Internet DRAFT - draft-ietf-calext-valarm-extensions
draft-ietf-calext-valarm-extensions
Network Working Group C. Daboo
Internet-Draft Apple
Updates: 5545 (if approved) K. Murchison, Ed.
Intended status: Standards Track Fastmail
Expires: September 4, 2021 March 3, 2021
VALARM Extensions for iCalendar
draft-ietf-calext-valarm-extensions-07
Abstract
This document defines a set of extensions to the iCalendar VALARM
component to enhance use of alarms and improve interoperability
between clients and servers.
This document updates RFC5545.
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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This Internet-Draft will expire on September 4, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Extensible syntax for VALARM . . . . . . . . . . . . . . . . 3
4. Alarm Unique Identifier . . . . . . . . . . . . . . . . . . . 5
5. Alarm Related To . . . . . . . . . . . . . . . . . . . . . . 6
6. Alarm Acknowledgement . . . . . . . . . . . . . . . . . . . . 6
6.1. Acknowledged Property . . . . . . . . . . . . . . . . . . 7
7. Snoozing Alarms . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Relationship Type Property Parameter . . . . . . . . . . 9
7.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 9
8. Alarm Proximity Trigger . . . . . . . . . . . . . . . . . . . 13
8.1. Proximity Property . . . . . . . . . . . . . . . . . . . 14
8.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16
10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
11.1. Property Registrations . . . . . . . . . . . . . . . . . 17
11.2. Relationship Types Registry . . . . . . . . . . . . . . 17
11.3. Proximity Value Registry . . . . . . . . . . . . . . . . 17
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
13.1. Normative References . . . . . . . . . . . . . . . . . . 18
13.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Change History (To be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
The iCalendar [RFC5545] specification defines a set of components
used to describe calendar data. One of those is the "VALARM"
component which appears as a sub-component of "VEVENT" and "VTODO"
components. The "VALARM" component is used to specify a reminder for
an event or task. Different alarm actions are possible, as are
different ways to specify how the alarm is triggered.
As iCalendar has become more widely used and as client-server
protocols such as CalDAV [RFC4791] have become more prevalent,
several issues with "VALARM" components have arisen. Most of these
relate to the need to extend the existing "VALARM" component with new
properties and behaviors to allow clients and servers to accomplish
specific tasks in an interoperable manner. For example, clients
typically need a way to specify that an alarm has been dismissed by a
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calendar user, or has been "snoozed" by a set amount of time. To
date, this has been done through the use of custom "X-" properties
specific to each client implementation, leading to poor
interoperability.
This specification defines a set of extensions to "VALARM" components
to cover common requirements for alarms not currently addressed in
iCalendar. Each extension is defined in a separate section below.
For the most part, each extension can be supported independently of
the others, though in some cases one extension will require another.
In addition, this specification describes mechanisms by which clients
can interoperably implement common features such as "snoozing".
2. Conventions Used in This Document
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.
When XML element types in the namespaces "DAV:" and
"urn:ietf:params:xml:ns:caldav" are referenced in this document
outside of the context of an XML fragment, the string "DAV:" and
"CALDAV:" will be prefixed to the element type names respectively.
3. Extensible syntax for VALARM
Section 3.6.6 of [RFC5545] defines the syntax for "VALARM" components
and properties within them. However, as written, it is hard to
extend this by adding, e.g., a new property common to all types of
alarm. Since many of the extensions defined in this document need to
extend the base syntax, an alternative form for the base syntax is
defined here, with the goal of simplifying specification of the
extensions while augmenting the existing functionality defined in
[RFC5545] to allow for nested sub-components (as required by
proximity alarm triggers (Section 8)).
