>
<dt class="editor">Editors:
<dd class="editor h-card p-author vcard"><a class="fn p-name u-url url" href="https://www.utwente.nl/en/eemcs/scs/">Luiz Olavo Bonino da Silva Santos</a> (<span class="org p-org">UTwente</span>)
<dd class="editor h-card p-author vcard"><a class="fn p-name u-url url" href="https://www.health-ri.nl/">Kees Burger</a> (<span class="org p-org">Health-RI</span>)
<dt class="editor">Former Editor:
<dd class="editor h-card p-author vcard"><a class="fn p-name u-url url" href="https://www.lumc.nl/">Rajaram Kaliyaperumal</a> (<span class="org p-org">LUMC</span>)
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<p class="copyright" data-fill-with="copyright"><a href="https://www.w3.org/policies/#copyright">Copyright</a> © 2026 <a href="https://www.w3.org/">World Wide Web Consortium</a>. <abbr title="World Wide Web Consortium">W3C</abbr><sup>®</sup> <a href="https://www.w3.org/policies/#Legal_Disclaimer">liability</a>, <a href="https://www.w3.org/policies/#W3C_Trademarks">trademark</a> and <a href="https://www.w3.org/copyright/software-license/" rel="license" title="W3C Software and Document License">permissive document license</a> rules apply.
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<div class="p-summary" data-fill-with="abstract">
<h2 class="heading no-num no-ref no-toc settled" id="abstract"><span class="content">Abstract</span></h2>
<p>This document provides specifications for the FAIR Data Point (FDP).
The document includes architecture of the core component, metadata structure and schema, API and validation rules.</p>
</div>
<h2 class="heading no-num no-ref no-toc settled" id="sotd"><span class="content">Status of this document</span></h2>
<div data-fill-with="status">
<p></p>
</div>
<div data-fill-with="at-risk"></div>
<nav data-fill-with="table-of-contents" id="toc">
<h2 class="no-num no-ref no-toc" id="contents">Table of Contents</h2>
<ol class="toc">
<li>
<a href="#introduction"><span class="secno">1</span> <span class="content">Introduction</span></a>
<ol class="toc">
<li><a href="#purpose"><span class="secno">1.1</span> <span class="content">Purpose</span></a>
<li><a href="#document-conventions"><span class="secno">1.2</span> <span class="content">Document conventions</span></a>
</ol>
<li>
<a href="#overall-description"><span class="secno">2</span> <span class="content">Overall Description</span></a>
<ol class="toc">
<li>
<a href="#usage-scenarios"><span class="secno">2.1</span> <span class="content">Usage Scenarios</span></a>
<ol class="toc">
<li><a href="#data-discovery"><span class="secno">2.1.1</span> <span class="content">Data discovery</span></a>
<li><a href="#data-access"><span class="secno">2.1.2</span> <span class="content">Data access</span></a>
<li><a href="#-metadata-publication"><span class="secno">2.1.3</span> <span class="content">(Meta)Data publication</span></a>
<li><a href="#publishing-other-types-of-content"><span class="secno">2.1.4</span> <span class="content">Publishing other types of content</span></a>
</ol>
</ol>
<li><a href="#architecture"><span class="secno">3</span> <span class="content">Architecture</span></a>
<li>
<a href="#metadata"><span class="secno">4</span> <span class="content">Metadata</span></a>
<ol class="toc">
<li><a href="#navigation-information"><span class="secno">4.1</span> <span class="content">Navigation information</span></a>
<li>
<a href="#metadata-schemas"><span class="secno">4.2</span> <span class="content">Metadata schemas</span></a>
<ol class="toc">
<li><a href="#fair-data-point-metadata"><span class="secno">4.2.1</span> <span class="content">FAIR Data Point metadata</span></a>
<li><a href="#catalog-metadata"><span class="secno">4.2.2</span> <span class="content">Catalog metadata</span></a>
</ol>
</ol>
<li><a href="#api"><span class="secno">5</span> <span class="content">API</span></a>
<li><a href="#fdp-specification-compliance"><span class="secno">6</span> <span class="content">FDP Specification Compliance</span></a>
<li>
<a href="#references"><span class="secno"></span> <span class="content">References</span></a>
<ol class="toc">
<li><a href="#normative"><span class="secno"></span> <span class="content">Normative References</span></a>
<li><a href="#informative"><span class="secno"></span> <span class="content">Informative References</span></a>
</ol>
</ol>
</nav>
<main>
<h2 class="heading settled" data-level="1" id="introduction"><span class="secno">1. </span><span class="content">Introduction</span><a class="self-link" href="#introduction"></a></h2>
<p>FAIR Data Point (FDP) is a metadata service that provides access to metadata following the FAIR principles <a data-link-type="biblio" href="#biblio-fair-principles" title="The FAIR Guiding Principles for scientific data management and stewardship">[FAIR-principles]</a>.
