draft-ietf-calext-availability-02.txt   draft-ietf-calext-availability-03.txt 
Network Working Group C. Daboo Network Working Group C. Daboo
Internet-Draft Apple Internet-Draft Apple
Intended status: Standards Track M. Douglass Intended status: Standards Track M. Douglass
Expires: November 24, 2016 RPI Expires: December 24, 2016 Spherical Cow Group
May 23, 2016 June 22, 2016
Calendar Availability Calendar Availability
draft-ietf-calext-availability-02 draft-ietf-calext-availability-03
Abstract Abstract
This document specifies a new iCalendar calendar component that This document specifies a new iCalendar calendar component that
allows the publication of available and unavailable time periods allows the publication of available and unavailable time periods
associated with a calendar user. This component can be used in associated with a calendar user. This component can be used in
standard iCalendar free-busy lookups, including iTIP free-busy standard iCalendar free-busy lookups, including iTIP free-busy
requests, to generate repeating blocks of available or busy time with requests, to generate repeating blocks of available or busy time with
exceptions as needed. exceptions as needed.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 24, 2016. This Internet-Draft will expire on December 24, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. iCalendar Extensions . . . . . . . . . . . . . . . . . . . . 4 3. iCalendar Extensions . . . . . . . . . . . . . . . . . . . . 4
3.1. VAVAILABILITY Component . . . . . . . . . . . . . . . . . 4 3.1. VAVAILABILITY Component . . . . . . . . . . . . . . . . . 4
3.2. Busy Time Type . . . . . . . . . . . . . . . . . . . . . 10 3.2. Busy Time Type . . . . . . . . . . . . . . . . . . . . . 10
4. Combining VAVAILABILITY components . . . . . . . . . . . . . 10 4. Combining VAVAILABILITY components . . . . . . . . . . . . . 10
5. Calculating Free-Busy Time . . . . . . . . . . . . . . . . . 11 5. Calculating Free-Busy Time . . . . . . . . . . . . . . . . . 11
5.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 13
6. Use with iTIP . . . . . . . . . . . . . . . . . . . . . . . . 14 6. Use with iTIP . . . . . . . . . . . . . . . . . . . . . . . . 14
7. CalDAV Extensions . . . . . . . . . . . . . . . . . . . . . . 14 7. CalDAV Extensions . . . . . . . . . . . . . . . . . . . . . . 15
7.1. CalDAV Requirements Overview . . . . . . . . . . . . . . 14 7.1. CalDAV Requirements Overview . . . . . . . . . . . . . . 15
7.2. New features in CalDAV . . . . . . . . . . . . . . . . . 15 7.2. New features in CalDAV . . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 20 8. Security Considerations . . . . . . . . . . . . . . . . . . . 19
9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 20 9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10.1. Component Registrations . . . . . . . . . . . . . . . . 20 10.1. Component Registrations . . . . . . . . . . . . . . . . 20
10.2. Property Registrations . . . . . . . . . . . . . . . . . 21 10.2. Property Registrations . . . . . . . . . . . . . . . . . 20
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
12. Normative References . . . . . . . . . . . . . . . . . . . . 21 12. Normative References . . . . . . . . . . . . . . . . . . . . 20
Appendix A. Example Calendar #1 . . . . . . . . . . . . . . . . 22 Appendix A. Example Calendar #1 . . . . . . . . . . . . . . . . 21
Appendix B. Change History (To be removed by RFC Editor before Appendix B. Change History (To be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 23 publication) . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
Calendar users often have regular periods of time when they are Calendar users often have regular periods of time when they are
either available to be scheduled or always unavailable. For example, either available to be scheduled or always unavailable. For example,
an office worker will often wish only to appear free to their work an office worker will often wish only to appear free to their work
colleagues during normal 'office hours' (e.g., Monday through Friday, colleagues during normal 'office hours' (e.g., Monday through Friday,
9 am through 5 pm). Or, a university professor might only be 9 am through 5 pm). Or, a university professor might only be
available to students during a set period of time (e.g., Thursday available to students during a set period of time (e.g., Thursday
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; but MUST NOT occur more than once ; but MUST NOT occur more than once
; ;
created / description / last-mod / created / description / last-mod /
location / recurid / rrule / summary / location / recurid / rrule / summary /
; ;
; the following are OPTIONAL, ; the following are OPTIONAL,
; and MAY occur more than once ; and MAY occur more than once
; ;