A "VALARM" calendar component is re-defined by the following
notation:
alarmcext = "BEGIN" ":" "VALARM" CRLF
*alarmprop *alarm-subcomp
"END" ":" "VALARM" CRLF
alarmprop = (
; the following are REQUIRED,
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; but MUST NOT occur more than once
action / trigger /
; one set of action properties MUST be
; present and MUST match the action specified
; in the ACTION property
actionprops /
; the following are OPTIONAL,
; and MAY occur more than once
x-prop / iana-prop
)
actionprops = *audiopropext / *disppropext / *emailpropext
audiopropext = (
; 'duration' and 'repeat' are both OPTIONAL,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat /
; the following is OPTIONAL,
; but MUST NOT occur more than once
attach
)
disppropext = (
; the following are REQUIRED,
; but MUST NOT occur more than once
description /
; 'duration' and 'repeat' are both OPTIONAL,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat
)
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emailpropext = (
; the following are all REQUIRED,
; but MUST NOT occur more than once
description / summary /
; the following is REQUIRED,
; and MAY occur more than once
attendee /
; 'duration' and 'repeat' are both OPTIONAL,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat
; the following is OPTIONAL,
; and MAY occur more than once
attach
)
alarm-subcomp = (
; the following are OPTIONAL,
; and MAY occur more than once
x-comp / iana-comp
)
4. Alarm Unique Identifier
This extension adds a "UID" property to "VALARM" components to allow
a unique identifier to be specified. The value of this property can
then be used to refer uniquely to the "VALARM" component.
The "UID" property defined here follows the definition in
Section 3.8.4.7 of [RFC5545] with the security and privacy updates in
Section 5.3 of [RFC7986]. In particular it MUST be a globally unique
identifier that does not contain any security- or privacy-sensitive
information.
The "VALARM" component defined in Section 3 is extended here as:
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alarmprop =/ (
; the following is OPTIONAL,
; but MUST NOT occur more than once
uid
)
5. Alarm Related To
It is often convenient to relate one or more "VALARM" components to
other "VALARM" components (e.g., see Section 7). This can be
accomplished if the "VALARM" components each have their own "UID"
property (as per Section 4).
This specification updates the usage of the "RELATED-TO" property
defined in Section 3.8.4.5 of [RFC5545] to enable its use with
"VALARM" components. Specific types of relationships between
"VALARM" components can be identified by registering new values for
the "RELTYPE" property parameter defined in Section 3.2.15 of
[RFC5545].
The "VALARM" component defined in Section 3 is extended here as:
alarmprop =/ (
; the following is OPTIONAL,
; and MAY occur more than once
related
)
6. Alarm Acknowledgement
There is currently no way for a "VALARM" component to indicate
whether it has been triggered and acknowledged. With the advent of a
standard client/server protocol for calendaring and scheduling data
([RFC4791]) it is quite possible for an event with an alarm to exist
on multiple clients in addition to the server. If each of those is
responsible for performing the action when an alarm triggers, then
multiple "alerts" are generated by different devices. In such a
situation, a calendar user would like to be able to "dismiss" the
alarm on one device and have it automatically dismissed on the others
too.
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Also, with recurring events that have alarms, it is important to know
when the last alarm in the recurring set was acknowledged, so that
the client can determine whether past alarms have been missed.
To address these needs, this specification adds an "ACKNOWLEDGED"
property to "VALARM" components to indicate when the alarm was last
acknowledged (or sent, if acknowledgement is not possible). This is
defined by the syntax below.
alarmprop =/ (
; the following is OPTIONAL,
; but MUST NOT occur more than once
acknowledged
)
6.1. Acknowledged Property
Property Name: ACKNOWLEDGED
Purpose: This property specifies the UTC date and time at which the
corresponding alarm was last sent or acknowledged.
Value Type: DATE-TIME
Property Parameters: IANA and non-standard property parameters can
be specified on this property.
Conformance: This property can be specified within "VALARM" calendar
components.
Description: This property is used to specify when an alarm was last
sent or acknowledged. This allows clients to determine when a
pending alarm has been acknowledged by a calendar user so that any
alerts can be dismissed across multiple devices. It also allows
clients to track repeating alarms or alarms on recurring events or
to-dos to ensure that the right number of missed alarms can be
tracked.
