Network Working Group C. Daboo
Internet-Draft Apple Computer
Expires: March 17, 2007 B. Desruisseaux
Oracle
L. Dusseault
OSAF
September 13, 2006
Calendaring Extensions to WebDAV (CalDAV)
draft-dusseault-caldav-15
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document specifies a set of methods, headers, message bodies,
properties, and reports that define calendar access extensions to the
WebDAV protocol. The new protocol elements are intended to make
WebDAV-based calendaring and scheduling an interoperable standard
that supports calendar access, calendar management, calendar sharing,
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and calendar publishing.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 5
1.2. XML Namespaces and Processing . . . . . . . . . . . . . . 5
1.3. Method Preconditions and Postconditions . . . . . . . . . 6
2. Requirements Overview . . . . . . . . . . . . . . . . . . . . 6
3. Calendaring Data Model . . . . . . . . . . . . . . . . . . . 7
3.1. Calendar Server . . . . . . . . . . . . . . . . . . . . . 7
3.2. Recurrence and the Data Model . . . . . . . . . . . . . . 8
4. Calendar Resources . . . . . . . . . . . . . . . . . . . . . 9
4.1. Calendar Object Resources . . . . . . . . . . . . . . . . 9
4.2. Calendar Collection . . . . . . . . . . . . . . . . . . . 10
5. Calendar Access Feature . . . . . . . . . . . . . . . . . . . 11
5.1. Calendar Access Support . . . . . . . . . . . . . . . . . 11
5.1.1. Example: Using OPTIONS for the Discovery of
Calendar Access Support . . . . . . . . . . . . . . . 12
5.2. Calendar Collection Properties . . . . . . . . . . . . . 12
5.2.1. CALDAV:calendar-description Property . . . . . . . . 12
5.2.2. CALDAV:calendar-timezone Property . . . . . . . . . . 13
5.2.3. CALDAV:supported-calendar-component-set Property . . 14
5.2.4. CALDAV:supported-calendar-data Property . . . . . . . 15
5.2.5. CALDAV:max-resource-size Property . . . . . . . . . . 16
5.2.6. CALDAV:min-date-time Property . . . . . . . . . . . . 17
5.2.7. CALDAV:max-date-time Property . . . . . . . . . . . . 18
5.2.8. CALDAV:max-instances Property . . . . . . . . . . . . 18
5.2.9. CALDAV:max-attendees-per-instance Property . . . . . 19
5.2.10. Additional Precondition for PROPPATCH . . . . . . . . 20
5.3. Creating Resources . . . . . . . . . . . . . . . . . . . 20
5.3.1. MKCALENDAR Method . . . . . . . . . . . . . . . . . . 20
5.3.1.1. Status Codes . . . . . . . . . . . . . . . . . . 22
5.3.1.2. Example: Successful MKCALENDAR request . . . . . 23
5.3.2. Creating Calendar Object Resources . . . . . . . . . 25
5.3.2.1. Additional Preconditions for PUT, COPY and MOVE . 26
5.3.3. Non-standard components, properties and parameters . 28
5.3.4. Calendar Object Resource Entity Tag . . . . . . . . . 28
6. Calendaring Access Control . . . . . . . . . . . . . . . . . 29
6.1. Calendaring Privilege . . . . . . . . . . . . . . . . . . 29
6.1.1. CALDAV:read-free-busy Privilege . . . . . . . . . . . 29
6.2. Additional Principal Property . . . . . . . . . . . . . . 30
6.2.1. CALDAV:calendar-home-set Property . . . . . . . . . . 30
7. Calendaring Reports . . . . . . . . . . . . . . . . . . . . . 31
7.1. REPORT Method . . . . . . . . . . . . . . . . . . . . . . 31
7.2. Ordinary collections . . . . . . . . . . . . . . . . . . 31
7.3. Date and floating time . . . . . . . . . . . . . . . . . 32
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7.4. Time range filtering . . . . . . . . . . . . . . . . . . 32
7.5. Searching Text: Collations . . . . . . . . . . . . . . . 33
7.5.1. CALDAV:supported-collation-set Property . . . . . . . 34
7.6. Partial Retrieval . . . . . . . . . . . . . . . . . . . . 34
7.7. Non-standard components, properties and parameters . . . 35
7.8. CALDAV:calendar-query Report . . . . . . . . . . . . . . 35
7.8.1. Example: Partial retrieval of events by time range . 38
7.8.2. Example: Partial retrieval of recurring events . . . 42
7.8.3. Example: Expanded retrieval of recurring events . . . 45
7.8.4. Example: Partial retrieval of stored free busy
components . . . . . . . . . . . . . . . . . . . . . 47
7.8.5. Example: Retrieval of to-dos by alarm time range . . 49
7.8.6. Example: Retrieval of event by UID . . . . . . . . . 51
7.8.7. Example: Retrieval of events by PARTSTAT . . . . . . 53
7.8.8. Example: Retrieval of events only . . . . . . . . . . 55
7.8.9. Example: Retrieval of all pending to-dos . . . . . . 59
7.8.10. Example: Attempt to query unsupported property . . . 62
7.9. CALDAV:calendar-multiget Report . . . . . . . . . . . . . 63
7.9.1. Example: Successful CALDAV:calendar-multiget Report . 64
7.10. CALDAV:free-busy-query Report . . . . . . . . . . . . . . 66
7.10.1. Example: Successful CALDAV:free-busy-query Report . . 68
8. Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . 68
8.1. Client-to-client Interoperability . . . . . . . . . . . . 69
8.2. Synchronization Operations . . . . . . . . . . . . . . . 69
8.2.1. Use of Reports . . . . . . . . . . . . . . . . . . . 69
8.2.1.1. Restrict the Time Range . . . . . . . . . . . . . 69
8.2.1.2. Synchronize by Time Range . . . . . . . . . . . . 69
8.2.1.3. Synchronization Process . . . . . . . . . . . . . 70
8.2.2. Restrict the Properties Returned . . . . . . . . . . 72
8.3. Use of Locking . . . . . . . . . . . . . . . . . . . . . 72
8.4. Finding calendars . . . . . . . . . . . . . . . . . . . . 72
8.5. Storing and Using Attachments . . . . . . . . . . . . . . 74
8.5.1. Inline attachments . . . . . . . . . . . . . . . . . 74
8.5.2. External attachments . . . . . . . . . . . . . . . . 75
8.6. Storing and Using Alarms . . . . . . . . . . . . . . . . 76
9. XML Element Definitions . . . . . . . . . . . . . . . . . . . 77
9.1. CALDAV:calendar XML Element . . . . . . . . . . . . . . . 77
9.2. CALDAV:mkcalendar XML Element . . . . . . . . . . . . . . 77
9.3. CALDAV:mkcalendar-response XML Element . . . . . . . . . 77
9.4. CALDAV:supported-collation XML Element . . . . . . . . . 78
9.5. CALDAV:calendar-query XML Element . . . . . . . . . . . . 78
9.6. CALDAV:calendar-data XML Element . . . . . . . . . . . . 79
9.6.1. CALDAV:comp XML Element . . . . . . . . . . . . . . . 80
9.6.2. CALDAV:allcomp XML Element . . . . . . . . . . . . . 80
9.6.3. CALDAV:allprop XML Element . . . . . . . . . . . . . 81
9.6.4. CALDAV:prop XML Element . . . . . . . . . . . . . . . 81
9.6.5. CALDAV:expand XML Element . . . . . . . . . . . . . . 82
9.6.6. CALDAV:limit-recurrence-set XML Element . . . . . . . 83
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9.6.7. CALDAV:limit-freebusy-set XML Element . . . . . . . . 84
9.7. CALDAV:filter XML Element . . . . . . . . . . . . . . . . 84
9.7.1. CALDAV:comp-filter XML Element . . . . . . . . . . . 85
9.7.2. CALDAV:prop-filter XML Element . . . . . . . . . . . 85
9.7.3. CALDAV:param-filter XML Element . . . . . . . . . . . 86
9.7.4. CALDAV:is-not-defined XML Element . . . . . . . . . . 87
9.7.5. CALDAV:text-match XML Element . . . . . . . . . . . . 87
9.8. CALDAV:timezone XML Element . . . . . . . . . . . . . . . 88
9.9. CALDAV:time-range XML Element . . . . . . . . . . . . . . 88
9.10. CALDAV:calendar-multiget XML Element . . . . . . . . . . 93
9.11. CALDAV:free-busy-query XML Element . . . . . . . . . . . 94
10. Internationalization Considerations . . . . . . . . . . . . . 94
11. Security Considerations . . . . . . . . . . . . . . . . . . . 94
12. IANA Consideration . . . . . . . . . . . . . . . . . . . . . 95
12.1. Namespace Registration . . . . . . . . . . . . . . . . . 95
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 96
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 96
14.1. Normative References . . . . . . . . . . . . . . . . . . 96
14.2. Informative References . . . . . . . . . . . . . . . . . 97
Appendix A. CalDAV Method Privilege Table (Normative) . . . . . 97
Appendix B. Calendar collections used in the examples . . . . . 98
Appendix C. Changes (to be removed prior to publication as an
RFC) . . . . . . . . . . . . . . . . . . . . . . . . 104
C.1. Changes in -15 . . . . . . . . . . . . . . . . . . . . . 104
C.2. Changes in -14 . . . . . . . . . . . . . . . . . . . . . 105
C.3. Changes in -13 . . . . . . . . . . . . . . . . . . . . . 105
C.4. Changes in -12 . . . . . . . . . . . . . . . . . . . . . 106
C.5. Changes in -11 . . . . . . . . . . . . . . . . . . . . . 106
C.6. Changes in -10 . . . . . . . . . . . . . . . . . . . . . 107
C.7. Changes in -09 . . . . . . . . . . . . . . . . . . . . . 108
C.8. Changes in -08 . . . . . . . . . . . . . . . . . . . . . 109
C.9. Changes in -07 . . . . . . . . . . . . . . . . . . . . . 110
C.10. Changes in -06 . . . . . . . . . . . . . . . . . . . . . 111
C.11. Changes in -05 . . . . . . . . . . . . . . . . . . . . . 111
C.12. Changes in -04 . . . . . . . . . . . . . . . . . . . . . 112
C.13. Changes in -03 . . . . . . . . . . . . . . . . . . . . . 113
C.14. Changes in -02 . . . . . . . . . . . . . . . . . . . . . 113
C.15. Changes in -01 . . . . . . . . . . . . . . . . . . . . . 113
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 114
Intellectual Property and Copyright Statements . . . . . . . . . 115
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1. Introduction
The concept of using HTTP [RFC2616] and WebDAV [RFC2518] as a basis
for a calendar access protocol is by no means a new concept: it was
discussed in the IETF CALSCH working group as early as 1997 or 1998.
Several companies have implemented calendar access protocols using
HTTP to upload and download iCalendar [RFC2445] objects, and using
WebDAV to get listings of resources. However, those implementations
do not interoperate because there are many small and big decisions to
be made in how to model calendaring data as WebDAV resources, as well
as how to implement required features that aren't already part of
WebDAV. This document proposes a way to model calendar data in
WebDAV, with additional features to make an interoperable calendar
access protocol.
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The term "protected" is used in the Conformance field of property
definitions as defined in Section 1.4.2 of [RFC3253].
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.
1.2. XML Namespaces and Processing
Definitions of XML elements in this document use XML element type
declarations (as found in XML Document Type Declarations), described
in Section 3.2 of [W3C.REC-xml-20060816].
The namespace "urn:ietf:params:xml:ns:caldav" is reserved for the XML
elements defined in this specification, its revisions, and related
CalDAV specifications. XML elements defined by individual
implementations MUST NOT use the "urn:ietf:params:xml:ns:caldav"
namespace, and instead should use a namespace that they control.
The XML declarations used in this document do not include namespace
information. Thus, implementers must not use these declarations as
the only way to create valid CalDAV properties or to validate CalDAV
XML element type. Some of the declarations refer to XML elements
defined by WebDAV [RFC2518] which use the "DAV:" namespace. Wherever
such XML elements appear, they are explicitly prefixed with "DAV:" to
avoid confusion.
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Also note that some CalDAV XML element names are identical to WebDAV
XML element names, though their namespace differs. Care must be
taken not to confuse the two sets of names.
Processing of XML by CalDAV clients and servers MUST follow the rules
described in [RFC2518], in particular Section 14, and Appendices 3
and 4 of that specification.
1.3. Method Preconditions and Postconditions
A "precondition" of a method describes the state of the server that
must be true for that method to be performed. A "postcondition" of a
method describes the state of the server that must be true after that
method has been completed. If a method precondition or postcondition
for a request is not satisfied, the response status of the request
MUST be either 403 (Forbidden) if the request should not be repeated
because it will always fail, or 409 (Conflict) if it is expected that
the user might be able to resolve the conflict and resubmit the
request.
In order to allow better client handling of 403 and 409 responses, a
distinct XML element type is associated with each method precondition
and postcondition of a request. When a particular precondition is
not satisfied or a particular postcondition cannot be achieved, the
appropriate XML element MUST be returned as the child of a top-level
DAV:error element in the response body, unless otherwise negotiated
by the request.
2. Requirements Overview
This section lists what functionality is required of a CalDAV server.
To advertise support for CalDAV, a server:
o MUST support iCalendar [RFC2445] as a media type for calendar
object resource format;
o MUST support WebDAV Class 1 [RFC2518] (note that [I-D.ietf-webdav-
rfc2518bis] describes clarifications to [RFC2518] that aid
interoperability);
o MUST support WebDAV ACL [RFC3744] with the additional privilege
defined in Section 6.1 of this document;
o MUST support transport over TLS [RFC2246] as defined in [RFC2818]
(note that [RFC2246] has been obsoleted by [RFC4346]);
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o MUST support ETags [RFC2616] with additional requirements
specified in Section 5.3.4 of this document;
o MUST support all calendaring REPORTs defined in Section 7 of this
document; and
o MUST advertise support on all calendar collections and calendar
object resources for the calendaring REPORTs in the DAV:supported-
report-set property as defined in Versioning Extensions to WebDAV
[RFC3253].
In addition, a server:
o SHOULD support the MKCALENDAR method defined in Section 5.3.1 of
this document.
3. Calendaring Data Model
One of the features which has made WebDAV a successful protocol is
its firm data model. This makes it a useful framework for other
applications such as calendaring. This specification follows the
same pattern by developing all features based on a well-described
data model.
As a brief overview, a CalDAV calendar is modeled as a WebDAV
collection with a defined structure; each calendar collection
contains a number of resources representing calendar objects as its
direct child resource. Each resource representing a calendar object
(event or to-do, or journal entry, or other calendar components) is
called a "calendar object resource". Each calendar object resource
and each calendar collection can be individually locked and have
individual WebDAV properties. Requirements derived from this model
are provided in Section 4.1 and Section 4.2.
3.1. Calendar Server
A CalDAV server is a calendaring-aware engine combined with a WebDAV
repository. A WebDAV repository is a set of WebDAV collections,
containing other WebDAV resources, within a unified URL namespace.
For example, the repository "http://www.example.com/webdav/" may
contain WebDAV collections and resources, all of which have URLs
beginning with "http://www.example.com/webdav/". Note that the root
URL "http://www.example.com/" may not itself be a WebDAV repository
(for example, if the WebDAV support is implemented through a servlet
or other Web server extension).
A WebDAV repository MAY include calendar data in some parts of its
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URL namespace, and non-calendaring data in other parts.
