Federation¶

ActivityPub¶

Mobilizon uses ActivityPub to federate content between instances. It only supports the server-to-server part of the ActivityPub spec.

It implements the HTTP signatures spec for authentication of inbox deliveries, but doesn't implement Linked Data Signatures for forwarded payloads, and instead fetches content when needed.

To match usernames to actors, Mobilizon uses WebFinger.

Limitations¶

see here

Instance subscriptions¶

Instances subscribe to each other through an internal actor named relay@instance.tld that publishes (through Announce) every item of created content to it's followers. Each content creation share is saved so that updates and deletes are correctly sent to every relay subscriber.

Activities¶

Supported Activity	Supported Object or Activity
`Accept`	`Follow`, `Join`
`Add`	`Document`, `ResourceCollection`
`Announce`	any `Object`
`Create`	any `Object`
`Delete`	any `Object`
`Flag`	any `Object`
`Follow`	any `Object`
`Invite`	`Group`
`Join`	`Event`
`Leave`	`Event`, `Group`
`Move`	`Document`, `ResourceCollection`
`Reject`	`Follow`, `Join`
`Remove`	`Note`, `Event`, `Member`
`Undo`	`Announce`, `Follow`
`Update`	`Object`

Objects¶

Person¶

Every Mobilizon profile is a Person.

Event¶

Every Mobilizon event is an Event with a few extensions, especially for location information since Place is limited.

Note¶

Every Mobilizon comment showing under an event is a Note, as well as every element from group discussions, where the context property is used to group messages in discussions.

Group¶

Every Mobilizon group is a Group.

Member¶

Every Mobilizon group member is a Member, that conveys the role information that the Person has in the Group.

%{
  "type" => "Member",
  "id" => "https://somemobilizon.instance/member/some-uuid",
  "actor" => "https://somemobilizon.instance/@some-person",
  "object" => "https://somemobilizon.instance/@some-group",
  "role" => "MODERATOR"
    }

The allowed values for role are: invited, not_approved, member, moderator, administrator, rejected.

Document¶

Attached pictures and other files are represented with Document.

Group resources are also represented with Document.

Article¶

Every Mobilizon group post is an Article.

ResourceCollection¶

Mobilizon's group resources (see Document) can be collected into folders named ResourceCollection, which have the same set of properties as a Document, without the url.

Extensions¶

Event¶

The vocabulary for Event is based on the Event object in ActivityStreams, extended with :

the Event Schema from Schema.org
some properties from iCalendar, such as ical:status (see this issue)

The following properties are added.

repliesModeration¶

Disabling replies is an ongoing issue with ActivityPub so we use a temporary property.

See the corresponding issue.

Accepted values: allow_all, closed, moderated (not used at the moment)

Info

We also support PeerTube's commentEnabled property as a fallback. It is set to true only when repliesModeration is equal to allow_all.

Example:

{
  "@context": [
    "...",
    {
      "mz": "https://joinmobilizon.org/ns#",
      "pt": "https://joinpeertube.org/ns#",
      "repliesModerationOption": {
        "@id": "mz:repliesModerationOption",
        "@type": "mz:repliesModerationOptionType"
      },
      "repliesModerationOptionType": {
        "@id": "mz:repliesModerationOptionType",
        "@type": "rdfs:Class"
      },
      "commentsEnabled": {
        "@id": "pt:commentsEnabled",
        "@type": "sc:Boolean"
      }
    }
  ],
  "...": "...",
  "repliesModerationOption": "allow_all",
  "commentsEnabled": true,
  "type": "Event",
  "url": "http://mobilizon1.com/events/8cf76e9f-c426-4912-9cd6-c7030b969611"
}

joinMode¶

Indicator of how new members may be able to join.

See the corresponding issue.

Accepted values: free, restricted, external, invite (not used at the moment)

If set to external, externalParticipationUrl must be set as well containing the target URL.

Examples:

{
  "@context": [
    "...",
    {
      "mz": "https://joinmobilizon.org/ns#",
      "joinMode": {
        "@id": "mz:joinMode",
        "@type": "mz:joinModeType"
      },
      "joinModeType": {
        "@id": "mz:joinModeType",
        "@type": "rdfs:Class"
      }
    }
  ],
  "...": "...",
  "joinMode": "restricted",
  "type": "Event",
  "url": "http://mobilizon1.com/events/8cf76e9f-c426-4912-9cd6-c7030b969611"
}

{
  "@context": [
    "...",
    {
      "mz": "https://joinmobilizon.org/ns#",
      "joinMode": {
        "@id": "mz:joinMode",
        "@type": "mz:joinModeType"
      },
      "joinModeType": {
        "@id": "mz:joinModeType",
        "@type": "rdfs:Class"
      }
    }
  ],
  "...": "...",
  "joinMode": "external",
  "type": "Event",
  "url": "http://mobilizon1.com/events/8cf76e9f-c426-4912-9cd6-c7030b969611",
  "externalParticipationUrl": "https://www.meetup.com/somegroup/events/00000/"
}

location¶

We use Schema.org's location property on Event. The ActivityStream vocabulary to represent places is quite limited so instead of just using Place from ActivityStreams we also add a few properties from Schema.org's Place vocabulary.

We add an address property, which we assume to be of PostalAddress type.

{
  "@context": [
    "...",
    {
      "PostalAddress": "sc:PostalAddress",
      "address": {
        "@id": "sc:address",
        "@type": "sc:PostalAddress"
      },
      "addressCountry": "sc:addressCountry",
      "addressLocality": "sc:addressLocality",
      "addressRegion": "sc:addressRegion",
      "postalCode": "sc:postalCode",
      "sc": "http://schema.org#",
      "streetAddress": "sc:streetAddress",
    }
  ],
  "id": "http://mobilizon2.com/events/945f350d-a3e6-4bcd-9bf2-0bd2e4d353c5",
  "location": {
      "address": {
        "addressCountry": "France",
        "addressLocality": "Lyon",
        "addressRegion": "Auvergne-Rhône-Alpes",
        "postalCode": "69007",
        "streetAddress": "10 Rue Jangot",
        "type": "PostalAddress"
      },
      "latitude": 4.8425657,
      "longitude": 45.7517141,
      "id": "http://mobilizon2.com/address/bdf7fb53-7177-46f3-8fb3-93c25a802522",
      "name": "10 Rue Jangot",
      "type": "Place"
    },
  "type": "Event"
}

maximumAttendeeCapacity¶

We use Schema.org's maximumAttendeeCapacity to know how many places there can be for an event.

anonymousParticipationEnabled¶

We add this boolean field to know whether or not anonymous participants can participate in an event.

Note

Even though this information is federated, we redirect anonymous participants to the original instance so they can participate.

Join¶

participationMessage¶

We add a participationMessage property on a Join activity so that participants may transmit a note to event organizers, to motivate their participation when event participations are manually approved. This field is restricted to plain text.

{
  "type": "Join",
  "object": "http://mobilizon.test/events/some-uuid",
  "id": "http://mobilizon2.test/@admin/join/event/1",
  "actor": "http://mobilizon2.test/@admin",
  "participationMessage": "I want to join !",
  "@context": [
    {
      "participationMessage": {
        "@id": "mz:participationMessage",
        "@type": "sc:Text"
      }
    }
  ]
}

Last update: December 3, 2023