Clients SHOULD set this property to the current date-time value in
UTC when a calendar user acknowledges a pending alarm. Certain
kinds of alarms, such as email-based alerts, might not provide
feedback as to when the calendar user sees them. For those kinds
of alarms, the client SHOULD set this property when the alarm is
triggered and the action successfully carried out.
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When an alarm is triggered on a client, clients can check to see
if an "ACKNOWLEDGED" property is present. If it is, and the value
of that property is greater than or equal to the computed trigger
time for the alarm, then the client SHOULD NOT trigger the alarm.
Similarly, if an alarm has been triggered and an "alert" presented
to a calendar user, clients can monitor the iCalendar data to
determine whether an "ACKNOWLEDGED" property is added or changed
in the alarm component. If the value of any "ACKNOWLEDGED"
property in the alarm changes and is greater than or equal to the
trigger time of the alarm, then clients SHOULD dismiss or cancel
any "alert" presented to the calendar user.
Format Definition: This property is defined by the following
notation:
acknowledged = "ACKNOWLEDGED" *acknowledgedparam ":" datetime CRLF
acknowledgedparam = (
; the following is OPTIONAL,
; and MAY occur more than once
(";" other-param)
)
Example: The following is an example of this property:
ACKNOWLEDGED:20090604T084500Z
7. Snoozing Alarms
Users often want to "snooze" an alarm, and this specification defines
a standard approach to accomplish that.
To "snooze" an alarm that has been triggered, clients MUST do the
following:
1. Set the "ACKNOWLEDGED" property (see Section 6.1) on the
triggered alarm.
2. Create a new "VALARM" component (the "snooze" alarm) within the
parent component of the triggered alarm (i.e., as a "sibling"
component of the triggered alarm).
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A. The new "snooze" alarm MUST be set to trigger at the user's
chosen "snooze" interval after the original alarm triggered.
Clients SHOULD use an absolute "TRIGGER" property with a
"DATE-TIME" value specified in UTC.
B. The new "snooze" alarm MUST have a "RELATED-TO" property (see
Section 5) with a value set to the "UID" property value of
the original "VALARM" component that was triggered. If the
triggered "VALARM" component does not already have a "UID"
property, the client MUST add one. The "RELATED-TO" property
added to the new "snooze" alarm MUST include a "RELTYPE"
property parameter with a value set to "SNOOZE" (see
Section 7.1).
3. When the "snooze" alarm is triggered, the client MUST do the
following:
A. Update the "ACKNOWLEDGED" property on the original related
alarm.
B. If the "snooze" alarm is itself "snoozed", the client MUST
remove the "snooze" alarm component, and return to step 2.
Otherwise, if the "snooze" alarm is dismissed, the client
MUST do one of the following:
+ Set the "ACKNOWLEDGED" property on the "snooze" alarm.
+ Remove the "snooze" alarm component.
Note that regardless of the final disposition of the "snooze" alarm
when triggered, the original "VALARM" component is left unchanged
other than updating its "ACKNOWLEDGED" property.
7.1. Relationship Type Property Parameter
This specification adds the "SNOOZE" relationship type for use with
the "RELTYPE" property defined in Section 3.2.15 of [RFC5545]. This
is used when relating a "snoozed" "VALARM" component to the original
alarm that the "snooze" was generated for.
7.2. Example
The following example shows the snoozing, re-snoozing, and dismissal
of an alarm. Note that the encompassing VCALENDAR component has been
omitted for brevity and that the line-breaks surrounding the VALARM
components are for clarity only and would not be present in the
actual iCalendar data.