categories / comment / contact / exdate / categories / comment / contact / exdate /
rdate / x-prop / iana-prop rdate / x-prop / iana-prop
;
) )
Description: A "VAVAILABILITY" component indicates a period of time Description: A "VAVAILABILITY" component indicates a period of time
within which availability information is provided. A within which availability information is provided. A
"VAVAILABILITY" component can specify a start time and an end time "VAVAILABILITY" component can specify a start time and an end time
or duration. If "DTSTART" is not present, then the start time is or duration. If "DTSTART" is not present, then the start time is
unbounded. If "DTEND" or "DURATION" are not present, then the end unbounded. If "DTEND" or "DURATION" are not present, then the end
time is unbounded. Within the specified time period, availability time is unbounded. Within the specified time period, availability
defaults to a free-busy type of "BUSY-UNAVAILABLE" (see defaults to a free-busy type of "BUSY-UNAVAILABLE" (see
Section 3.2), except for any time periods corresponding to Section 3.2), except for any time periods corresponding to
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of the "RECURRENCE-ID" property). of the "RECURRENCE-ID" property).
If specified, the "DTSTART" and "DTEND" properties in If specified, the "DTSTART" and "DTEND" properties in
"VAVAILABILITY" components and "AVAILABLE" sub-components MUST be "VAVAILABILITY" components and "AVAILABLE" sub-components MUST be
"DATE-TIME" values specified as either date with UTC time or date "DATE-TIME" values specified as either date with UTC time or date
with local time and a time zone reference. with local time and a time zone reference.
The iCalendar object containing the "VAVAILABILITY" component MUST The iCalendar object containing the "VAVAILABILITY" component MUST
contain appropriate "VTIMEZONE" components corresponding to each contain appropriate "VTIMEZONE" components corresponding to each
unique "TZID" parameter value used in any DATE-TIME properties in unique "TZID" parameter value used in any DATE-TIME properties in
all components. Note that extensions, such as [RFC7809], might all components, unless [RFC7809] is in effect.
relax this constraint.
When used to publish available time, the "ORGANIZER" property When used to publish available time, the "ORGANIZER" property
specifies the calendar user associated with the published specifies the calendar user associated with the published
available time. available time.
If the "PRIORITY" property is specified in "VAVAILABILITY" If the "PRIORITY" property is specified in "VAVAILABILITY"
components, it is used to determine how that component is combined components, it is used to determine how that component is combined
with other "VAVAILABILITY" components. See Section 4. with other "VAVAILABILITY" components. See Section 4.
Other calendar properties MAY be specified in "VAVAILABILITY" or Other calendar properties MAY be specified in "VAVAILABILITY" or
"AVAILABLE" components and are considered attributes of the marked "AVAILABLE" components and are considered attributes of the marked
block of time. Their usage is application specific. For example, block of time. Their usage is application specific. For example,
the "LOCATION" property might be used to indicate that a person is the "LOCATION" property might be used to indicate that a person is
available in one location for part of the week and a different available in one location for part of the week and a different
location for another part of the week. location for another part of the week (but see Section 9 for when
it is appropriate to add additional data like this).
Example: The following is an example of a "VAVAILABILITY" calendar Example: The following is an example of a "VAVAILABILITY" calendar
component used to represent the availability of a user, always component used to represent the availability of a user, always
available Monday through Friday, 9:00 AM to 5:00 PM in the available Monday through Friday, 9:00 AM to 5:00 PM in the
America/Montreal time zone: America/Montreal time zone:
BEGIN:VAVAILABILITY BEGIN:VAVAILABILITY
ORGANIZER:mailto:bernard@example.com ORGANIZER:mailto:bernard@example.com
UID:vavail-1@example.com UID:vavail-1@example.com
DTSTAMP:20111005T133225Z DTSTAMP:20111005T133225Z
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Step through the resulting list of "VAVAILABILITY" components. For Step through the resulting list of "VAVAILABILITY" components. For
each, the time range covered by the "VAVAILABILITY" component is set each, the time range covered by the "VAVAILABILITY" component is set
to busy and then portions of it defined by the "AVAILABLE" components to busy and then portions of it defined by the "AVAILABLE" components
in the "VAVAILABILITY" component are set to free. in the "VAVAILABILITY" component are set to free.
