Network Working Group C. Daboo
Internet-Draft Apple
Intended status: Standards Track June 9, 2012
Expires: December 11, 2012
VALARM Extensions for iCalendar
draft-daboo-valarm-extensions-04
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.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 11, 2012.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
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 URI Action . . . . . . . . . . . . . . . . . . . . . . . 6
7. Alarm Agent . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Alarm Agent Property . . . . . . . . . . . . . . . . . . . 8
7.2. Agent ID Property Parameter . . . . . . . . . . . . . . . 9
8. Alarm Acknowledgement . . . . . . . . . . . . . . . . . . . . 10
8.1. Acknowledged Property . . . . . . . . . . . . . . . . . . 10
9. Snoozing Alarms . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Relationship Type Property Parameter . . . . . . . . . . . 12
10. Alarm Proximity Trigger . . . . . . . . . . . . . . . . . . . 12
10.1. Proximity Property . . . . . . . . . . . . . . . . . . . . 13
10.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 14
11. Default Alarms in CalDAV . . . . . . . . . . . . . . . . . . . 15
11.1. Server Behavior . . . . . . . . . . . . . . . . . . . . . 15
11.2. Client Behavior . . . . . . . . . . . . . . . . . . . . . 16
11.3. Action None . . . . . . . . . . . . . . . . . . . . . . . 17
11.4. Default Alarm Property . . . . . . . . . . . . . . . . . . 18
12. Security Considerations . . . . . . . . . . . . . . . . . . . 19
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
13.1. Property Registrations . . . . . . . . . . . . . . . . . . 19
13.2. Parameter Registrations . . . . . . . . . . . . . . . . . 20
13.3. Actions Registry . . . . . . . . . . . . . . . . . . . . . 20
13.4. Relationship Types Registry . . . . . . . . . . . . . . . 20
13.5. Proximity Value Registry . . . . . . . . . . . . . . . . . 20
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21
15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
15.1. Normative References . . . . . . . . . . . . . . . . . . . 21
15.2. Informative References . . . . . . . . . . . . . . . . . . 21
Appendix A. Change History (To be removed by RFC Editor
before publication) . . . . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 23
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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 to-do. 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 popular, 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
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
[RFC2119].
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
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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.
A "VALARM" calendar component is re-defined by the following
notation:
alarmcext = "BEGIN" ":" "VALARM" CRLF
alarmprop
"END" ":" "VALARM" CRLF
alarmprop = *(
; the following are REQUIRED,
; 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 is 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
)
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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
)
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
)
4. Alarm Unique Identifier
Several of the other extensions in this specification require
identifying a specific instance of a "VALARM" component in an
iCalendar stream. To aid that, this extension adds a "UID" property
to "VALARM" components to allow a unique identifier to 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]. In particular it MUST be a globally unique
identifier.
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The "VALARM" component defined in Section 3 is extended here as:
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 9). 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,
; but MAY occur more than once
related
)
6. Alarm URI Action
Currently "VALARM" components have actions for audio, display and
email. New types of action are of interest, e.g., SMS, instant
messaging, etc. Rather then specify separate actions for these, an
alternative is to define a "URI" action that allows any URI scheme to
be used as an action, where it makes sense. Thus URI schemes for IM
[RFC3860], SIP [RFC3261], TEL [RFC3966]etc could be used.
This extension defines a new "URI" property value for use with the
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"ACTION" property in "VALARM" components. A new set of action
properties is defined for "VALARM" components based on this new
action as defined by the syntax below.
actionvalue /= "URI"
; Adds a new action for a "VALARM"
actionprop /= uriprop
; Re-defines the "VALARM" component to include
; "uriprop" as a new set of action properties
uriprop = *(
; the following is REQUIRED,
; and MUST occur only once
uri /
; 'duration' and 'repeat' are both OPTIONAL,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat
)
7. Alarm Agent
With the advent of a standard client/server protocol for calendaring
and scheduling data ([RFC4791]) there is a need to specify which
client or server should handle the presentation of an alarm when it
is triggered. For example, calendar users want to be able to receive
alarms at all times, even when their desktop client might be
unavailable. Since the server is "always on", a service running on
the server could monitor alarm status and, when appropriate, trigger
those alarms. In addition it may be important for only the server or
the client to be set to handle an alarm - and in some cases only
specific servers or clients.