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Assume that we have the following event with an alarm set to trigger
15 minutes before the meeting:
BEGIN:VEVENT
CREATED:20210302T151004Z
UID:AC67C078-CED3-4BF5-9726-832C3749F627
DTSTAMP:20210302T151004Z
DTSTART;TZID=America/New_York:20210302T103000
DTEND;TZID=America/New_York:20210302T113000
SUMMARY:Meeting
BEGIN:VALARM
UID:8297C37D-BA2D-4476-91AE-C1EAA364F8E1
TRIGGER:-PT15M
DESCRIPTION:Event reminder
ACTION:DISPLAY
END:VALARM
END:VEVENT
When the alarm is triggered, the user decides to snooze it for 5
minutes. The client acknowledges the original alarm and creates a
new "snooze" alarm as a sibling of, and relates it to, the original
alarm (note that both VALARMs reside within the same "parent"
VEVENT):
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BEGIN:VEVENT
CREATED:20210302T151004Z
UID:AC67C078-CED3-4BF5-9726-832C3749F627
DTSTAMP:20210302T151516Z
DTSTART;TZID=America/New_York:20210302T103000
DTEND;TZID=America/New_York:20210302T113000
SUMMARY:Meeting
BEGIN:VALARM
UID:8297C37D-BA2D-4476-91AE-C1EAA364F8E1
TRIGGER:-PT15M
DESCRIPTION:Event reminder
ACTION:DISPLAY
ACKNOWLEDGED:20210302T151514Z
END:VALARM
BEGIN:VALARM
UID:DE7B5C34-83FF-47FE-BE9E-FF41AE6DD097
TRIGGER;VALUE=DATE-TIME:20210302T152000Z
RELATED-TO;RELTYPE=SNOOZE:8297C37D-BA2D-4476-91AE-C1EAA364F8E1
DESCRIPTION:Event reminder
ACTION:DISPLAY
END:VALARM
END:VEVENT
When the "snooze" alarm is triggered, the user decides to snooze it
again for an additional 5 minutes. The client once again
acknowledges the original alarm, removes the triggered "snooze"
alarm, and creates another new "snooze" alarm as a sibling of, and
relates it to, the original alarm (note the different UID for the new
snooze alarm):
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BEGIN:VEVENT
CREATED:20210302T151004Z
UID:AC67C078-CED3-4BF5-9726-832C3749F627
DTSTAMP:20210302T152026Z
DTSTART;TZID=America/New_York:20210302T103000
DTEND;TZID=America/New_York:20210302T113000
SUMMARY:Meeting
BEGIN:VALARM
UID:8297C37D-BA2D-4476-91AE-C1EAA364F8E1
TRIGGER:-PT15M
DESCRIPTION:Event reminder
ACTION:DISPLAY
ACKNOWLEDGED:20210302T152024Z
END:VALARM
BEGIN:VALARM
UID:87D690A7-B5E8-4EB4-8500-491F50AFE394
TRIGGER;VALUE=DATE-TIME:20210302T152500Z
RELATED-TO;RELTYPE=SNOOZE:8297C37D-BA2D-4476-91AE-C1EAA364F8E1
DESCRIPTION:Event reminder
ACTION:DISPLAY
END:VALARM
END:VEVENT
When the second "snooze" alarm is triggered, the user decides to
dismiss it. The client acknowledges both the original alarm and the
second "snooze" alarm:
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BEGIN:VEVENT
CREATED:20210302T151004Z
UID:AC67C078-CED3-4BF5-9726-832C3749F627
DTSTAMP:20210302T152508Z
DTSTART;TZID=America/New_York:20210302T103000
DTEND;TZID=America/New_York:20210302T113000
SUMMARY:Meeting
BEGIN:VALARM
UID:8297C37D-BA2D-4476-91AE-C1EAA364F8E1
TRIGGER:-PT15M
DESCRIPTION:Event reminder
ACTION:DISPLAY
ACKNOWLEDGED:20210302T152507Z
END:VALARM
BEGIN:VALARM
UID:87D690A7-B5E8-4EB4-8500-491F50AFE394
TRIGGER;VALUE=DATE-TIME:20210302T152500Z
RELATED-TO;RELTYPE=SNOOZE:8297C37D-BA2D-4476-91AE-C1EAA364F8E1
DESCRIPTION:Event reminder
ACTION:DISPLAY
ACKNOWLEDGED:20210302T152507Z
END:VALARM
END:VEVENT
8. Alarm Proximity Trigger
VALARMs are currently triggered when a specific date-time is reached.
It is also desirable to be able to trigger alarms based on location,
e.g. when arriving at or departing from a particular location.
