CoAP Protocol Indication
draft-amsuess-core-transport-indication-00

Document Type Active Internet-Draft (individual)
Author Christian Amsüss 
Last updated 2021-03-12
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CoRE                                                           C. Amsüss
Internet-Draft                                             12 March 2021
Intended status: Standards Track                                        
Expires: 13 September 2021

                        CoAP Protocol Indication
               draft-amsuess-core-transport-indication-00

Abstract

   The Constrained Application Protocol (CoAP) is available over
   different transports (UDP / DTLS since [RFC7252], TCP / TLS /
   WebSockets since [RFC8323]), but lacks a way to unify these
   addresses.  This document provides terminology based on Web Linking
   [RFC8288] to express alternative transports available to a device,
   and to optimize exchanges using these.

Discussion Venues

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

   Discussion of this document takes place on the Constrained RESTful
   Environments Working Group mailing list (core@ietf.org), which is
   archived at https://mailarchive.ietf.org/arch/browse/core/.

   Source for this draft and an issue tracker can be found at
   https://github.com/git@gitlab.com:chrysn/transport-indication.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 13 September 2021.

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Copyright Notice

   Copyright (c) 2021 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
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
     1.2.  Goals . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Indicating alternative transports . . . . . . . . . . . . . .   4
     2.1.  Example . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Elision of Proxy-Scheme and Uri-Host  . . . . . . . . . . . .   5
   4.  Third party proxy services  . . . . . . . . . . . . . . . . .   6
   5.  Client picked proxies . . . . . . . . . . . . . . . . . . . .   6
   6.  Security considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   7
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   [ See Abstract for the moment ]

   [ This document is being developed at https://gitlab.com/chrysn/
   transport-indication (https://gitlab.com/chrysn/transport-
   indication). ]

1.1.  Terminology

   Same-host proxy  A CoAP server that accepts forward proxy requests
      (i.e., requests carrying the Proxy-Scheme option) exclusively for
      URIs that it is the authoritative server for is defined as a
      "same-host proxy".

   hosts  The verb "to host" is used here in the sense of the link
      relation of the same name defined in [RFC6690].

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      For resources discovered via CoAP's discovery interface, a hosting
      statement is typically provided by the defaults implied by
      [RFC6690] where a link like "</sensor/temp>" is implied to have
      the relation "hosts" and the anchor "/", such that a statement
      "coap://hostname hosts coap://hostname/sensor/temp" can be
      inferred.

      For many application it can make sense to assume that any resource
      has a "host" relation leading from the root path of the server
      without having performed that discovery explicitly.

      [ TBD: The last paragraph could be a contentuous point; things
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