To address this need, this specification defines an "ALARM-AGENT"
iCalendar property that can be added to any "VALARM" component. This
property specifies whether a client or server or both should be
responsible for processing the alarm when it triggers. In addition,
an "AGENT-ID" property parameter can be added to uniquely identify
the client or server that should process the alarm. This is defined
by the syntax below.
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alarmprop /= *(
; the following is OPTIONAL,
; and MAY occur more than once
alarm-agent
)
7.1. Alarm Agent Property
Property Name: ALARM-AGENT
Purpose: This property specifies whether a client, server, both or
none gets to process an alarm when it is triggered.
Value Type: TEXT
Property Parameters: IANA, non-standard, and id 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 who is responsible for
processing an alarm when it is triggered. When the value "SERVER"
is specified, only a server that has a copy of the event is
responsible. When the value "CLIENT" is specified, only a client
that has a copy of the event is responsible. When the value
"BOTH" is specified, either a client or server is responsible.
When the value "NONE" is specified, neither a client nor server is
responsible (i.e., the alarm action is never carried out when it
triggers).
If the "AGENT-ID" property parameter is specified for "SERVER" or
"CLIENT" values, then only the client or server identified by the
"AGENT-ID" value is responsible. Clients or servers that are not
responsible for the alarm SHOULD NOT process the alarm action when
it is triggered. If multiple clients or servers need to be
specified, then the "ALARM-AGENT" property should be included
multiple times in the "VALARM" component, with each one containing
the appropriate "AGENT-ID" property parameter value to identify
each client or server.
In the absence of this property clients and servers can choose to
process the alarm themselves as appropriate. i.e., a default value
of "BOTH".
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This property MAY occur more than once to allow multiple
processors of an alarm.
Format Definition: This property is defined by the following
notation:
alarm-agent = "ALARM-AGENT" alarmagentparam ":"
alarmagentvalue CRLF
alarmagentparam = *(
; the following is OPTIONAL,
; but MUST NOT occur more than once
(";" agentidparam) /
; the following is OPTIONAL,
; and MAY occur more than once
(";" other-param)
)
alarmagentvalue = "SERVER" / "CLIENT" / "BOTH" / "NONE" /
iana-token / x-name
Example: The following are examples of this property:
ALARM-AGENT:SERVER
ALARM-AGENT;AGENT-ID="tag:example.com,2011:cyrus-desktop":CLIENT
7.2. Agent ID Property Parameter
Parameter Name: AGENT-ID
Purpose: This property parameter specifies a URI identifier for the
property it is applied to.
Format Definition: This property parameter is defined by the
following notation:
agentidparam = "AGENT-ID" "=" DQUOTE uri DQUOTE
Description: This property parameter is used to specify a URI
identifier that is associated with the property it is applied to.
Each property that allows this parameter to be specified MUST
indicate what the value of the URI represents.
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Example: The following is an example of this property parameter:
ALARM-AGENT;AGENT-ID="http://calendar.example.com":SERVER
8. 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.
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
sent or acknowledged. This is defined by the syntax below.
alarmprop /= *(
; the following is OPTIONAL,
; but MUST NOT occur more than once
acknowledged
)
8.1. 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.
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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 alarm may not provide feedback as to when the calendar
user sees them, for example email based alerts. For those kinds
of alarms, the client SHOULD set this property when the alarm is
triggered and the action successfully carried out.
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" is added or changed in the
alarm component. If the value of any "ACKNOWLEDGED" 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)
)
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Example: The following is an example of this property:
ACKNOWLEDGED:20090604T084500Z
9. Snoozing Alarms
Users often want to "snooze" an alarm, and this specification defines
a standard approach to accomplish that.