FDP uses a REST API for creating, storing and serving FAIR metadata.
FDP is software that, from one side, allows digital objects owners/publishers to expose the metadata of their digital objects in a FAIR manner and, from the other side, allows digital objects' consumers to discover information (metadata) about offered digital objects.
Commonly, the FAIR Data Point is used to expose metadata of datasets but metadata of other types of digital objects can also be exposed such as ontologies, repositories, analysis algorithms, websites, etc.</p>
<p>Many different repositories and their digital objects should interoperate in order to allow increasingly complex questions to be answered.
These repositories and their content should be interoperable in order for client applications to autonomously (re)use them.
However, interoperability happens at different levels, including syntactical and semantical interoperabilities.
The FDP aims at addressing these interoperability issues by providing:</p>
<ul>
<li data-md>
<p>A common interface to access information (metadata) about digital objects;</p>
<li data-md>
<p>A common representation format <a data-link-type="biblio" href="#biblio-rdf11-primer" title="RDF 1.1 Primer">[RDF11-PRIMER]</a> to express the metadata in a machine-actionable manner;</p>
<li data-md>
<p>A common approach to inform to clients how to navigate through the FDP’s metadata structure;</p>
<li data-md>
<p>A common representation format <a data-link-type="biblio" href="#biblio-shacl" title="Shapes Constraint Language (SHACL)">[SHACL]</a> to represent each metadata record’s schema.</p>
</ul>
<p>The main goal of the FDP is to establish a common method for metadata provisioning and accessing and, as a consequence, provide to client applications a predictable way of accessing and interacting with metadata content.
To fulfill this goal, this document contains a set of specifications to help developers to extend the functionality of their applications so these applications can also behave as a FAIR Data Point.</p>
<h3 class="heading settled" data-level="1.1" id="purpose"><span class="secno">1.1. </span><span class="content">Purpose</span><a class="self-link" href="#purpose"></a></h3>
<p>The purpose of this document is to specify the FAIR Data Point.
This document includes requirements, architecture and design of the FDP as well as the metadata schemas used.
This specification is primarily intended to be a reference for developers willing to add the FDP functionality into their existing applications or develop their own FAIR Data Point implementation.
In order to better understand this specification, knowledge of RDF, LDP, SHACL and REST APIs is required.</p>
<h3 class="heading settled" data-level="1.2" id="document-conventions"><span class="secno">1.2. </span><span class="content">Document conventions</span><a class="self-link" href="#document-conventions"></a></h3>
<p>Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC 2119.
However, for readability, these words do not appear in all uppercase letters in this specification.</p>
<p>All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. <a data-link-type="biblio" href="#biblio-rfc2119" title="Key words for use in RFCs to Indicate Requirement Levels">[RFC2119]</a></p>
<h2 class="heading settled" data-level="2" id="overall-description"><span class="secno">2. </span><span class="content">Overall Description</span><a class="self-link" href="#overall-description"></a></h2>
<p>The basis for any infrastructure is its suitability to the issues it should address.