This specification adds the following elements to "VALARM" components
to indicate when an alarm can be triggered based on location.
"PROXIMITY" property - indicates that a location based trigger is
to be used and which action is used for the trigger
"VLOCATION" component(s) [I-D.ietf-calext-eventpub-extensions] -
used to indicate the actual location(s) to trigger off of,
specified with a URL property containing a geo: URI [RFC5870]
which allows for two or three coordinate values with an optional
uncertainty
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alarmprop =/ (
; the following is OPTIONAL,
; but MUST NOT occur more than once
proximity /
)
alarm-subcomp =/ (
; the following is OPTIONAL,
; and MAY occur more than once, but only
; when a PROXIMITY property is also present
locationc
)
Typically, when a "PROXIMITY" property is used there is no need to
specify a time-based trigger using the "TRIGGER" property. However,
since "TRIGGER" is defined as a required property for a "VALARM"
component, for backwards compatibility it has to be present, but
ignored. To indicate a "TRIGGER" that is to be ignored, clients
SHOULD use a value a long time in the past. A value of
"19760401T005545Z" has been commonly used for this purpose.
8.1. Proximity Property
Property Name: PROXIMITY
Purpose: This property indicates that a location based trigger is
applied to an alarm.
Value Type: TEXT
Property Parameters: IANA and non-standard property parameters can
be specified on this property.
Conformance: This property can be specified within "VALARM" calendar
components.
Description: This property is used to indicate that an alarm has a
location-based trigger. Its value identifies the action that will
trigger the alarm.
When the property value is set to "ARRIVE", the alarm is triggered
when the calendar user agent arrives in the vicinity of one or
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more locations. When set to "DEPART", the alarm is triggered when
the calendar user agent departs from the vicinity of one or more
locations. Each location which MUST be specified with a
"VLOCATION" component. Note that the meaning of "vicinity" in
this context is implementation defined.
When the property value is set to "CONNECT", the alarm is
triggered when the calendar user agent connects to a automobile to
which is has been paired via Bluetooth(R) [BTcore]. When set to
"DISCONNECT", the alarm is triggered when the calendar user agent
disconnects from a automobile to which it has been paired via
Bluetooth(R). Note that neither current implementations of
proximty alarms nor this document have a mechanism to target a
particular automobile. Such a mechanism may be specified in a
future extension.
Format Definition: This property is defined by the following
notation:
proximity = "PROXIMITY" *proximityparam ":" proximityvalue CRLF
proximityparam = (
; the following is OPTIONAL,
; and MAY occur more than once
(";" other-param)
)
proximityvalue = "ARRIVE" / "DEPART" /
"CONNECT" / "DISCONNECT" / iana-token / x-name
8.2. Example
The following example shows a VALARM component with a proximity
trigger set to trigger when the device running the calendar user
agent leaves the vicinity defined by the URL property in the
VLOCATION component. Note use of the "u=" parameter with the "geo"
URI to define the uncertainty of the location determination.
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BEGIN:VALARM
UID:77D80D14-906B-4257-963F-85B1E734DBB6
ACTION:DISPLAY
TRIGGER;VALUE=DATE-TIME:19760401T005545Z
DESCRIPTION:Remember to buy milk
PROXIMITY:DEPART
BEGIN:VLOCATION
UID:123456-abcdef-98765432
NAME:Office
URL:geo:40.443,-79.945;u=10
END:VLOCATION
END:VALARM
9. Security Considerations
In addition to the security properties of iCalendar (see Section 7 of
[RFC5545]), VALARMs, if not monitored properly, can be used to
disturb users and/or leak personal information. For instance, an
undesirable audio alert could cause embarassment. An unwanted
display alert could be considered an annoyance. Or an email alert
could be used to leak a user's location to a third party or to send
unsolicited email to multiple users. Therefore, CalDAV clients and
servers that accept iCalendar data from a third party (e.g. via iTIP
[RFC5546], a subscription feed, or a shared calendar) SHOULD remove
all VALARMs from the data prior to storing in their calendar system.