Note that, if any "VAVAILABILITY" component completely covers the Note that, if any "VAVAILABILITY" component completely covers the
date range of interest, then any lower priority "VAVAILABILITY" date range of interest, then any lower priority "VAVAILABILITY"
components can be ignored. components can be ignored.
Typically, a calendar user's "default" availability (e.g., business
hours of Monday through Friday, 9:00 am to 5:00 pm) would use the
lowest level of priority: zero. Any overrides to the "default" would
use higher levels as needed. To avoid having to keep readjusting the
"PRIORITY" property value when an override has to be "inserted"
between two existing components, priority values SHOULD be "spaced
out" over the full range of values. e.g., the "default" availability
is created with priority zero, then the first override created with
priority 5, a subsequent availability can be inserted between the two
by using priority 7, and another, taking precedence over all existing
ones, with priority 3.
5. Calculating Free-Busy Time 5. Calculating Free-Busy Time
This section describes how free-busy time information for a calendar This section describes how free-busy time information for a calendar
user is calculated in the presence of "VAVAILABILITY" calendar user is calculated in the presence of "VAVAILABILITY" calendar
components. components.
An iCalendar "VFREEBUSY" component is used to convey "rolled-up" An iCalendar "VFREEBUSY" component is used to convey "rolled-up"
free-busy time information for a calendar user. This can be free-busy time information for a calendar user. This can be
generated as the result of an iTIP free-busy [RFC5546] request or generated as the result of an iTIP free-busy [RFC5546] request or
through some other mechanism (e.g., a CalDAV calendar-access through some other mechanism (e.g., a CalDAV calendar-access
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the time-range for the free-busy request, first available time is the time-range for the free-busy request, first available time is
calculated, as outlined in Section 4. Once that is done, regular calculated, as outlined in Section 4. Once that is done, regular
"VEVENT" and "VFREEBUSY" components can be "overlaid" in the usual "VEVENT" and "VFREEBUSY" components can be "overlaid" in the usual
way to block out time. way to block out time.
An example procedure for this is as follows: An example procedure for this is as follows:
1. Initially mark the entire period of the free-busy request as 1. Initially mark the entire period of the free-busy request as
free. free.
2. For each "VAVAILABILITY" component ordered by PRIORITY: 2. For each "VAVAILABILITY" component ordered by PRIORITY (lowest to
highest):
1. Determine if the "VAVAILABILITY" intersects the time-range of 1. Determine if the "VAVAILABILITY" intersects the time-range of
the free-busy request. If not ignore it. the free-busy request. If not ignore it.
2. Determine if the "VAVAILABILITY" is completely overridden by 2. Determine if the "VAVAILABILITY" is completely overridden by
a higher priority component. If so ignore it. a higher priority component. If so ignore it.
3. For the time period covered by the "VAVAILABILITY" component, 3. For the time period covered by the "VAVAILABILITY" component,
mark time in the free-busy request result set as busy, using mark time in the free-busy request result set as busy, using
the busy time type derived from the "BUSYTYPE" property in the busy time type derived from the "BUSYTYPE" property in
the "VAVAILABILITY" component. the "VAVAILABILITY" component.
3. For each remaining "VAVAILABILITY" component in order: 4. Append the "VAVAILABILITY" component to a list of components
for further processing in step 3, if it has not been ignored.
3. For each "VAVAILABILITY" component in the list resulting from
step 2, in order from the first item to the last item:
1. For each "AVAILABLE" component in the "VAVAILABILITY" 1. For each "AVAILABLE" component in the "VAVAILABILITY"
component: component:
1. Expand all recurring instances, taking into account 1. Expand all recurring instances, taking into account
overridden instances, ignoring instances or parts of overridden instances, ignoring instances or parts of
instances that fall outside of the free-busy request instances that fall outside of the free-busy request
time-range or the time period specified by the time-range or the time period specified by the
"VAVAILABILITY" component. "VAVAILABILITY" component.