Therefore, the first step is to identify these issues.
One common approach for this identification is to investigate current practices that could benefit from a supporting infrastructure.
Once we analyse these practices, we can elicit the requirements for the infrastructure.
In this document we list a number of data usage scenarios that represent regular practices in data-intensive domains.
These usage scenarios have been gathered through interactions with a variety of representative stakeholders in different domains.
These stakeholders represent data producers, data consumers and providers of both infrastructure and services for supporting data activities.</p>
<h3 class="heading settled" data-level="2.1" id="usage-scenarios"><span class="secno">2.1. </span><span class="content">Usage Scenarios</span><a class="self-link" href="#usage-scenarios"></a></h3>
<p>From the different semantic interoperability projects we have been and are involved in, the following usage scenarios have been identified.
These usage scenarios do not represent one particular situation in a real project but depict data interoperability-related situations that we experienced in a number of different projects.
From these scenarios we derived a set of requirements for metadata storage and accessibility infrastructure and they also guided the design and development of the solution.</p>
<h4 class="heading settled" data-level="2.1.1" id="data-discovery"><span class="secno">2.1.1. </span><span class="content">Data discovery</span><a class="self-link" href="#data-discovery"></a></h4>
<p>A researcher needs to find datasets containing data about a given subject, e.g., proteins that are activated in specific tissues, polution level in a given region, or infrared observation of a particular galaxy; integrate the discovered data with other pre-selected datasets and analyse them.
In another situation, the researcher needs to know which biobanks carry a given type of biosample (e.g., blood samples) from patients possessing a specific disease (e.g., Alzheimer’s disease) taken from a patient registry whose onset age was lower than 45 years old.
These data users need to use a straightforward search application that allows them to find the required information.
However, the search application first needs to have indexed information about existing datasets wherever their location.</p>
<h4 class="heading settled" data-level="2.1.2" id="data-access"><span class="secno">2.1.2. </span><span class="content">Data access</span><a class="self-link" href="#data-access"></a></h4>
<p>Once a data user/consumer finds the desired datasets, including the information about their licenses and access protocols, the user wants to access the data, retrieving it, or sending an algorithm to analyse the data.
In many situations the data user will integrate many different datasets.
To carry out these integrations, the user needs to know in which formats the data can be accessed, and which access methods are available.
This information comes in the form of metadata.
In order to facilitate the usage of metadata, the method with which the metadata will be accessed should be common in all different metadata sources and a common representation technology should be used for the metadata.</p>
<h4 class="heading settled" data-level="2.1.3" id="-metadata-publication"><span class="secno">2.1.3. </span><span class="content">(Meta)Data publication</span><a class="self-link" href="#-metadata-publication"></a></h4>
<p>An organization is running a project in which data is being created.
The data will be analyzed during the project but may also be useful for other users.
The group would therefore like to publish the data in a way that allows potential users to retrieve information about the datasets (metadata), allows data search engines to index the metadata, and allows users to acces the data.
Some of the produced datasets have an open license but others have more restrictive licenses.
All these metadata should be available so that potential data users would have enough information to assess whether the data described in the metadata fits their needs.</p>
<h4 class="heading settled" data-level="2.1.4" id="publishing-other-types-of-content"><span class="secno">2.1.4. </span><span class="content">Publishing other types of content</span><a class="self-link" href="#publishing-other-types-of-content"></a></h4>
<p>An organization is running a project in which different types of deliverables will be created.
One group is developing a piece of software, another group is working on a controlled vocabulary, while a third group will generate a number of reference documents.
The organization would like to publish information about these materials so others could discover and reuse them.</p>
<h2 class="heading settled" data-level="3" id="architecture"><span class="secno">3. </span><span class="content">Architecture</span><a class="self-link" href="#architecture"></a></h2>
<p>From the usage scenarios, we have identified a need for a metadata provisioning infrastructure that we call FAIR Data Point (FDP).
