VCON for MIMI Messages

Syntax A MIMI conversation (or portion thereof) is represented in VCON with a mandatory list of parties and dialogs, a new top-level room object.

Room information This document adds a top-level room object. It contains metadata known about the room at the start of the VCON period.

id is the MIMI room ID URL. It is mandatory.
name is the textual name of the room. It is optional.

Parties The parties array MUST contain all the participants who were in the conversation at any point in time during the period represented by the VCON. This document adds a new party_object_type: imUri. It is mandatory. The name field is optional. The role indicates the MIMI role and is optional.

Extensions to the dialog object The dialog object consists of an array of instant messages of type "text". The start time is set to the hub received timestamp when available. The duration is zero. The parties array consist of the party indexes of those who were active participants when the message was sent. The originator is set to the parties index of the sender of the message.

messageId is the base64url encoding of the MIMI content messageId. It is mandatory.
replaces is the base64url encoding of the MIMI content messageId of the message this message replaces. It is optional if empty.
expires is the expiration date/time of the message expressed as a VCON (text) date_type. It is optional if empty.
inReplyTo is the base64url encoding of the MIMI content messageId of the message to which this message is replying (or reacting). It is optional if empty.
lastSeen is an array of base64url-encoded message ids. It is mandatory.
mimiExtensions is a object (map) containing MIMI extensions. It is optional.

VCON typically expresses content using the body, encoding, and mimetype fields. In order to preserve this convention we use these fields directly for a MIMI SinglePart structure, but use new MultiPart and ExternalPart structure for those MIMI structures. ExternalPart has several fields for the decryption and integrity of the referenced content. These can be omitted once the content has been downloaded, decrypted, verified, and included in the VCON attachments array.

disposition - optional if set to the default value ("render")
language - optional if absent
partIndex is an integer. It is mandatory

MultiPart

partSemantics is one of "chooseOne", "singleUnit", or "processAll". It is mandatory.
parts is an array of Parts. It is mandatory.

ExternalPart

mimetype (contentType in MIMI). optional but recommended.
url is the URL of the content as a text string. mandatory
expires is a date_type (text) date. optional.
size is an integer number of octets. optional.
description is a text string. optional.
filename is a text string. optional.

These encryption/validation related fields can be omitted once the content is available locally as an attachment. All of them are base64url encoded strings. Otherwise they are mandatory if present in the MIMI content.

encAlg
key
nonce
aad
hashAlg
contentHash

TODO: how to represent a downloaded and decrypted object in attachments?

Part

disposition - optional if set to the default value ("render")
language - optional if absent
partIndex is an integer. It is mandatory
cardinality is one of "nullpart", "single", "external", or "multi". mandatory.

if cardinality is "single", then body, encoding, and mimetype fields are included directly in the Part object.

Changes to the room Changes to the room metadata or participation should be accompanied by a new dialog type:

room metadata changes
participants joining and leaving
participants adding new clients
moderation events?

TODO

party_event_type events

add: user added herself directly
welcome: user added by someone else
leave: user leaves of their own accord
remove: user is removed by another user
ban: user is banned from the group