To "snooze" an alarm, clients create a new "VALARM" component within
the parent component of the "VALARM" that was triggered and is being
"snoozed" (i.e., as a "sibling" component of the "VALARM" being
snoozed). The new "VALARM" 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. Clients SHOULD add a "RELATED-TO" property to the
new "VALARM" component with a value set to the "UID" property value
of the "VALARM" component being snoozed. If the "VALARM" component
being snoozed does not already have a "UID" property, the client
SHOULD add one. The "RELATED-TO" property added to the new "VALARM"
component SHOULD include a "RELTYPE" property parameter with a value
set to "SNOOZE".
When the "snooze" alarm is triggered and dismissed the client SHOULD
remove the corresponding "VALARM" component, or set the
"ACKNOWLEDGED" property (see Section 8.1). Alternatively, if the
"snooze" alarm is itself "snoozed", the client SHOULD remove the
original "snooze" alarm and create a new one, with the appropriate
trigger time and relationship set.
9.1. 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 to relate a "snoozed" "VALARM" component to the original
alarm that the "snooze" was generated for.
10. 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 properties to "VALARM"
components to indicate when an alarm can be triggered based on
location.
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"PROXIMITY" - indicates that a location based trigger is to be
used and which direction of motion is used for the trigger
"STRUCTURED-LOCATION" - used to indicate the actual location to
trigger off, specified using a geo: URI [RFC5870] which allows for
two or three co-ordinate values with an optional uncertainty
alarmprop /= *(
; the following is OPTIONAL,
; but MUST NOT occur more than once
proximity /
; the following is OPTIONAL,
; and MAY occur more than once, but only
; when a PROXIMITY property is also present
structured-location
)
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 that.
10.1. 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.
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Description: This property is used to indicate that an alarm has a
location-based trigger. Its value identifies the direction of
motion used to trigger the alarm. One or more location values are
set using "STRUCTURED-LOCATION" properties.
When the property value is set to "ARRIVE", the alarm is triggered
when the calendar user agent arrives in the vicinity of any of the
specified locations. When set to "DEPART", the alarm is triggered
when the calendar user agent departs from the vicinity of any
specified locations.
The time-based "TRIGGER" property MUST also be present in the
"VALARM" calendar component and MUST be set to a positive duration
value (or zero duration). That value indicates a time delay to be
applied to the triggering of the alarm after the location trigger
is triggered. e.g., an alarm could be set to trigger 30 minutes
after arriving home.
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" / iana-token / x-name
Example: The following is an example of this property:
PROXIMITY:ARRIVE
10.2. 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 structured location
property. Note use of the "u=" parameter with the "geo" URI to
define the precision of the location determination.
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BEGIN:VALARM
UID:77D80D14-906B-4257-963F-85B1E734DBB6
TRIGGER;VALUE=DATE-TIME:19760401T005545Z
ACTION:DISPLAY
PROXIMITY:DEPART
STRUCTURE-LOCATION;VALUE=URI:geo:40.443,-79.945;u=10
DESCRIPTION:Remember to buy milk
END:VALARM
11. Default Alarms in CalDAV
Users often want to have a default alarm applied to new events that
they create or to new invitations that arrive on a CalDAV [RFC4791]
server. Since this behavior is expected to occur no matter which
client a user is using, or whether any client is even connected at
the time, it is beneficial if the server itself is responsible for
managing the creation of the default alarm.
This specification defines four new WebDAV properties that can be
used to specify different sets of default alarms. Clients can store
"VALARM" components in these properties to setup the defaults. When
a new event or todo is created on the server, the server will
automatically add the default, as appropriate. When a new event or
todo invitation is delivered to the calendar user, the server will
automatically add the default alarm, as appropriate.
11.1. Server Behavior
A server supporting the features described in this document MUST
include "calendar-default-alarms" as a field in the DAV response
header from an OPTIONS request on a calendar home or calendar
collection.