A WebDAV repository can advertise itself as a CalDAV server if it
supports the functionality defined in this specification at any point
within the root of the repository. That might mean that calendaring
data is spread throughout the repository and mixed with non-calendar
data in nearby collections (e.g., calendar data may be found in
/home/lisa/calendars/ as well as in /home/bernard/calendars/, and
non-calendar data in /home/lisa/contacts/). Or, it might mean that
calendar data can be found only in certain sections of the repository
(e.g., /calendar/). Calendaring features are only required in the
repository sections that are or contain calendar object resources.
So a repository confining calendar data to the /calendar/ collection
would only need to support the CalDAV required features within that
collection.
The CalDAV server or repository is the canonical location for
calendar data and state information. Clients may submit requests to
change data or download data. Clients may store calendar objects
offline and attempt to synchronize at a later time. However, clients
MUST be prepared for calendar data on the server to change between
the time of last synchronization and when attempting an update, as
calendar collections may be shared and accessible via multiple
clients. Entity tags and other features make this possible.
3.2. Recurrence and the Data Model
Recurrence is an important part of the data model because it governs
how many resources are expected to exist. This specification models
a recurring calendar component and its recurrence exceptions as a
single resource. In this model, recurrence rules, recurrence dates,
exception rules, and exception dates are all part of the data in a
single calendar object resource. This model avoids problems of
limiting how many recurrence instances to store in the repository,
how to keep recurrence instances in sync with the recurring calendar
component, and how to link recurrence exceptions with the recurring
calendar component. It also results in less data to synchronize
between client and server, and makes it easier to make changes to all
recurrence instances or to a recurrence rule. It makes it easier to
create a recurring calendar component, and easier to delete all
recurrence instances.
Clients are not forced to retrieve information about all recurrence
instances of a recurring component. The CALDAV:calendar-query and
CALDAV:calendar-multiget REPORTs defined in this document allow
clients to retrieve only recurrence instances that overlap a given
time range.
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4. Calendar Resources
4.1. Calendar Object Resources
Calendar object resources contained in calendar collections MUST NOT
contain more than one type of calendar component (e.g., VEVENT,
VTODO, VJOURNAL, VFREEBUSY, etc.) with the exception of VTIMEZONE
components which MUST be specified for each unique TZID parameter
value specified in the iCalendar object. For instance, a calendar
object resource can contain two VEVENT components and one VTIMEZONE
component, but it cannot contain one VEVENT component and one VTODO
component. Instead the VEVENT and VTODO components would have to be
stored in separate calendar object resources in the same collection.
Calendar object resources contained in calendar collections MUST NOT
specify the iCalendar METHOD property.
The UID property value of the calendar components contained in a
calendar object resource MUST be unique in the scope of the calendar
collection in which they are stored.
Calendar components in a calendar collection that have different UID
property values MUST be stored in separate calendar object resources.
Calendar components with the same UID property value, in a given
calendar collection, MUST be contained in the same calendar object
resource. This ensures that all components in a recurrence "set" are
contained in the same calendar object resource. It is possible for a
calendar object resource to just contain components that represent
"overridden" instances (ones which modify the behavior of a regular
instance, and thus include a RECURRENCE-ID property), without also
including the "master" recurring component (the one that defines the
recurrence "set" and does not contain any "RECURRENCE-ID" property).
For example, given the following iCalendar object:
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BEGIN:VCALENDAR
PRODID:-//Example Corp.//CalDAV Client//EN
VERSION:2.0
BEGIN:VEVENT
UID:1@example.com
SUMMARY:One-off Meeting
DTSTAMP:20041210T183904Z
DTSTART:20041207T120000Z
DTEND:20041207T130000Z
END:VEVENT
BEGIN:VEVENT
UID:2@example.com
SUMMARY:Weekly Meeting
DTSTAMP:20041210T183838Z
DTSTART:20041206T120000Z
DTEND:20041206T130000Z
RRULE:FREQ=WEEKLY
END:VEVENT
BEGIN:VEVENT
UID:2@example.com
SUMMARY:Weekly Meeting
RECURRENCE-ID:20041213T120000Z
DTSTAMP:20041210T183838Z
DTSTART:20041213T130000Z
DTEND:20041213T140000Z
END:VEVENT
END:VCALENDAR
The VEVENT component with the UID value "1@example.com", would be
stored in its own calendar object resource. The two VEVENT
components with the UID value "2@example.com", which represent a
recurring event where one recurrence instance has been overridden,
would be stored in the same calendar object resource.
4.2. Calendar Collection
A calendar collection contains calendar object resources that
represent calendar components within a calendar. A calendar
collection is manifested to clients as a WebDAV resource collection
identified by a URL. A calendar collection MUST report the DAV:
collection and CALDAV:calendar XML elements in the value of the DAV:
resourcetype property. The element type declaration for CALDAV:
calendar is:
A calendar collection can be created through provisioning (e.g.,
automatically created when a user's account is provisioned), or it
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can be created with the MKCALENDAR method (see Section 5.3.1). This
method can be useful for a user to create additional calendars (e.g.,
soccer schedule) or for users to share a calendar (e.g., team events
or conference room). Note however that this document doesn't define
what extra calendar collections are for. Users must rely on non-
standard cues to find out what a calendar collection is for, or use
the CALDAV:calendar-description property defined in Section 5.2.1 to
provide such a cue.
The following restrictions are applied to the resources within a
calendar collection:
a. Calendar collections MUST only contain calendar object resources
and collections that are not calendar collections. i.e., the only
"top-level" non-collection resources allowed in a calendar
collection are calendar object resources. This ensures that
calendar clients do not have to deal with non-calendar data in a
calendar collection, though they do have to distinguish between
calendar object resources and collections when using standard
WebDAV techniques to examine the contents of a collection.
b. Collections contained in calendar collections MUST NOT contain
calendar collections at any depth. i.e., "nesting" of calendar
collections within other calendar collections at any depth is not
allowed. This specification does not define how collections
contained in a calendar collection are used or how they relate to
any calendar object resources contained in the calendar
collection.
Multiple calendar collections MAY be children of the same collection.
5. Calendar Access Feature
5.1. Calendar Access Support
A server supporting the features described in this document MUST
include "calendar-access" as a field in the DAV response header from
an OPTIONS request on any resource that supports any calendar
properties, reports, method, or privilege. A value of "calendar-
access" in the DAV response header MUST indicate that the server
supports all MUST level requirements specified in this document.
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5.1.1. Example: Using OPTIONS for the Discovery of Calendar Access
Support
>> Request <<
OPTIONS /home/bernard/calendars/ HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 200 OK
Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
Allow: PROPFIND, PROPPATCH, LOCK, UNLOCK, REPORT, ACL
DAV: 1, 2, 3, access-control, calendar-access
Date: Fri, 11 Nov 2005 09:32:12 GMT
Content-Length: 0
In this example, the OPTIONS method returns the value "calendar-
access" in the DAV response header to indicate that the collection
"/home/bernard/calendars/" supports the properties, reports, methods,
or privileges defined in this specification.
5.2. Calendar Collection Properties
This section defines properties that MAY be defined on calendar
collections.
5.2.1. CALDAV:calendar-description Property
Name: calendar-description
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Provides a human-readable description of the calendar
collection.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MAY be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]). An xml:lang attribute indicating the human language
of the description SHOULD be set for this property by clients or
through server provisioning. Servers MUST return any xml:lang
attribute if set for the property.
Description: If present, the property contains a description of the
calendar collection that is suitable for presentation to a user.
If not present, the client should assume no description for the
calendar collection.
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Definition:
PCDATA value: string
Example:
Calendrier de Mathilde Desruisseaux
5.2.2. CALDAV:calendar-timezone Property
Name: calendar-timezone
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a time zone on a calendar collection.
Conformance: This property SHOULD be defined on all calendar
collections. If defined, it SHOULD NOT be returned by a PROPFIND
DAV:allprop request (as defined in Section 12.14.1 of [RFC2518]).
Description: The CALDAV:calendar-timezone property is used to specify
the time zone the server should rely on to resolve "date" values
and "date with local time" values (i.e., floating time) to "date
with UTC time" values. The server will require this information
to determine if a calendar component scheduled with "date" values
or "date with local time" values overlaps a CALDAV:time-range
specified in a CALDAV:calendar-query REPORT. The server will also
require this information to compute the proper FREEBUSY time
period as "date with UTC time" in the VFREEBUSY component returned
in a response to a CALDAV:free-busy-query REPORT request that
takes into account calendar components scheduled with "date"
values or "date with local time" values. In the absence of this
property the server MAY rely on the time zone of their choice.
Note: The iCalendar data embedded within the CALDAV:calendar-timezone
XML element MUST follow the standard XML character data encoding
rules, including use of <, >, & etc entity encoding or
the use of a construct. In the later case the
iCalendar data cannot contain the character sequence "]]>" which
is the end delimiter for the CDATA section.
Definition:
PCDATA value: an iCalendar object with exactly one VTIMEZONE
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component.
Example:
BEGIN:VCALENDAR
PRODID:-//Example Corp.//CalDAV Client//EN
VERSION:2.0
BEGIN:VTIMEZONE
TZID:US-Eastern
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:Eastern Standard Time (US & Canada)
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:Eastern Daylight Time (US & Canada)
END:DAYLIGHT
END:VTIMEZONE
END:VCALENDAR
5.2.3. CALDAV:supported-calendar-component-set Property
Name: supported-calendar-component-set
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies the calendar component types (e.g., VEVENT, VTODO,
etc.) that calendar object resources can contain in the calendar
collection.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MUST be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
Description: The CALDAV:supported-calendar-component-set property is
used to specify restrictions on the calendar component types that
calendar object resources may contain in a calendar collection.
Any attempt by the client to store calendar object resources with
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component types not listed in this property, if it exists, MUST
result in an error, with the CALDAV:supported-calendar-component
precondition (Section 5.3.2.1) being violated. Since this
property is protected it cannot be changed by clients using a
PROPPATCH request. However, clients can initialize the value of
this property when creating a new calendar collection with
MKCALENDAR. The empty-element tag MUST
only be specified if support for calendar object resources that
only contain VTIMEZONE components is provided or desired. Support
for VTIMEZONE components in calendar object resources that contain
VEVENT or VTODO components is always assumed. In the absence of
this property the server MUST accept all component types, and the
client can assume that.
Definition:
Example:
5.2.4. CALDAV:supported-calendar-data Property
Name: supported-calendar-data
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies what media types are allowed for calendar object
resources in a calendar collection.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MUST be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
Description: The CALDAV:supported-calendar-data property is used to
specify the media type supported for the calendar object resources
contained in a given calendar collection (e.g., iCalendar version
2.0). Any attempt by the client to store calendar object
resources with a media type not listed in this property MUST
result in an error, with the CALDAV:supported-calendar-data
precondition (Section 5.3.2.1) being violated. In the absence of
this property the server MUST only accept data with the media type
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"text/calendar" and iCalendar version 2.0, and clients can assume
that.
Definition:
Example:
5.2.5. CALDAV:max-resource-size Property
Name: max-resource-size
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Provides a numeric value indicating the maximum size of
resource in octets that the server is willing to accept when a
calendar object resource is stored in a calendar collection.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MUST be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
Description: The CALDAV:max-resource-size is used to specify a
numeric value that represents the maximum size in octets that the
server is willing to accept when a calendar object resource is
stored in a calendar collection. Any attempt to store a calendar
object resource exceeding this size MUST result in an error, with
the CALDAV:max-resource-size precondition (Section 5.3.2.1) being
violated. In the absence of this property the client can assume
that the server will allow storing a resource of any reasonable
size.
Definition:
PCDATA value: a numeric value (positive integer)
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Example:
102400
5.2.6. CALDAV:min-date-time Property
Name: min-date-time
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Provides a date-time value indicating the earliest date and
time (in UTC) that the server is willing to accept for any date or
time value in a calendar object resource stored in a calendar
collection.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MUST be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
Description: The CALDAV:min-date-time is used to specify an iCalendar
DATE-TIME value in UTC that indicates the earliest inclusive date
that the server is willing to accept for any explicit date or time
value in a calendar object resource stored in a calendar
collection. Any attempt to store a calendar object resource using
a date or time value earlier than this value MUST result in an
error, with the CALDAV:min-date-time precondition
(Section 5.3.2.1) being violated. Note that servers MUST accept
recurring components that specify instances beyond this limit,
provided none of those instances have been overridden. In that
case the server MAY simply ignore those instances outside of the
acceptable range when processing reports on the calendar object
resource. In the absence of this property the client can assume
any valid iCalendar date may be used at least up to the CALDAV:
max-date-time value if that is defined.
Definition:
PCDATA value: an iCalendar format DATE-TIME value in UTC
Example:
19000101T000000Z
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5.2.7. CALDAV:max-date-time Property
Name: max-date-time
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Provides a date-time value indicating the latest date and
time (in UTC) that the server is willing to accept for any date or
time value in a calendar object resource stored in a calendar
collection.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MUST be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
Description: The CALDAV:max-date-time is used to specify an iCalendar
DATE-TIME value in UTC that indicates the inclusive latest date
that the server is willing to accept for any date or time value in
a calendar object resource stored in a calendar collection. Any
attempt to store a calendar object resource using a date or time
value later than this value MUST result in an error, with the
CALDAV:max-date-time precondition (Section 5.3.2.1) being
violated. Note that servers MUST accept recurring components that
specify instances beyond this limit, provided none of those
instances have been overridden. In that case the server MAY
simply ignore those instances outside of the acceptable range when
processing reports on the calendar object resource. In the
absence of this property the client can assume any valid iCalendar
date may be used at least down to the CALDAV:min-date-time value
if that is defined.
Definition:
PCDATA value: an iCalendar format DATE-TIME value in UTC
Example:
20491231T235959Z
5.2.8. CALDAV:max-instances Property
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Name: max-instances
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Provides a numeric value indicating the maximum number of
recurrence instances that a calendar object resource stored in a
calendar collection can generate.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MUST be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
Description: The CALDAV:max-instances is used to specify a numeric
value that indicates the maximum number of recurrence instances
that a calendar object resource stored in a calendar collection
can generate. Any attempt to store a calendar object resource
with a recurrence pattern that generates more instances than this
value MUST result in an error, with the CALDAV:max-instances
precondition (Section 5.3.2.1) being violated. In the absence of
this property the client can assume that the server has no limits
on the number of recurrence instances it can handle or expand.
Definition:
PCDATA value: a numeric value (integer greater than zero)
Example:
100
5.2.9. CALDAV:max-attendees-per-instance Property
Name: max-attendees-per-instance
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Provides a numeric value indicating the maximum number of
ATTENDEE properties in any instance of a calendar object resource
stored in a calendar collection.
Conformance: This property MAY be defined on any calendar collection.
If defined, it MUST be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
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Description: The CALDAV:max-attendees-per-instance is used to specify
a numeric value that indicates the maximum number of iCalendar
ATTENDEE properties on any one instance of a calendar object
resource stored in a calendar collection. Any attempt to store a
calendar object resource with more ATTENDEE properties per
instance than this value MUST result in an error, with the CALDAV:
max-attendees-per-instance precondition (Section 5.3.2.1) being
violated. In the absence of this property the client can assume
that the server can handle any number of ATTENDEE properties in a
calendar component.
Definition:
PCDATA value: a numeric value (integer greater than zero)
Example:
25
5.2.10. Additional Precondition for PROPPATCH
This specification requires an additional Precondition for the
PROPPATCH method. The precondition is:
(CALDAV:valid-calendar-data): The time zone specified in CALDAV:
calendar-timezone property MUST be a valid iCalendar object
containing a single valid VTIMEZONE component.
5.3. Creating Resources
The creation of calendar collections and calendar object resources
may be initiated by either a CalDAV client or by the CalDAV server.
