Network Working Group C. Daboo
Internet-Draft ISAMET
Expires: November 25, 2005 B. Desruisseaux
Oracle
L. Dusseault
OSAF
May 24, 2005
Calendaring Extensions to WebDAV (CalDAV)
draft-dusseault-caldav-06
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document specifies a set of methods, headers, message bodies,
properties, and reports that define calendar access extensions to the
WebDAV protocol. The new protocol elements are intended to make
WebDAV-based calendaring and scheduling an interoperable standard
that supports single-user calendar access, calendar sharing, and
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calendar publishing.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 XML Namespaces . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Notational Conventions . . . . . . . . . . . . . . . . . . 5
1.3 Method Preconditions and Postconditions . . . . . . . . . 6
2. CalDAV Requirements Overview . . . . . . . . . . . . . . . . . 7
3. Calendaring Data Model . . . . . . . . . . . . . . . . . . . . 8
3.1 Calendar Server . . . . . . . . . . . . . . . . . . . . . 8
3.2 Recurrence and the Data Model . . . . . . . . . . . . . . 9
4. New Resource Types . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Calendar Collection . . . . . . . . . . . . . . . . . . . 10
4.2 Calendar Resources Restrictions in Calendar Collections . 10
5. Creating Resources . . . . . . . . . . . . . . . . . . . . . . 13
5.1 MKCALENDAR Method . . . . . . . . . . . . . . . . . . . . 13
5.1.1 Status Codes . . . . . . . . . . . . . . . . . . . . . 14
5.1.2 Example - MKCALENDAR . . . . . . . . . . . . . . . . . 15
5.2 Additional OPTIONS Semantics . . . . . . . . . . . . . . . 15
5.2.1 Capability Discovery . . . . . . . . . . . . . . . . . 15
5.2.1.1 Example: Using OPTIONS for the Discovery of
Support for CalDAV . . . . . . . . . . . . . . . . 15
5.2.2 CALDAV:calendar-collection-set OPTIONS request . . . . 16
5.2.3 CALDAV:current-user-calendar-collection-set
OPTIONS request . . . . . . . . . . . . . . . . . . . 16
5.2.4 Example - OPTIONS . . . . . . . . . . . . . . . . . . 17
5.3 Creating calendar resources . . . . . . . . . . . . . . . 18
6. Calendaring Properties . . . . . . . . . . . . . . . . . . . . 20
6.1 CALDAV:calendar-description Property . . . . . . . . . . . 20
7. Calendaring Access Control . . . . . . . . . . . . . . . . . . 21
7.1 Calendaring Privileges . . . . . . . . . . . . . . . . . . 21
7.1.1 CALDAV:view-free-busy Privilege . . . . . . . . . . . 21
7.1.2 Privilege aggregation and the
DAV:supported-privilege-set property . . . . . . . . . 21
7.1.2.1 Partial example of DAV:supported-privilege-set
property . . . . . . . . . . . . . . . . . . . . . 22
7.2 Additional Principal Properties . . . . . . . . . . . . . 23
7.2.1 CALDAV:calendar-URL Property . . . . . . . . . . . . . 23
8. Calendaring Reports . . . . . . . . . . . . . . . . . . . . . 25
8.1 REPORT Method . . . . . . . . . . . . . . . . . . . . . . 25
8.2 Reports on collections containing calendar collections . . 25
8.3 CALDAV:calendar-query Report . . . . . . . . . . . . . . . 25
8.3.1 Example: Partial retrieval of events by time range . . 26
8.3.2 Example: Retrieval of todos by alarm time range . . . 29
8.3.3 Example: Retrieval of event by UID . . . . . . . . . . 29
8.3.4 Example: Retrieval of events by participation
status . . . . . . . . . . . . . . . . . . . . . . . . 30
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8.3.5 Example: Retrieval of events only . . . . . . . . . . 31
8.4 CALDAV:calendar-multiget Report . . . . . . . . . . . . . 32
8.4.1 Example: CALDAV:calendar-multiget Report . . . . . . . 33
8.5 CALDAV:free-busy-query Report . . . . . . . . . . . . . . 35
8.5.1 Example: CALDAV:free-busy-query Report . . . . . . . . 37
9. Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9.1 Client-to-client Interoperability . . . . . . . . . . . . 39
9.2 Sychronization Operations . . . . . . . . . . . . . . . . 39
