This document gives an overview how remote `Event` objects are treated by common Fediverse applications.
## Mastodon
**Last updated**: 2024-10-20
Mastodon does not have support or events, but an `Event` object is in the [list of converted object types](https://github.com/mastodon/mastodon/pull/12637/commits/0428c00e30abcb0580558f9bdca672abc8b68f81).
It neglets all event related fields but `title`, `summary` and `url` which it uses to create a Mastodon status (toot) representation of the event.
## Mobilizon
**Last uptaded**: 2024-01-20
**Information sources**:
- [Mobilizon ActivityStreams converter for Event](https://framagit.org/framasoft/mobilizon/-/blob/main/lib/federation/activity_stream/converter/event.ex?ref_type=heads)
- [Mobilizon Database schema for Event](https://framagit.org/framasoft/mobilizon/-/blob/main/lib/mobilizon/event.ex?ref_type=heads)
### Required
- [`attributedTo`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-attributedTo) or [`actor`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-actor): Mobilizon uses actor for the user profile and attributedTo for the group. But as `actor` being part of an object is not part of the ActivityPub spec, solely using `attributedTo` might preferred if they are similar.
-`category`: default list of categories can be found [in the source code](https://framagit.org/framasoft/mobilizon/-/blob/main/lib/mobilizon/events/categories.ex?ref_type=heads#L28), but it can be extended via environment variables. Note that the source code shows them in lowercase, but they have to be passed as uppercase, e.g. `MOVEMENTS_POLITICS`.
-`externalParticipationUrl`: Only used if `joinMode` is set to `external`.
-`is_online`: Boolean indicating whether the Event is online.
- [`joinMode`](https://docs.joinmobilizon.org/contribute/activity_pub/#joinmode): `[free, restricted, invite, external]` default is `free`.
- [`location`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-location): The subkey [`address`](https://schema.org/address) is accepted, both as [`PostalAddress`](https://schema.org/PostalAddress) and pure text.
-`url`: [Documentation](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-url) - Note: `url` was added to the list as it was referenced in the text but not explicitly listed in the initial set.
- [`url`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-url): internally Mobilizon uses the `id` as URL.
### To Test:
### Handling of visibility, comments and discoverability
- If `https://www.w3.org/ns/activitystreams#Public` is not in `to` it will be treated as `unlisted`, else as `public`. This are the only options for remote events, even though internally Mobilizon supports `[public, unlisted, restricted, private]`.
- For comments to be enabled within Mobilizon either [`commentsEnabled`](https://docs.joinpeertube.org/api/activitypub) must be `true` or `repliesModerationOption` must be set to `allow_all`. `repliesModerationOption` is more important. If none is of both is passed replies will be disabled.
- When the `attributedTo` (or if `attributedTo` is not set, but `actor` is set) contains an `Actor` of type `Person` the remote `Event` will not be listed and searchable.
- If `timezone` is not defined Mobilizon might calculate the timezone via the `location`.
Mobilizon currently expects all images to by within `attachment` and to be an `Object` of type `Document`. It first looks for an object where the `name` is equal to `Banner`. If that is not found it uses ´attachment[0]`.
-`id`: even though Gancio currently does not [list it as required in its source code](https://framagit.org/les/gancio/-/blob/master/server/federation/events.js?ref_type=heads#L19), there will be an error without out it.
- [`attachment`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-attachment) Only the first one is used as a banner image, all others are ignored, see below.
- [`content`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-content) `contentMap` is currently not supported by Gancio.
- [`location`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-location): The subkey [`address`](https://schema.org/address) is accepted, both as [`PostalAddress`](https://schema.org/PostalAddress) and pure text. For `PostalAddress` only `streetAddress`, `addressLocality`, and `addressCountry` are used.
-`attributedTo`/`actor`: Gancio does not support fetching event other than by receiving a `Create` or `Update` activity (TODO: what about `Announce`), the actor is always just fetched from the activity, not the object within.
Currently Gancio does not seem to handle any visibility or replies-policy options. It sets all remote events it received to the internal `is_visible` to `true`.
### Banner image
Gancio takes the first `attachment` of the `Event` object as the banner image of the event. It optionally supports [`name`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-name) as the alternative text and [`focalPoint`](https://docs.joinmastodon.org/spec/activitypub/#focalPoint).
**Information sources**: Plemora has a open [Pull Request towards Mobilizon compatible events](https://git.pleroma.social/pleroma/pleroma/-/merge_requests/3955/diffs) which Rebased (a fork of Plemora) has already merged.
### Required
This probably has a lot of errors still. [Source Code](https://git.pleroma.social/pleroma/pleroma/-/blob/b1a06c394736be833f8220a5ec3d5d2702d9519c/lib/pleroma/web/activity_pub/object_validators/event_validator.ex).
-`id`: even though Gancio currently does not [list it as required in its source code](https://framagit.org/les/gancio/-/blob/master/server/federation/events.js?ref_type=heads#L19), there will be an error without out it.
- [`name`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-name): The events title.
- [`joinMode`](https://docs.joinmobilizon.org/contribute/activity_pub/#joinmode): `[free, restricted, invite, external]` default is `free`.
- [`location`](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-location): The subkey [`address`](https://schema.org/address) is accepted, but currently ony as [`PostalAddress`](https://schema.org/PostalAddress) with the fields `postalCode`, `addressRegion`, `streetAddress`, `addressCountry` and `addressLocality`.
