Calendar subscription upgrades
draft-ietf-calext-subscription-upgrade-01

Document Type Active Internet-Draft (calext WG)
Last updated 2019-11-21 (latest revision 2019-11-03)
Replaces draft-douglass-subscription-upgrade
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Network Working Group                                        M. Douglass
Internet-Draft                                       Spherical Cow Group
Updates: 5988,7240 (if approved)                        November 3, 2019
Intended status: Standards Track
Expires: May 6, 2020

                     Calendar subscription upgrades
               draft-ietf-calext-subscription-upgrade-01

Abstract

   This specification introduces an approach to allow subscribers to
   calendar feeds to upgrade to a more performant protocol.

   This specification updates [RFC5545] to add the value DELETED to the
   STATUS property.

   This specification also updates [RFC7240] to add the subscribe-
   enhanced-get and limit preferences.

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 May 6, 2020.

Copyright Notice

   Copyright (c) 2019 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

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Internet-Draft       Calendar subscription upgrades        November 2019

   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.  Terms and Definitions . . . . . . . . . . . . . . . . . .   3
   2.  Discovering alternative access methods  . . . . . . . . . . .   3
   3.  Enhanced GET  . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Deletions . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Handling of invalid sync tokens . . . . . . . . . . . . .   5
     3.4.  Paging the response . . . . . . . . . . . . . . . . . . .   5
     3.5.  Caching of responses  . . . . . . . . . . . . . . . . . .   6
     3.6.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Changes to the iCalendar specifications . . . . . . . . . . .   8
     4.1.  Redefined Status property . . . . . . . . . . . . . . . .   8
   5.  Header Field: Sync-Token  . . . . . . . . . . . . . . . . . .  10
   6.  New Prefer header field preferences . . . . . . . . . . . . .  10
     6.1.  Preference subscribe-enhanced-get . . . . . . . . . . . .  10
     6.2.  Preference limit  . . . . . . . . . . . . . . . . . . . .  10
   7.  Link relations  . . . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .  10
     7.2.  subscribe-caldav  . . . . . . . . . . . . . . . . . . . .  11
     7.3.  subscribe-caldav-auth . . . . . . . . . . . . . . . . . .  11
     7.4.  subscribe-webdav-sync . . . . . . . . . . . . . . . . . .  11
     7.5.  subscribe-enhanced-get  . . . . . . . . . . . . . . . . .  11
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Sync-Token HTTP Header Field Registration . . . . . . . .  12
     9.2.  Preference Registrations  . . . . . . . . . . . . . . . .  12
     9.3.  Link Relation Registrations . . . . . . . . . . . . . . .  13
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   11. Normative References  . . . . . . . . . . . . . . . . . . . .  13
   Appendix A.  Open issues  . . . . . . . . . . . . . . . . . . . .  15
   Appendix B.  Change log . . . . . . . . . . . . . . . . . . . . .  15
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Currently clients subscribe to calendar feeds as an iCalendar file
   which is often published as a resource accessible using the
   unofficial 'webcal' scheme.

   The only available option for updating that resource is the usual
   HTTP polling of cached resources using Etags.

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