9.2.1 Use of Reports . . . . . . . . . . . . . . . . . . . . 39
9.2.1.1 Restrict the Time Range . . . . . . . . . . . . . 39
9.2.1.2 Synchronize by Time Range . . . . . . . . . . . . 39
9.2.1.3 Synchronization Process . . . . . . . . . . . . . 40
9.2.2 Restrict the Properties Returned . . . . . . . . . . . 42
9.3 Use of Locking . . . . . . . . . . . . . . . . . . . . . . 43
9.4 Finding calendars . . . . . . . . . . . . . . . . . . . . 43
10. XML Element Definitions . . . . . . . . . . . . . . . . . . 45
10.1 CALDAV:calendar-query XML Element . . . . . . . . . . . . 45
10.2 CALDAV:calendar-data XML Element . . . . . . . . . . . . . 45
10.2.1 CALDAV:comp XML Element . . . . . . . . . . . . . . . 45
10.2.2 CALDAV:allcomp XML Element . . . . . . . . . . . . . . 46
10.2.3 CALDAV:allprop XML Element . . . . . . . . . . . . . . 46
10.2.4 CALDAV:prop XML Element . . . . . . . . . . . . . . . 47
10.2.5 CALDAV:expand-recurrence-set XML Element . . . . . . . 47
10.3 CALDAV:filter XML Element . . . . . . . . . . . . . . . . 48
10.3.1 CALDAV:comp-filter XML Element . . . . . . . . . . . . 48
10.3.2 CALDAV:prop-filter XML Element . . . . . . . . . . . . 49
10.3.3 CALDAV:param-filter XML Element . . . . . . . . . . . 49
10.3.4 CALDAV:is-defined XML Element . . . . . . . . . . . . 50
10.3.5 CALDAV:text-match XML Element . . . . . . . . . . . . 50
10.4 CALDAV:time-range XML Element . . . . . . . . . . . . . . 50
10.5 DAV:response XML Element . . . . . . . . . . . . . . . . . 52
10.6 CALDAV:calendar-multiget XML Element . . . . . . . . . . . 52
10.7 CALDAV:free-busy-query XML Element . . . . . . . . . . . . 52
11. Internationalization Considerations . . . . . . . . . . . . 53
12. Security Considerations . . . . . . . . . . . . . . . . . . 54
12.1 Authentication of Clients . . . . . . . . . . . . . . . . 54
12.2 Denial of Service . . . . . . . . . . . . . . . . . . . . 54
13. IANA Consideration . . . . . . . . . . . . . . . . . . . . . 55
13.1 Namespace Registration . . . . . . . . . . . . . . . . . . 55
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 56
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 57
15.1 Normative References . . . . . . . . . . . . . . . . . . . 57
15.2 Informative References . . . . . . . . . . . . . . . . . . 57
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 58
A. CalDAV Method Privilege Table (Normative) . . . . . . . . . . 59
B. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
B.1 Changes in -06 . . . . . . . . . . . . . . . . . . . . . . 60
B.2 Changes in -05 . . . . . . . . . . . . . . . . . . . . . . 60
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B.3 Changes in -04 . . . . . . . . . . . . . . . . . . . . . . 61
B.4 Changes in -03 . . . . . . . . . . . . . . . . . . . . . . 61
B.5 Changes in -02 . . . . . . . . . . . . . . . . . . . . . . 61
B.6 Changes in -01 . . . . . . . . . . . . . . . . . . . . . . 62
Intellectual Property and Copyright Statements . . . . . . . . 63
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1. Introduction
The concept of using HTTP [4] and WebDAV [3] as a basis for a
calendaring server 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 calendaring servers using HTTP PUT/GET to
upload and download iCalendar [2] objects, and using WebDAV PROPFIND
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 is therefore intended to propose a standard
way of modeling calendar data in WebDAV, plus some additional
features to make calendar access work well.
Discussion of this Internet-Draft is being done on the mailing list
<http://lists.osafoundation.org/mailman/listinfo/ietf-caldav>.
1.1 XML Namespaces
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 [8].
The namespace "urn:ietf:params:xml:ns:caldav" is reserved for the XML
elements defined in this specification, or in other Standards Track
IETF RFCs written to extend CalDAV. It MUST NOT be used for
proprietary extensions.