Security considerations related to unique identifiers for VALARMs are
discussed in Section 4.
10. Privacy Considerations
Proximity VALARMs, if not used carefully, can leak a user's past,
present, or future location. For instance, storing an iCalendar
resource containing proxmity VALARMs to a shared calendar on CalDAV
server can expose to anyone that has access to that calendar the
user's intent to leave from or arrive at a particular location at
some future time. Furthermore, if a CalDAV client updates the shared
iCalendar resource with an ACKNOWLEDGED property when the alarm is
triggered, will leak the exact date and time that the user left from
or arrived at the location. Therefore, CalDAV clients that implement
proximity alarms SHOULD give users the option of storing and/or
acknowledging the alarms on the local device only and not storing the
alarm and/or acknowledgment on a remote server.
Privacy considerations related to unique identifiers for VALARMs are
discussed in Section 4.
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11. IANA Considerations
11.1. Property Registrations
This document defines the following new iCalendar properties to be
added to the registry defined in Section 8.2.3 of [RFC5545] and
located here: <https://www.iana.org/assignments/icalendar#properties>
+--------------+---------+----------------------+
| Property | Status | Reference |
+--------------+---------+----------------------+
| ACKNOWLEDGED | Current | RFCXXXX, Section 6.1 |
| PROXIMITY | Current | RFCXXXX, Section 8.1 |
+--------------+---------+----------------------+
11.2. Relationship Types Registry
This document defines the following new iCalendar relationship type
to be added to the registry defined in Section 8.3.8 of [RFC5545] and
located here: <https://www.iana.org/assignments/
icalendar#relationship-types>
+-------------------+---------+----------------------+
| Relationship Type | Status | Reference |
+-------------------+---------+----------------------+
| SNOOZE | Current | RFCXXXX, Section 7.1 |
+-------------------+---------+----------------------+
11.3. Proximity Value Registry
This document creates a new iCalendar registry for values of the
"PROXIMITY" property located here: <https://www.iana.org/assignments/
icalendar#proximity-values>
Additional values MAY be used, provided the process described in
Section 8.2.1 of [RFC5545] is used to register them, using the
template in Section 8.2.6 of [RFC5545].
The following table has been used to initialize the Proximity Value
Registry.
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+------------+---------+----------------------+
| Value | Status | Reference |
+------------+---------+----------------------+
| ARRIVE | Current | RFCXXXX, Section 8.1 |
| DEPART | Current | RFCXXXX, Section 8.1 |
| CONNECT | Current | RFCXXXX, Section 8.1 |
| DISCONNECT | Current | RFCXXXX, Section 8.1 |
+------------+---------+----------------------+
12. Acknowledgments
This specification came about via discussions at the Calendaring and
Scheduling Consortium. Also, thanks to the following for providing
feedback: Bernard Desruisseaux, Mike Douglass, Jacob Farkas, Jeffrey
Harris, Ciny Joy, Barry Leiba, and Daniel Migault.
13. References
13.1. Normative References
[I-D.ietf-calext-eventpub-extensions]
Douglass, M., "Event Publishing Extensions to iCalendar",
draft-ietf-calext-eventpub-extensions-18 (work in
progress), January 2021.
[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/info/rfc2119>.
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 5545, DOI 10.17487/RFC5545, September 2009,
<https://www.rfc-editor.org/info/rfc5545>.
[RFC5870] Mayrhofer, A. and C. Spanring, "A Uniform Resource
Identifier for Geographic Locations ('geo' URI)",
RFC 5870, DOI 10.17487/RFC5870, June 2010,
<https://www.rfc-editor.org/info/rfc5870>.
[RFC7986] Daboo, C., "New Properties for iCalendar", RFC 7986,
DOI 10.17487/RFC7986, October 2016,
<https://www.rfc-editor.org/info/rfc7986>.
[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/info/rfc8174>.
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13.2. Informative References
[BTcore] Bluetooth Special Interest Group, "Bluetooth Core
Specification Version 5.0", December 2016,
<https://www.bluetooth.com/specifications/bluetooth-core-
specification>.
[RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault,
"Calendaring Extensions to WebDAV (CalDAV)", RFC 4791,
DOI 10.17487/RFC4791, March 2007,
<https://www.rfc-editor.org/info/rfc4791>.
[RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent
Interoperability Protocol (iTIP)", RFC 5546,
DOI 10.17487/RFC5546, December 2009,
<https://www.rfc-editor.org/info/rfc5546>.
Appendix A. Change History (To be removed by RFC Editor before
publication)
Changes in ietf-06:
1. Corrected timestamps in snooze example.
2. Editorial changes from Benjamim Kaduk.
Changes in ietf-05:
1. Updated to use VLOCATION components rather than (deprecated)
STRUCTURED-LOCATION properties for proximity alarms.
2. Reorganized and clarified the process of snoozing an alarm and
added an example.
3. Noted that there is currently no mechanism for specifying a
particular automobile for CONNECT/DISCONNECT proximity alarms.
4. Replaced the term "spam" with new wording in Security
Considerations.
5. Addressed IESG comments from Benjamim Kaduk.
6. Addressed IESG comments from Robert Wilton.
7. Addressed IESG comments Alissa Cooper.
Changes in ietf-04:
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1. Addressed security review comments from Valery Smyslov.
2. Addressed Genart review comments from Roni Even.
3. Added text addressing management of Proximity Value Registry.
Changes in ietf-03:
1. Fixed ABNF to be properly extended.
2. Addressed AD review comments from Barry Leiba.
Changes in ietf-02:
1. Addressed some WGLC comments from Daniel Migault.
Changes in ietf-01:
1. Reintroduced the RELATED-TO property for VALARMs and the SNOOZE
value for the RELTYPE property parameter.
2. Add Privacy Considerations section.
Changes in ietf-00:
1. Submitted as CALEXT draft.
Changes in daboo-05:
1. Added Murchison as editor.
2. Updated keywords boilerplate.
3. Added reference to UID security/privacy recommendations.
4. Removed default alarms.
5. Removed ALARM-AGENT property.
6. Added text about using TRIGGER value in the past in addition to
ACTION:NONE to have a default alarm be ignored.
7. Removed text about related alarms.
8. Removed URL alarm action.
9. Added reference to draft-ietf-calext-eventpub-extensions for
STRUCTURED-LOCATION.
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10. Added CONNECT and DISCONNECT PROXIMITY property values.
11. Added Security Considerations.
12. Editorial fixes.
Changes in daboo-04:
1. Changed "ID" to "AGENT-ID".
2. Add more text on using "ACKNOWLEDGED" property.
3. Add "RELATED-TO" as a valid property for VALARMs.
4. Add "SNOOZE" relationship type for use with VALARMs.
5. State that "TRIGGER" is typically ignored in proximity alarms.
6. Added "PROXIMITY" value registry.
7. Added a lot more detail on default alarms including new action
and property.
Changes in daboo-03: none - resubmission of -02
Changes in daboo-02:
1. Updated to 5545 reference.
2. Clarified use of absolute trigger in UTC in snooze alarms
3. Snooze alarms should be removed when completed
4. Removed status and replaced last-triggered by acknowledged
property
5. Added location-based trigger
6. IANA registry tables added
Changes in daboo-01:
1. Removed DESCRIPTION as an allowed property in the URI alarm.
2. Added statement about what to do when ALARM-AGENT is not present.
3. Allow multiple ALARM-AGENT properties to be present.
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4. Removed SNOOZE-UNTIL - snoozing now accomplished by creating a
new VALARM.
5. Remove VALARM by reference section.
6. Added more detail to CalDAV default alarms.
Authors' Addresses
Cyrus Daboo
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
USA
Email: cyrus@daboo.name
URI: http://www.apple.com/
Kenneth Murchison (editor)
Fastmail US LLC
1429 Walnut St, Suite 1201
Philadephia, PA 19102
USA
Email: murch@fastmailteam.com
URI: http://www.fastmail.com/
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