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Chats

Chats are a way to represent an IM-style conversation between two actors. They are not the same as direct messages and they are not Statuses, even though they have a lot in common.

Why Chats?

There are no 'visibility levels' in ActivityPub, their definition is purely a Mastodon convention. Direct Messaging between users on the fediverse has mostly been modeled by using ActivityPub addressing following Mastodon conventions on normal Note objects. In this case, a 'direct message' would be a message that has no followers addressed and also does not address the special public actor, but just the recipients in the to field. It would still be a Note and is presented with other Notes as a Status in the API.

This is an awkward setup for a few reasons:

  • As DMs generally still follow the usual Status conventions, it is easy to accidentally pull somebody into a DM thread by mentioning them. (e.g. "I hate @badguy so much")
  • It is possible to go from a publicly addressed Status to a DM reply, back to public, then to a 'followers only' reply, and so on. This can be become very confusing, as it is unclear which user can see which part of the conversation.
  • The standard Status format of implicit addressing also leads to rather ugly results if you try to display the messages as a chat, because all the recipients are always mentioned by name in the message.
  • As direct messages are posted with the same api call (and usually same frontend component) as public messages, accidentally making a public message private or vice versa can happen easily. Client bugs can also lead to this, accidentally making private messages public.

As a measure to improve this situation, the Conversation concept and related Pleroma extensions were introduced. While it made it possible to work around a few of the issues, many of the problems remained and it didn't see much adoption because it was too complicated to use correctly.

Chats explained

For this reasons, Chats are a new and different entity, both in the API as well as in ActivityPub. A quick overview:

  • Chats are meant to represent an instant message conversation between two actors. For now these are only 1-on-1 conversations, but the other actor can be a group in the future.
  • Chat messages have the ActivityPub type ChatMessage. They are not Notes. Servers that don't understand them will just drop them.
  • The only addressing allowed in ChatMessages is one single ActivityPub actor in the to field.
  • There's always only one Chat between two actors. If you start chatting with someone and later start a 'new' Chat, the old Chat will be continued.
  • ChatMessages are posted with a different api, making it very hard to accidentally send a message to the wrong person.
  • ChatMessages don't show up in the existing timelines.
  • Chats can never go from private to public. They are always private between the two actors.

Caveats

  • Chats are NOT E2E encrypted (yet). Security is still the same as email.

API

In general, the way to send a ChatMessage is to first create a Chat, then post a message to that Chat. Groups will later be supported by making them a sub-type of Account.

This is the overview of using the API. The API is also documented via OpenAPI, so you can view it and play with it by pointing SwaggerUI or a similar OpenAPI tool to https://yourinstance.tld/api/openapi.

Creating or getting a chat.

To create or get an existing Chat for a certain recipient (identified by Account ID) you can call:

POST /api/v1/pleroma/chats/by-account-id/:account_id

The account id is the normal FlakeId of the user 

POST /api/v1/pleroma/chats/by-account-id/someflakeid

If you already have the id of a chat, you can also use

GET /api/v1/pleroma/chats/:id

There will only ever be ONE Chat for you and a given recipient, so this call will return the same Chat if you already have one with that user.

Returned data:

{
  "account": {
    "id": "someflakeid",
    "username": "somenick",
    ...
  },
  "id" : "1",
  "unread" : 2,
  "last_message" : {...}, // The last message in that chat
  "updated_at": "2020-04-21T15:11:46.000Z"
}

Marking a chat as read

To mark a number of messages in a chat up to a certain message as read, you can use

POST /api/v1/pleroma/chats/:id/read

Parameters: - last_read_id: Given this id, all chat messages until this one will be marked as read. Required.

Returned data:

{
  "account": {
    "id": "someflakeid",
    "username": "somenick",
    ...
  },
  "id" : "1",
  "unread" : 0,
  "updated_at": "2020-04-21T15:11:46.000Z"
}

Marking a single chat message as read

To set the unread property of a message to false

POST /api/v1/pleroma/chats/:id/messages/:message_id/read

Returned data:

The modified chat message

Getting a list of Chats

GET /api/v1/pleroma/chats

This will return a list of chats that you have been involved in, sorted by their last update (so new chats will be at the top).

Parameters:

  • with_muted: Include chats from muted users (boolean).

Returned data:

[
   {
      "account": {
        "id": "someflakeid",
        "username": "somenick",
        ...
      },
      "id" : "1",
      "unread" : 2,
      "last_message" : {...}, // The last message in that chat
      "updated_at": "2020-04-21T15:11:46.000Z"
   }
]

The recipient of messages that are sent to this chat is given by their AP ID. No pagination is implemented for now.

Getting the messages for a Chat

For a given Chat id, you can get the associated messages with

GET /api/v1/pleroma/chats/:id/messages

This will return all messages, sorted by most recent to least recent. The usual pagination options are implemented.

Returned data:

[
  {
    "account_id": "someflakeid",
    "chat_id": "1",
    "content": "Check this out :firefox:",
    "created_at": "2020-04-21T15:11:46.000Z",
    "emojis": [
      {
        "shortcode": "firefox",
        "static_url": "https://dontbulling.me/emoji/Firefox.gif",
        "url": "https://dontbulling.me/emoji/Firefox.gif",
        "visible_in_picker": false
      }
    ],
    "id": "13",
    "unread": true
  },
  {
    "account_id": "someflakeid",
    "chat_id": "1",
    "content": "Whats' up?",
    "created_at": "2020-04-21T15:06:45.000Z",
    "emojis": [],
    "id": "12",
    "unread": false,
    "idempotency_key": "75442486-0874-440c-9db1-a7006c25a31f"
  }
]
  • idempotency_key: The copy of the idempotency-key HTTP request header that can be used for optimistic message sending. Included only during the first few minutes after the message creation.

Posting a chat message

Posting a chat message for given Chat id works like this:

POST /api/v1/pleroma/chats/:id/messages

Parameters: - content: The text content of the message. Optional if media is attached. - media_id: The id of an upload that will be attached to the message.

Currently, no formatting beyond basic escaping and emoji is implemented.

Returned data:

{
  "account_id": "someflakeid",
  "chat_id": "1",
  "content": "Check this out :firefox:",
  "created_at": "2020-04-21T15:11:46.000Z",
  "emojis": [
    {
      "shortcode": "firefox",
      "static_url": "https://dontbulling.me/emoji/Firefox.gif",
      "url": "https://dontbulling.me/emoji/Firefox.gif",
      "visible_in_picker": false
    }
  ],
  "id": "13",
  "unread": false
}

Deleting a chat message

Deleting a chat message for given Chat id works like this:

DELETE /api/v1/pleroma/chats/:chat_id/messages/:message_id

Returned data is the deleted message.

Notifications

There's a new pleroma:chat_mention notification, which has this form. It is not given out in the notifications endpoint by default, you need to explicitly request it with include_types[]=pleroma:chat_mention:

{
  "id": "someid",
  "type": "pleroma:chat_mention",
  "account": { ... } // User account of the sender,
  "chat_message": {
    "chat_id": "1",
    "id": "10",
    "content": "Hello",
    "account_id": "someflakeid",
    "unread": false
  },
  "created_at": "somedate"
}

Streaming

There is an additional user:pleroma_chat stream. Incoming chat messages will make the current chat be sent to this user stream. The event of an incoming chat message is pleroma:chat_update. The payload is the updated chat with the incoming chat message in the last_message field.

Web Push

If you want to receive push messages for this type, you'll need to add the pleroma:chat_mention type to your alerts in the push subscription.