Note that the XML declarations used in this document are incomplete,
in that they do not include namespace information. Thus, the reader
MUST NOT use these declarations as the only way to create valid
CalDAV properties or to validate CalDAV XML element type. Some of
the declarations refer to XML elements defined by WebDAV which use
the "DAV:" namespace. Wherever such elements appear, they are
explicitly given the "DAV:" prefix to help avoid confusion.
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.
1.2 Notational Conventions
The augmented BNF used by this document to describe protocol elements
is described in Section 2.1 of [4]. Because this augmented BNF uses
the basic production rules provided in Section 2.2 of [4], those
rules apply to this document as well.
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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 [1].
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 types respectively.
1.3 Method Preconditions and Postconditions
A "precondition" of a method describes the state of the server that
must be true for that method to be performed. A "postcondition" of a
method describes the state of the server that must be true after that
method has been completed. If a method precondition or postcondition
for a request is not satisfied, the response status of the request
MUST be either 403 (Forbidden) if the request should not be repeated
because it will always fail, or 409 (Conflict) if it is expected that
the user might be able to resolve the conflict and resubmit the
request.
In order to allow better client handling of 403 and 409 responses, a
distinct XML element type is associated with each method precondition
and postcondition of a request. When a particular precondition is
not satisfied or a particular postcondition cannot be achieved, the
appropriate XML element MUST be returned as the child of a top-level
DAV:error element in the response body, unless otherwise negotiated
by the request. In a 207 Multi-Status response, the DAV:error
element would appear in the appropriate DAV:responsedescription
element.
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2. CalDAV Requirements Overview
This section lists what functionality is required of a CalDAV server.
To advertise support for CalDAV, a server:
o MUST support WebDAV Class 1.
o MUST support WebDAV ACL [7] with the privilege defined in
Section 7.1 of this document.
o MUST support SSL.
o MUST support strong ETags to support disconnected operations.
o MUST support all required calendaring REPORTs defined in this
document.
o MUST advertise calendaring REPORTs via the DAV:supported-report-
set property as defined in DeltaV [5].
In addition, a server:
o SHOULD support MKCALENDAR.
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3. Calendaring Data Model
One of the features which has made WebDAV a successful protocol is
its firm data model. This makes it a useful framework for other
applications such as calendaring. This specification attempts to
follow the same pattern by developing all new features based on a
well-described data model.
In the CalDAV data model, every iCalendar VEVENT, VJOURNAL, VTODO and
VFREEBUSY component is stored as an individual HTTP/WebDAV resource.
That means each calendar resource may be individually locked and have
individual WebDAV properties. These resources are placed into WebDAV
collections with a mostly-fixed structure.
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://example.org/webdav/" may contain
WebDAV collections and resources, all of which have URLs beginning
with "http://example.org/webdav/". Note that the root URL
"http://example.org/" 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 may advertise itself as a CalDAV server if it
supports the functionality defined in this specification at any point
within the root of the repository. That might mean that calendaring
data is spread throughout the repository and mixed with non-calendar
data in nearby collections (e.g., calendar data may be found in
/lisa/calendar/ as well as in /bernard/calendar/, and non-calendar
data in /lisa/contacts/). Or, it might mean that calendar data can
be found only in certain sections of the repository (e.g.,
/calendars/user/). Calendaring features are only required in the
repository sections that are or contain calendaring objects. So a
repository confining calendar data to the /caldav/ 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. Both CalDAV servers and clients
MUST ensure that the data is consistent and compliant. Clients may
submit requests to change data or download data. Clients may store
calendar objects offline and attempt to synchronize at a later time.
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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. HTTP ETags and other tools help this work.
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 proposal models a
recurring resource and its recurrence exceptions as a single WebDAV
resource. In this model, recurrence patterns, recurrence dates,
exception dates, and exception information are all part of the data
in a single master event. This decision avoids problems of limiting
how many recurrence instances to store in the repository, how to keep
instances in synch with the master, and how to link recurrence
exceptions with the master. It also results in less data to
synchronize between client and server, and makes it easier to make
changes to all recurrences or to a recurrence pattern. It makes it
easier to create a recurring component, and easier to delete all
recurrences.
Clients are not forced to retrieve information about all recurrence
instances of a recurring component. The CALDAV:calendar-query REPORT
defined in this document allow clients to retrieve only the
recurrence instances that occurs in a given time range.