For example, a server might come pre-configured with a user's
calendar collection, or the CalDAV client might request the server to
create a new calendar collection for a given user. Servers might
populate events as calendar objects inside a calendar collection, or
clients might request the server to create events. Either way, both
client and server MUST comply with the requirements in this document,
and MUST understand objects appearing in calendar collections or
according to the data model defined here.
5.3.1. MKCALENDAR Method
An HTTP request using the MKCALENDAR method creates a new calendar
collection resource. A server MAY restrict calendar collection
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creation to particular collections.
Support for MKCALENDAR on the server is only RECOMMENDED and not
REQUIRED because some calendar stores only support one calendar per
user (or principal) and those are typically pre-created for each
account. However, servers and clients are strongly encouraged to
support MKCALENDAR whenever possible to allow users to create
multiple calendar collections to better help organize their data.
Clients SHOULD use the DAV:displayname property for a human-readable
name of the calendar. Clients can either specify the value of the
DAV:displayname property in the request body of the MKCALENDAR
request, or alternatively issue a PROPPATCH request to change the
DAV:displayname property to the appropriate value immediately after
issuing the MKCALENDAR request. Clients SHOULD NOT set the DAV:
displayname property to be the same as any other calendar collection
at the same URI "level". When displaying calendar collections to
users, clients SHOULD check the DAV:displayname property and use that
value as the name of the calendar. In the event that the DAV:
displayname property is empty, the client MAY use the last part of
the calendar collection URI as the name, however that path segment
may be "opaque" and not represent any meaningful human-readable text.
If a MKCALENDAR request fails, the server state preceding the request
MUST be restored.
Marshalling:
If a request body is included, it MUST be a CALDAV:mkcalendar XML
element. Instruction processing MUST occur in the order
instructions are received (i.e., from top to bottom).
Instructions MUST either all be executed or none executed. Thus
if any error occurs during processing, all executed instructions
MUST be undone and a proper error result returned. Instruction
processing details can be found in the definition of the DAV:set
instruction in Section 12.13.2 of [RFC2518].
If a response body for a successful request is included, it MUST
be a CALDAV:mkcalendar-response XML element.
The response MUST include a Cache-Control:no-cache header.
Preconditions:
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(DAV:resource-must-be-null): A resource MUST NOT exist at the
Request-URI;
(CALDAV:calendar-collection-location-ok): The Request-URI MUST
identify a location where a calendar collection can be created;
(CALDAV:valid-calendar-data): The time zone specified in the
CALDAV:calendar-timezone property MUST be a valid iCalendar object
containing a single valid VTIMEZONE component;
(DAV:needs-privilege): The DAV:bind privilege MUST be granted to
the current user on the parent collection of the Request-URI.
Postconditions:
(CALDAV:initialize-calendar-collection): A new calendar collection
exists at the Request-URI. The DAV:resourcetype of the calendar
collection MUST contain both DAV:collection and CALDAV:calendar
XML elements.
5.3.1.1. Status Codes
The following are examples of response codes one would expect to get
in a response to a MKCALENDAR request. Note that this list is by no
means exhaustive.
201 (Created) - The calendar collection resource was created in
its entirety;
207 (Multi-Status) - The calendar collection resource was not
created since one or more DAV:set instructions specified in the
request body could not be processed successfully. The following
are examples of response codes one would expect to be used in a
207 (Multi-Status) response in this situation:
403 (Forbidden) - The client, for reasons the server chooses
not to specify, cannot alter one of the properties;
409 (Conflict) - The client has provided a value whose
semantics are not appropriate for the property. This includes
trying to set read-only properties;
424 (Failed Dependency) - The DAV:set instruction on the
specified resource would have succeeded if it were not for the
failure of another DAV:set instruction specified in the request
body;
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423 (Locked) - The specified resource is locked and the client
either is not a lock owner or the lock type requires a lock
token to be submitted and the client did not submit it; and
507 (Insufficient Storage) - The server did not have sufficient
space to record the property;
403 (Forbidden) - This indicates at least one of two conditions:
1) the server does not allow the creation of calendar collections
at the given location in its namespace, or 2) the parent
collection of the Request-URI exists but cannot accept members;
409 (Conflict) - A collection cannot be made at the Request-URI
until one or more intermediate collections have been created;
415 (Unsupported Media Type) - The server does not support the
request type of the body; and
507 (Insufficient Storage) - The resource does not have sufficient
space to record the state of the resource after the execution of
this method.
5.3.1.2. Example: Successful MKCALENDAR request
This example creates a calendar collection called /home/lisa/
calendars/events/ on the server cal.example.com with specific values
for the properties DAV:displayname, CALDAV:calendar-description,
CALDAV:supported-calendar-component-set, and CALDAV:calendar-
timezone.
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>> Request <<
MKCALENDAR /home/lisa/calendars/events/ HTTP/1.1
Host: cal.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Lisa's Events
Calendar restricted to events.
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>> Response <<
HTTP/1.1 201 Created
Cache-Control: no-cache
Date: Fri, 11 Nov 2005 09:32:12 GMT
Content-Length: 0
5.3.2. Creating Calendar Object Resources
Clients populate calendar collections with calendar object resources.
The URL for each calendar object resource is entirely arbitrary, and
does not need to bear a specific relationship to the calendar object
resource's iCalendar properties or other metadata. New calendar
object resources MUST be created with a PUT request targeted at an
unmapped URI. A PUT request targeted at a mapped URI updates an
existing calendar object resource.
When servers create new resources, it's not hard for the server to
choose an unmapped URI. It's slightly tougher for clients, because a
client might not want to examine all resources in the collection, and
might not want to lock the entire collection to ensure that a new
resource isn't created with a name collision. However, there is an
HTTP feature to mitigate this. If the client intends to create a new
non-collection resource, such as a new VEVENT, the client SHOULD use
the HTTP request header "If-None-Match: *" on the PUT request. The
Request-URI on the PUT request MUST include the target collection,
where the resource is to be created, plus the name of the resource in
the last path segment. The "If-None-Match: *" request header ensures
that the client will not inadvertently overwrite an existing
resource, if the last path segment turned out to already be used.
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>> Request <<
PUT /home/lisa/calendars/events/qwue23489.ics HTTP/1.1
If-None-Match: *
Host: cal.example.com
Content-Type: text/calendar
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:20010712T182145Z-123401@example.com
DTSTAMP:20060712T182145Z
DTSTART:20060714T170000Z
DTEND:20060715T040000Z
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR
>> Response <<
HTTP/1.1 201 Created
Content-Length: 0
Date: Fri, 11 Nov 2005 09:32:12 GMT
ETag: "123456789-000-111"
The request to change an existing event is the same, but with a
specific ETag in the "If-Match" header, rather than the "If-None-
Match" header.
As indicated in Section 3.10 of [RFC2445], the URL of calendar object
resources containing (an arbitrary set of) calendaring and scheduling
information may be suffixed by ".ics", and the URL of calendar object
resources containing free or busy time information may be suffixed by
".ifb".
5.3.2.1. Additional Preconditions for PUT, COPY and MOVE
This specification creates additional Preconditions for PUT, COPY and
MOVE methods. These preconditions apply:
When a PUT operation of a calendar object resource into a calendar
collection occurs.
When a COPY or MOVE operation of a calendar object resource into a
calendar collection occurs.
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The new preconditions are:
(CALDAV:supported-calendar-data): The resource submitted in the
PUT request, or targeted by a COPY or MOVE request MUST be a
supported media type (i.e., iCalendar) for calendar object
resources;
(CALDAV:valid-calendar-data): The resource submitted in the PUT
request, or targeted by a COPY or MOVE request MUST be valid data
for the media type being specified (i.e., MUST contain valid
iCalendar data);
(CALDAV:valid-calendar-object-resource): The resource submitted in
the PUT request, or targeted by a COPY or MOVE request MUST obey
all restrictions specified in Section 4.1 (e.g., calendar object
resources MUST NOT contain more than one type of calendar
component, calendar object resources MUST NOT specify the
iCalendar METHOD property, etc.);
(CALDAV:supported-calendar-component): The resource submitted in
the PUT request, or targeted by a COPY or MOVE request MUST
contain a type of calendar component that is supported in the
targeted calendar collection;
(CALDAV:no-uid-conflict): The resource submitted in the PUT
request, or targeted by a COPY or MOVE request MUST NOT specify an
iCalendar UID property value already in use in the targeted
calendar collection or overwrite an existing calendar object
resource with one that has a different UID property value.
Servers SHOULD report the URL of the resource that is already
making use of the same UID property value in the DAV:href element;
(CALDAV:calendar-collection-location-ok): In a COPY or MOVE
request, when the Request-URI is a calendar collection, the
Destination-URI MUST identify a location where a calendar
collection can be created;
(CALDAV:max-resource-size): The resource submitted in the PUT
request, or targeted by a COPY or MOVE request MUST have an octet
size less than or equal to the value of the CALDAV:max-resource-
size property value (Section 5.2.5) on the calendar collection
where the resource will be stored;
(CALDAV:min-date-time): The resource submitted in the PUT request,
or targeted by a COPY or MOVE request MUST have all of its
iCalendar date or time property values (for each recurring
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instance) greater than or equal to the value of the CALDAV:min-
date-time property value (Section 5.2.6) on the calendar
collection where the resource will be stored;
(CALDAV:max-date-time): The resource submitted in the PUT request,
or targeted by a COPY or MOVE request MUST have all of its
iCalendar date or time property values (for each recurring
instance) less than the value of the CALDAV:max-date-time property
value (Section 5.2.7) on the calendar collection where the
resource will be stored;
(CALDAV:max-instances): The resource submitted in the PUT request,
or targeted by a COPY or MOVE request MUST generate a number of
recurring instances less than or equal to the value of the CALDAV:
max-instances property value (Section 5.2.8) on the calendar
collection where the resource will be stored;
(CALDAV:max-attendees-per-instance): The resource submitted in the
PUT request, or targeted by a COPY or MOVE request MUST have a
number of ATTENDEE properties on any one instance less than or
equal to the value of the CALDAV:max-attendees-per-instance
property value (Section 5.2.9) on the calendar collection where
the resource will be stored;
5.3.3. Non-standard components, properties and parameters
iCalendar provides a "standard mechanism for doing non-standard
things". This extension support allows implementers to make use of
non-standard components, properties and parameters whose names are
prefixed with the text "X-".
Servers MUST support the use of non-standard components, properties
and parameters in calendar object resources stored via the PUT
method.
Servers may need to enforce rules for their own "private" components,
properties or parameters, so servers MAY reject any attempt by the
client to change those or use values for those outside of any
restrictions the server may have. Servers SHOULD ensure that any
"private" components, properties or parameters it uses follow the
convention of including a vendor id in the "X-" name as described in
Section 4.2 of [RFC2445], e.g., "X-ABC-Private".
5.3.4. Calendar Object Resource Entity Tag
The DAV:getetag property MUST be defined and set to a strong entity
tag on all calendar object resources.
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A response to a GET request targeted at a calendar object resource
MUST contain an ETag response header field indicating the current
value of the strong entity tag of the calendar object resource.
Servers SHOULD return a strong entity tag (ETag header) in a PUT
response when the stored calendar object resource is equivalent by
octet equality to the calendar object resource submitted in the body
of the PUT request. This allows clients to reliably use the returned
strong entity tag for data synchronization purposes. For instance,
the client can do a PROPFIND request on the stored calendar object
resource and have the DAV:getetag property returned, and compare that
value with the strong entity tag it received on the PUT response, and
know that if they are equal, then the calendar object resource on the
server has not been changed.
In the case where the data stored by a server as a result of a PUT
request is not equivalent by octet equality to the submitted calendar
object resource, the behavior of the ETag response header is not
specified here, with the exception that a strong entity tag MUST NOT
be returned in the response. As a result, clients may need to
retrieve the modified calendar object resource (and ETag) as a basis
for further changes, rather than use the calendar object resource it
had sent with the PUT request.
6. Calendaring Access Control
6.1. Calendaring Privilege
CalDAV servers MUST support and adhere to the requirements of WebDAV
ACL [RFC3744]. WebDAV ACL provides a framework for an extensible set
of privileges that can be applied to WebDAV collections and ordinary
resources. CalDAV servers MUST also support the calendaring
privilege defined in this section.
6.1.1. CALDAV:read-free-busy Privilege
Calendar users often wish to allow other users to see their busy time
information, without viewing the other details of the calendar
components (e.g., location, summary, attendees). This allows a
significant amount of privacy while still allowing other users to
schedule meetings at times when the user is likely to be free.
The CALDAV:read-free-busy privilege controls which calendar
collections, regular collections and calendar object resources are
examined when a CALDAV:free-busy-query REPORT request is processed
(see Section 7.10). This privilege can be granted on calendar
collections, regular collections or calendar object resources.
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Servers MUST support this privilege on all calendar collections,
regular collections and calendar object resources.
The CALDAV:read-free-busy privilege MUST be aggregated in the DAV:
read privilege. Servers MUST allow the CALDAV:read-free-busy to be
granted without the DAV:read privilege being granted.
Clients should note that when only the CALDAV:read-free-busy
privilege has been granted on a resource, this does not imply access
to GET, HEAD, OPTIONS and PROPFIND on the resource -- those
operations are governed by the DAV:read privilege.
6.2. Additional Principal Property
This section defines an additional property for WebDAV principal
resources as defined in [RFC3744].
6.2.1. CALDAV:calendar-home-set Property
Name: calendar-home-set
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identifies the URL of any WebDAV collections that contain
calendar collections owned by the associated principal resource.
Conformance: This property SHOULD be defined on a principal resource.
If defined, it MAY be protected and SHOULD NOT be returned by a
PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
[RFC2518]).
Description: The CALDAV:calendar-home-set property is meant to allow
users to easily find the calendar collections owned by the
principal. Typically, users will group all the calendar
collections that they own under a common collection. This
property specifies the URL of collections that either are calendar
collections or ordinary collections that have child or descendant
calendar collections owned by the principal.
Definition:
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Example:
http://cal.example.com/home/bernard/calendars/
7. Calendaring Reports
This section defines the REPORTs that CalDAV servers MUST support on
calendar collections and calendar object resources.
CalDAV servers MUST advertise support for these REPORTs on all
calendar collections and calendar object resources with the DAV:
supported-report-set property defined in Section 3.1.5 of [RFC3253].
CalDAV servers MAY also advertise support for these REPORTs on
ordinary collections.
Some of these REPORTs allow calendar data (from possibly multiple
resources) to be returned.
7.1. REPORT Method
The REPORT method (defined in Section 3.6 of [RFC3253]) provides an
extensible mechanism for obtaining information about one or more
resources. Unlike the PROPFIND method, which returns the value of
one or more named properties, the REPORT method can involve more
complex processing. REPORT is valuable in cases where the server has
access to all of the information needed to perform the complex
request (such as a query), and where it would require multiple
requests for the client to retrieve the information needed to perform
the same request.
CalDAV servers MUST support the DAV:expand-property REPORT defined in
Section 3.8 of [RFC3253].
7.2. Ordinary collections
Servers MAY support the REPORTs defined in this document on ordinary
collections (collections that are not calendar collections) in
addition to calendar collections or calendar object resources. In
computing responses to the REPORTs on ordinary collections, servers
MUST only consider calendar object resources contained in calendar
collections that are targeted by the REPORT based on the value of the
Depth request header.