The FDP has the following goals:</p>
<ul>
<li data-md>
<p>Allow owners/creators/publishers to expose the metadata of their digital objects in a way that follows the FAIR Data Principles.</p>
<li data-md>
<p>Allow consumers/users to discover information about digital objects they are interested in.</p>
<li data-md>
<p>Provide meaningful information about digital objects for both humans and software agents.</p>
</ul>
<p>Based on these goals, Figure 3.1 depicts the general architecture of an FDP.
In this architecture, the FDP exposes its functionality to the users through an application programming interface (API).
In our reference implementation, besides the FDP itself we developed an FDP web client, which connects to the FDP API and allows human users to interact with the application through a web-based interface.</p>
<figure>
<img alt="High-level architecture of the FAIR Data Point" height="884" src="images/FDParchitecture.png" width="1053">
<figcaption class="no-marker"><strong>Figure 3.1</strong> High-level architecture of the FAIR Data Point.</figcaption>
</figure>
<p>Figure 3.1 also depicts the FDP’s internal components, namely the Metadata Provider, Access Control, Metadata Schemas and the RDF Metadata Store.</p>
<ul>
<li data-md>
<p><strong>Metadata Provider</strong> - responsible for the provisioning of the metadata content available in the FDP;</p>
<li data-md>
<p><strong>Access Control</strong> - reponsible for controlling the access to the metadata content.
In general, metadata can be openly accessible for reading, but it is expected that only a select number of people have access to add, delete or edit the metadata content.
Moreover, in some situations, metadata or part of the metadata may also have access restrictions for reading.
The Access Control component makes sure that these restrictions are enforced;</p>
<li data-md>
<p><strong>RDF Metadata Source</strong> - The FDP <em>MUST</em> present its metadata content as <code>RDF</code>, and, more specifically, in at least <code>turtle</code> and <code>JSON-LD</code> syntaxes.
Therefore, these metadata can be stored in an RDF Metadata Source.
The FDP reference implementation supports native in-memory or on-disk storage, as well as the connection with existing triple stores such as GraphDB, Allegro Graph, Blazegraph, etc.
If one is extending an existing application based on this FDP specification, the RDF metadata can be provided using different implementation strategies.
For instance, metadata stored in other representation formats can be dynamically converted to RDF through a conversion component that serves as the RDF Metadata Source.</p>
<li data-md>
<p><strong>Metadata Schemas</strong> - the FDP exposes metadata about different types of digital objects, e.g., repositories, content catalogs, and datasets, among others.
These metadata should comply with schemas defined by their related communities.
In the FDP, the metadata schemas <em>MUST</em> be represented in <code>SHACL</code>.
The FDP reference implementation is shipped with four basic metadata schemas:
for the FDP itself as a metadata service, for catalogs, for datasets, and for datasets' distributions.
These schemas allow the FDP to check and validate metadata content that is added.
Addition of metadata schemas for other types of digital objects and extensions of the base schemas are also supported by the FDP reference implementation.</p>
</ul>
<h2 class="heading settled" data-level="4" id="metadata"><span class="secno">4. </span><span class="content">Metadata</span><a class="self-link" href="#metadata"></a></h2>
<p>The FAIR principles give special attention to metadata.
In fact, all principles relate to metadata in at least one aspect.
Metadata can be defined as data that provides information about other data.
Here we extend this notion to define metadata as information about other digital objects.
This information includes descriptions of the origin, structure, provenance, rights and obligations, or other characteristics of digital objects.
The FAIR Data Point’s metadata approach follows this idea of supporting the creation of metadata about different types of digital objects.
The first object to provide metadata about is the FDP itself.
When a client interacts with a service, it should know what it is dealing with.
