Groups Extension

Groups are a way to organize users and notes into communities. They can be used for any purpose, such as forums, blogs, image galleries, video sharing, audio sharing, and messaging. They are similar to Discord's channels or Matrix's rooms.

Refer to Note's group property for how notes can be associated with groups.

Entity Definition

{
    "type": "pub.versia:groups/Group",
    "id": "ed480922-b095-4f09-9da5-c995be8f5960",
    "name": {
        "text/html": {
            "content": "The <strong>Woozy</strong> fan club"
        }
    },
    "description": {
        "text/plain": {
            "content": "A group for fans of the Woozy emoji."
        }
    },
    "open": false
}

Collections

The following Collections are available:

• members: URI Collection of Users that are members of the group.
• notes: URI Collection of Notes that are associated with the group.

These can be fetched using the Federation API

Subscribing to Groups

Users may "subscribe" to a Group in order to receive all Notes posted to it. The mechanism by which federation is handled is described at the end of this document.

First, a User must send a GroupSubscribe activity to the group. The group will then respond with either a GroupSubscribeAccept or a GroupSubscribeReject activity.

If the group accepts the subscription, the user will receive all notes posted to the group. If the group rejects the subscription, the user will not receive any notes posted to the group.

GroupSubscribe

Indicates that a User wishes to subscribe to a group.

{
    "type": "pub.versia:groups/Subscribe",
    "subscriber": "e9277471-8aa1-4d40-a3d0-0878e818ccdc",
    "group": "example.com:ed480922-b095-4f09-9da5-c995be8f5960",
    "created_at": "2021-01-01T00:00:00Z"
}

GroupUnsubscribe

Indicates that a User wishes to unsubscribe from a group.

{
    "type": "pub.versia:groups/Unsubscribe",
    "subscriber": "e9277471-8aa1-4d40-a3d0-0878e818ccdc",
    "group": "example.com:ed480922-b095-4f09-9da5-c995be8f5960",
    "created_at": "2021-01-01T00:00:00Z"
}

GroupSubscribeAccept

Indicates that a Group has accepted a User's subscription request. Should be sent by the instance hosting the group.

{
    "type": "pub.versia:groups/SubscribeAccept",
    "subscriber": "e9277471-8aa1-4d40-a3d0-0878e818ccdc",
    "group": "example.com:ed480922-b095-4f09-9da5-c995be8f5960",
    "created_at": "2021-01-01T00:00:00Z"
}

GroupSubscribeReject

Indicates that a Group has rejected a User's subscription request. Should be sent by the instance hosting the group.

{
    "type": "pub.versia:groups/SubscribeReject",
    "subscriber": "e9277471-8aa1-4d40-a3d0-0878e818ccdc",
    "group": "example.com:ed480922-b095-4f09-9da5-c995be8f5960",
    "created_at": "2021-01-01T00:00:00Z"
}

Federation

Group federation represents a particularly challenging problem, as it requires a way to make sure every single Note posted to it is delivered to every single member of the group.

All Notes posted to a group (using the group field) must be sent to its instance's inbox.

Once this is done, the group's instance must then federate this Note to every member of the group. However, this cannot be done the "normal way", as the group's instance does not have the private key to sign the Note.

GroupFederate

The GroupFederate entity allows a group to federate a note to all of its members, without needing to sign the note itself. It contains a URI to the note being federated, which must be fetched by the receiving instances. This entity is sent by the group's instance.

{
    "type": "pub.versia:groups/Federate",
    "note": "c5aa65fa-0356-4029-b61c-6b237e5d1393",
    "group": "example.com:ed480922-b095-4f09-9da5-c995be8f5960",
    "created_at": "2021-01-01T00:00:00Z"
}