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7.3. Date and floating time
iCalendar provides a way to specify DATE and DATE-TIME values that
are not bound to any time zone in particular, hereafter called
"floating date" and "floating time" respectively. These values are
used to represent the same day, hour, minute and second value
regardless of which time zone is being observed. For instance, the
DATE value "20051111", represents November 11th, 2005 in no specific
time zone, while the DATE-TIME value "20051111T111100" represents
November 11th, 2005 at 11:11 AM in no specific time zone.
CalDAV servers may need to convert "floating date" and "floating
time" values in date with UTC time values in the processing of
calendaring REPORT requests.
For the CALDAV:calendar-query REPORT, CalDAV servers MUST rely on the
value of the CALDAV:timezone XML element, if specified as part of the
request body, to perform the proper conversion of "floating date" and
"floating time" values to date with UTC time values. If the CALDAV:
timezone XML element is not specified in the request body, CalDAV
servers MUST rely on the value of the CALDAV:calendar-timezone
property, if defined, else the CalDAV servers MAY rely on the time
zone of their choice.
For the CALDAV:free-busy-query REPORT, CalDAV servers MUST rely on
the value of the CALDAV:calendar-timezone property, if defined, to
compute the proper FREEBUSY time period value as date with UTC time,
for calendar components scheduled with "floating date" or "floating
time". If the CALDAV:calendar-timezone property is not defined,
CalDAV servers MAY rely on the time zone of their choice.
7.4. Time range filtering
Some of the reports defined in this section can include a time range
filter that is used to restrict the set of calendar object resources
returned to just those that overlap the specified time range. The
time range filter can be applied to a calendar component as a whole,
or to specific calendar component properties with date or date-time
value types.
To determine whether a calendar object resource matches the time
range filter element, the start and end times for the targeted
component or property are determined and then compared to the
requested time range. If there is an overlap with the requested time
range, then the calendar object resource matches the filter element.
The rules defined in [RFC2445] for determining the actual start and
end times of calendar components MUST be used, and these are fully
enumerated in Section 9.9 of this document.
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When such time range filtering is used, special consideration must be
given to recurring calendar components such as VEVENT and VTODO
components. The server MUST expand recurring components to determine
whether any recurrence instances overlap the specified time range.
If one or more recurrence instances overlap the time range, then the
calendar object resource matches the filter element.
7.5. Searching Text: Collations
Some of the reports defined in this section do text matches of
character strings provided by the client and compared to stored
calendar data. Since iCalendar data is by default encoded in the
UTF-8 charset and may include characters outside of the US-ASCII
charset range in some property and parameter values, there is a need
to ensure that text matching follows well-defined rules.
To deal with this, this specification makes use of the IANA Collation
Registry defined in [I-D.newman-i18n-comparator] to specify
collations that may be used to carry out the text comparison
operations with a well-defined rule.
The comparisons used in CalDAV are all "substring" matches as per
[I-D.newman-i18n-comparator] Section 4.2. Collations supported by
the server MUST support "substring" match operations.
CalDAV servers are REQUIRED to support the "i;ascii-casemap" and
"i;octet" collations as described in [I-D.newman-i18n-comparator],
and MAY support other collations.
Servers MUST advertise the set of collations that they support via
the CALDAV:supported-collation-set property defined on any resource
that supports reports that use collations.
Clients MUST only use collations from the list advertised by the
server.
In the absence of a collation explicitly specified by the client, or
if the client specifies the "default" collation identifier (as
defined in [I-D.newman-i18n-comparator] Section 3.1), the server MUST
default to using "i;ascii-casemap" as the collation.
Wildcards (as defined in [I-D.newman-i18n-comparator] Section 3.2)
MUST NOT be used in the collation identifier.
If the client chooses a collation not supported by the server, the
server MUST respond with a CALDAV:supported-collation precondition
error response.
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7.5.1. CALDAV:supported-collation-set Property
Name: supported-collation-set
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identifies the set of collations supported by the server for
text matching operations.
Conformance: This property MUST be defined on any resource that
supports a REPORT that does text matching. If defined, it MUST be
protected and SHOULD NOT be returned by a PROPFIND DAV:allprop
request (as defined in Section 12.14.1 of [RFC2518]).
Description: The CALDAV:supported-collation-set property contains
zero or more CALDAV:supported-collation elements which specify the
collection identifiers of the collations supported by the server.
Definition:
Example:
i;ascii-casemap
i;octet
7.6. Partial Retrieval
Some calendaring REPORTs defined in this document allow partial
retrieval of calendar object resources. A CalDAV client can specify
what information to return in the body of a calendaring REPORT
request.
A CalDAV client can request particular WebDAV property values, all
WebDAV property values, or a list of the names of the resource's
WebDAV properties. A CalDAV client can also request calendar data to
be returned and whether all calendar components and properties should
be returned or only particular ones. See CALDAV:calendar-data in
Section 9.6.
By default, the returned calendar data will include the component
that defines the recurrence set, referred to as the "master
component", as well as the components that define exceptions to the
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recurrence set, referred to as the "overridden components".
A CalDAV client only interested in the recurrence instances that
overlap a specified time range can request to receive only the
"master component" along with the "overridden components" that impact
the specified time range and thus limit the data returned by the
server. See CALDAV:limit-recurrence-set in Section 9.6.6. An
overridden component impacts a time range if its current start and
end times overlap the time range, or if the original start and end
times - the ones that would have been used if the instance were not
overridden - overlap the time range.
A CalDAV client with no support for recurrence properties (i.e.,
EXDATE, EXRULE, RDATE and RRULE) and possibly VTIMEZONE components,
or a client not willing to perform recurrence expansion because of
limited processing capability can request to receive only the
recurrence instances that overlap a specified time range as separate
calendar components that each define exactly one recurrence instance.
See CALDAV:expand in Section 9.6.5.
Finally, in the case of VFREEBUSY components, a CalDAV client can
request to receive only the FREEBUSY property values that overlap a
specified time range. See CALDAV:limit-freebusy-set in
Section 9.6.7.
7.7. Non-standard components, properties and parameters
Servers MUST support the use of non-standard component, property or
parameter names in the CALDAV:calendar-data XML element in
calendaring REPORT requests to allow clients to request that non-
standard components, properties and parameters be returned in the
calendar data provided in the response.
Servers MAY support the use of non-standard component, property or
parameter names in the CALDAV:comp-filter, CALDAV:prop-filter and
CALDAV:param-filter XML elements specified in the CALDAV:filter XML
element of calendaring REPORT requests.
Servers MUST fail with the CALDAV:supported-filter precondition if a
calendaring REPORT request uses a CALDAV:comp-filter, CALDAV:prop-
filter or CALDAV:param-filter XML element that makes reference to a
non-standard component, property or parameter name which the server
does not support queries on.
7.8. CALDAV:calendar-query Report
The CALDAV:calendar-query REPORT performs a search for all calendar
object resources that match a specified filter. The response of this
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REPORT will contain all the WebDAV properties and calendar object
resource data specified in the request. In the case of the CALDAV:
calendar-data XML element, one can explicitly specify the calendar
components and properties that should be returned in the calendar
object resource data that matches the filter.
The format of this REPORT is modeled on the PROPFIND method. The
request and response bodies of the CALDAV:calendar-query REPORT use
XML elements that are also used by PROPFIND. In particular the
request can include XML elements to request WebDAV properties to be
returned. When that occurs the response should follow the same
behavior as PROPFIND with respect to the DAV:multistatus response
elements used to return specific property results. For instance, a
request to retrieve the value of a property which does not exist is
an error and MUST be noted with a response XML element which contains
a 404 (Not Found) status value.
Support for the CALDAV:calendar-query REPORT is REQUIRED.
Marshalling:
The request body MUST be a CALDAV:calendar-query XML element as
defined in Section 9.5.
The request MAY include a Depth header. If no Depth header is
included, Depth:0 is assumed.
The response body for a successful request MUST be a DAV:
multistatus XML element (i.e., the response uses the same format
as the response for PROPFIND). In the case where there are no
response elements, the returned DAV:multistatus XML element is
empty.
The response body for a successful CALDAV:calendar-query REPORT
request MUST contain a DAV:response element for each iCalendar
object that matched the search filter. Calendar data is being
returned in the CALDAV:calendar-data XML element inside the DAV:
propstat XML element.
Preconditions:
(CALDAV:supported-calendar-data): The attributes "content-type"
and "version" of the CALDAV:calendar-data XML element (see
Section 9.6) specify a media type supported by the server for
calendar object resources.
(CALDAV:valid-filter): The CALDAV:filter XML element (see
Section 9.7) specified in the REPORT request MUST be valid. For
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instance, a CALDAV:filter cannot nest a
element in a element, or a CALDAV:filter
cannot nest a element in a
element.
(CALDAV:supported-filter): The CALDAV:comp-filter (see
Section 9.7.1), CALDAV:prop-filter (see Section 9.7.2) and CALDAV:
param-filter (see Section 9.7.3) XML elements used in the CALDAV:
filter XML element (see Section 9.7) in the REPORT request only
make reference to components, properties and parameters for which
queries are supported by the server. i.e., if the CALDAV:filter
element attempts to reference an unsupported component, property
or parameter, this precondition is violated. Servers SHOULD
report the CALDAV:comp-filter, CALDAV:prop-filter or CALDAV:param-
filter for which it does not provide support.
(CALDAV:valid-calendar-data): The time zone specified in the
REPORT request MUST be a valid iCalendar object containing a
single valid VTIMEZONE component.
(CALDAV:min-date-time): Any XML element specifying a range of time
MUST have its start or end date or time values greater than or
equal to the value of the CALDAV:min-date-time property value
(Section 5.2.6) on the calendar collections being targeted by the
REPORT;
(CALDAV:max-date-time): Any XML element specifying a range of time
MUST have its start or end date or time values less than or equal
to the value of the CALDAV:max-date-time property value
(Section 5.2.7) on the calendar collections being targeted by the
REPORT;
(CALDAV:supported-collation): Any XML attribute specifying a
collation MUST specify a collation supported by the server as
described in Section 7.5.
Postconditions:
(DAV:number-of-matches-within-limits): The number of matching
calendar object resources must fall within server-specific,
predefined limits. For example, this condition might be triggered
if a search specification would cause the return of an extremely
large number of responses.
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7.8.1. Example: Partial retrieval of events by time range
In this example, the client requests the server to return specific
components and properties of the VEVENT components that overlap the
time range from January 4th, 2006 at 00:00:00 AM UTC to January 5th,
2006 at 00:00:00 AM UTC. In addition the DAV:getetag property is
also requested and returned as part of the response. Note that the
first calendar object returned is a recurring event whose first
instance lies outside of the requested time range, but whose third
instance does overlap the time range. Note that due to the CALDAV:
calendar-data element restrictions, the DTSTAMP property in VEVENT
components has not been returned, and the only property returned in
the VCALENDAR object is VERSION.
See Appendix B for the calendar data being targeted by this example.
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>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2005 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
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http://cal.example.com/bernard/work/abcd2.ics
"fffff-abcd2"
BEGIN:VCALENDAR
VERSION:2.0
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
DTSTART;TZID=US/Eastern:20060102T120000
DURATION:PT1H
RRULE:FREQ=DAILY;COUNT=5
SUMMARY:Event #2
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=US/Eastern:20060104T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060104T120000
SUMMARY:Event #2 bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=US/Eastern:20060106T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060106T120000
SUMMARY:Event #2 bis bis
UID:00959BC664CA650E933C892C@example.com
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END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd3.ics
"fffff-abcd3"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
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7.8.2. Example: Partial retrieval of recurring events
In this example, the client requests the server to return VEVENT
components that overlap the time range from January 3rd, 2006 at 00:
00:00 AM UTC to January 5th, 2006 at 00:00:00 AM UTC. Use of the
CALDAV:limit-recurrence-set element causes the server to only return
overridden recurrence components that overlap the time range
specified in that element, or that affect other instances that
overlap the time range (e.g., in the case of a "THISANDFUTURE"
behavior). In this example the first overridden component in the
matching resource is returned but the second one is not.
See Appendix B for the calendar data being targeted by this example.
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
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http://cal.example.com/bernard/work/abcd2.ics
"fffff-abcd2"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060102T120000
DURATION:PT1H
RRULE:FREQ=DAILY;COUNT=5
SUMMARY:Event #2
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060104T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060104T120000
SUMMARY:Event #2 bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
END:VCALENDAR
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HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd3.ics
"fffff-abcd3"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
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7.8.3. Example: Expanded retrieval of recurring events
In this example, the client requests the server to return VEVENT
components that overlap the time range from January 2nd, 2006 at 00:
00:00 AM UTC to January 5th, 2006 at 00:00:00 AM UTC and to return
recurring calendar components expanded into individual recurrence
instance calendar components. Use of the CALDAV:expand element
causes the server to only return overridden recurrence instances that
overlap the time range specified in that element.
See Appendix B for the calendar data being targeted by this example.
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
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http://cal.example.com/bernard/work/abcd2.ics
"fffff-abcd2"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART:20060103T170000
DURATION:PT1H
RECURRENCE-ID:20060103T170000
SUMMARY:Event #2
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART:20060104T190000
DURATION:PT1H
RECURRENCE-ID:20060104T170000
SUMMARY:Event #2 bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd3.ics
"fffff-abcd3"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART:20060104T150000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
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ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
7.8.4. Example: Partial retrieval of stored free busy components
In this example, the client requests the server to return the
VFREEBUSY components that have free busy information that overlap the
time range from January 2nd, 2006 at 00:00:00 AM UTC (inclusively) to
January 3rd, 2006 at 00:00:00 AM UTC (exclusively). Use of the
CALDAV:limit-freebusy-set element causes the server to only return
the FREEBUSY property values that overlap the time range specified in
that element. Note that this is not an example of discovering when
the calendar owner is busy.
See Appendix B for the calendar data being targeted by this example.
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>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
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>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
http://cal.example.com/bernard/work/abcd8.ics
"fffff-abcd8"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VFREEBUSY
ORGANIZER;CN="Bernard Desruisseaux":mailto:bernard@example.com
UID:76ef34-54a3d2@example.com
DTSTAMP:20050530T123421Z
DTSTART:20060101T100000Z
DTEND:20060108T100000Z
FREEBUSY;FBTYPE=BUSY-TENTATIVE:20060102T100000Z/20060102T120000Z
END:VFREEBUSY
END:VCALENDAR
HTTP/1.1 200 OK
7.8.5. Example: Retrieval of to-dos by alarm time range
In this example, the client requests the server to return the VTODO
components that have an alarm trigger scheduled in the specified time
range.
See Appendix B for the calendar data being targeted by this example.
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>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
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>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
http://cal.example.com/bernard/work/abcd4.ics
"fffff-abcd4"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235300Z
DUE;TZID=US/Eastern:20060106T120000
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:NEEDS-ACTION
SUMMARY:Task #2
UID:E10BA47467C5C69BB74E8720@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
HTTP/1.1 200 OK
7.8.6. Example: Retrieval of event by UID
In this example, the client requests the server to return the VEVENT
component that has the UID property set to
"DC6C50A017428C5216A2F1CD@example.com".
See Appendix B for the calendar data being targeted by this example.
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>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
DC6C50A017428C5216A2F1CD@example.com
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
http://cal.example.com/bernard/work/abcd3.ics
"fffff-abcd3"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
BEGIN:DAYLIGHT
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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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
7.8.7. Example: Retrieval of events by PARTSTAT
In this example, the client requests the server to return the VEVENT
components that have the ATTENDEE property with the value
"mailto:lisa@example.com" and for which the PARTSTAT parameter is set
to "NEEDS-ACTION".
See Appendix B for the calendar data being targeted by this example.