Therefore, the FDP provides metadata about itself and, from that point on, the client can navigate its metadata content to discover the other metadata records.</p>
<p>The FDP uses the W3C’s Data Catalog Vocabulaire (DCAT) version 2 <a data-biblio-obsolete data-link-type="biblio" href="#biblio-vocab-dcat-2" title="Data Catalog Vocabulary (DCAT) - Version 2">[VOCAB-DCAT-2]</a> model as the basis for its metadata content.
Figure 4.1 depicts the FDP extensions to the DCAT model.</p>
<figure>
<img alt="FDP metadata structure" height="1069" src="images/FDPmetadatadiagram.png" width="1593">
<figcaption class="no-marker"><strong>Figure 4.1</strong> FDP extensions to the DCAT model</figcaption>
</figure>
<p>A DCAT <code>Resource</code> represents entities that can be described by a metadata record.
Since <code>Resource</code> is defined as an abstract class, it is not intended to be used directly.
We should use one of its subclasses, such as <code>Dataset</code> or <code>Data Service</code> instead.
<code>Dataset</code> represents a collection of data while <code>Data Service</code> represents a service, accessible through an interface (API), that serves datasets.
<code>Catalog</code>, a subclass of <code>Dataset</code>, represents aggregations of metadata records about digital objects.
For instance, a <code>Catalog</code> may contain references to the metadata records of <code>Datasets</code>.</p>
<p>The FDP extends the DCAT model by adding the concept of a <code>FAIRDataPoint</code> as a specific type of data service that serves metadata catalogs and metadata records.
The DCAT extensions and other FDP-specific concepts and relations are defined in the FDP ontology (using the namespace prefix <code>fdp-o</code>).
In the FDP ontology, the FAIR Data Point is represented by a sub-class of the concept of <code>MetadataService</code>.
Figure 4.1 only depicts the properties that are not already inherited from <code>Data Service</code> and <code>Resource</code>.</p>
<p>With the definition of the FDP as a type of metadata service that serves metadata catalogs, the relation between the <code>MetadataService</code> and <code>dcat:Catalog</code> is represented by the predicate <code>fdp-o:metadataCatalog</code>.
Following the DCAT approach of providing qualified relations between resources, the <code>fdp-o:metadataCatalog</code> is defined as a sub-property of <code>dcat:Relationship</code> having <code>fdp-o:MetadataService</code> as its domain and <code>dcat:Catalog</code> as its range.</p>
<p><strong class="advisement"> An implementation of the FDP specifications <em>MUST</em> minimally provide the metadata records of the <code>MetadataService</code>, and the metadata records of the other types of resources <em>MUST</em> be grouped in at least one <code>Catalog</code>.</strong></p>
<h3 class="heading settled" data-level="4.1" id="navigation-information"><span class="secno">4.1. </span><span class="content">Navigation information</span><a class="self-link" href="#navigation-information"></a></h3>
<p>Since the FDP supports the provisioning of metadata about different types of digital objects and the relations among these metadata records can be customized, each FDP installation may have a different structure.
For instance, the FDP reference implementation is pre-loaded with the structure of metadata about <code>FAIR Data Point</code> → <code>Catalog</code> → <code>Dataset</code> → <code>Distribution</code>.
Another FDP could have a different metadata structure, e.g., <code>FAIR Data Point</code> → <code>Catalog</code> → <code>Semantic Artefact</code>.
With this flexibility, a client application would not know how to navigate the FDP metadata content unless it follows all URIs in the metadata, which may be extensive.
Therefore, the FDP <em>MUST</em> describe its own navigation structure.
This navigation information <em>MUST</em> be provided by using the Linked Data Platform (LDP) containment predicates <code>ldp:contains</code> or <code>ldp:hasMemberRelation</code>.
