136 lines
4.7 KiB
Markdown
136 lines
4.7 KiB
Markdown
---
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title: ActivityPub compliance
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description: What objects and properties of the ActivityPub spec Mastodon supports
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menu:
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docs:
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parent: development
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weight: 5
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---
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## APIs
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- Mastodon supports the server-to-server part of the [ActivityPub spec](https://www.w3.org/TR/activitypub/).
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- It implements the [HTTP signatures spec](https://tools.ietf.org/html/draft-cavage-http-signatures-10) for authentication of inbox deliveries.
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- Mastodon also supports [Linked Data Signatures](https://w3c-dvcg.github.io/ld-signatures/) for forwarded payloads.
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## Restrictions
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- All object IDs must use the `https://` schema.
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- Servers must offer a [WebFinger](https://tools.ietf.org/html/rfc7033) endpoint for turning usernames into actors.
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- Activities attributed to an actor must have an ID on the same host as the actor.
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## Activities
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|Supported activity|Supported objects|
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|------------------|-----------------|
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|`Accept`|`Follow`|
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|`Add`|`Note`|
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|`Announce`|`Object`|
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|`Block`|`Object`|
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|`Create`|`Note`, `Article`, `Image`, `Video`, `Page`|
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|`Delete`|`Object`|
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|`Flag`|`Object`|
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|`Follow`|`Object`|
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|`Like`|`Object`|
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|`Move`|`Object`|
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|`Reject`|`Follow`|
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|`Remove`|`Note`|
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|`Undo`|`Accept`, `Announce`, `Block`, `Follow`, `Like`|
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|`Update`|`Object`|
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As far as the `Create` activity is concerned, only `Note` is a first-class citizen in Mastodon, because Mastodon is a microblogging engine. For other types of supported objects, Mastodon internally creates a toot representation, for example, an `Article` or `Page` becomes a toot with the `name` and `url` of the original object, as users are expected to navigate to the original URL to read the article with rich text formatting. For `Image` and `Video` objects, the `name` is likewise used to fill the content of the toot, with the original file attached to the toot.
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The `Flag` activity allows reporting content on another server, and its `object` can be either one or more actors, or one or more objects attributed to various actors. The `Add` and `Remove` activities only work with [featured collections](#featured-collection). The `Delete` activity can be used to delete all local data of the sender when the `object` of it is the sender. The `Update` activity can only be used to update the profile of the sender. Likewise, the `Move` activity allows re-assigning followers from the sender (`object`) to another actor (`target`), but only if the other actor references the sender in the `alsoKnownAs` property.
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## Extensions
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### Featured collection
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What is known in Mastodon as "pinned toots", or statuses that are always featured at the top of people's profiles, is implemented using an extra property `featured` on the actor object that points to a `Collection` of objects. Example:
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```json
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{
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"@context": [
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"https://www.w3.org/ns/activitystreams",
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{
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"toot": "http://joinmastodon.org/ns#",
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"featured": {
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"@id": "toot:featured",
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"@type": "@id"
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}
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}
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],
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"id": "https://example.com/@alice",
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"type": "Person",
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"featured": "https://example.com/@alice/collections/featured"
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}
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```
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### Custom emojis
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Mastodon supports arbitrary emojis, that is, small images uploaded by admins and invokable via shortcodes. For this, an `Emoji` type is used. These emojis are listed in the `tag` property just like `Mention` and `Hashtag` objects, since they are entities that affect how the text is rendered. Example:
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```json
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{
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"@context": [
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"https://www.w3.org/ns/activitystreams",
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{
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"toot": "http://joinmastodon.org/ns#",
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"Emoji": "toot:Emoji"
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}
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],
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"id": "https://example.com/@alice/hello-world",
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"type": "Note",
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"content": "Hello world :Kappa:",
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"tag": [
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{
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"id": "https://example.com/emoji/123",
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"type": "Emoji",
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"name": ":Kappa:",
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"icon": {
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"type": "Image",
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"mediaType": "image/png",
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"url": "https://example.com/files/kappa.png"
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}
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}
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]
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}
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```
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### Focal points
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Mastodon supports setting a focal point on uploaded images, so that wherever that image is displayed, the focal point stays in view. This is implemented using an extra property `focalPoint` on the `Image` objects. The property is simply an array of two floating points between 0 and 1. Example:
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```json
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{
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"@context": [
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"https://www.w3.org/ns/activitystreams",
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{
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"toot": "http://joinmastodon.org/ns#",
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"focalPoint": {
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"@container": "@list",
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"@id": "toot:focalPoint"
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}
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}
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],
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"id": "https://example.com/@alice/hello-world",
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"type": "Note",
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"content": "A picture attached!",
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"attachment": [
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{
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"type": "Image",
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"mediaType": "image/png",
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"url": "https://example.com/files/cats.png",
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"focalPoint": [
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0.55,
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0.43
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]
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}
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]
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}
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``` |