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RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR
LOCATION:Montreal LOCATION:Montreal
END:AVAILABLE END:AVAILABLE
END:VAVAILABILITY END:VAVAILABILITY
BEGIN:VAVAILABILITY BEGIN:VAVAILABILITY
ORGANIZER:mailto:bernard@example.com ORGANIZER:mailto:bernard@example.com
UID:vavail-2@example.com UID:vavail-2@example.com
DTSTAMP:20111005T133225Z DTSTAMP:20111005T133225Z
DTSTART;TZID=America/Los_Angeles:20111023T000000 DTSTART;TZID=America/Los_Angeles:20111023T000000
DTEND;TZID=America/Los_Angeles:20111030T000000 DTEND;TZID=America/Los_Angeles:20111030T000000
PRIORITY:1
BEGIN:AVAILABLE BEGIN:AVAILABLE
UID:avail-2-A@example.com UID:avail-2-A@example.com
SUMMARY:Monday to Friday from 9:00 to 17:00 SUMMARY:Monday to Friday from 9:00 to 17:00
DTSTART;TZID=America/Los_Angeles:20111023T090000 DTSTART;TZID=America/Los_Angeles:20111023T090000
DTEND;TZID=America/Los_Angeles:20111023T170000 DTEND;TZID=America/Los_Angeles:20111023T170000
PRIORITY:1
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR
LOCATION:Los Angeles LOCATION:Los Angeles
END:AVAILABLE END:AVAILABLE
END:VAVAILABILITY END:VAVAILABILITY
6. Use with iTIP 6. Use with iTIP
This specification does not define how "VAVAILABILITY" components are This specification does not define how "VAVAILABILITY" components are
used in scheduling messages sent using the iTIP [RFC5546] protocol. used in scheduling messages sent using the iTIP [RFC5546] protocol.
It is expected that future specifications will define how iTIP It is expected that future specifications will define how iTIP
scheduling can make use of "VAVAILABILITY" components. scheduling can make use of "VAVAILABILITY" components.
7. CalDAV Extensions 7. CalDAV Extensions
7.1. CalDAV Requirements Overview 7.1. CalDAV Requirements Overview
This section lists what functionality is required of a CalDAV server This section lists what functionality is required of a CalDAV server
which supports "VAVAILBILITY" components in stored calendar data. A which supports "VAVAILABILITY" components in stored calendar data. A
server: server:
o MUST advertise support for "VAVAILABILITY" components in o MUST advertise support for "VAVAILABILITY" components in
CALDAV:supported-calendar-component-set properties on calendars CALDAV:supported-calendar-component-set properties on calendars
which allow storing of such components; which allow storing of such components;
o MUST support CALDAV:free-busy-query REPORTs that aggregate the o MUST support CALDAV:free-busy-query REPORTs that aggregate the
information in any "VAVAILABILITY" components in the calendar information in any "VAVAILABILITY" components in the calendar
collections targeted by the request; collections targeted by the request;
o MUST support "VAVAILABILITY" components stored in a o MUST support "VAVAILABILITY" components stored in a
CALDAV:calendar-availability WebDAV property on a CALDAV CALDAV:calendar-availability WebDAV property on a CalDAV
scheduling inbox collection, if the CALDAV calendar-auto-schedule scheduling inbox collection, if the CalDAV calendar-auto-schedule
feature is supported; feature is supported;
o MUST support iTIP [RFC5546] free-busy requests that aggregate the o MUST support iTIP [RFC5546] free-busy requests that aggregate the
information in any "VAVAILABILITY" components in calendar information in any "VAVAILABILITY" components in calendar
collections that contribute to free-busy, or in any collections that contribute to free-busy, or in any
"VAVAILABILITY" components stored in the CALDAV:calendar- "VAVAILABILITY" components stored in the CALDAV:calendar-
availability property on the CALDAV scheduling inbox collection of availability property on the CalDAV scheduling inbox collection of
the calendar user targeted by the iTIP free-busy request, if the the calendar user targeted by the iTIP free-busy request, if the
CalDAV calendar-auto-schedule feature is available. CalDAV calendar-auto-schedule feature is available.