This information <em>MUST</em> be present in every metadata record that leads to other metadata records.</p>
<p>The following RDF turtle code shows an example of a MetadataService metadata record with navigation information.</p>
<pre class="highlight include-code"><c- k>@prefix</c-> <c- nn>dct:</c-> <c- g><http://purl.org/dc/terms/></c-> <c- p>.</c->
<c- k>@prefix</c-> <c- nn>fdp-o:</c-> <c- g><https://w3id.org/fdp/fdp-o#></c-> <c- p>.</c->
<c- k>@prefix</c-> <c- nn>ldp:</c-> <c- g><http://www.w3.org/ns/ldp#></c-> <c- p>.</c->
<c- g><https://fairdatapoint.org/app></c-> <c- b>a</c-> <c- nn>fdp-o</c-><c- p>:</c-><c- f>FairDataPoint</c->
<c- nn>dct</c-><c- p>:</c-><c- f>title</c-> <c- s>"Demonstration FAIR Data Point"</c-><c- p>;</c->
<c- nn>dct</c-><c- p>:</c-><c- f>conformsTo</c-> <c- g><https://www.purl.org/fairtools/fdp/schema/0.1/fdpMetadata></c-><c- p>;</c->
<c- nn>dct</c-><c- p>:</c-><c- f>description</c-> <c- s>"This FAIR Data Point deployment is used for demonstration of the application and to allow the navigation through its metadata content. The metadata presented here is also for demonstration purposes only and not necessarily describe properly their related resources."</c-><c- p>;</c->
<c- nn>dct</c-><c- p>:</c-><c- f>hasVersion</c-> <c- s>"1.0"</c-> <c- p>;</c->
<c- nn>dct</c-><c- p>:</c-><c- f>license</c-> <c- g><http://rdflicense.appspot.com/rdflicense/cc-by-nc-nd4.0></c-><c- p>;</c->
<c- nn>dct</c-><c- p>:</c-><c- f>publisher</c-> <c- g><https://purl.org/fairdatapoint/app#publisher></c-><c- p>;</c->
<c- nn>fdp-o</c-><c- p>:</c-><c- f>metadataIdentifier</c-> <c- g><https://purl.org/fairdatapoint/app#identifier></c-><c- p>;</c->
<c- nn>fdp-o</c-><c- p>:</c-><c- f>metadataIssued</c-> <c- s>"2020-05-29T09:55:08.580Z"</c-><c- o>^^</c-><http://www.w3.org/2001/XMLSchema#dateTime><c- p>;</c->
<c- nn>fdp-o</c-><c- p>:</c-><c- f>metadataModified</c-> <c- s>"2020-09-30T11:17:43.008Z"</c-><c- o>^^</c-><http://www.w3.org/2001/XMLSchema#dateTime><c- p>;</c->
<c- nn>fdp-o</c-><c- p>:</c-><c- f>metadataCatalog</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/3dde263d-0a7c-4f2a-9813-ccb3a51f70a8></c-><c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/508d3c96-8106-49d2-910c-13706aca75e3></c-> <c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/6e43c568-c6fa-41c8-a88a-7ee4c85035af></c-> <c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/a46aa445-3be0-4db8-8968-3338d1061a47></c-> <c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/a91d3db7-fe83-4de1-b678-fe1b0c82f2f1></c-> <c- p>.</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/></c-> <c- b>a</c-> <c- nn>ldp</c-><c- p>:</c-><c- f>DirectContainer</c-> <c- p>;</c->
<c- nn>dct</c-><c- p>:</c-><c- f>title</c-> <c- s>"Catalogs"</c-> <c- p>;</c->
<c- nn>ldp</c-><c- p>:</c-><c- f>membershipResource</c-> <c- g><https://fairdatapoint.org/app></c-> <c- p>;</c->
<c- nn>ldp</c-><c- p>:</c-><c- f>hasMemberRelation</c-> <c- nn>fdp-o</c-><c- p>:</c-><c- f>metadataCatalog</c-> <c- p>;</c->
<c- nn>ldp</c-><c- p>:</c-><c- f>contains</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/3dde263d-0a7c-4f2a-9813-ccb3a51f70a8></c-> <c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/508d3c96-8106-49d2-910c-13706aca75e3></c-> <c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/6e43c568-c6fa-41c8-a88a-7ee4c85035af></c-> <c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/a46aa445-3be0-4db8-8968-3338d1061a47></c-> <c- p>,</c->
<c- g><https://purl.org/fairdatapoint/app/catalog/a91d3db7-fe83-4de1-b678-fe1b0c82f2f1></c-> <c- p>.</c-></pre>
<p>In the metadata record, the FDP (<code>f:app</code>) has the relation <code>fdp-o:metadataCatalog</code> with its catalogs.
