Media Over QUIC                                              A. Frindell
Internet-Draft                                                      Meta
Intended status: Informational                           21 October 2024
Expires: 24 April 2025


                                MoQ Chat
                       draft-frindell-moq-chat-00

Abstract

   MoQ Chat (moq-chat) is a simple text based protocol for exercising
   MoQ Transport.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://afrind.github.io/draft-frindell-moq-chat/draft-frindell-moq-
   chat.html.  Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-frindell-moq-chat/.

   Discussion of this document takes place on the Media Over QUIC
   Working Group mailing list (mailto:moq@ietf.org), which is archived
   at https://mailarchive.ietf.org/arch/browse/moq/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/moq/.

   Source for this draft and an issue tracker can be found at
   https://github.com/afrind/draft-frindell-moq-chat.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 24 April 2025.




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Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   2
   3.  Chat Operation  . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  MoQ Relay . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Chat ID . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.3.  Track Names . . . . . . . . . . . . . . . . . . . . . . .   3
     3.4.  Joining the Chat  . . . . . . . . . . . . . . . . . . . .   3
     3.5.  Subscribing to Chat Messages  . . . . . . . . . . . . . .   4
     3.6.  Chat Messages . . . . . . . . . . . . . . . . . . . . . .   4
     3.7.  Leaving the Chat  . . . . . . . . . . . . . . . . . . . .   4
     3.8.  Stream Mapping  . . . . . . . . . . . . . . . . . . . . .   4
     3.9.  Session Closure by the Server . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   MoQ Chat (moq-chat) is a simple text based protocol for exercising
   MoQ Transport [MOQT].  The protocol allows many participants to join
   a virtual chat room, publish messages to the room and receive
   messages published by others.

2.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.



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   Commonly used terms in this document are described below.

3.  Chat Operation

3.1.  MoQ Relay

   The protocol requires a MoQ relay to act as a chat server.  The relay
   maintains the set of connected clients that have announced a chat
   track.

3.2.  Chat ID

   Every chat has a unique ID.  The ID is a string of arbitrary length
   and uniquely identifies the chat.  The creation of chat IDs and
   discovery of the relay is out of the scope of this document.

3.3.  Track Names

   Each chat participant has a chat track.  The namespace of the track
   is ("moq-chat", <id>, <user-id>, <device-id>, <timestamp>) and the
   name track is "chat".

   *  id - the ID of the chatroom

   *  user-id - the user ID

   *  device-id - a unique identifier for each device for the user.
      This allows the same user to join the chat from multiple devices

   *  timestamp - the timestamp in seconds when the track started,
      encoded as a string.  This allows a stateless client to start
      publishing without accidentally overwriting a previously sent
      group and object.  Note: the protocol will still function so long
      as each chat client selects a monotonically increasing number for
      this field.  Using the common format described here could support
      future functionality like pulling chat history.

3.4.  Joining the Chat

   To join the chat a participant sends a SUBSCRIBE_NAMESPACE message to
   the relay with a namespace prefix ("moq-chat", <id>).  MoQ Relays
   track the current state of all announced namespaces and namespace
   subscriptions, and forward any matching ANNOUNCE or UNANNOUNCE
   messages to interested endpoints.

   The participant also sends an ANNOUNCE message for their chat track
   namespace.




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3.5.  Subscribing to Chat Messages

   When receiving an ANNOUNCE that matches the chat prefix, the client
   extracts the client's user-id, device-id and timestamp from the
   third, fourth and fifth tuple elements, respectively.  The client
   SHOULD subscribe to the latest timestamp track for each (user-id,
   device-id) pair.

   Upon receiving an UNANNOUNCE, a client SHOULD UNSUBSCRIBE from that
   matching track if it had previously subscribed.

3.6.  Chat Messages

   Each chat message is sent in a new Group and new Object.  The format
   of a chat chat message this draft is UTF-8 Encoded text.  There is no
   limit to the length of a chat message beyond those imposed on QUIC
   streams.  Chat clients MUST send an END_OF_GROUP message for each
   Group.

   The starting Group ID for each track starts at 0 and increments by 1.
   The Object ID for each chat message starts at 0 and increments by 1.

3.7.  Leaving the Chat

   When a user leaves the chat, they SHOULD send an UNANNOUNCE message
   for their namespace.  They also SHOULD publish an object with status
   END_OF_TRACK_AND_GROUP on their chat track, since they will start a
   new track if they rejoin.  Finally, they SHOULD send an UNSUBSCRIBE
   message for any tracks they subscribed to before closing their
   Transport Session.

   If all publishers of a given namespace disconnect from the relay
   abruptly, the relay will send UNANNOUNCE messages matching
   SUBSCRIBE_NAMESPACE to interested endpoints.

3.8.  Stream Mapping

   The RECOMMENDED forwarding preference for the chat track is Subgroup,
   with all subgroup IDs set to 0, though clients MAY use other
   forwarding preferences at their discretion.

3.9.  Session Closure by the Server

   If a client detects a MOQT session has been closed by the relay, it
   assumes the relay has exited or crashed, and does not attempt to
   reconnect.





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4.  Security Considerations

   TODO Security

5.  IANA Considerations

   This document has no IANA actions.

6.  Normative References

   [MOQT]     Curley, L., Pugin, K., Nandakumar, S., Vasiliev, V., and
              I. Swett, "Media over QUIC Transport", Work in Progress,
              Internet-Draft, draft-ietf-moq-transport-07, 21 October
              2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
              moq-transport-07>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

Acknowledgments

   TODO acknowledge.

Author's Address

   Alan Frindell
   Meta
   Email: afrind@meta.com

















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