"VAVAILABILITY" components are treated in a manner similar to "VAVAILABILITY" components are treated in a manner similar to
"VEVENT" and "VTODO" components, and MUST satisfy the other "VEVENT" and "VTODO" components, and MUST satisfy the other
requirements CalDAV imposes on calendar object resources (see requirements CalDAV imposes on calendar object resources (see
Section 4.1 of [RFC4791]). Section 4.1 of [RFC4791]).
7.2. New features in CalDAV 7.2. New features in CalDAV
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DAV response header MUST indicate that the server supports all MUST DAV response header MUST indicate that the server supports all MUST
level requirements specified in this document. level requirements specified in this document.
7.2.1.1. Example: Using OPTIONS for the Discovery of Calendar 7.2.1.1. Example: Using OPTIONS for the Discovery of Calendar
Availability Support Availability Support
>> Request << >> Request <<
OPTIONS /home/bernard/calendars/ HTTP/1.1 OPTIONS /home/bernard/calendars/ HTTP/1.1
Host: cal.example.com Host: cal.example.com
>> Response << >> Response <<
HTTP/1.1 200 OK HTTP/1.1 200 OK
Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
Allow: PROPFIND, PROPPATCH, LOCK, UNLOCK, REPORT, ACL Allow: PROPFIND, PROPPATCH, LOCK, UNLOCK, REPORT, ACL
DAV: 1, 2, 3, access-control, calendar-access, DAV: 1, 2, 3, access-control, calendar-access,
calendar-availability calendar-availability
Date: Fri, 11 Nov 2005 09:32:12 GMT Date: Fri, 11 Nov 2005 09:32:12 GMT
Content-Length: 0 Content-Length: 0
In this example, the OPTIONS method returns the value "calendar- In this example, the OPTIONS method returns the value "calendar-
availability" in the DAV response header to indicate that the availability" in the DAV response header to indicate that the
collection "/home/bernard/calendars/" supports the new features collection "/home/bernard/calendars/" supports the new features
defined in this specification. defined in this specification.
7.2.2. CALDAV Time Range Queries 7.2.2. CalDAV Time Range Queries
Section 9.9 of [RFC4791] describes how to specify time ranges to Section 9.9 of [RFC4791] describes how to specify time ranges to
limit the set of calendar components returned by the server. This limit the set of calendar components returned by the server. This
specification extends [RFC4791] to describe how to apply time range specification extends [RFC4791] to describe how to apply time range
filtering to "VAVAILABILITY" components. filtering to "VAVAILABILITY" components.
A "VAVAILABILITY" component is said to overlap a given time range if A "VAVAILABILITY" component is said to overlap a given time range if
the condition for the corresponding component state specified in the the condition for the corresponding component state specified in the
table below is satisfied. The conditions depend on the presence of table below is satisfied. The conditions depend on the presence of
the "DTSTART", "DTEND", and "DURATION" properties in the the "DTSTART", "DTEND", and "DURATION" properties in the
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Namespace: urn:ietf:params:xml:ns:caldav Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Defines a "VAVAILABILITY" component that will be used in Purpose: Defines a "VAVAILABILITY" component that will be used in
calculating free-busy time when an iTIP free-busy request is calculating free-busy time when an iTIP free-busy request is
targeted at the calendar user who owns the Inbox. targeted at the calendar user who owns the Inbox.
Conformance: This property MAY be protected and SHOULD NOT be Conformance: This property MAY be protected and SHOULD NOT be
returned by a PROPFIND DAV:allprop request. Support for this returned by a PROPFIND DAV:allprop request. Support for this
property is REQUIRED. The value of this property MUST be a valid property is REQUIRED. The value of this property MUST be a valid
iCalendar object containing "VAVAILABILITY" components and iCalendar object containing a "VAVAILABILITY" component.
"VTIMEZONE" components (if required) only. "VTIMEZONE" components SHOULD NOT be present if [RFC7809] is in
effect. For simplicity, only a single "VAVAILABILITY" component
MUST be present in the property. For more complex availability
scenarios, clients can store multiple "VAVAILABILITY" components
in the calendar user's calendar collections.