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>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
mailto:lisa@example.com
NEEDS-ACTION
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
http://cal.example.com/bernard/work/abcd3.ics
"fffff-abcd3"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
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BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
7.8.8. Example: Retrieval of events only
In this example, the client requests the server to return all VEVENT
components.
See Appendix B for the calendar data being targeted by this example.
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>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
http://cal.example.com/bernard/work/abcd1.ics
"fffff-abcd1"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
BEGIN:DAYLIGHT
DTSTART:20000404T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
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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
DTSTAMP:20060206T001102Z
DTSTART;TZID=US/Eastern:20060102T100000
DURATION:PT1H
SUMMARY:Event #1
Description:Go Steelers!
UID:74855313FA803DA593CD579A@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd2.ics
"fffff-abcd2"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
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END:VTIMEZONE
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060102T120000
DURATION:PT1H
RRULE:FREQ=DAILY;COUNT=5
SUMMARY:Event #2
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060104T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060104T120000
SUMMARY:Event #2 bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060106T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060106T120000
SUMMARY:Event #2 bis bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd3.ics
"fffff-abcd3"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
BEGIN:DAYLIGHT
DTSTART:20000404T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
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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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
7.8.9. Example: Retrieval of all pending to-dos
In this example, the client requests the server to return all VTODO
components that do not include a "COMPLETED" property and do not have
a "STATUS" property value matching "CANCELLED". i.e., VTODOs that
still need to be worked on.
See Appendix B for the calendar data being targeted by this example.
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>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
CANCELLED
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
http://cal.example.com/bernard/work/abcd4.ics
"fffff-abcd4"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
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DTSTAMP:20060205T235335Z
DUE;VALUE=DATE:20060104
STATUS:NEEDS-ACTION
SUMMARY:Task #1
UID:DDDEEB7915FA61233B861457@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd5.ics
"fffff-abcd5"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235300Z
DUE;VALUE=DATE:20060106
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:NEEDS-ACTION
SUMMARY:Task #2
UID:E10BA47467C5C69BB74E8720@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
HTTP/1.1 200 OK
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7.8.10. Example: Attempt to query unsupported property
In this example, the client requests the server to return all VEVENT
components that include an "X-ABC-GUID" property with a value
matching "ABC". However, the server does not support querying that
non-standard property and instead returns and error response.
See Appendix B for the calendar data being targeted by this example.
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
ABC
>> Response <<
HTTP/1.1 403 Forbidden
Date: Fri, 11 Nov 2005 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
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7.9. CALDAV:calendar-multiget Report
The CALDAV:calendar-multiget REPORT is used to retrieve specific
calendar object resources from within a collection, if the Request-
URI is a collection, or to retrieve a specific calendar object
resource, if the Request-URI is a calendar object resource. This
REPORT is similar to the CALDAV:calendar-query REPORT (see
Section 7.8), except that it takes a list of DAV:href elements
instead of a CALDAV:filter element to determine which calendar object
resources to return.
Support for the calendar-multiget REPORT is REQUIRED.
Marshalling:
The request body MUST be a CALDAV:calendar-multiget XML element
(see Section 9.10). If the Request-URI is a collection resource,
then the DAV:href elements MUST refer to calendar object resources
within that collection, and they MAY refer to calendar object
resources at any depth within the collection. As a result the
"Depth" header MUST be ignored by the server and SHOULD NOT be
sent by the client. If the Request-URI refers to a non-collection
resource, then there MUST be a single DAV:href element that is
equivalent to the Request-URI.
The response body for a successful request MUST be a DAV:
multistatus XML element.
The response body for a successful CALDAV:calendar-multiget REPORT
request MUST contain a DAV:response element for each calendar
object resource referenced by the provided set of DAV:href
elements. Calendar data is being returned in the CALDAV:calendar-
data element inside the DAV:prop element.
In the case of an error accessing any of the provided DAV:href
resources, the server MUST return the appropriate error status
code in the DAV:status element of the corresponding DAV:response
element.
Preconditions:
(CALDAV:supported-calendar-data): The attributes "content-type"
and "version" of the CALDAV:calendar-data XML elements (see
Section 9.6) specify a media type supported by the server for
calendar object resources.
(CALDAV:min-date-time): Any XML element specifying a range of time
MUST have its start or end date or time values greater than or
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equal to the value of the CALDAV:min-date-time property value
(Section 5.2.6) on the calendar collections being targeted by the
REPORT;
(CALDAV:max-date-time): Any XML element specifying a range of time
MUST have its start or end date or time values less than or equal
to the value of the CALDAV:max-date-time property value
(Section 5.2.7) on the calendar collections being targeted by the
REPORT;
Postconditions:
None.
7.9.1. Example: Successful CALDAV:calendar-multiget Report
In this example, the client requests the server to return specific
properties of the VEVENT components referenced by specific URIs. In
addition the DAV:getetag property is also requested and returned as
part of the response. Note that in this example, the resource at
http://cal.example.com/bernard/work/mtg1.ics does not exist,
resulting in an error status response.
See Appendix B for the calendar data being targeted by this example.
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
/bernard/work/abcd1.ics
/bernard/work/mtg1.ics
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
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Content-Length: xxxx
http://cal.example.com/bernard/work/abcd1.ics
"fffff-abcd1"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
DTSTAMP:20060206T001102Z
DTSTART;TZID=US/Eastern:20060102T100000
DURATION:PT1H
SUMMARY:Event #1
Description:Go Steelers!
UID:74855313FA803DA593CD579A@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/mtg1.ics
HTTP/1.1 404 Not Found
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7.10. CALDAV:free-busy-query Report
The CALDAV:free-busy-query REPORT generates a VFREEBUSY component
containing free busy information for all the calendar object
resources targeted by the request and which have the CALDAV:read-
free-busy or DAV:read privilege granted to the current user.
Only VEVENT components without a TRANSP property or with the TRANSP
property set to "OPAQUE", and VFREEBUSY components SHOULD be
considered to generate the free busy time information.
In the case of VEVENT components, the free or busy time type (FBTYPE)
of the FREEBUSY properties in the returned VFREEBUSY component SHOULD
be derived from the value of the TRANSP and STATUS properties as
outlined in the table below:
+---------------------------++------------------+
| VEVENT || VFREEBUSY |
+-------------+-------------++------------------+
| TRANSP | STATUS || FBTYPE |
+=============+=============++==================+
| | CONFIRMED || BUSY |
| | (default) || |
| OPAQUE +-------------++------------------+
| (default) | CANCELLED || FREE |
| +-------------++------------------+
| | TENTATIVE || BUSY-TENTATIVE |
| +-------------++------------------+
| | x-name || BUSY or |
| | || x-name |
+-------------+-------------++------------------+
| | CONFIRMED || |
| TRANSPARENT | CANCELLED || FREE |
| | TENTATIVE || |
| | x-name || |
+-------------+-------------++------------------+
Duplicate busy time periods with the same FBTYPE parameter value
SHOULD NOT be specified in the returned VFREEBUSY component. Servers
SHOULD coalesce consecutive or overlapping busy time period of the
same type. Busy time periods with different FBTYPE parameter values
MAY overlap.
Support for the CALDAV:free-busy-query REPORT is REQUIRED.
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Marshalling:
The request body MUST be a CALDAV:free-busy-query XML element (see
Section 9.11, which MUST contain exactly one CALDAV:time-range XML
element, as defined in Section 9.9.
The request MAY include a Depth header. If no Depth header is
included, Depth:0 is assumed.
The response body for a successful request MUST be an iCalendar
object that contains exactly one VFREEBUSY component that
describes the busy time intervals for the calendar object
resources containing VEVENT or VFREEBUSY components that satisfy
the Depth value and for which the current user is at least granted
the CALDAV:read-free-busy privilege. If no calendar object
resources are found to satisfy these conditions a VFREEBUSY
component with no FREEBUSY property MUST be returned. This REPORT
only returns busy time information. Free time information can be
inferred from the returned busy time information.
If the current user is not granted the CALDAV:read-free-busy or
DAV:read privileges on the Request-URI, the CALDAV:free-busy-query
REPORT request MUST fail and return a 404 (Not Found) status
value. This restriction will prevent users from discovering URLs
of resources for which they are only granted the CALDAV:read-free-
busy privilege.
The CALDAV:free-busy-query REPORT request can only be run against
a collection (either a regular collection or a calendar
collection). An attempt to run the report on a calendar object
resource MUST fail and return a 403 (Forbidden) status value.
Preconditions:
None.
Postconditions:
(DAV:number-of-matches-within-limits): The number of matching
calendar object resources must fall within server-specific,
predefined limits. For example, this postcondition might fail if
the specified CALDAV:time-range would cause an extremely large
number calendar object resources to be considered to compute the
response.
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7.10.1. Example: Successful CALDAV:free-busy-query Report
In this example, the client requests the server to return free busy
information on the calendar collection /bernard/work/, between 9:00
AM and 5:00 PM EST (2:00 PM and 10:00 PM UTC) on the 4th January
2006. The server responds indicating two busy time intervals of one
hour, one of which is tentative.
See Appendix B for the calendar data being targeted by this example.
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
>> Response <<
HTTP/1.1 200 OK
Date: Fri, 11 Nov 2006 09:32:12 GMT
Content-Type: text/calendar
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
BEGIN:VFREEBUSY
DTSTAMP:20050125T090000Z
DTSTART:20060104T140000Z
DTEND:20060105T220000Z
FREEBUSY;FBTYPE=BUSY-TENTATIVE:20060104T150000Z/PT1H
FREEBUSY:20060104T190000Z/PT1H
END:VFREEBUSY
END:VCALENDAR
8. Guidelines
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8.1. Client-to-client Interoperability
There are a number of actions clients can take which will be legal
(the server will not return errors) but which can degrade
interoperability with other client implementations accessing the same
data. For example, a recurrence rule could be replaced with a set of
recurrence dates, a single recurring event could be replaced with a
set of independent resources to represent each recurrence, or the
start/end time values can be translated from the original time zone
to another time zone. Although this advice amounts to iCalendar
interoperability best practices and is not limited only to CalDAV
usage, interoperability problems are likely to be more evident in
CalDAV use cases.
8.2. Synchronization Operations
WebDAV already provides functionality required to synchronize a
collection or set of collections, make changes offline, and a simple
way to resolve conflicts when reconnected. ETags are the key to
making this work, but these are not required of all WebDAV servers.
Since offline functionality is more important to calendar
applications than to some other WebDAV applications, CalDAV servers
MUST support ETags as specified in Section 5.3.4.
8.2.1. Use of Reports
8.2.1.1. Restrict the Time Range
The REPORTs provided in CalDAV can be used by clients to optimize
their performance in terms of network bandwidth usage, and resource
consumption on the local client machine. Both are certainly major
considerations for mobile or handheld devices with limited capacity,
but they are also relevant to desktop client applications in cases
where the calendar collections contain large amounts of data.
Typically clients present calendar data to users in views that span a
finite time interval, so whenever possible clients should only
retrieve calendar components from the server using CALDAV:calendar-
query REPORT combined with a CALDAV:time-range element to limit the
set of returned components to just those needed to populate the
current view.
8.2.1.2. Synchronize by Time Range
Typically in a calendar, historical data (events, to-dos etc. that
have completed prior to the current date) do not change, though they
may be deleted. As a result, a client can speed up the
synchronization process by only considering data for the present time
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and the future up to a reasonable limit (e.g., one week, one month).
If the user then tries to examine a portion of the calendar outside
of the range that has been synchronized, the client can perform
another synchronization operation on the new time interval being
examined. This "just-in-time" synchronization can minimize bandwidth
for common user interaction behaviors.
8.2.1.3. Synchronization Process
If a client wants to support calendar data synchronization, as
opposed to downloading calendar data each time it is needed, it needs
to cache the calendar object resource's URI and ETag along with the
actual calendar data. While the URI remains static for the lifetime
of the calendar object resource, the ETag will change with each
successive change to the calendar object resource. Thus to
synchronize a local data cache with the server, the client can first
fetch the URI/ETag pairs for the time interval being considered, and
compare those results with the cached data. Any cached component
whose ETag differs from that on the server needs to be refreshed.
In order to properly detect the changes between the server and client
data, the client will need to keep a record of which calendar object
resources have been created, changed or deleted since the last
synchronization operation so that it can reconcile those changes with
the data on the server.
Here's an example of how to do that:
The client issues a CALDAV:calendar-query REPORT request for a
specific time range, and asks for only the DAV:getetag property to be
returned:
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REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
The client then uses the results to determine which calendar object
resources have changed, been created or deleted on the server and how
those relate to locally cached calendar object resources that may
have changed, been created or deleted. If the client determines that
there are calendar object resources on the server that need to be
fetched, the client issues a CALDAV:calendar-multiget REPORT request
to fetch their calendar data:
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
/bernard/work/abcd1.ics
/bernard/work/mtg1.ics
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8.2.2. Restrict the Properties Returned
Clients may not need all the calendar properties of a calendar object
resource when presenting information to the user. Since some
calendar property values can be large (e.g., ATTACH or ATTENDEE)
clients can choose to restrict the calendar properties to be returned
in a calendaring REPORT request to those it knows it will use.
However, if a client needs to make a change to a calendar object
resource, it can only change the entire calendar object resource via
a PUT request. There is currently no way to incrementally make a
change to a set of calendar properties of a calendar object resource.
As a result the client will have to get the entire calendar object
resource that is being changed.
8.3. Use of Locking
WebDAV locks can be used to prevent two clients modifying the same
resource from either overwriting each others' changes (though that
problem can also be solved by using ETags) or wasting time making
changes that will conflict with another set of changes. In a multi-
user calendar system, an interactive calendar client could lock an
event while the user is editing the event, and unlock the event when
the user finishes or cancels. Locks can also be used to prevent
changes while data is being reorganized. For example, a calendar
client might lock two calendar collections prior to moving a bunch of
calendar resources from one to another.
Clients are responsible for requesting a lock timeout period that is
appropriate to the use case. When the user explicitly decides to
reserve a resource and prevent other changes, a long timeout might be
appropriate, but in cases when the client automatically decides to
lock the resource the timeout should be short (and the client can
always refresh the lock should it need to). A short lock timeout
means that if the client is unable to remove the lock, the other
calendar users aren't prevented from making changes.
8.4. Finding calendars
Much of the time a calendar client (or agent) will discover a new
calendar's location by being provided directly with the URL. E.g., a
user will type his or her own calendar location into client
configuration information, or copy and paste a URL from email into
the calendar application. The client need only confirm that the URL
points to a resource which is a calendar collection. The client may
also be able to browse WebDAV collections to find calendar
collections.
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The choice of HTTP URLs means that calendar object resources are
backward compatible with existing software, but does have the
disadvantage that existing software does not usually know to look at
the OPTIONS response to that URL to determine what can be done with
it. This is somewhat of a barrier for WebDAV usage as well as with
CalDAV usage. This specification does not offer a way through this
other than making the information available in the OPTIONS response
should this be requested.
For calendar sharing and scheduling use cases, one might wish to find
the calendar belonging to another user. If the other user has a
calendar in the same repository, that calendar can be found by using
the principal namespace required by WebDAV ACL support. For other
cases, the authors have no universal solution but implementers can
consider whether to use vCard [RFC2426] or LDAP [RFC4511] standards
together with calendar attributes [RFC2739].
Because CalDAV requires servers to support WebDAV ACL [RFC3744]
including principal namespaces, and with the addition of the CALDAV:
calendar-home-set property, there are a couple options for CalDAV
clients to find one's own calendar or another user's calendar.
In this case, a DAV:principal-match REPORT is used to find a named
property (the CALDAV:calendar-home-set) on the Principal-URL of the
current user. Using this, a WebDAV client can learn "who am I" and
"where are my calendars". The REPORT request body looks like this:
To find other users calendars, the DAV:principal-property-search
REPORT can be used to filter on some properties and return others.
