cadmium-docs-legacy/protocol-spec/core.md

Protocol Core

• Protocol Core
  • Transport
  • Entity ID
  • BaseMessage

Transport

For starting we simply use JSON + Websockets.

Entity ID

• Room alias: #<roomAlias>@<serverpart>
• Username: @<username>@<serverpart>
• User ID with any 3PID: %<type>:<data>@<serverpart>
  • Currently supported only following types: email and msisdn.
• Raw User ID: @<UUID>@<serverpart>
• Message ID: &<uuid>@<serverpart (from which server the message was sent)>
• Room ID: !<roomID>@<serverpart>
• Single server-part: <serverpart>

Server-part:

• hostname: IPv4 / [IPv6] / dns-domain:<port (1-65535)> (for end-users use)
• server ID: static SHA256 hash string from 4096 characters (for internal protocol use)

Username/Room alias/RoomID - MUST NOT be empty, and MUST contain only the characters a-z, 0-9, ., _, =, -, and /.

Special business rules:

• RoomID SHOULD be UUID identifier.
• Servers MUST use server ID in internal purposes instead of normal server-part with hostname. Only end-users MUST use normal server-part with hostname. This is done for easy multi-domain serving.

BaseMessage

BaseMessage is a basic message model, basis of the whole protocol. It is used for a very easy protocol extension process.

BaseMessage scheme:

interface BaseMessage {
    /**
     * Message identifier (used to track the request-response chain)
     */
    id: string,

    /**
     * Type of message (used to determine which extension this message belongs to)
     */
    type: string,
    /**
     * From which entity this message is send
     */
    from: EntityID,

    /**
     * Message recipient
     */
    to: EntityID,

    /**
     * Operation success indicator (used to determine if the error happened while processing request)
     */
    ok: boolean,

    /**
     * Message payload (used to store extra information in message, list of permissible fields in the payload depends on "type" field)
     */
    payload: Map<K,V>
}