Description: This property allows a user to specify their Description: This property allows a user to specify their
availability by including an "VAVAILABILITY" component in the availability by including an "VAVAILABILITY" component in the
value of this property. If present, the server MUST use this value of this property. If present, the server MUST use this
"VAVAILABILITY" component when determining free-busy information "VAVAILABILITY" component when determining free-busy information
as part of an iTIP free-busy request being handled by the server. as part of an iTIP free-busy request being handled by the server.
Fot simplicity, only a single "VAVAILABILITY" component MUST be
present in the property. For more complex availability scenarios,
clients can store multiple "VAVAILABILITY" components in the
calendar user's calendar collections.
Definition: Definition:
<!ELEMENT calendar-availability (#PCDATA) > <!ELEMENT calendar-availability (#PCDATA) >
; Data value MUST be iCalendar object containing ; Data value MUST be iCalendar object containing
; "VAVAILABILITY" or "VTIMEZONE" components. ; "VAVAILABILITY" or "VTIMEZONE" components.
Example: Example:
<C:calendar-availability xmlns:D="DAV:" <C:calendar-availability xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:C="urn:ietf:params:xml:ns:caldav"
>BEGIN:VCALENDAR >BEGIN:VCALENDAR
CALSCALE:GREGORIAN CALSCALE:GREGORIAN
PRODID:-//example.com//iCalendar 2.0//EN PRODID:-//example.com//iCalendar 2.0//EN
VERSION:2.0 VERSION:2.0
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:America/Montreal
BEGIN:DAYLIGHT
DTSTART:20000404T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
END:DAYLIGHT
BEGIN:STANDARD
DTSTART:20001026T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
END:STANDARD
END:VTIMEZONE
BEGIN:VAVAILABILITY BEGIN:VAVAILABILITY
UID:vavail-1@example.com UID:vavail-1@example.com
DTSTAMP:20111005T133225Z DTSTAMP:20111005T133225Z
DTSTART;TZID=America/Montreal:20111002T000000 DTSTART;TZID=America/Montreal:20111002T000000
BEGIN:AVAILABLE BEGIN:AVAILABLE
UID:avail-1-A@example.com UID:avail-1-A@example.com
SUMMARY:Monday to Friday from 9:00 to 18:00 SUMMARY:Monday to Friday from 9:00 to 18:00
DTSTART;TZID=America/Montreal:20111002T090000 DTSTART;TZID=America/Montreal:20111002T090000
DTEND;TZID=America/Montreal:20111002T180000 DTEND;TZID=America/Montreal:20111002T180000
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR
skipping to change at page 19, line 50 skipping to change at page 18, line 46
END:VAVAILABILITY END:VAVAILABILITY
END:VCALENDAR END:VCALENDAR
</C:calendar-availability> </C:calendar-availability>
7.2.5. iTIP free-busy requests 7.2.5. iTIP free-busy requests
The [RFC6638] processing of an iTIP free-busy request targeted at the The [RFC6638] processing of an iTIP free-busy request targeted at the
owner of the CALDAV:schedule-inbox will include free-busy information owner of the CALDAV:schedule-inbox will include free-busy information
derived from "VAVAILABILITY" components in any calendar collection derived from "VAVAILABILITY" components in any calendar collection
targeted during the request, as described in Section 5. In addition, targeted during the request, as described in Section 5. In addition,
any "VAVAILABILITY" component specified in the CALDAV:calendar- the "VAVAILABILITY" component specified in the CALDAV:calendar-
availability property on the owner's Inbox, MUST be included in the availability property on the owner's Inbox, MUST be included in the
free-busy calculation. free-busy calculation.
8. Security Considerations 8. Security Considerations
Calculation of availability information, particularly with multiple Calculation of availability information, particularly with multiple
overlapping time-ranges, can be complex, and CalDAV servers MAY limit overlapping time-ranges, can be complex, and CalDAV servers MAY limit
the complexity of such data stored by a client. the complexity of such data stored by a client.
An attacker able to "inject" availability information into a calendar An attacker able to "inject" availability information into a calendar
user's calendar data could ensure that the user never appears free user's calendar data could ensure that the user never appears free
for meetings, or appears free at inappropriate times. Calendar for meetings, or appears free at inappropriate times. Calendar
systems MUST ensure that availability information for a calendar user systems MUST ensure that availability information for a calendar user
can only be modified by authorized users. can only be modified by authorized users.
