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 state is "Replaced".
|
|
|---|---|---|---|
| Author | Michael Douglass | ||
| Last updated | 2017-02-13 | ||
| Replaced by | draft-ietf-calext-subscription-upgrade | ||
| RFC stream | (None) | ||
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| Consensus boilerplate | Unknown | ||
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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.
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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
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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
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"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?
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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:
...
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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>.
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[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
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