This is the parent-child relation that should be followed by a client that wants to navigate the FDP metadata structure.
To explicitly inform the navigation structure, we have the code segment at the bottom of this example metadata record informing that we have a container, identified as <code>https://purl.org/fairdatapoint/app/catalog/</code>, which is the container for the <code>https://purl.org/fairdatapoint/app</code> (the object of the <code>ldp:membershipResource</code>) and it relates to its contained members using the relation <code>fdp-o:metadataCatalog</code>.</p>
<h3 class="heading settled" data-level="4.2" id="metadata-schemas"><span class="secno">4.2. </span><span class="content">Metadata schemas</span><a class="self-link" href="#metadata-schemas"></a></h3>
<p>The FAIR Data Point supports user defined metadata schemas.
This follows the acknowledgment that every application scenario may require different sets of properties to properly describe a given digital object.
Moreover, the metadata records may have some relevant relationships that connect one to other.
For instance, it seems straightforward to argue that a FAIR Data Point, as a metadata service, may have a number of catalogs that are used to organise the metadata records of other types of digital object, for instance, datasets.</p>
<p>Therefore, to improve interoperability and provide a minimal level of predictability and organisation of different FDPs, the metadata structure of the FDP starts with the metadata of itself (as a metadata service), followed by the catalogs that it contains, and each catalog contains the metadata of given types of digital objects.</p>
<p>Below we present the metadata schemas of the two types of digital object that are mandatory for each FDP: the <code>FAIR Data Point</code> and the <code>Catalog</code>.</p>
<p class="note" role="note"><span class="marker">NOTE:</span> In the FDP Ontology the <code>FAIR Data Point</code> is defined as a subclass of <code>MetadataService</code>, which is a sub-class of <code>dcat:DataService</code>.</p>
<h4 class="heading settled" data-level="4.2.1" id="fair-data-point-metadata"><span class="secno">4.2.1. </span><span class="content">FAIR Data Point metadata</span><a class="self-link" href="#fair-data-point-metadata"></a></h4>
<table class="def">
<caption>FAIR Data Point metadata schema</caption>
<thead>
<tr>
<th>Ontology
<th>Property name
<th>Datatype
<th>Cardinality
<th>Description
<tbody>
<tr>
<td>RDF
<td>rdf:type
<td>IRI
<td>1
<td>The type of the object described by the metadata record, which, in this case, is a FAIR Data Point.
The value <em class="rfc2119">MUST</em> be <code>fdp-o:FAIRDataPoint</code>.
<tr>
<td>DC terms
<td>dct:title
<td>String
<td>1..*
<td>Name of the FAIR Data Point with the language tag.
<tr>
<td>
<td>dct:description
<td>String
<td>0..*
<td>Description of the FAIR Data Point with the language tag.
<tr>
<td>
<td>dct:publisher
<td><code>foaf:Agent</code>
<td>1..*
<td>The entity or entities (person or organization) responsible for the FAIR Data Point.
<tr>
<td>
<td>dct:language
<td>IRI
<td>0..*
<td>The language(s) used in the metadata record.
<tr>
<td>
<td>dct:license
<td>IRI
<td>1
<td>The reference to the usage license of the FAIR Data Point.
<tr>
<td>
<td>dct:conformsTo
<td>IRI
<td>1
<td>This property points to a profile that contains the specification of the FAIR Data Point’s metadata schema (in <code>SHACL</code>).