Beyond this, this specification does not add any additional security Security considerations in [RFC5545], [RFC5546], [RFC4791],
issues that are not already present in [RFC5545], [RFC5546], [RFC6638], and [RFC7809] MUST also be adhered to.
[RFC4791] and [RFC6638].
9. Privacy Considerations 9. Privacy Considerations
Normal free-busy information generated from "VAVAILABILITY"
components MUST NOT include information other than busy or free time
periods. In particular, user specified property values such as
"SUMMARY", "LOCATION" and "DESCRIPTION" MUST NOT be copied into the
free-busy result data.
Free-busy and availability information can be used by attackers to Free-busy and availability information can be used by attackers to
infer the whereabouts or overall level of "activity" of the infer the whereabouts or overall level of "activity" of the
corresponding calendar user. Any calendar system that allows a user corresponding calendar user. Any calendar system that allows a user
to expose their free-busy and availability information MUST limit to expose their free-busy and availability information MUST limit
access to that information to only authorized users. access to that information to only authorized users.
10. IANA Considerations When "VAVAILABILITY" components are sent to or shared with other
calendar users, care has to be taken to not expose more information
than is needed by each recipient. In particular, user specified
property values such as "SUMMARY", "LOCATION" and "DESCRIPTION"
properties might need to be removed from the "VAVAILABILITY"
components exposed to other calendar users. For example, family
members might be willing to expose their location to each other, but
a business owner will likely not want to do that with their
customers.
iCalendar "VFREEBUSY" information generated from "VAVAILABILITY"
components MUST NOT include information other than busy or free time
periods. In particular, user specified property values such as
"SUMMARY", "LOCATION" and "DESCRIPTION" MUST NOT be copied into the
free-busy result data.
Privacy considerations in [RFC5545], [RFC5546], [RFC4791], [RFC6638],
and [RFC7809] MUST also be adhered to.
10. IANA Considerations
10.1. Component Registrations 10.1. Component Registrations
This documents defines the following new iCalendar components to be This documents defines the following new iCalendar components to be
added to the registry defined in Section 8.2.2 of [RFC5545]: added to the registry defined in Section 8.3.1 of [RFC5545]:
+---------------+---------+-----------------------+ +---------------+---------+-----------------------+
| Component | Status | Reference | | Component | Status | Reference |
+---------------+---------+-----------------------+ +---------------+---------+-----------------------+
| VAVAILABILITY | Current | RFCXXXX, Section 3.1 | | VAVAILABILITY | Current | RFCXXXX, Section 3.1 |
| AVAILABLE | Current | RFCXXXX, Section 3.1 | | AVAILABLE | Current | RFCXXXX, Section 3.1 |
+---------------+---------+-----------------------+ +---------------+---------+-----------------------+
10.2. Property Registrations 10.2. Property Registrations
This documents defines the following new iCalendar properties to be This documents defines the following new iCalendar properties to be
added to the registry defined in Section 8.2.3 of [RFC5545]: added to the registry defined in Section 8.3.2 of [RFC5545]:
+----------+---------+-----------------------+ +----------+---------+-----------------------+
| Property | Status | Reference | | Property | Status | Reference |
+----------+---------+-----------------------+ +----------+---------+-----------------------+
| BUSYTYPE | Current | RFCXXXX, Section 3.2 | | BUSYTYPE | Current | RFCXXXX, Section 3.2 |
+----------+---------+-----------------------+ +----------+---------+-----------------------+
11. Acknowledgments 11. Acknowledgments
Thanks to the following for providing feedback: Toby Considine Thanks to the following for providing feedback: Toby Considine
Bernard Desruisseaux, Ken Murchison, Evert Pot, Dave Thewlis. This Bernard Desruisseaux, Alexey Melnikov, Daniel Migault, Ken Murchison,
specification came about via discussions at the Calendaring and Evert Pot, Dave Thewlis. This specification came about via
Scheduling Consortium. discussions at the Calendaring and Scheduling Consortium.