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4. New Resource Types
CalDAV defines the following new resource types for use in WebDAV
repositories holding calendar data.
4.1 Calendar Collection
Calendar collections are manifested to clients as a WebDAV resource
collection, identified by a URL. A calendar collection MUST have a
non-empty DAV:displayname property (defined in Section 13.2 of
RFC2518 [3]), and a DAV:resourcetype property (defined in Section
13.9 of RFC2518 [3]). Additionally, 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:
<!ELEMENT calendar EMPTY>
A calendar collection contains resources that represent the iCalendar
objects within a calendar. A calendar collection may be created
through provisioning (e.g., automatically created when a user's
account is created), or it may be created through MKCALENDAR. This
can be useful for a user to create a second calendar (e.g., soccer
schedule) or for users to share a calendar (e.g., team events or
conference room). Note however that this document doesn't define
what extra calendar collections are for, users must rely on non-
standard cues to find out what a calendar collection is for, or use
the CALDAV:calendar-description property defined in Section 6.1 to
provide such a cue.
Calendar collections MUST NOT contain other calendar collections.
Multiple calendar collections MAY be children of the same WebDAV
collection.
A calendar collection MAY contain additional collections and non-
collection resources of types not defined here. How such items are
used is not defined by this specification. However, additional
collections contained in a calendar collection MUST NOT contain
calendar collections.
4.2 Calendar Resources Restrictions in Calendar Collections
Calendar resources contained in calendar collections MUST NOT contain
more than one type of calendar component (e.g., VEVENT, VTODO, 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 resource may contain two VEVENT
components and one VTIMEZONE component, but it may not contain one
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VEVENT component and one VTODO component.
Calendar resources that contain more than one calendar components of
the same type (e.g., VEVENT), with the exception of VTIMEZONE
components, are REQUIRED to have the same UID property value. For
instance, a calendar resource with two VEVENT components MUST specify
the same UID property value in the two VEVENT components. One of the
two VEVENT components could define the recurrence rule of an event,
and the other one could define an exception to the same event.
Calendar components with the same UID property value, in a given
calendar collection, MUST be contained in the same calendar resource.
All the recurrence instances of the same recurring calendar
component, that is, calendar components with the same UID property
value but with different RECURRENCE-ID property value MUST be
contained in the same calendar resource.
The UID property value of the calendar components contained in a
calendar resource MUST be unique in the scope of the calendar
collection, and all its descendant collections, in which the calendar
resource is contained.
For example, given the following iCalendar object:
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BEGIN:VCALENDAR
CALSCALE:GREGORIAN
PRODID:-//Example, Inc.\, Inc.//Example App//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
RECURRENCE-ID:20041213T120000Z
DTSTAMP:20041210T183838Z
DTSTART:20041213T130000Z
END:VEVENT
END:VCALENDAR
The VEVENT component with the UID value "1@example.com", would need
to be stored in its own calendar 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 need to be
stored in the same calendar resource.
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5. Creating Resources
The creation of calendar collections and calendar resources may be
initiated by either a CalDAV client or by the CalDAV server. For
example, a server might come preconfigured with a user's calendar
collection, or the CalDAV client might request the server to create a
new calendar collection for a given user. Servers might populate
events as calendar objects inside a calendar collection, or clients
might request the server to create events. Either way, both client
and server MUST comply with the requirements in this document, and
MUST understand objects appearing in calendar collections or
according to the data model defined here.
5.1 MKCALENDAR Method
A MKCALENDAR request creates a new calendar collection resource. A
server MAY restrict calendar collection creation to particular
collections, but a client can determine the location of these
collections from a CALDAV:calendar-collection-set OPTIONS request
(see Section 5.2.2).
Support for MKCALENDAR on the server is OPTIONAL because some
calendar stores only support one calendar per user (or principal) and
those are typically pre-created for each account. However, servers
and clients are strongly encouraged to support MKCALENDAR whenever
possible to allow users to create multiple calendar collections to
better help organize their data.
Clients SHOULD use the DAV:displayname property for a human-readable
name of the calendar. This requires the clients to issue a PROPPATCH
request to change the DAV:displayname property to the appropriate
value immediately after issuing the MKCALENDAR request. 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.
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.