The four new WebDAV properties are:
CALDAV:default-alarm-vevent-datetime A default alarm applied to
"VEVENT" components whose "DTSTART" property value type is "DATE-
TIME"
CALDAV:default-alarm-vevent-date A default alarm applied to "VEVENT"
components whose "DTSTART" property value type is "DATE"
CALDAV:default-alarm-vtodo-datetime A default alarm applied to
"VTODO" components whose "DUE" or "DTSTART" property value type is
"DATE-TIME"
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CALDAV:default-alarm-vtodo-date A default alarm applied to "VTODO"
components whose "DUE" or "DTSTART" property value type is "DATE",
or when neither of those properties is present
The WebDAV properties are defined on a calendar user's "calendar
home" collection, or on individual calendar collections. When events
or tasks are created in a calendar, the server will first inspect the
WebDAV properties on the calendar collection to see if the
appropriate property is present. If it is, the server will use the
value of that property to set the default in the new component. If
the property is not present on the calendar collection, the server
will determine whether the property is present on the calendar home
collection that contains the calendar collection. If present on the
calendar home, the property value there is used as the default.
The WebDAV property value MUST be one or more "VALARM" components or
the empty string. If an empty string is used, no default alarms are
applied. Note that these values contain just the "BEGIN:
VALARM...END:VALARM" data (i.e., syntactically the "alarmcext"
element as per Section 3).
When adding a default alarm to an event or task, the server MUST
ensure that a "DEFAULT-ALARM" property with a value of "TRUE" is
present in the "VALARM" component.
If a "DESCRIPTION" property is present in the "VALARM" component, but
its value is empty, the server SHOULD insert the value from any
"SUMMARY" property of the component in which the default "VALARM" is
being added.
A default alarm MUST NOT be added to individual event or task
components in a calendar object resource being created, if a "VALARM"
component is already present in the component.
When the client stores a new alarm in any of the WebDAV properties,
servers MUST NOT change any existing calendar data within the
calendar home or calendar where the WebDAV property is stored. This
avoids the server having to rewrite potentially large amounts of
calendar data to update the default alarm, and thus avoids the need
for clients to re-download that data when they next synchronize with
the server. The reasoning for this is described further in the next
section.
11.2. Client Behavior
Clients that support default alarms SHOULD allow users to set the
four types of default provided by the WebDAV properties defined in
Section 11.1. Clients SHOULD check for the presence of those
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properties and the calendar user's calendar home and individual
calendars and use the values for defaults that they themselves apply.
Since existing calendar data with a default alarm is not changed when
the default alarm property changes, clients SHOULD do the following:
Treat the default alarm values in the WebDAV properties as
"overrides" for any alarms appearing in cached calendar data that
have the "DEFAULT-ALARM" property set to a value of "TRUE". In
effect the client ignores the default alarm in the calendar data
and use the current default from the WebDAV properties.
When a client updates calendar data on the server, it SHOULD
replace any existing default alarms in the calendar data with the
latest defaults retrieved from the WebDAV properties.
The approach of not having the server rewrite existing calendar data
when an alarm changes, and having the client "override" defaults in
calendar data with the current default values is a compromise
designed to provide some backwards compatibility with clients not
supporting default alarm behavior.
11.3. Action None
When default alarms are being used it is necessary to know when a
calendar user has set a default alarm that does nothing as opposed to
specifying that no alarm be used. This is important because clients
are expected to "override" any default alarm present in calendar data
with the current value retrieved from the server. However, if the
calendar user explicitly removed the default alarm, then the
"override" does not happen.
This extension defines a new "NONE" property value for use with the
"ACTION" property in "VALARM" components. A new set of action
properties is defined for "VALARM" components based on this new
action as defined by the syntax below. The "NONE" action is used
solely to indicate a default alarm that does not alert the calendar
user.