To search for a calendar owned by a user named "Laurie", the REPORT
request body would look like this:
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Laurie
The server performs a case-sensitive or caseless search for a
matching string subset of "Laurie" within the DAV:displayname
property. Thus, the server might return "Laurie Dusseault", "Laurier
Desruisseaux" or "Wilfrid Laurier" all as matching DAV:displayname
values, and the calendars for each of these.
8.5. Storing and Using Attachments
CalDAV clients MAY create attachments in calendar components either
as inline or external. This section contains some guidelines on
creating and managing attachments.
8.5.1. Inline attachments
CalDAV clients MUST support inline attachments as specified in
iCalendar [RFC2445]. CalDAV servers MUST support inline attachments,
so clients can rely on being able to create attachments this way. On
the other hand, inline attachments have some drawbacks:
o Servers MAY impose limitations on the size of calendar object
resources (i.e., refusing PUT requests of very large iCalendar
objects). Servers that do that MUST use the CALDAV:max-resource-
size property on a calendar collection to inform the client as to
what the limitation is (see Section 5.2.5).
o Servers MAY impose storage quota limitations on calendar
collections (See [RFC4331]).
o Any change to a calendar object resource containing an attachment
requires the entire attachment to be re-uploaded.
o Clients synchronizing a changed calendar object resource have to
download the entire calendar object resource even if the
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attachment is unchanged.
8.5.2. External attachments
CalDAV clients SHOULD support downloading of external attachments
referenced by arbitrary URI schemes, by either processing them
directly, or by passing the attachment URI to a suitable "helper
application" for processing, if such an application exists. CalDAV
clients MUST support downloading of external attachments referenced
by the "http" or "https" URI schemes. An external attachment could
be:
o In a collection in the calendar collection containing the calendar
object resource;
o Somewhere else in the same repository that hosts the calendar
collection; or
o On an HTTP or FTP server elsewhere.
CalDAV servers MAY provide support for child collections in calendar
collections. CalDAV servers MAY allow the MKCOL method to create
child collections in calendar collections. Child collections of
calendar collections MAY contain any type of resource except calendar
collections which they MUST NOT contain. Some CalDAV servers won't
allow child collections in calendar collections, and it may be
possible on such a server to discover other locations where
attachments can be stored.
Clients are entirely responsible for maintaining reference
consistency with calendar components that link to external
attachments. A client deleting a calendar component with an external
attachment might therefore also delete the attachment if that's
appropriate, however appropriateness can be very hard to determine.
A new component might easily reference some pre-existing Web resource
which is intended to have independent existence from the calendar
component (the "attachment" could be a major proposal to be discussed
in a meeting, for instance). Best practices will probably emerge and
should probably be documented but for now clients should be wary of
engaging in aggressive "cleanup" of external attachments. A client
could involve the user in making decisions about removing
unreferenced documents, or a client could be conservative in only
deleting attachments it had created.
Also, clients are responsible for consistency of permissions when
using external attachments. One reason for servers to support the
storage of attachments within child collections of calendar
collections is that ACL inheritance might make it easier to grant the
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same permissions to attachments that are granted on the calendar
collection. Otherwise, it can be very difficult to keep permissions
synchronized. With attachments stored on separate repositories, it
can be impossible to keep permissions consistent -- the two
repositories may not support the same permissions or have the same
set of principals. Some systems have used tickets or other anonymous
access control mechanisms to provide partially satisfactory solutions
to these kinds of problems.
8.6. Storing and Using Alarms
Note that all CalDAV calendar collections (including those which the
user might treat as public or group calendars) can contain alarm
information on events and to-dos. Users can synchronize a calendar
between multiple devices and decide to have alarms execute on a
different device than the device that created the alarm. Not all
alarm action types are completely interoperable (e.g., those which
name a sound file to play).
When the action is "AUDIO", and the client is configured to
execute the alarm, the client SHOULD play the suggested sound if
it's available or play another sound, but SHOULD NOT rewrite the
alarm just to replace the suggested sound with a sound that's
locally available.
When the action is "DISPLAY", and the client is configured to
execute the alarm, the client SHOULD execute a display alarm by
displaying either according to the suggested description or some
reasonable replacement, but SHOULD NOT rewrite the alarm for its
own convenience.
When the action is "EMAIL", and the client is incapable of sending
email, it SHOULD ignore the alarm but MUST continue to synchronize
the alarm itself.
This specification makes no recommendations about executing alarms
of type PROCEDURE except to note that clients are advised to take
care to avoid creating security holes by executing these.
Non-interoperable alarm information (e.g., should somebody define a
color to be used in a display alarm) should be put in non-standard
properties inside the VALARM component in order to keep the basic
alarm usable on all devices.
Clients that allow changes to calendar object resources MUST
synchronize the alarm data that already exists in the resources.
Clients MAY execute alarms that are downloaded in this fashion,
possibly based on user preference. If a client is only doing read
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operations on a calendar and there is no risk of losing alarm
information, then the client MAY discard alarm information.
This specification makes no attempt to provide multi-user alarms on
group calendars or to find out who an alarm is intended for.
Addressing those issues might require extensions to iCalendar, for
example to store alarms per-user or indicate which user a VALARM was
intended for. In the meantime, clients might maximize
interoperability by generally not uploading alarm information to
public, group or resource calendars.
9. XML Element Definitions
9.1. CALDAV:calendar XML Element
Name: calendar
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies the resource type of a calendar collection.
Description: See Section 4.2.
Definition:
9.2. CALDAV:mkcalendar XML Element
Name: mkcalendar
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a request that includes the WebDAV property values
to be set for a calendar collection resource when it is created.
Description: See Section 5.3.1.
Definition:
9.3. CALDAV:mkcalendar-response XML Element
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Name: mkcalendar-response
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a response body for a successful MKCALENDAR
request.
Description: See Section 5.3.1.
Definition:
9.4. CALDAV:supported-collation XML Element
Name: supported-collation
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identifies a single collation via its collation identifier
as defined by [I-D.newman-i18n-comparator].
Description: The CALDAV:supported-collation contains the text of a
collation identifier as described in Section 7.5.1.
Definition:
PCDATA value: collation identifier
9.5. CALDAV:calendar-query XML Element
Name: calendar-query
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Defines a REPORT for querying calendar object resources.
Description: See Section 7.8.
Definition:
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9.6. CALDAV:calendar-data XML Element
Name: calendar-data
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Used to (1) specify a supported media type for calendar
object resources when nested in the CALDAV:supported-calendar-data
property; (2) specify which parts of a calendar object resource
should be returned by a given calendaring REPORT; and (3) specify
the content of a calendar object resource in a response to a
calendaring REPORT.
Description: When nested in the CALDAV:supported-calendar-data
property, the CALDAV:calendar-data XML element specifies a media
type supported by the CalDAV server for calendar object resources.
When used in a calendaring REPORT request, the CALDAV:calendar-
data XML element specifies which parts of calendar object
resources need to be returned in the response. If the CALDAV:
calendar-data XML element doesn't contain any CALDAV:comp element,
calendar object resources will be returned in their entirety.
Finally, when used in a calendaring REPORT response, the CALDAV:
calendar-data XML element specifies the content of a calendar
object resource. Given that XML parsers normalize the two-
character sequence CRLF (US-ASCII decimal 13 and US-ASCII decimal
10) to a single LF character (US-ASCII decimal 10), the CR
character (US-ASCII decimal 13) MAY be omitted in calendar object
resources specified in the CALDAV:calendar-data XML element.
Furthermore, calendar object resources specified in the CALDAV:
calendar-data XML element MAY be invalid per their media type
specification if the CALDAV:calendar-data XML element part of the
calendaring REPORT request did not specify required properties
(e.g., UID, DTSTAMP, etc.) or specified a CALDAV:prop XML element
with the "novalue" attribute set to "yes".
Note: The CALDAV:calendar-data XML element is specified in requests
and responses inside the DAV:prop XML element as if it were a
WebDAV property. However, the CALDAV:calendar-data XML element is
not a WebDAV property and as such it is not returned in PROPFIND
responses nor used in PROPPATCH requests.
Note: The iCalendar data embedded within the CALDAV:calendar-data XML
element MUST follow the standard XML character data encoding
rules, including use of <, >, & etc entity encoding or
the use of a construct. In the later case the
iCalendar data cannot contain the character sequence "]]>" which
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is the end delimiter for the CDATA section.
Definition:
PCDATA value: iCalendar object
version CDATA "2.0">
content-type value: a MIME media type
version value: a version string
9.6.1. CALDAV:comp XML Element
Name: comp
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Defines which component types to return.
Description: The name value is a calendar component name (e.g.,
"VEVENT").
Definition:
name value: a calendar component name
Note: The CALDAV:prop and CALDAV:allprop elements have the same name
as the DAV:prop and DAV:allprop elements defined in [RFC2518].
However, the CALDAV:prop and CALDAV:allprop element are defined in
the "urn:ietf:params:xml:ns:caldav" namespace instead of the
"DAV:" namespace.
9.6.2. CALDAV:allcomp XML Element
Name: allcomp
Namespace: urn:ietf:params:xml:ns:caldav
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Purpose: Specifies that all components shall be returned.
Description: The CALDAV:allcomp XML element can be used when the
client wants all types of components returned by a calendaring
REPORT request.
Definition:
9.6.3. CALDAV:allprop XML Element
Name: allprop
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies that all properties shall be returned.
Description: The CALDAV:allprop XML element can be used when the
client wants all properties of components returned by a
calendaring REPORT request.
Definition:
Note: The CALDAV:allprop element has the same name as the DAV:allprop
element defined in [RFC2518]. However, the CALDAV:allprop element
is defined in the "urn:ietf:params:xml:ns:caldav" namespace
instead of the "DAV:" namespace.
9.6.4. CALDAV:prop XML Element
Name: prop
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Defines which properties to return in the response.
Description: The "name" attribute specifies the name of the calendar
property to return (e.g., "ATTENDEE"). The "novalue" attribute
can be used by clients to request that the actual value of the
property not be returned (if the "novalue" attribute is set to
"yes"). In that case the server will return just the iCalendar
property name and any iCalendar parameters and a trailing ":"
without the subsequent value data.
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Definition:
name value: a calendar property name
novalue value: "yes" or "no"
Note: The CALDAV:prop element has the same name as the DAV:prop
element defined in [RFC2518]. However, the CALDAV:prop element is
defined in the "urn:ietf:params:xml:ns:caldav" namespace instead
of the "DAV:" namespace.
9.6.5. CALDAV:expand XML Element
Name: expand
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Forces the server to expand recurring components into
individual recurrence instances.
Description: The CALDAV:expand XML element specifies that for a given
calendaring REPORT request the server MUST expand the recurrence
set into calendar components that define exactly one recurrence
instance and MUST return only those whose scheduled time intersect
a specified time range. The "start" attribute specifies the
inclusive start of the time range, and the "end" attribute
specifies the non-inclusive end of the time range. Both
attributes are specified as date with UTC time value. The value
of the "end" attribute MUST be greater than the value of the
"start" attribute. The server MUST use the same logic as defined
for CALDAV:time-range to determine if a recurrence instance
intersects the specified time range. Recurring components, other
than the initial instance, MUST include a RECURRENCE-ID property
indicating which instance they refer to. The returned calendar
components MUST NOT use recurrence properties (i.e., EXDATE,
EXRULE, RDATE and RRULE) and MUST NOT have reference to or include
VTIMEZONE components. Date and local time with reference to time
zone information MUST be converted into date with UTC time.
Definition:
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start value: an iCalendar "date with UTC time"
end value: an iCalendar "date with UTC time"
9.6.6. CALDAV:limit-recurrence-set XML Element
Name: limit-recurrence-set
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a time range to limit the set of "overridden
components" returned by the server.
Description: The CALDAV:limit-recurrence-set XML element specifies
that for a given calendaring REPORT request the server MUST
return, in addition to the "master component", only the
"overridden components" that impact a specified time range. An
overridden component impacts a time range if its current start and
end times overlap the time range, or if the original start and end
times - the ones that would have been used if the instance were
not overridden - overlap the time range. The "start" attribute
specifies the inclusive start of the time range, and the "end"
attribute specifies the non-inclusive end of the time range. Both
attributes are specified as date with UTC time value. The value
of the "end" attribute MUST be greater than the value of the
"start" attribute. The server MUST use the same logic as defined
for CALDAV:time-range to determine if the current or original
scheduled time of an "overridden" recurrence instance intersect
the specified time range. Overridden components that have a RANGE
parameter on their RECURRENCE-ID property may specify one or more
instances in the recurrence set, and some of those instances may
fall within the specified time range, or may have originally
fallen within the specified time range prior to being overridden.
If that is the case, the overridden component MUST be included in
the results as it has a direct impact on the interpretation of
instances within the specified time range.
Definition:
start value: an iCalendar "date with UTC time"
end value: an iCalendar "date with UTC time"
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9.6.7. CALDAV:limit-freebusy-set XML Element
Name: limit-freebusy-set
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a time range to limit the set of FREEBUSY values
returned by the server.
Description: The CALDAV:limit-freebusy-set XML element specifies that
for a given calendaring REPORT request the server MUST only return
the FREEBUSY property values of a VFREEBUSY component that
intersect a specified time range. The "start" attribute specifies
the inclusive start of the time range, and the "end" attribute
specifies the non-inclusive end of the time range. Both
attributes are specified as "date with UTC time" value. The value
of the "end" attribute MUST be greater than the value of the
"start" attribute. The server MUST use the same logic as defined
for CALDAV:time-range to determine if a FREEBUSY property value
intersect the specified time range.
Definition:
start value: an iCalendar "date with UTC time"
end value: an iCalendar "date with UTC time"
9.7. CALDAV:filter XML Element
Name: filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a filter to limit the set of calendar components
returned by the server.
Description: The CALDAV:filter XML element specifies the search
filter used to limit the calendar components returned by a
calendaring REPORT request.
Definition:
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9.7.1. CALDAV:comp-filter XML Element
Name: comp-filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies search criteria on calendar components.
Description: The CALDAV:comp-filter XML element specifies the queried
calendar component type (e.g., "VEVENT"). A calendar object
resource is said to match a CALDAV:comp-filter if:
* A component of the type specified by the "name" attribute
exists, and the CALDAV:comp-filter is empty, or it contains at
least one recurrence instance scheduled to overlap a given time
range if a CALDAV:time-range XML element is specified, and that
any CALDAV:prop-filter and CALDAV:comp-filter child elements
also match.
or:
* A component of the type specified by the "name" attribute does
not exist, and the CALDAV:is-not-defined element is specified.
Definition:
name value: a calendar component name (e.g., "VEVENT")
9.7.2. CALDAV:prop-filter XML Element
Name: prop-filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies search criteria on calendar properties.
Description: The CALDAV:prop-filter XML element specifies a search
criteria on a specific calendar property (e.g., CATEGORIES) in the
scope of a given CALDAV:comp-filter. A calendar component is said
to match a CALDAV:prop-filter if:
* A property of the type specified by the "name" attribute
exists, and the CALDAV:prop-filter is empty, or it matches the
CALDAV:time-range XML element or CALDAV:text-match conditions
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if specified, and that any CALDAV:param-filter child elements
also match.
or:
* A property of the type specified by the "name" attribute does
not exist, and the CALDAV:is-not-defined element is specified.
Definition:
name value: a calendar property name (e.g., "ATTENDEE")
9.7.3. CALDAV:param-filter XML Element
Name: param-filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Limits the search to specific parameter values.