<!ELEMENT mkcalendar ANY>
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If a response body for a successful request is included, it MUST
be a CALDAV:mkcalendar-response XML element.
<!ELEMENT mkcalendar-response ANY>
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.
(CALDAV:calendar-collection-location-ok): The Request-URI MUST
identify a location where a calendar collection can be created.
(CALDAV:insufficient-privilege): The DAV:bind privilege MUST be
granted to the current authenticated user.
Postconditions:
(CALDAV:initialize-calendar-collection): A new calendar collection
exists at the Request-URI. The DAV:resourcetype of the calendar
collection MUST be DAV:collection. Additionally, a calendar
collection MUST report the CALDAV:calendar XML element in the
value of the DAV:resourcetype property.
5.1.1 Status Codes
201 (Created) - The calendar collection resource was created in its
entirety.
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.
405 (Method Not Allowed) - MKCALENDAR can only be executed on a null
resource.
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.
507 (Insufficient Storage) - The resource does not have sufficient
space to record the state of the resource after the execution of this
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method.
5.1.2 Example - MKCALENDAR
>> Request <<
MKCALENDAR /calendars/user/lisa/ HTTP/1.1
Host: cal.example.com
Content-Length: 0
>> Response <<
HTTP/1.1 201 Created
Date: Fri, 22 Oct 2004 12:17:08 GMT
Content-Length: 0
Cache-Control: no-cache
In this example, a new calendar collection is created at
http://cal.example.com/calendars/user/lisa/
5.2 Additional OPTIONS Semantics
5.2.1 Capability Discovery
If the server supports the calendar-access feature, it 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, or methods. A value of "calendar-access" in the
DAV header MUST indicate that the server supports all MUST level
requirements and REQUIRED features specified in this document.
5.2.1.1 Example: Using OPTIONS for the Discovery of Support for CalDAV
>> Request <<
OPTIONS /calendars/users/ HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 200 OK
Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, REPORT
Allow: MKCALENDAR, ACL
DAV: 1, 2, access-control, calendar-access
Content-Length: 0
In this example, the OPTIONS response indicates that the server
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supports CalDAV in this namespace, therefore the '/calendars/users/'
collection may be used as a parent for calendar collections as the
MKCALENDAR method is available, and as a possible target for REPORT
requests for calendaring reports.
5.2.2 CALDAV:calendar-collection-set OPTIONS request
A CALDAV:calendar-collection-set element MAY be included in the
request body to identify collections that may contain calendar
collection resources.
Additional Marshalling:
If an XML request body is included, it MUST be a DAV:options XML
element.
<!ELEMENT options ANY>
ANY value: A sequence of elements with at most one
calendar-collection-set element.
If an XML response body for a successful request is included, it
MUST be a DAV:options-response XML element.
<!ELEMENT options-response ANY>
ANY value: A sequence of elements with at most one
calendar-collection-set element.
<!ELEMENT calendar-collection-set (href*)>
If CALDAV:calendar-collection-set is included in the request body,
the response body for a successful request MUST contain a CALDAV:
calendar-collection-set element identifying collections that may
contain calendar collections. An identified collection MAY be the
root collection of a tree of collections, all of which may contain
calendar collections. Since different servers can control
different parts of the URL namespace, different resources on the
same host MAY have different CALDAV:calendar-collection-set
values. The identified collections MAY be located on different
hosts from the resource.
5.2.3 CALDAV:current-user-calendar-collection-set OPTIONS request
A CALDAV:current-user-calendar-collection-set element MAY be included
in the request body to identify the calendar collections owned by the
current authenticated user.
Additional Marshalling:
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If an XML request body is included, it MUST be a DAV:options XML
element.
<!ELEMENT options ANY>
ANY value: A sequence of elements with at most one
current-user-calendar-collection-set element.
If an XML response body for a successful request is included, it
MUST be a DAV:options-response XML element.
<!ELEMENT options-response ANY>
ANY value: A sequence of elements with at most one
current-user-calendar-collection-set element.
<!ELEMENT current-user-calendar-collection-set (href*)>
If CALDAV:current-user-calendar-collection-set is included in the
request body, the response body for a successful request MUST
contain a CALDAV:current-user-calendar-collection-set element
identifying calendar collections owned by the current
authenticated user.
