Fep-2677 identifying the application actor (#188)

Reviewed-on: https://codeberg.org/fediverse/fep/pulls/188 Co-authored-by: Helge <helge.krueger@gmail.com> Co-committed-by: Helge <helge.krueger@gmail.com>
2026-08-05 19:55:46 +00:00 · 2023-10-15 16:58:00 +00:00
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+---
+slug: "2677"
+authors: Helge <helge.krueger@gmail.com>
+status: DRAFT
+dateReceived: 2023-10-14
+---
+# FEP-2677: Identifying the Application Actor
+
+## Summary
+
+It is a common pattern in Fediverse applications to have a special
+actor of type Application. This is for example the actor at `https://mastodon.example/actor`
+for Mastodon or at `https://pleroma.example/internal/fetch` for Pleroma.
+This application actor can be fetched with an unsigned request, so it
+is possible to use it to fetch public keys.
+
+The goal of this FEP is to provide an explicit mechanism of identifying
+the application actor, with the goal of making it usable for further tasks,
+e.g.
+
+- Allowing for application to application communication by having
+application actor send activities to another application actor's inbox.
+- Having an object one can attach further information to. This means, one
+could attach a list of implemented FEPs to the application actor.
+
+## Requirements
+
+The key word "MUST"  in this specification are to be interpreted as described in [RFC 2119].
+
+Following [NodeInfo], see also [FEP-f1d5], a Fediverse application implementing this
+FEP, i.e. FEP-2677, MUST provide the well-known path `/.well-known/nodeinfo` and serve a document in JRD format [RFC 7033].
+This document MUST then contain a link with relation `https://purl.archive.org/funfedi/applicationActor`,
+whose link resolves to an actor of type `Application` (see [ActivityPub]). This actor MUST be retrievable with an unsigned HTTP request.
+
+## Example
+
+We will consider the server with domain `node.example`. This means that a request
+to `https://node.example/.well-known/nodeinfo` will resolve to
+
+```json
+ {
+    "links": [
+        {
+            "rel": "http://nodeinfo.diaspora.software/ns/schema/2.0",
+            "href": "https://node.example/nodeinfo/2.0"
+        },
+        {
+            "rel": "https://purl.archive.org/funfedi/applicationActor",
+            "href": "https://node.example/actor"
+        }
+    ]
+ }
+```
+
+Next, a request to `https://node.example/actor` with accept header `application/activity+json`
+could return
+
+```json
+{
+    "@context": [
+        "https://www.w3.org/ns/activitystreams",
+        "https://w3id.org/security/v1",
+    ],
+    "id": "https://node.example/actor",
+    "type": "Application",
+    "inbox": "https://node.example/actor/inbox",
+    "outbox": "https://node.example/actor/outbox",
+    "publicKey": {
+        "id": "https://node.example/actor#main-key",
+        "owner": "https://node.example/actor",
+        "publicKeyPem": "-----BEGIN PUBLIC KEY-----\n....\n-----END PUBLIC KEY-----\n"
+    }
+}
+```
+
+## References
+
+- [ActivityPub] Christine Lemmer Webber, Jessica Tallon, [ActivityPub](https://www.w3.org/TR/activitypub/), 2018
+- [FEP-f1d5] CJ, silverpill, [NodeInfo in Fediverse Software](https://codeberg.org/fediverse/fep/src/branch/main/fep/f1d5/fep-f1d5.md), 2023
+- [NodeInfo] [NodeInfo protocol 2.1](http://nodeinfo.diaspora.software/protocol.html)
+- [RFC 2119] S. Bradner, [Key words for use in RFCs to Indicate Requirement Levels](https://tools.ietf.org/html/rfc2119.html), 1997
+- [RFC 7033] P. Jones, G. Salgueiro, M. Jones, J. Smarr, [Webfinger](https://www.rfc-editor.org/rfc/rfc7033.html), 2013
+
+## 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.