Description: The CALDAV:param-filter XML element specifies a search
criteria on a specific calendar property parameter (e.g.,
PARTSTAT) in the scope of a given CALDAV:prop-filter. A calendar
property is said to match a CALDAV:param-filter if:
* A parameter of the type specified by the "name" attribute
exists, and the CALDAV:param-filter is empty, or it matches the
CALDAV:text-match conditions if specified.
or:
* A parameter of the type specified by the "name" attribute does
not exist, and the CALDAV:is-not-defined element is specified.
Definition:
name value: a property parameter name (e.g., "PARTSTAT")
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9.7.4. CALDAV:is-not-defined XML Element
Name: is-not-defined
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies that a match should occur if the enclosing
component, property or parameter does not exist.
Description: The CALDAV:is-not-defined XML element specifies that a
match occurs if the enclosing component, property or parameter
value specified in a calendaring REPORT request does not exist in
the calendar data being tested.
Definition:
9.7.5. CALDAV:text-match XML Element
Name: text-match
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a substring match on a property or parameter
value.
Description: The CALDAV:text-match XML element specifies text used
for a substring match against the property or parameter value
specified in a calendaring REPORT request.
The "collation" attribute is used to select the collation that the
server MUST use for character string matching. In the absence of
this attribute the server MUST use the "i;ascii-casemap"
collation.
The "negate-condition" attribute is used to indicate that this
test returns a match if the text matches, when the attribute value
is set to "no", or return a match if the text does not match, if
the attribute value is set to "yes". For example, this can be
used to match components with a STATUS property not set to
CANCELLED.
Definition:
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PCDATA value: string
9.8. CALDAV:timezone XML Element
Name: timezone
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies the time zone component to use when determining
the results of a report.
Description: The CALDAV:timezone XML element specifies that for a
given calendaring REPORT request the server MUST rely on the
specified VTIMEZONE component instead of the CALDAV:calendar-
timezone property of the calendar collection in which the calendar
object resource is contained to resolve "date" values and "date
with local time" values (i.e., floating time) to "date with UTC
time" values. The server will require this information to
determine if a calendar component scheduled with "date" values or
"date with local time" values intersect a CALDAV:time-range
specified in a CALDAV:calendar-query REPORT.
Note: The iCalendar data embedded within the CALDAV:timezone XML
element MUST follow the standard XML character data encoding
rules, including use of <, >, & etc entity encoding or
the use of a construct. In the later case the
iCalendar data cannot contain the character sequence "]]>" which
is the end delimiter for the CDATA section.
Definition:
PCDATA value: an iCalendar object with exactly one VTIMEZONE
9.9. CALDAV:time-range XML Element
Name: time-range
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a time range to limit the set of calendar
components returned by the server.
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Description: The CALDAV:time-range XML element specifies that for a
given calendaring REPORT request the server MUST only return the
calendar object resources that, depending on the context, have a
component or property whose value intersect a specified time
range. The "start" attribute specifies the inclusive start of the
time range, and the "end" attribute specifies the non-inclusive
end of the time range. Both attributes MUST be specified as "date
with UTC time" value. Time ranges open at one end can be
specified by including only one attribute, however at least one
attribute MUST always be present in the CALDAV:time-range element.
If either the "start" or "end" attribute is not specified in the
CALDAV:time-range XML element, assume "-infinity" and "+infinity"
as their value respectively. If both "start" and "end" are
present, the value of the "end" attribute MUST be greater than the
value of the "start" attribute.
Time range tests MUST consider every recurrence instance when
testing the time range condition - if any one instance matches,
then the test returns true. Testing recurrence instances requires
the server to infer an effective value for DTSTART, DTEND,
DURATION and DUE properties for an instance based on the
recurrence patterns and any overrides.
A VEVENT component overlaps a given time range if the condition
for the corresponding component state specified in the table below
is satisfied. Note that as specified in [RFC2445] the DTSTART
property is REQUIRED in the VEVENT component. The conditions
depend on the presence of the DTEND and DURATION properties in the
VEVENT component. Furthermore, the value of the DTEND property
MUST be later in time than the value of the DTSTART property. The
duration of a VEVENT component with no DTEND and DURATION
properties is 1 day (+P1D) when the DTSTART is a DATE value, and 0
seconds when the DTSTART is a DATE-TIME value.
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+---------------------------------------------------------------+
| VEVENT has the DTEND property? |
| +-----------------------------------------------------------+
| | VEVENT has the DURATION property? |
| | +-------------------------------------------------------+
| | | DURATION property value is greater than 0 seconds? |
| | | +---------------------------------------------------+
| | | | DTSTART property is a DATE-TIME value |
| | | | +-----------------------------------------------+
| | | | | Condition to evaluate |
+---+---+---+---+-----------------------------------------------+
| Y | N | N | * | (start < DTEND AND end > DTSTART) |
+---+---+---+---+-----------------------------------------------+
| N | Y | Y | * | (start < DTSTART+DURATION AND end > DTSTART) |
| | +---+---+-----------------------------------------------+
| | | N | * | (start <= DTSTART AND end > DTSTART) |
+---+---+---+---+-----------------------------------------------+
| N | N | N | Y | (start <= DTSTART AND end > DTSTART) |
+---+---+---+---+-----------------------------------------------+
| N | N | N | N | (start < DTSTART+P1D AND end > DTSTART) |
+---+---+---+---+-----------------------------------------------+
A VTODO component is said to overlap a given time range if the
condition for the corresponding component state specified in the
table below is satisfied. The conditions depend on the presence
of the DTSTART, DURATION, DUE, COMPLETED and CREATED properties in
the VTODO component. Note that as specified in [RFC2445] the DUE
value MUST be a DATE-TIME value equal to or after the DTSTART
value, if specified.
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+-------------------------------------------------------------------+
| VTODO has the DTSTART property? |
| +---------------------------------------------------------------+
| | VTODO has the DURATION property? |
| | +-----------------------------------------------------------+
| | | VTODO has the DUE property? |
| | | +-------------------------------------------------------+
| | | | VTODO has the COMPLETED property? |
| | | | +---------------------------------------------------+
| | | | | VTODO has the CREATED property? |
| | | | | +-----------------------------------------------+
| | | | | | Condition to evaluate |
+---+---+---+---+---+-----------------------------------------------+
| Y | Y | N | * | * | (start <= DTSTART+DURATION) AND |
| | | | | | ((end > DTSTART) OR |
| | | | | | (end >= DTSTART+DURATION)) |
+---+---+---+---+---+-----------------------------------------------+
| Y | N | Y | * | * | ((start < DUE) OR (start <= DTSTART)) |
| | | | | | AND |
| | | | | | ((end > DTSTART) OR (end >= DUE)) |
+---+---+---+---+---+-----------------------------------------------+
| Y | N | N | * | * | (start <= DTSTART) AND (end > DTSTART) |
+---+---+---+---+---+-----------------------------------------------+
| N | N | Y | * | * | (start < DUE) AND (end >= DUE) |
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | Y | Y | ((start <= CREATED) OR (start <= COMPLETED))|
| | | | | | AND |
| | | | | | ((end >= CREATED) OR (end >= COMPLETED))|
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | Y | N | (start <= COMPLETED) AND (end >= COMPLETED) |
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | N | Y | (end > CREATED) |
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | N | N | TRUE |
+---+---+---+---+---+-----------------------------------------------+
A VJOURNAL component overlaps a given time range if the condition
for the corresponding component state specified in the table below
is satisfied. The conditions depend on the presence of the
DTSTART property in the VJOURNAL component and on whether the
DTSTART is a DATE-TIME or DATE value. The effective "duration" of
a VJOURNAL component is 1 day (+P1D) when the DTSTART is a DATE
value, and 0 seconds when the DTSTART is a DATE-TIME value.
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+----------------------------------------------------+
| VJOURNAL has the DTSTART property? |
| +------------------------------------------------+
| | DTSTART property is a DATE-TIME value |
| | +--------------------------------------------+
| | | Condition to evaluate |
+---+---+--------------------------------------------+
| Y | Y | (start <= DTSTART) AND (end > DTSTART) |
+---+---+--------------------------------------------+
| Y | N | (start < DTSTART+P1D) AND (end > DTSTART) |
+---+---+--------------------------------------------+
| N | * | FALSE |
+---+---+--------------------------------------------+
A VFREEBUSY component overlaps a given time range if the condition
for the corresponding component state specified in the table below
is satisfied. The conditions depend on the presence in the
VFREEBUSY component of the DTSTART and DTEND properties and any
FREEBUSY properties in the absence of DTSTART and DTEND. Any
DURATION property is ignored as it has a special meaning when used
in a VFREEBUSY component.
When only FREEBUSY properties are used, each period in each
FREEBUSY property is compared against the time range, irrespective
of the type of free busy information (free, busy, busy-tentative,
busy-unavailable) represented by the property.
+------------------------------------------------------+
| VFREEBUSY has both the DTSTART and DTEND properties? |
| +--------------------------------------------------+
| | VFREEBUSY has the FREEBUSY property? |
| | +----------------------------------------------+
| | | Condition to evaluate |
+---+---+----------------------------------------------+
| Y | * | (start <= DTEND) AND (end > DTSTART) |
+---+---+----------------------------------------------+
| N | Y | (start < freebusy-period-end) AND |
| | | (end > freebusy-period-start) |
+---+---+----------------------------------------------+
| N | N | FALSE |
+---+---+----------------------------------------------+
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A VALARM component is said to overlap a given time range if the
following condition holds:
(start <= trigger-time) AND (end > trigger-time)
A VALARM component can be defined such that it triggers
repeatedly. Such a VALARM component is said to overlap a given
time range if at least one of its triggers overlaps the time
range.
The calendar properties COMPLETED, CREATED, DTEND, DTSTAMP,
DTSTART, DUE and LAST-MODIFIED overlap a given time range if the
following condition holds:
(start <= date-time) AND (end > date-time)
Note that if DTEND is not present in a VEVENT, but DURATION is,
then the test should instead operate on the 'effective' DTEND,
i.e. DTSTART+DURATION. Similarly, if DUE is not present in a
VTODO, but DTSTART and DURATION are, then the test should instead
operate on the 'effective' DUE, i.e. DTSTART+DURATION.
The semantic of CALDAV:time-range is not defined for any other
calendar properties.
Definition:
start value: an iCalendar "date with UTC time"
end value: an iCalendar "date with UTC time"
9.10. CALDAV:calendar-multiget XML Element
Name: calendar-multiget
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: CalDAV REPORT used to retrieve specific calendar object
resources.
Description: See Section 7.9.
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Definition:
9.11. CALDAV:free-busy-query XML Element
Name: free-busy-query
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: CalDAV REPORT used to generate a VFREEBUSY to determine busy
time over a specific time range.
Description: See Section 7.10.
Definition:
10. Internationalization Considerations
CalDAV allows internationalized strings to be stored and retrieved
for the description of calendar collections (see Section 5.2.1).
The CALDAV:calendar-query report (Section 7.8) includes a text
searching option controlled by the CALDAV:text-match element and
details of character handling are covered in the description of that
element (see Section 9.7.5).
11. Security Considerations
HTTP protocol transactions are sent in the clear over the network
unless protection from snooping is negotiated. This can be
accomplished by use of TLS as defined in [RFC2818]. In particular,
HTTP Basic authentication MUST NOT be used unless TLS is in effect.
Servers MUST take adequate precautions to ensure malicious clients
cannot consume excessive server resources (CPU, memory, disk, etc.)
through carefully crafted reports. For example, a client could
upload an event with a recurrence rule that specifies a recurring
event occurring every second for the next 100 years which would
result in approximately 3 x 10^9 instances! A REPORT that asks for
recurrences to be expanded over that range would likely constitute a
denial-of-service attack on the server.
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When creating new resources (including calendar collections), clients
MUST ensure that the resource name (the last path segment of the
resource URI) assigned to the new resource does not expose any data
from within the iCalendar resource itself and information about the
nature of a calendar collection. This is required to ensure that the
presence of a specific iCalendar component or nature of components in
a collection cannot be inferred based on the name of a resource.
When rolling up free-busy information, more information about a
user's events is exposed if busy periods overlap or are adjacent
(this tells the client requesting the free-busy information that the
calendar owner has at least two events, rather than knowing only that
the calendar owner has one or more events during the busy period).
Thus, a conservative approach to calendar data privacy would have
servers always coalesce such busy periods when they are the same
type.
Procedure alarms are a known security risk for either clients or
servers to handle, particularly when the alarm was created by another
agent. Clients and servers are not required to execute such
procedure alarms.
Security considerations described in iCalendar [RFC2445] and iTIP
[RFC2446] are also applicable to CalDAV.
Beyond these, CalDAV does not raise any security considerations that
are not present in HTTP [RFC2616] and WebDAV [RFC2518], [RFC3253],
[RFC3744], as discussed in those documents.
12. IANA Consideration
This document uses one new URN to identify a new XML namespace. The
URN conforms to a registry mechanism described in [RFC3688].
12.1. Namespace Registration
Registration request for the CalDAV namespace:
URI: urn:ietf:params:xml:ns:caldav
Registrant Contact: See the "Author's Address" section of this
document.
XML: None. Namespace URIs do not represent an XML specification.
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13. Acknowledgements
The authors would like to thank the following individuals for
contributing their ideas and support for writing this specification:
Michael Arick, Mario Bonin, Chris Bryant, Scott Carr, Mike Douglass,
Ted Hardie, Sam Hartman, Helge Hess, Jeff McCullough, Alexey
Melnikov, Dan Mosedale, Brian Moseley, Kervin L. Pierre, Julian F.
Reschke, Wilfredo Sanchez Vega, Mike Shaver, Jari Urpalainen, Simon
Vaillancourt, Jim Whitehead.
The authors would also like to thank the Calendaring and Scheduling
Consortium for advice with this specification, and for organizing
interoperability testing events to help refine it.
14. References
14.1. Normative References
[I-D.newman-i18n-comparator]
Newman, C., "Internet Application Protocol Collation
Registry", draft-newman-i18n-comparator-13 (work in
progress), August 2006.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999.
[RFC2445] Dawson, F. and Stenerson, D., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 2445, November 1998.
[RFC2446] Silverberg, S., Mansour, S., Dawson, F., and R. Hopson,
"iCalendar Transport-Independent Interoperability Protocol
(iTIP) Scheduling Events, BusyTime, To-dos and Journal
Entries", RFC 2446, November 1998.
[RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S., and D.
Jensen, "HTTP Extensions for Distributed Authoring --
WEBDAV", RFC 2518, February 1999.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
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[RFC3253] Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J.
Whitehead, "Versioning Extensions to WebDAV (Web
Distributed Authoring and Versioning)", RFC 3253,
March 2002.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[RFC3744] Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web
Distributed Authoring and Versioning (WebDAV) Access
Control Protocol", RFC 3744, May 2004.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
[W3C.REC-xml-20060816]
Yergeau, F., Paoli, J., Bray, T., Sperberg-McQueen, C.,
and E. Maler, "Extensible Markup Language (XML) 1.0
(Fourth Edition)", World Wide Web Consortium
Recommendation REC-xml-20060816, August 2006,
.
14.2. Informative References
[I-D.ietf-webdav-rfc2518bis]
Dusseault, L., "HTTP Extensions for Distributed Authoring
- WebDAV", draft-ietf-webdav-rfc2518bis-15 (work in
progress), May 2006.
[RFC2426] Dawson, F. and T. Howes, "vCard MIME Directory Profile",
RFC 2426, September 1998.
