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---
title: Event sourcing on Web-scale
description: >-
  LDES (Linked Data Event Streams) lets you publish an append-only collection
  of immutable Linked Data on the Web, so consumers can copy data and follow updates.
hide_nav_brand: true
---
{% include header.html %}

<header class="site-header">
  <img src="{{ '/assets/logo-ldes.svg' | relative_url }}" alt="LDES logo" class="hero-logo"/>
  <h1>Linked Data Event Streams</h1>
  <p class="tagline">Event sourcing on Web-scale</p>
  <p class="hero-summary">Publish your data and its changes. Let consumers build their own views and keep them up to date.</p>
  <div class="hero-ctas">
    <a href="https://w3id.org/ldes/specification">Read the specification</a>
    <a href="{{ '/examples/' | relative_url }}">Explore LDES examples</a>
    <a href="https://matrix.to/#/#ldes:chat.semantic.works">Join the chat</a>
  </div>
</header>

{% include nav.html %}

<main id="main-content" class="container">

  <section id="what-is-ldes" typeof="schema:TechArticle">
    <h2>What is LDES?</h2>
    <p class="section-intro">
      Linked Data Event Streams (LDES) is an open specification for publishing an append-only collection of
      immutable members as Linked Data. Members can describe events, observations, or successive versions of a record.
      Consumers can copy the available data, then follow new members as they are published.
    </p>
    <h3>Publish once. Support many uses.</h3>
    <p>
      Publisher provides a common source without having to build an API for every use case.
    </p>
    <ol class="how-it-works">
      <li><strong>Publish changes.</strong> Add new members instead of overwriting existing ones. Use shared RDF vocabularies to describe the data.</li>
      <li><strong>Copy and follow.</strong> Clients traverse linked pages over HTTP and check for new members, reusing cached responses where possible.</li>
      <li><strong>Build your own view.</strong> Maintain a local database, search index, or API, and process updates at your own pace.</li>
    </ol>
    <p>
      LDES uses <a href="https://w3id.org/tree/specification">TREE</a> links to let clients discover and navigate
      pages of members. Views can be fragmented by time or other properties; the stream itself is not necessarily
      delivered in chronological order. How far a client can go back depends on the publisher’s retention policy.
    </p>
    <p>
      Developed in the <a href="https://github.com/SEMICeu/LinkedDataEventStreams">SEMIC community</a>,
      LDES gives publishers and consumers a shared contract for exchanging changing data.
      <a href="https://w3id.org/ldes/specification"><strong>Read the specification &rarr;</strong></a>
    </p>
  </section>

  <section id="supported-by" class="ecosystem" aria-labelledby="supported-by-heading" about="https://ldes.tech/#organization">
    <div class="ecosystem-intro">
      <h2 id="supported-by-heading">An open specification.<br>Real-world adoption.</h2>
      <p>Supported by public institutions. Put to work by cities, museums, and research organisations.
        Discover the people turning shared data into reusable services.</p>
    </div>

    <div class="supporters">
      <a class="supporter supporter-primary" href="https://interoperable-europe.ec.europa.eu/collection/semic-support-centre/linked-data-event-streams-ldes" resource="https://interoperable-europe.ec.europa.eu/" property="schema:funder schema:maintainer" typeof="schema:GovernmentOrganization">
        <div class="supporter-logo"><img src="{{ '/assets/logos/interoperable-europe.svg' | relative_url }}" alt="" property="schema:logo" loading="lazy"/></div>
        <h3 property="schema:name">Interoperable Europe</h3>
        <p>The main current funder and maintainer of LDES, through the European Commission programme for cross-border digital public services.</p>
        <span class="org-link">Discover the programme <span aria-hidden="true">&rarr;</span></span>
      </a>
      <a class="supporter supporter-flanders" href="https://openldes.org/" resource="https://www.vlaanderen.be/digitaal-vlaanderen" property="schema:funder" typeof="schema:GovernmentOrganization">
        <div class="supporter-logo"><img src="{{ '/assets/logos/vlaanderen.svg' | relative_url }}" alt="" property="schema:logo" loading="lazy"/></div>
        <h3 property="schema:name">Flanders</h3>
        <p>Supporting LDES through the OpenLDES community.</p>
        <span class="org-link">Explore the community <span aria-hidden="true">&rarr;</span></span>
      </a>
    </div>

