Network Working Group C. Daboo
Request for Comments: 4791 Apple
Category: Standards Track B. Desruisseaux
Oracle
L. Dusseault
CommerceNet
March 2007
Calendaring Extensions to WebDAV (CalDAV)
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This document defines extensions to the Web Distributed Authoring and
Versioning (WebDAV) protocol to specify a standard way of accessing,
managing, and sharing calendaring and scheduling information based on
the iCalendar format. This document defines the "calendar-access"
feature of CalDAV.
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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 . . . . . . . . . . . . 19
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
7.4. Time Range Filtering . . . . . . . . . . . . . . . . . . . 32
7.5. Searching Text: Collations . . . . . . . . . . . . . . . . 33
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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 . . . . . . . . . . . . . . . 36
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 . . . . . . . . . . . . . . . . . . . . . . 48
7.8.5. Example: Retrieval of To-Dos by Alarm Time Range . . . 50
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 . . . . . . . . . . . . . . . . . . . . . . . . . . 69
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 . . . . . . . . . . . . 70
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 . . . . . . . . . . 78
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 . . . . . . . . . . . . . . 81
9.6.3. CALDAV:allprop XML Element . . . . . . . . . . . . . . 81
9.6.4. CALDAV:prop XML Element . . . . . . . . . . . . . . . 82
9.6.5. CALDAV:expand XML Element . . . . . . . . . . . . . . 82
9.6.6. CALDAV:limit-recurrence-set XML Element . . . . . . . 83
9.6.7. CALDAV:limit-freebusy-set XML Element . . . . . . . . 84
9.7. CALDAV:filter XML Element . . . . . . . . . . . . . . . . 85
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9.7.1. CALDAV:comp-filter XML Element . . . . . . . . . . . . 85
9.7.2. CALDAV:prop-filter XML Element . . . . . . . . . . . . 86
9.7.3. CALDAV:param-filter XML Element . . . . . . . . . . . 87
9.7.4. CALDAV:is-not-defined XML Element . . . . . . . . . . 88
9.7.5. CALDAV:text-match XML Element . . . . . . . . . . . . 88
9.8. CALDAV:timezone XML Element . . . . . . . . . . . . . . . 89
9.9. CALDAV:time-range XML Element . . . . . . . . . . . . . . 90
9.10. CALDAV:calendar-multiget XML Element . . . . . . . . . . . 94
9.11. CALDAV:free-busy-query XML Element . . . . . . . . . . . . 95
10. Internationalization Considerations . . . . . . . . . . . . . 95
11. Security Considerations . . . . . . . . . . . . . . . . . . . 95
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 96
12.1. Namespace Registration . . . . . . . . . . . . . . . . . . 96
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 96
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 97
14.1. Normative References . . . . . . . . . . . . . . . . . . . 97
14.2. Informative References . . . . . . . . . . . . . . . . . . 98
Appendix A. CalDAV Method Privilege Table (Normative) . . . . . . 99
Appendix B. Calendar Collections Used in the Examples . . . . . . 99
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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 types. 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 Appendix 3 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 either be 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 the calendar
object resource format;
o MUST support WebDAV Class 1 [RFC2518] (note that [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]);
o MUST support ETags [RFC2616] with additional requirements
specified in Section 5.3.4 of this document;
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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 that 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, to-do, 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
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
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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.
Therefore, 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 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 one VEVENT component 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 that 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).
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For example, given the following iCalendar object:
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:
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A calendar collection can be created through provisioning (i.e.,
automatically created when a user's account is provisioned), or it
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 rooms). However, note that this document doesn't
define the purpose of extra calendar collections. 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, access-control, calendar-access
Date: Sat, 11 Nov 2006 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, method,
or privilege defined in this specification.
5.2. Calendar Collection Properties
This section defines properties for 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.
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Definition:
PCDATA value: an iCalendar object with exactly one VTIMEZONE
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]).
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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
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 all component types are accepted.
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
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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 "text/calendar" and iCalendar version 2.0, and clients can
assume that the server will only accept this data.
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 a
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
DATE-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 DATE-TIME value in a calendar object resource
stored in a calendar collection. Any attempt to store a calendar
object resource using a DATE or DATE-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
DATE-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 DATE-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
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5.2.8. CALDAV:max-instances Property
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
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returned by a PROPFIND DAV:allprop request (as defined in Section
12.14.1 of [RFC2518]).
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
Calendar collections and calendar object resources may be created by
either a CalDAV client or by the CalDAV server. This specification
defines restrictions and a data model that both clients and servers
MUST adhere to when manipulating such calendar data.
5.3.1. MKCALENDAR Method
An HTTP request using the MKCALENDAR method creates a new calendar
collection resource. A server MAY restrict calendar collection
creation to particular collections.
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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 help organize their data better.
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:
(DAV:resource-must-be-null): A resource MUST NOT exist at the
Request-URI;
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(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;
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
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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: Sat, 11 Nov 2006 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: Sat, 11 Nov 2006 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, or when
a COPY or MOVE operation of a calendar object resource into a
calendar collection occurs, or when a COPY or MOVE operation occurs
on a calendar collection.
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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 DATE-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 DATE-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, access to GET, HEAD,
OPTIONS, and PROPFIND on the resource is not implied (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 are either 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 request, based on the
value of the Depth request header.
Daboo, et al. Standards Track [Page 31]
RFC 4791 CalDAV March 2007
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 11, 2005 in no specific
time zone, while the DATE-TIME value "20051111T111100" represents
November 11, 2005, at 11:11 A.M. 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, or 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.