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actionvalue /= "NONE"
; Adds a new action for a "VALARM"
actionprop /= noneprop
; Re-defines the "VALARM" component to include
; "noneprop" as a new set of action properties
noneprop = (
; No properties used
)
11.4. Default Alarm Property
Property Name: DEFAULT-ALARM
Purpose: This property indicates that an alarm is a default alarm.
Value Type: BOOLEAN
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 a "VALARM"
component is a default alarm.
Format Definition: This property is defined by the following
notation:
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alarmprop /= *(
; the following is OPTIONAL,
; but MUST NOT occur more than once
default-alarm
)
default-alarm = "DEFAULT-ALARM" defaultalarmparam ":"
boolean CRLF
defaultalarmparam = *(
; the following is OPTIONAL,
; and MAY occur more than once
(";" other-param)
)
12. Security Considerations
TODO:talk about importance of stripping VALARMs from incoming iTIP.
Talk about VALARMs being used to "spam" - particularly nasty if the
server handles it.
13. IANA Considerations
13.1. Property Registrations
This document defines the following new iCalendar properties to be
added to the registry defined in Section 8.2.3 of [RFC5545]:
+---------------+---------+-----------------------+
| Property | Status | Reference |
+---------------+---------+-----------------------+
| ALARM-AGENT | Current | RFCXXXX, Section 7.1 |
| ACKNOWLEDGED | Current | RFCXXXX, Section 8.1 |
| PROXIMITY | Current | RFCXXXX, Section 10.1 |
| DEFAULT-ALARM | Current | RFCXXXX, Section 11.4 |
+---------------+---------+-----------------------+
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13.2. Parameter Registrations
This document defines the following new iCalendar property parameters
to be added to the registry defined in Section 8.2.4 of [RFC5545]:
+--------------------+---------+----------------------+
| Property Parameter | Status | Reference |
+--------------------+---------+----------------------+
| AGENT-ID | Current | RFCXXXX, Section 7.2 |
+--------------------+---------+----------------------+
13.3. Actions Registry
This document defines the following new iCalendar action to be added
to the registry defined in Section 8.3.10 of [RFC5545]:
+--------+---------+-----------------------+
| Action | Status | Reference |
+--------+---------+-----------------------+
| URI | Current | RFCXXXX, Section 6 |
| NONE | Current | RFCXXXX, Section 11.3 |
+--------+---------+-----------------------+
13.4. 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]:
+-------------------+---------+----------------------+
| Relationship Type | Status | Reference |
+-------------------+---------+----------------------+
| SNOOZE | Current | RFCXXXX, Section 9.1 |
+-------------------+---------+----------------------+
13.5. Proximity Value Registry
This document creates a new iCalendar registry for values of the
"PROXIMITY" property:
+--------+---------+-----------------------+
| Value | Status | Reference |
+--------+---------+-----------------------+
| ARRIVE | Current | RFCXXXX, Section 10.1 |
| DEPART | Current | RFCXXXX, Section 10.1 |
+--------+---------+-----------------------+
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14. 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, and Ciny Joy.
15. References
15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault,
"Calendaring Extensions to WebDAV (CalDAV)", RFC 4791,
March 2007.
[RFC5545] Desruisseaux, B., "Internet Calendaring and Scheduling
Core Object Specification (iCalendar)", RFC 5545,
September 2009.
[RFC5870] Mayrhofer, A. and C. Spanring, "A Uniform Resource
Identifier for Geographic Locations ('geo' URI)",
RFC 5870, June 2010.
15.2. Informative References
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC3860] Peterson, J., "Common Profile for Instant Messaging
(CPIM)", RFC 3860, August 2004.
[RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers",
RFC 3966, December 2004.
Appendix A. Change History (To be removed by RFC Editor before
publication)
Changes in -04:
1. Changed "ID" to "AGENT-ID".
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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 -03: none - resubmission of -02
Changes in -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 -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.
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.
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Author's Address
Cyrus Daboo
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
USA
Email: cyrus@daboo.name
URI: http://www.apple.com/
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