[RFC2739] Small, T., Hennessy, D., and F. Dawson, "Calendar
Attributes for vCard and LDAP", RFC 2739, January 2000.
[RFC4331] Korver, B. and L. Dusseault, "Quota and Size Properties
for Distributed Authoring and Versioning (DAV)
Collections", RFC 4331, February 2006.
[RFC4511] Sermersheim, J., "Lightweight Directory Access Protocol
(LDAP): The Protocol", RFC 4511, June 2006.
Appendix A. CalDAV Method Privilege Table (Normative)
The following table extends the WebDAV Method Privilege Table
specified in Appendix B of [RFC3744].
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+------------+------------------------------------------------------+
| METHOD | PRIVILEGES |
+------------+------------------------------------------------------+
| MKCALENDAR | DAV:bind |
| REPORT | DAV:read or CALDAV:read-free-busy (on all referenced |
| | resources) |
+------------+------------------------------------------------------+
Appendix B. Calendar collections used in the examples
This appendix shows the calendar object resources contained in the
calendar collection queried in the examples throughout this document.
The content of the calendar collection is being shown as it would be
returned by a CALDAV:calendar-query REPORT request designed to return
all the calendar data in the collection:
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
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http://cal.example.com/bernard/work/abcd1.ics
"fffff-abcd1"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
DTSTAMP:20060206T001102Z
DTSTART;TZID=US/Eastern:20060102T100000
DURATION:PT1H
SUMMARY:Event #1
Description:Go Steelers!
UID:74855313FA803DA593CD579A@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd2.ics
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"fffff-abcd2"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060102T120000
DURATION:PT1H
RRULE:FREQ=DAILY;COUNT=5
SUMMARY:Event #2
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060104T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060104T120000
SUMMARY:Event #2 bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd3.ics
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"fffff-abcd3"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
LAST-MODIFIED:20040110T032845Z
TZID:US/Eastern
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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
END:VEVENT
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd4.ics
"fffff-abcd4"
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BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235335Z
DUE;VALUE=DATE:20060104
STATUS:NEEDS-ACTION
SUMMARY:Task #1
UID:DDDEEB7915FA61233B861457@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd5.ics
"fffff-abcd5"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235300Z
DUE;VALUE=DATE:20060106
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:NEEDS-ACTION
SUMMARY:Task #2
UID:E10BA47467C5C69BB74E8720@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
HTTP/1.1 200 OK
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http://cal.example.com/bernard/work/abcd6.ics
"fffff-abcd6"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
COMPLETED:20051223T122322Z
DTSTAMP:20060205T235400Z
DUE;VALUE=DATE:20051225
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:COMPLETED
SUMMARY:Task #3
UID:E10BA47467C5C69BB74E8722@example.com
END:VTODO
END:VCALENDAR
HTTP/1.1 200 OK
http://cal.example.com/bernard/work/abcd7.ics
"fffff-abcd7"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235600Z
DUE;VALUE=DATE:20060101
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:CANCELLED
SUMMARY:Task #4
UID:E10BA47467C5C69BB74E8725@example.com
END:VTODO
END:VCALENDAR
HTTP/1.1 200 OK
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http://cal.example.com/bernard/work/abcd8.ics
"fffff-abcd8"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VFREEBUSY
ORGANIZER;CN="Bernard Desruisseaux":mailto:bernard@example.com
UID:76ef34-54a3d2@example.com
DTSTAMP:20050530T123421Z
DTSTART:20060101T000000Z
DTEND:20060108T000000Z
FREEBUSY:20050531T230000Z/20050601T010000Z
FREEBUSY;FBTYPE=BUSY-TENTATIVE:20060102T100000Z/20060102T120000Z
FREEBUSY:20060103T100000Z/20060103T120000Z
FREEBUSY:20060104T100000Z/20060104T120000Z
FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:20060105T100000Z/20060105T120000Z
FREEBUSY:20060106T100000Z/20060106T120000Z
END:VFREEBUSY
END:VCALENDAR
HTTP/1.1 200 OK
Appendix C. Changes (to be removed prior to publication as an RFC)
C.1. Changes in -15
a. Switched to using collations for text-match element in calendar-
query report.
b. Removed caseless attribute from text-match element.
c. Removed UNICODE4 reference.
d. Removed mailing list comment.
e. Made calendar-home-set property a SHOULD as it was in previous
drafts.
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f. Now require https download of external attachments.
g. Changed some improper uses of 2119 terms to lowercase.
h. Updated some references to latest specs.
C.2. Changes in -14
a. Reverted to normative reference to 2518 and added informative
reference to 2518bis.
b. Reinserted section describing preconditions/postconditions.
c. Removed redundant compliance statement in last paragraph of
Section 3.
d. Clarify that only text/calendar is allowed if supported-calendar-
data property is not present.
e. Removed redundant compliance statement in Conformance paragraph
of Section 6.2.1.
f. Removed redundant compliance statement in first paragraph of
Section 7.5.
g. Fixed incorrect whitespace in elements in example in Section
7.7.6.
h. Fixed incorrect CDATA descriptions in various places.
C.3. Changes in -13
a. Changed mailing list draft description.
b. Added security review suggested text to Security Considerations.
c. Changed external attachment support to require http URI
downloads, and optionally others.
d. Added reference to text-match element in Internationalization
Considerations section.
e. Changed 'undefined' to 'not specified here' in ETag behavior
section.
f. Added reference to RFC4346 with note that it obsoletes RFC2246
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C.4. Changes in -12
a. Changed requirements for ETags on PUT to better reflect the needs
of CalDAV clients wrt synchronization and reflect what other
standards define or do not define.
b. Changed CALDAV:read-free-busy privilege so that it is also
defined on regular collections.
C.5. Changes in -11
a. Added statement that calendar-query Depth defaults to zero if
header is not present. Fixed one multiget example's Depth
header.
b. Fixed reference to WebDAV Quota RFC.
c. Changed DAV:resource to DAV:href in CALDAV:no-uid-conflict
element.
d. Added CALDAV:calendar-collection-location-ok pre-condition for
COPY and MOVE.
e. Added CALDAV:max-resource-size, CALDAV:min-date-time, CALDAV:max-
date-time, CALDAV:max-instances, CALDAV:max-attendees-per-
instance properties and preconditions.
f. Changed to 2518bis reference.
g. Now require 2518bis Class 3 behaviour.
h. Fixed indentation in examples and removed bogus whitespace before
tags.
i. Fixed typo.
j. Added text to element definition as a reminder
about the need to do XML character data encoding on any iCalendar
data within that element.
k. Major reworking of CALDAV:time-range element description to
better cover all possibilities for each type of component based
on which properties are present.
l. Added is-not-defined and negate-condition options to reports and
a new example to illustrate use of those.
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m. Fixed descriptions of some calendar collection properties.
n. Removed section describing preconditions/postconditions as this
is incorporated into 2518bis.
o. Clarified issue about separate component types in separate
resources.
p. Reworded section on servers being allowed to reject changes to
their own private use iCal values.
q. Clarified overridden component 'current' and 'original' time
range overlap.
r. Added more section references for XML element definitions.
s. Reworded limit-recurrence-set definition to try and make it clear
that mast component is always returned, but only some overridden
one are returned.
t. Clarified dependence on UNICODE reference for caseless matching.
C.6. Changes in -10
a. Added new section about support for X- items when storing data.
b. Added new precondition to allow servers to reject queries on
unsupported X- items, and a new example.
c. Added new text about always supporting X- in calendar-data.
d. Created new section for PUT, COPY and MOVE preconditions.
e. Report examples re-done with full listing of calendar data in
Appendix.
f. Removed description of using UID, SUMMARY etc as resource name.
g. Indicate that calendar object resource may contain only
overridden components.
h. Add security consideration about not expose details in resource
names.
i. Add constraint that free-busy-query can only be run on a
collection.
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j. Add preconditions for calendar-timezone property/elements in
MKCALENDAR, PROPPATCH and calendar-query REPORT.
k. Fix principal-match example.
C.7. Changes in -09
a. Numerous editorial changes.
b. Removed the CALDAV:is-defined XML element.
c. Removed section on privilege aggregation.
d. Renamed the CALDAV:expand-recurrence-set XML element to CALDAV:
expand and clarified the server behavior.
e. Renamed the CALDAV:calendar-component-restriction-set XML
element to CALDAV:supported-calendar-component-set.
f. Renamed the CALDAV:calendar-restrictions XML element to CALDAV:
supported-calendar-data.
g. Renamed some preconditions as "success conditions" instead of
"failure causes". For instance, the precondition CALDAV:
calendar-collection-location-bad has been renamed to CALDAV:
calendar-collection-location-ok.
h. Reordered some sections.
i. Clarified the definition of CALDAV:time-range to specify that a
repeating VALARM component is said to intersect a given time
range if at least one of its trigger intersect the time range.
j. Clarified that calendar object resources stored in calendar
collections MUST NOT specify the iCalendar METHOD property.
k. Clarified that CALDAV:calendar-data XML element is not a WebDAV
property even though it is specified in the DAV:prop XML element
in both calendaring REPORT requests and responses.
l. Clarified CALDAV:limit-recurrence-set with respect to the RANGE
parameter on the RECURRENCE-ID property.
m. Changed the CALDAV:free-busy-query XML element to contain
exactly one CALDAV:time-range XML element.
n. Changed many ELEMENT and ATTLIST declarations to comply with DTD
syntax.
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o. Changed XML element CALDAV:calendar-query to allow new XML
element CALDAV:timezone.
p. Changed the XML elements CALDAV:time-range, CALDAV:expand and
CALDAV:limit-recurrence-set to only allow DATE-TIME with UTC
time values for the "start" and "end" attributes.
q. Changed description of CALDAV:limit-recurrence-set to specify
that re-scheduled "overridden" recurrence instances whose
original scheduled time used to overlap the time range specified
by the "start" and "end" attribute should always be returned in
a REPORT response.
r. Changed the description of the value of CALDAV:calendar-data XML
element to specify that the CR character (US-ASCII decimal 13)
MAY be omitted in the iCalendar object specified in this XML
element.
s. Added specific requirements for entity tags support.
t. Added more preconditions.
u. Added further guidelines about finding calendars.
v. Added XML element CALDAV:limit-freebusy-set to limit the set of
FREEBUSY property values returned in VFREEBUSY components.
w. Added property CALDAV:calendar-timezone on calendar collections.
x. Added XML element CALDAV:timezone to override the CALDAV:
calendar-timezone property for a given CALDAV:calendar-query
REPORT request.
y. Added text on the conversion of "floating date" and "floating
time" values to date with UTC time values.
z. Completed internationalization considerations section.
aa. Completed security considerations section.
C.8. Changes in -08
a. Removed statement that said that client SHOULD always request
DAV:getetag in calendar REPORTs.
b. Removed redefiniton of DAV:response.
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c. Removed XML elements CALDAV:calendar-data-only.
d. Removed resource type CALDAV:calendar-home.
e. Moved the CALDAV:calendar-data element in the DAV:prop element in
requests, and in the DAV:propstat element in responses.
f. Further defined the request body of MKCALENDAR to allow clients
to set properties at calendar collection creation time.
g. Renamed CALDAV:calendar-home-URL to CALDAV:calendar-home-set
h. Clarified the fact that calendar collections may only contain
calendar object resources and ordinary collections.
i. Clarified that calendar REPORTs should only be applied to
calendar object resources contained in calendar collections.
j. Changed the CALDAV:calendar-component-restriction-set and CALDAV:
calendar-restriction properties to always be protected.
k. Changed to use existing postcondition DAV:needs-privileges
instead of a new CALDAV:insufficient-privilege postcondition.
l. Added example for limit-recurrence-set.
m. Added example for expand-recurrence-set.
n. Moved CALDAV:calendar-address-set in the calendar-schedule draft
and renamed it to CALDAV:calendar-user-address-set.
o. Added guidelines on attachments and alarms.
C.9. Changes in -07
a. Various editorial changes.
b. Added properties calendar-restrictions and calendar-component-
restriction-set on calendar collections.
c. Added properties calendar-home-URL and calendar-address-set on
principal resources.
d. Removed property calendar-URL on principal resources.
e. Added pre- and postconditions to reports.
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f. Added new XML elements calendar-data-only and limit-recurrent-
set.
g. Modified calendar-data XML element to support the attributes
content-type and version.
h. Reorganised sections 3, 4, 5 & 6 into two sections and re-ordered
sub-sections.
i. Added comment about client not setting a duplicate displayname.
j. Removed three CalDAV OPTIONS requests.
k. Changed "authenticated user" to "user" in various places.
l. Rewrote section on calendar object resource restrictions for
better clarity.
C.10. Changes in -06
a. Reworded section "Recurrence and the Data Model".
b. Removed timezone collection feature.
c. Removed ability for a server to return the Location header on a
successful PUT request.
d. Clarified restrictions on calendar object resources contained in
calendar collections.
e. Added preconditions on PUT in calendar collections.
f. Added informative "Guidelines" section, with information on
locking and how to find calendar collections.
g. Moved "Sychronization Operations" section in the "Guidelines"
section.
C.11. Changes in -05
a. Removed a lot of non-normative text.
b. Removed property promotion/demotion requirements.
c. Removed calendar-owner and cal-scale properties.
d. Removed 'ical' prefix/text from element names.
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e. Relaxed WebDAV Class 2 (locking) requirement to a MAY.
f. Relaxed MKCALENDAR requirement to a SHOULD.
g. Moved the XML Namespace section in the Introduction.
h. Added CALDAV: prefix to CalDAV XML elements in the text.
i. Added CALDAV:calendar-multiget report.
j. Added CALDAV:free-busy-query report.
k. Added CALDAV:calendar-description property.
l. Changed CALDAV:calendar-query-result element name to CALDAV:
calendar-data
m. Added description and examples of handling timezones.
n. Added mandatory "start" and "end" attributes to the CALDAV:
expand-recurrence-set element.
o. Added three CalDAV OPTIONS requests.
p. Grouped XML Element declarations in a separate section.
C.12. Changes in -04
a. Added a note about the HTTP Location response header.
b. Added report calendar-query.
c. Removed reports calendar-property-search and calendar-time-range.
d. Removed section on CalDAV and timezones.
e. Added requirement to return ETag on creation.
f. Revised data model to remove sub-collections from calendar
collection.
g. Added informative references section.
h. Removed dependencies on DASL.
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C.13. Changes in -03
a. Removed Calendar Containers (simplification that doesn't seem to
remove much functionality)
b. Added MKCALENDAR to create calendars and all sub-collections
c. Added cal-scale property to calendars
C.14. Changes in -02
Basically still adding major sections of content:
a. Defined new field values to the OPTIONS "DAV:" response header
b. Added new resource properties
c. Added new principal properties
d. Added new SCHEDULE method and related headers
e. Added new privileges for scheduling
C.15. Changes in -01
a. Added section on privileges for calendaring, extending WebDAV ACL
privilege set
b. Defined what to do with unrecognized properties in the bodies of
iCalendar events, with respect to property promotion/demotion
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Authors' Addresses
Cyrus Daboo
Apple Computer, Inc.
1 Infinite Loop
Cupertino, CA 95014
USA
Email: cyrus@daboo.name
URI: http://www.apple.com/
Bernard Desruisseaux
Oracle Corporation
600 Blvd. de Maisonneuve West
Suite 1900
Montreal, QC H3A 3J2
CA
Email: bernard.desruisseaux@oracle.com
URI: http://www.oracle.com/
Lisa Dusseault
Open Source Application Foundation
2064 Edgewood Dr.
Palo Alto, CA 94303
US
Email: lisa@osafoundation.org
URI: http://www.osafoundation.org/
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