Skip to main content

Calendar subscription upgrades
draft-douglass-subscription-upgrade-00

The information below is for an old version of the document.
Document Type This is an older version of an Internet-Draft whose latest revision is Replaced
Author Michael Douglass
Last updated 2017-02-13
Replaced by draft-ietf-calext-subscription-upgrade
Stream (None)
Formats
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-douglass-subscription-upgrade-00
Network Working Group                                        M. Douglass
Internet-Draft                                       Spherical Cow Group
Updates: 5545,5546 (if approved)                       February 13, 2017
Intended status: Standards Track
Expires: August 17, 2017

                     Calendar subscription upgrades
                 draft-douglass-subscription-upgrade-00

Abstract

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

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 http://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 August 17, 2017.

Copyright Notice

   Copyright (c) 2017 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
   (http://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.

Douglass                 Expires August 17, 2017                [Page 1]
Internet-Draft       Calendar subscription upgrades        February 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   2
   2.  Changes to the iCalendar specifications . . . . . . . . . . .   3
   3.  Link Header . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Link relation subscribe-caldav  . . . . . . . . . . . . . . .   3
   5.  Link relation subscribe-caldav-auth . . . . . . . . . . . . .   3
   6.  Link relation subscribe-webdav-sync . . . . . . . . . . . . .   3
   7.  Link relation subscribe-something-else  . . . . . . . . . . .   4
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   9.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   4
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     10.1.  Link Relation Registrations  . . . . . . . . . . . . . .   4
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   12. Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Appendix A.  Open issues  . . . . . . . . . . . . . . . . . . . .   6
   Appendix B.  Change log . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Currently clients subscribe to calendar feeds as an ics 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.

   There is the usual tension between clients wishing to see a timely
   response to changes and servers not wishing to be overloaded by
   frequent requests for possibly large amounts of data.

   This specification introduces an approach whereby clients can
   discover a more performant access method.  Given the location of the
   resource as an ics file, the client can download the file and inspect
   the returned headers which will offer a number of alternative access
   methods.

   Given that many clients already support CalDAV this provides an easy
   upgrade path for those clients.  CalDAV and DAV subsets are specified
   here to allow lighter weight implementations.

1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and

Douglass                 Expires August 17, 2017                [Page 2]
Internet-Draft       Calendar subscription upgrades        February 2017

   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

2.  Changes to the iCalendar specifications

   This speciifcation does not require any changes to [RFC5545]  or its
   extensions.  However it does introduce the use of some properties to
   provide more information about the resource, for example the time
   range it covers.

3.  Link Header

   The advertising of other access points is achieved through the use of
   the LINK header as defined in [RFC5988].  New link relation types are
   defined in this specification - each being associated with a protocol
   or protocol subset.

4.  Link relation subscribe-caldav

   This specifies an access point which is a full implementation of
   caldav but requires no authentication.  The end point is read only
   but allows the full range of reports as defined by the CalDAV
   specification.

   The client MUST follow the specification to determine exactly what
   operations are allowed on the access point - for example to determine
   if sync-report is supported.

5.  Link relation subscribe-caldav-auth

   This specifies an access point which is a full implementation of
   caldav and requires authentication.  This may allow read-write access
   to the resource.

   The client MUST follow the specification to determine exactly what
   operations are allowed on the access point - for example to determine
   if sync-report is supported.

6.  Link relation subscribe-webdav-sync

   This specifies an access point which supports only webdav sync.

   This allows the client to issue a sync-report on the resource to
   obtain updates.

   NOTE: say something about initial startup - use ics to populate?
   Initial token?

Douglass                 Expires August 17, 2017                [Page 3]
Internet-Draft       Calendar subscription upgrades        February 2017

   The client MUST follow that specification.

7.  Link relation subscribe-something-else

   This specifies an access point which supports something new.

   The client MUST follow that specification.

8.  Security Considerations

   Applications using these properties need to be aware of the risks
   entailed in using the URIs provided as values.  See [RFC3986] for a
   discussion of the security considerations relating to URIs.

9.  Privacy Considerations

   Properties with a "URI" value type can expose their users to privacy
   leaks as any network access of the URI data can be tracked.  Clients
   SHOULD NOT automatically download data referenced by the URI without
   explicit instruction from users.  This specification does not
   introduce any additional privacy concerns beyond those described in
   [RFC5545].

10.  IANA Considerations

10.1.  Link Relation Registrations

   This document defines the following new iCalendar properties to be
   added to the registry defined in Section 8.2.3 of [RFC5545]:

      +--------------------------+-------------+--------------------+
      | Relation Name            | Description | Reference          |
      +--------------------------+-------------+--------------------+
      | subscribe-caldav         | Current     | RFCXXXX, Section 4 |
      | subscribe-caldav_auth    | Current     | RFCXXXX, Section 5 |
      | subscribe-webdav-sync    | Current     | RFCXXXX, Section 6 |
      | subscribe-something-else | Current     | RFCXXXX, Section 7 |
      +--------------------------+-------------+--------------------+

11.  Acknowledgements

   The author would also like to thank the members of the Calendaring
   and Scheduling Consortium Calendar Sharing technical committee and
   the following individuals for contributing their ideas and support:

   ...

Douglass                 Expires August 17, 2017                [Page 4]
Internet-Draft       Calendar subscription upgrades        February 2017

   The authors would also like to thank the Calendaring and Scheduling
   Consortium for advice with this specification.

12.  Normative References

   [I-D.ietf-calext-extensions]
              Daboo, C., "New Properties for iCalendar", draft-ietf-
              calext-extensions-05 (work in progress), August 2016.

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

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 2434,
              DOI 10.17487/RFC2434, October 1998,
              <http://www.rfc-editor.org/info/rfc2434>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <http://www.rfc-editor.org/info/rfc3688>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <http://www.rfc-editor.org/info/rfc3986>.

   [RFC4589]  Schulzrinne, H. and H. Tschofenig, "Location Types
              Registry", RFC 4589, DOI 10.17487/RFC4589, July 2006,
              <http://www.rfc-editor.org/info/rfc4589>.

   [RFC5545]  Desruisseaux, B., Ed., "Internet Calendaring and
              Scheduling Core Object Specification (iCalendar)",
              RFC 5545, DOI 10.17487/RFC5545, September 2009,
              <http://www.rfc-editor.org/info/rfc5545>.

   [RFC5546]  Daboo, C., Ed., "iCalendar Transport-Independent
              Interoperability Protocol (iTIP)", RFC 5546,
              DOI 10.17487/RFC5546, December 2009,
              <http://www.rfc-editor.org/info/rfc5546>.

   [RFC5988]  Nottingham, M., "Web Linking", RFC 5988,
              DOI 10.17487/RFC5988, October 2010,
              <http://www.rfc-editor.org/info/rfc5988>.

Douglass                 Expires August 17, 2017                [Page 5]
Internet-Draft       Calendar subscription upgrades        February 2017

   [W3C.REC-xml-20060816]
              Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
              F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fourth
              Edition)", World Wide Web Consortium Recommendation REC-
              xml-20060816, August 2006,
              <http://www.w3.org/TR/2006/REC-xml-20060816>.

Appendix A.  Open issues

   restype values:  Need to determine what if any registry of resource
      types already exists and use that.

Appendix B.  Change log

   v05 2016-11-08 MD

   o  First pass

Author's Address

   Michael Douglass
   Spherical Cow Group
   226 3rd Street
   Troy, NY  12180
   USA

   Email: mdouglass@sphericalcowgroup.com
   URI:   http://sphericalcowgroup.com

Douglass                 Expires August 17, 2017                [Page 6]