BasicMessage 2.0

Roles

There are two roles in this protocol: sender and receiver. It is anticipated that both roles are supported by agents that provide an interface for humans, but it is possible for an agent to only act as a sender (do not process received messages) or a receiver (will never send messages).

Connectivity

There are no assumptions about this protocol. It can be used to send a message, and there is no protocol level expectation of a response.

States

There are not really states in this protocol, as sending a message leaves both parties in the same state they were before.

Basic Walkthrough

Using this protocol, either party can send a message to the other at any time. There are no rules about taking turns or requiring a response.

Messages are assumed to be made visible to the recipient or evaluated by automated processes.

Design By Contract

No protocol specific errors exist. Any errors related to headers or other core features are documented in the appropriate places.

Security

This protocol expects messages to be encrypted during transmission, and repudiable.

Composition

Message Reference

message

Message Type URI: https://didcomm.org/basicmessage/2.0/message

The message message is sent by the sender to the recipient. Note that the role is only specific to the creation of messages, and that both parties may play both roles.

Attributes:

content - content of the user intended message.

Supported decorators/headers:

• The message should indicate the language used in the message. DIDComm V1 and DIDComm V2 have different methods for this. See examples below.
• The time the message is sent must be included. DIDComm V2 uses the created_time header. DIDComm V1 must include a sent_time as a message attribute containing the timestamp in ISO 8601 UTC format.

DIDComm V1 Example:

{
    "@id": "123456780",
    "@type": "https://didcomm.org/basicmessage/2.0/message",
    "~l10n": { "locale": "en" },
    "sent_time": "2019-01-15 18:42:01Z",
    "content": "Your hovercraft is full of eels."
}

DIDComm V2 Example:

{
    "id": "123456780",
    "type": "https://didcomm.org/basicmessage/2.0/message",
    "lang": "en",
    "created_time": 1547577721,
    "body": {
        "content": "Your hovercraft is full of eels."
    }
}

L10n

The language SHOULD be specified according to the method used in the DIDComm base protocol version.

Implementations

Endnotes

1 Out of Scope

There are many useful features of user messaging systems that we will not be adding to this protocol. We anticipate the development of more advanced and full-featured message protocols to fill these needs. Features that are considered out of scope for this protocol include:

• read receipts
• emojii responses
• typing indicators
• message replies (threading)
• multi-party (group) messages
• attachments