<tr>
<td>
<td>dct:rights
<td>IRI
<td>0..*
<td>
<tr>
<td>
<td>dct:accessRights
<td>IRI
<td>0..*
<td>
<tr>
<td>DCAT
<td>dcat:contactPoint
<td><code>vCard</code>
<td>0..*
<td>Relevant contact information for the FAIR Data Point.
<tr>
<td>
<td>dcat:keyword
<td>String
<td>0..*
<td>Keyword(s) describing the FAIR Data Point.
<tr>
<td>
<td>dcat:theme
<td><code>skos:subject</code>
<td>0..*
<td>
Main concept(s) related to the FAIR Data Point.
DCAT themes are similar to keywords in the sense of representing concepts that are related to the entity.
However, keywords are natural language terms, intended for human consumption, whereas themes are concepts defined in ontologies/vocabularies, for machine consumption.
<tr>
<td>
<td>dcat:endPointURL
<td>IRI
<td>1
<td>The URL of the FDP API endpoint.
<tr>
<td>
<td>dcat:endPointDescription
<td>IRI
<td>0..*
<td>
The URL of the document describing the endpoint, its operations, services, parameters, etc.
The description should be expressed in a machine-readable format, such as an OpenAPI or SmartAPI description.
<tr>
<td>FDP ontology
<td>fdp-o:metadataIdentifier
<td><code>IRI</code>
<td>1
<td>Identifier of the metadata entry.
<tr>
<td>
<td>fdp-o:metadataIssued
<td><code>xsd:dateTime</code>
<td>1
<td>Creation data of the metadata entry.
<tr>
<td>
<td>fdp-o:metadataModified
<td><code>xsd:dateTime</code>
<td>1
<td>Last modified data of the metadata entry.
<tr>
<td>
<td>fdp-o:startDate
<td>xsd:date
<td>0..1
<td>Date when the metadata service started its operations.
<tr>
<td>
<td>fdp-o:endDate
<td>xsd:date
<td>0..1
<td>Date when the metadata service ended its operations.
<tr>
<td>
<td>fdp-o:uiLanguage
<td>IRI
<td>0..*
<td>The user interface language(s) of the FAIR Data Point, which is different from the <code>dcat:Resource</code> property of <code>dct:language</code> that relates to the language of the metadata record.
<tr>
<td>
<td>fdp-o:hasSoftwareVersion
<td>String
<td>0..1
<td>Version of the metadata service software that exposes the FDP behaviour.
<tr>
<td>
<td>fdp-o:conformsToFdpSpec
<td>IRI
<td>1
<td>The relation should point to a URI that contains the version of the FDP specifications which this instance of the FDP conforms to.
</table>
<p>The navigation information for the FAIR Data Point metadata record is defined below:</p>
<table class="def">
<caption>FAIR Data Point metadata’s navigation information schema</caption>
<thead>
<tr>
<th>Ontology
<th>Property name
<th>Datatype
<th>Cardinality
<th>Description
<tbody>
<tr>
<td>RDF
<td>rdf:type
<td>IRI
<td>1
<td>
The type of the object described by the navigation information metadata segment which, in this case, is a Direct Container.
The value <em class="rfc2119">MUST</em> be <code>ldp:DirectContainer</code>.
<tr>
<td>DC terms
<td>dct:title
<td>String
<td>1..*
<td>Name of the container.
<tr>
<td>LDP
<td>ldp:contains
<td><code>IRI</code>
<td>1..*
<td>
Identifier of the resources contained in this container.
In this case, the identifiers of the catalogs available in this FAIR Data Point.
The object of this property <em class="rdc2119">MUST</em> be an instance of <code>dcat:Catalog</code> or a sub-class of it.
<tr>
<td>LDP
<td>ldp:hasMemberRelation
<td><code>IRI</code>
<td>1