12. Normative References 12. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault, [RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault,
"Calendaring Extensions to WebDAV (CalDAV)", RFC 4791, "Calendaring Extensions to WebDAV (CalDAV)", RFC 4791,
skipping to change at page 22, line 13 skipping to change at page 21, line 26
March 2016, <http://www.rfc-editor.org/info/rfc7809>. March 2016, <http://www.rfc-editor.org/info/rfc7809>.
Appendix A. Example Calendar #1 Appendix A. Example Calendar #1
iCalendar object iCalendar object
BEGIN:VCALENDAR BEGIN:VCALENDAR
CALSCALE:GREGORIAN CALSCALE:GREGORIAN
PRODID:-//example.com//iCalendar 2.0//EN PRODID:-//example.com//iCalendar 2.0//EN
VERSION:2.0 VERSION:2.0
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:America/Montreal
BEGIN:DAYLIGHT
DTSTART:20000404T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
END:DAYLIGHT
BEGIN:STANDARD
DTSTART:20001026T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT BEGIN:VEVENT
DTSTAMP:20111113T044111Z DTSTAMP:20111113T044111Z
DTSTART;TZID=America/Montreal:20111106T120000 DTSTART;TZID=America/Montreal:20111106T120000
DURATION:PT1H DURATION:PT1H
SUMMARY:Meeting SUMMARY:Meeting
UID:60A48841ECB90F3F215FE3D2@example.com UID:60A48841ECB90F3F215FE3D2@example.com
END:VEVENT END:VEVENT
BEGIN:VAVAILABILITY BEGIN:VAVAILABILITY
UID:vavail-1@example.com UID:vavail-1@example.com
DTSTAMP:20111005T133225Z DTSTAMP:20111005T133225Z
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DTSTART;TZID=America/Montreal:20111002T080000 DTSTART;TZID=America/Montreal:20111002T080000
DTEND;TZID=America/Montreal:20111002T180000 DTEND;TZID=America/Montreal:20111002T180000
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR
END:AVAILABLE END:AVAILABLE
END:VAVAILABILITY END:VAVAILABILITY
END:VCALENDAR END:VCALENDAR
Appendix B. Change History (To be removed by RFC Editor before Appendix B. Change History (To be removed by RFC Editor before
publication) publication)
Changes in draft-ietf-calext-availability-03:
1. [EXPERT] Make 7809 reference more authoritative.
2. [EXPERT] Add reference to privacy section when describing use of
LOCATION.
3. [EXPERT] Added more text to privacy section to cover published
or iTIP-messaged VAVAILABILITY components.
4. [EXPERT] Clarify highest to lowest priority ordering in free-
busy calculation.
5. [EXPERT] Fixed PRIORITY in example.
6. [EXPERT] Editorial fixes.
7. [EXPERT] Clarify that calendar-availability follows the RFC7809
rule wrt VTIMEZONE presence.
8. [WGCHAIR] Added text suggesting how best to assign priority
values.
9. [WGCHAIR] Clarify example procedure step 3 ordering.
10. Be more explicit about dependent security and privacy
considerations.
Changes in draft-ietf-calext-availability-02: Changes in draft-ietf-calext-availability-02:
1. [WGLC] Change Appendix A example to start available time at 1. [WGLC] Change Appendix A example to start available time at
08:00. 08:00.
2. [WGLC] Added new section with table describing CalDAV time range 2. [WGLC] Added new section with table describing CalDAV time range
query behavior. query behavior.
3. Added text and reference to RFC7809. 3. Added text and reference to RFC7809.
skipping to change at page 25, line 4 skipping to change at page 24, line 19
Authors' Addresses Authors' Addresses
Cyrus Daboo Cyrus Daboo
Apple Inc. Apple Inc.
1 Infinite Loop 1 Infinite Loop
Cupertino, CA 95014 Cupertino, CA 95014
USA USA
Email: cyrus@daboo.name Email: cyrus@daboo.name
URI: http://www.apple.com/ URI: http://www.apple.com/
Michael Douglass Michael Douglass
Rensselaer Polytechnic Institute Spherical Cow Group
110 8th Street 226 3rd Street
Troy, NY 12180 Troy, NY 12180
USA USA
Email: douglm@rpi.edu Email: mdouglass@sphericalcowgroup.com
URI: http://www.rpi.edu/ URI: http://sphericalcowgroup.com
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