    <div class="adopters-intro">
      <h3>Already putting LDES to work</h3>
      <p>Different domains. A shared way to publish and follow change.</p>
    </div>
    <ul class="adopters">
      <li>
        <a class="adopter" href="https://coghent.github.io/API/" resource="https://stad.gent/" typeof="schema:GovernmentOrganization">
          <div class="adopter-logo"><img src="{{ '/assets/logos/gent.svg' | relative_url }}" alt="" property="schema:logo" loading="lazy"/></div>
          <h4 property="schema:name">City of Ghent</h4>
          <p>Sharing the CoGhent heritage collections.</p>
          <span class="org-link">Explore CoGhent <span aria-hidden="true">&rarr;</span></span>
        </a>
      </li>
      <li>
        <a class="adopter" href="https://open-science.vliz.be/linked-data" resource="https://www.vliz.be/" typeof="schema:ResearchOrganization">
          <div class="adopter-logo"><img src="{{ '/assets/logos/vliz.jpg' | relative_url }}" alt="" property="schema:logo" loading="lazy"/></div>
          <h4 property="schema:name">VLIZ</h4>
          <p>Connecting marine data through Linked Data.</p>
          <span class="org-link">Explore marine data <span aria-hidden="true">&rarr;</span></span>
        </a>
      </li>
      <li>
        <a class="adopter" href="https://data.rijksmuseum.nl/docs/ldes/" resource="https://www.rijksmuseum.nl/" typeof="schema:Organization">
          <div class="adopter-logo"><img src="{{ '/assets/logos/rijksmuseum.svg' | relative_url }}" alt="" property="schema:logo" loading="lazy"/></div>
          <h4 property="schema:name">Rijksmuseum</h4>
          <p>Making collection updates available to reusers.</p>
          <span class="org-link">Explore the collection <span aria-hidden="true">&rarr;</span></span>
        </a>
      </li>
      <li>
        <a class="adopter" href="https://semiceu.github.io/LDES-implementation-reports/era-dcat-ap-feed/" resource="https://www.era.europa.eu/" typeof="schema:GovernmentOrganization">
          <div class="adopter-logo"><img src="{{ '/assets/logos/era.png' | relative_url }}" alt="" property="schema:logo" loading="lazy"/></div>
          <h4 property="schema:name">EU Agency for Railways</h4>
          <p>Publishing catalog changes as an event stream.</p>
          <span class="org-link">Read the report <span aria-hidden="true">&rarr;</span></span>
        </a>
      </li>
    </ul>
    <div class="ecosystem-actions">
      <a class="ecosystem-button" href="{{ '/examples/' | relative_url }}">See LDES in action <span aria-hidden="true">&rarr;</span></a>
      <a href="{{ '/community/' | relative_url }}">Build with the community <span aria-hidden="true">&rarr;</span></a>
    </div>
  </section>
  <section id="quicklinks">
    <h2>Find your way around</h2>
    <ul class="card-list cols-3">
      <li>
        <h3><a href="{{ '/examples/' | relative_url }}">LDES examples</a></h3>
        <p>Discover known LDES feeds and their sources &mdash; from museum collections to marine gazetteers.</p>
      </li>
      <li>
        <h3><a href="{{ '/news/' | relative_url }}">News and blog</a></h3>
        <p>Announcements, tutorials and deep dives &mdash; also available as an <a href="{{ '/news/feed.xml' | relative_url }}">RSS feed</a>.</p>
      </li>
      <li>
        <h3><a href="{{ '/community/' | relative_url }}">Community</a></h3>
        <p>Join the Matrix chat room, watch talks on our YouTube playlist, and meet the people building LDES.</p>
      </li>
      <li>
        <h3><a href="{{ '/tools/' | relative_url }}">Tools</a></h3>
        <p>Open-source clients and servers for LDES, including RDF-Connect (JavaScript) and the OpenLDES ecosystem (Java).</p>
      </li>
      <li>
        <h3><a href="https://w3id.org/ldes/specification">Specification</a></h3>
        <p>The LDES vocabulary, publishing requirements, and guidance for clients and servers.</p>
      </li>
    </ul>
  </section>

  <section id="latest-news">
    <h2>Latest from the blog</h2>
    <div class="news-list news-list-compact">
      {% assign latest_posts = site.posts | slice: 0, 3 %}
      {% for post in latest_posts %}
        {% include news-story.html post=post %}
      {% endfor %}
    </div>
    <p><a href="{{ '/news/' | relative_url }}">View all news &rarr;</a></p>
  </section>
  <section id="paper">
          {% include paper-citation.html paper="base-registries" context="The original base registries paper introduces LDES as a common source for independent data services." %}
  </section>
  

</main>

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{% include footer.html %}