Submit FEP 22b6 (#729)

Reviewed-on: https://codeberg.org/fediverse/fep/pulls/729 Co-authored-by: Helge <helge.krueger@gmail.com> Co-committed-by: Helge <helge.krueger@gmail.com>
2026-08-06 04:05:53 +00:00 · 2025-11-12 10:16:48 +01:00
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+---
+slug: "22b6"
+authors: Helge <@helge@mymath.rocks>
+status: DRAFT
+dateReceived: 2025-11-12
+discussionsTo: https://socialhub.activitypub.rocks/t/fep-22b6-linking-an-activitypub-object-to-a-html-page-and-back/8369
+---
+# FEP-22b6: Linking an ActivityPub Object to a HTML page and back
+
+## Summary
+
+Links are a fundamental part of the internet. This FEP describes how to use
+links to link a HTML page to an ActivityPub object. The mechanisms described
+in this document are not new and are used to link to RSS feeds (see [alternate][],
+second example).
+
+## Linking from a HTML page
+
+The HTML living standard states about [alternate][]
+
+> The keyword creates a hyperlink referencing an alternate representation of the current document.
+
+In this sense, we can link from the HTML page to an ActivityPub object
+using 
+
+```html
+<head>
+    ...
+    <link rel="alternate" type="application/activity+json" href="http://location.example/object.id">
+    ...
+</head>
+```
+
+which can be used for automatic discovery.
+To provide a link for the user, one should use an anchor, e.g.
+
+```html
+<body>
+    ...
+    <a rel="alternate" type="application/activity+json" href="http://location.example/object.id">
+        ActivityPub Object
+    </a>
+    ...
+</body>
+```
+
+We recommend using both forms as they serve different purposes.
+
+>[!WARNING]
+> One might be tempted to use [canonical][] instead of [alternate][] if the HTML page
+> just renders the content of the ActivityPub object. The author believes that sticking
+> to the single format giving here has the highest chance of leading to widespread support.
+
+### Discussions
+
+As the [example](#example) below shows, there are use cases when the ActivityPub object
+and the page are on different servers. One can however still check the relationship,
+by verifying the ActivityPub object contains a link back to the page.
+
+Similarly, the ActivityPub object might provide less content than the webpage.
+
+### Example
+
+The page [https://bovine.codeberg.page/comments/](https://bovine.codeberg.page/comments/) contains
+the link element
+
+```html
+<link rel="alternate"
+  href="https://comments.bovine.social/pages/aHR0cHM6Ly9ib3ZpbmUuY29kZWJlcmcucGFnZS9jb21tZW50cy8="
+  type="application/activity+json">
+```
+
+and the linked object resolves to
+
+```json
+{
+  "@context": "https://www.w3.org/ns/activitystreams",
+  "type": "Page",
+  "attributedTo": "https://comments.bovine.social/actor/rF4xnx1QraAIU3Krg-2Qzg",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "published": "2025-10-20T17:45:11Z",
+  "url": [
+    {
+      "type": "Link",
+      "href": "https://bovine.codeberg.page/comments/",
+      "mediaType": "text/html"
+    }
+  ],
+  "name": "Comment Tracking System",
+  "summary": null,
+  "id": "https://comments.bovine.social/pages/aHR0cHM6Ly9ib3ZpbmUuY29kZWJlcmcucGFnZS9jb21tZW50cy8=",
+  "context": "https://comments.bovine.social/pages/aHR0cHM6Ly9ib3ZpbmUuY29kZWJlcmcucGFnZS9jb21tZW50cy8=/context",
+  "replies": "https://comments.bovine.social/pages/aHR0cHM6Ly9ib3ZpbmUuY29kZWJlcmcucGFnZS9jb21tZW50cy8=/replies",
+  "likes": "https://comments.bovine.social/pages/aHR0cHM6Ly9ib3ZpbmUuY29kZWJlcmcucGFnZS9jb21tZW50cy8=/likes",
+  "shares": "https://comments.bovine.social/pages/aHR0cHM6Ly9ib3ZpbmUuY29kZWJlcmcucGFnZS9jb21tZW50cy8=/shares"
+}
+``` 
+
+The Page object can be understood as [Page in the ActivityVocabulary][as-page] here, i.e. "Represents a Web Page".
+
+## Alternatives
+
+As already said, we recommend using this suggested approach to link from
+the HTML to an ActivityPub object.
+
+However, there are other methods that are in use to provide the link,
+and should be considered valid options.
+
+* [Content Negotiation][contneg]
+* [Link Headers][link-headers]
+
+For the use case of [FEP-136c: Comment Tracking Services][FEP-136c], that motivates
+this work, embedding the links in the HTML is the only viable option.
+This is due to the HTML often being hosted on static sites that do
+not provide the option to use Content Negotiation or Link Headers.
+
+## References
+
+- Helge, [FEP-136c: Comment Tracking Services][FEP-136c], in preparation
+- HTML Living Standard, [4.6.7.1 Link type "alternate"][alternate]
+- HTML Living Standard, [4.6.7.4 Link type "canonical"][canonical]
+- James M Snell, Evan Prodromou, [Activity Vocabulary][as-page]
+
+
+[alternate]: https://html.spec.whatwg.org/multipage/links.html#rel-alternate
+[canonical]: https://html.spec.whatwg.org/multipage/links.html#link-type-canonical
+[contneg]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Content_negotiation
+[link-headers]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Link
+[as-page]: https://www.w3.org/TR/activitystreams-vocabulary/#dfn-page
+[FEP-136c]: https://bovine.codeberg.page/comments/136c/fep-136c/
+
+## Copyright
+
+CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+
+To the extent possible under law, the authors of this Fediverse Enhancement Proposal have waived all copyright and related or neighboring rights to this work.