Daboo, et al. Standards Track [Page 32]
RFC 4791 CalDAV March 2007
When such time range filtering is used, special consideration must be
given to recurring calendar components, such as VEVENT and VTODO.
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 are compared to stored
calendar data. Since iCalendar data is, by default, encoded in the
UTF-8 charset and may include characters outside 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 [RFC4790] 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
[RFC4790], 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 [RFC4790], 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 [RFC4790], Section 3.1), the server MUST default to using
"i;ascii-casemap" as the collation.
Wildcards (as defined in [RFC4790], 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.
Daboo, et al. Standards Track [Page 33]
RFC 4791 CalDAV March 2007
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 specify whether all calendar components and
properties should be returned, or only particular ones. See CALDAV:
calendar-data in Section 9.6.
Daboo, et al. Standards Track [Page 34]
RFC 4791 CalDAV March 2007
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
recurrence set, referred to as the "overridden components".
A CalDAV client that is 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, or if it affects other
instances that 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 unwilling 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 on which the
server does not support queries.
Daboo, et al. Standards Track [Page 35]
RFC 4791 CalDAV March 2007
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
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 that does not exist is an
error and MUST be noted with a response XML element that 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
Daboo, et al. Standards Track [Page 36]
RFC 4791 CalDAV March 2007
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
instance, a CALDAV:filter cannot nest a
element in a element, and 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 DATE-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 request;
(CALDAV:max-date-time): Any XML element specifying a range of time
MUST have its start or end DATE or DATE-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 request;
(CALDAV:supported-collation): Any XML attribute specifying a
collation MUST specify a collation supported by the server as
described in Section 7.5.
Daboo, et al. Standards Track [Page 37]
RFC 4791 CalDAV March 2007
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.
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 4, 2006, at 00:00:00 A.M. UTC to January 5,
2006, at 00:00:00 A.M. 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 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.
Daboo, et al. Standards Track [Page 38]
RFC 4791 CalDAV March 2007
>> 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: Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Daboo, et al. Standards Track [Page 39]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 40]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 41]
RFC 4791 CalDAV March 2007
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 3, 2006, at 00:
00:00 A.M. UTC to January 5, 2006, at 00:00:00 A.M. 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: Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Daboo, et al. Standards Track [Page 42]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 43]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 44]
RFC 4791 CalDAV March 2007
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 2, 2006, at 00:
00:00 A.M. UTC to January 5, 2006, at 00:00:00 A.M. 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: Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Daboo, et al. Standards Track [Page 45]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 46]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 47]
RFC 4791 CalDAV March 2007
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 2, 2006, at 00:00:00 A.M. UTC (inclusively)
to January 3, 2006, at 00:00:00 A.M. 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.
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Daboo, et al. Standards Track [Page 48]
RFC 4791 CalDAV March 2007
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Sat, 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
Daboo, et al. Standards Track [Page 49]
RFC 4791 CalDAV March 2007
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.
>> Request <<
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Daboo, et al. Standards Track [Page 50]
RFC 4791 CalDAV March 2007
>> Response <<
HTTP/1.1 207 Multi-Status
Date: Sat, 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.
Daboo, et al. Standards Track [Page 51]
RFC 4791 CalDAV March 2007
>> 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: Sat, 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
Daboo, et al. Standards Track [Page 52]
RFC 4791 CalDAV March 2007
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.
Daboo, et al. Standards Track [Page 53]
RFC 4791 CalDAV March 2007
>> 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: Sat, 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
Daboo, et al. Standards Track [Page 54]
RFC 4791 CalDAV March 2007
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.
Daboo, et al. Standards Track [Page 55]
RFC 4791 CalDAV March 2007
>> 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: Sat, 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
Daboo, et al. Standards Track [Page 56]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 57]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 58]
RFC 4791 CalDAV March 2007
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.
Daboo, et al. Standards Track [Page 59]
RFC 4791 CalDAV March 2007
>> 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: Sat, 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
Daboo, et al. Standards Track [Page 60]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 61]
RFC 4791 CalDAV March 2007
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 an 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: Sat, 11 Nov 2005 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Daboo, et al. Standards Track [Page 62]
RFC 4791 CalDAV March 2007
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 CALDAV: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 DATE-TIME values greater than
Daboo, et al. Standards Track [Page 63]
RFC 4791 CalDAV March 2007
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 request;
(CALDAV:max-date-time): Any XML element specifying a range of time
MUST have its start or end DATE or DATE-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 request;
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: Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Daboo, et al. Standards Track [Page 64]
RFC 4791 CalDAV March 2007
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
Daboo, et al. Standards Track [Page 65]
RFC 4791 CalDAV March 2007
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 that 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
in generating 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 periods of the
same type. Busy time periods with different FBTYPE parameter values
MAY overlap.
Support for the CALDAV:free-busy-query REPORT is REQUIRED.
Daboo, et al. Standards Track [Page 66]
RFC 4791 CalDAV March 2007
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 of calendar object resources to be considered in computing
the response.
Daboo, et al. Standards Track [Page 67]
RFC 4791 CalDAV March 2007
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
A.M. and 5:00 P.M. EST (2:00 P.M. and 10:00 P.M. UTC) on the January
4, 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: Sat, 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
Daboo, et al. Standards Track [Page 68]
RFC 4791 CalDAV March 2007
8. Guidelines
8.1. Client-to-Client Interoperability
There are a number of actions clients can take that will be legal
(the server will not return errors), but that 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, to ma