5.2.4 Example - OPTIONS
>> Request <<
OPTIONS /caldav-root/ HTTP/1.1
Host: cal.example.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:options xmlns:D="DAV:">
<C:calendar-collection-set
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
</D:options>
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>> Response <<
HTTP/1.1 200 OK
DAV: 1, calendar-access
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:options-response xmlns:D="DAV:">
<C:calendar-collection-set
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:href>http://cal.example.com/calendars/user/</D:href>
<D:href>http://cal.example.com/calendars/public/</D:href>
</C:calendar-collection-set>
</D:options-response>
In this example, the server indicates that it provides Class 1 DAV
support and calendar-access support. In addition, the server
indicates the requested locations of the calendar collection
resources. Naturally, the server may also have done an
authentication step (not shown) to ensure this operation was allowed.
5.3 Creating calendar resources
Clients typically populate calendar collections with calendar
resources. The URL for each calendar resource is entirely arbitrary,
and does not need to bear a specific relationship (but might) to the
calendar resource's subject, scheduled time, UID or other metadata.
A new calendar resource must have a new URL, otherwise the new
component would instead be an update to an existing calendar
resource.
When servers create new resources, it's not hard for the server to
choose a unique URL. 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 one
isn't created with a name collision. However, there are tools 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 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 last path segment could be a random number, or it could be a
sequence number, or a string related to the object's 'summary'
property. No matter how the name is chosen, the "If-None-Match"
header ensures that the client cannot overwrite an existing resource
even if it has accidentally chosen a duplicate resource name.
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Servers SHOULD return an ETag header containing the actual ETag of
the newly created resource on a successful creation.
>> Request <<
PUT /lisa/calendar/newevent.ics HTTP/1.1
If-None-Match: *
Host: cal.example.com
Content-Type: text/calendar
Content-Length: xxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:20010712T182145Z-123401@example.com
DTSTART:20010714T170000Z
DTEND:20010715T035959Z
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR
>> Response <<
HTTP/1.1 201 Created
Date: Thu, 02 Sep 2004 16:53:32 GMT
Content-Length: 0
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 RFC 2445 [2], the URL of calendar
resources containing (an arbitrary set of) calendaring and scheduling
information may be suffixed by ".ics", and the URL of calendar
resources containing free or busy time information may be suffixed by
".ifb".
Preconditions for PUT within calendar collections:
(CALDAV:uid-already-exists): The component UID chosen is not
unique and the client must choose another if it attempts again.
(CALDAV:invalid-calendar-resource): The iCalendar object syntax or
structure was invalid. (Note that the server MAY support upload
formats other than iCalendar but then the server MUST validate
each component uploaded according to the chosen format syntax.)
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6. Calendaring Properties
This specification defines new properties for WebDAV resources.
Calendar access properties may be retrieved just like other WebDAV
properties, using the PROPFIND method.
A DAV:allprop PROPFIND request SHOULD NOT return any of the
properties defined in this section.
6.1 CALDAV:calendar-description Property
Name: calendar-description
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Provides a description for the resource that is suitable for
presentation to a user.
Description: The CALDAV:calendar-description property MAY be defined
on all calendar collection resources. If present, the property
contains a description of the resource that is suitable for
presentation layer.
<!ELEMENT calendar-description (#PCDATA) >
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7. Calendaring Access Control
7.1 Calendaring Privileges
A CalDAV server MUST support WebDAV ACL [7]. WebDAV ACL provides a
framework for an extensible list of privileges on WebDAV collections
and ordinary resources. A CalDAV server MUST also support the
calendaring privilege defined in this section.
7.1.1 CALDAV:view-free-busy Privilege
Calendar users often wish to allow other users to see their free-busy
time intervals, without viewing the other details of the calendar
components (location, subject, attendees). This allows a significant
amount of privacy while still allowing those other users to schedule
meetings at times when the calendar user is likely to be free.
The CALDAV:view-free-busy privilege controls access to view the start
times and end times of free and busy time intervals. This privilege
may be granted on an entire calendar collection. It may also make
sense to grant this privilege on individual calendar resources (in
which case the time allocated to those calendar resources would show
up as free in the free-busy rollup to an unauthorized viewer), but a
server MAY forbid the CALDAV:view-free-busy privilege from being used
on individual calendar resources. A CalDAV server MUST support the
CALDAV:view-free-busy privilege on calendar collections.
<!ELEMENT view-free-busy EMPTY>
The CALDAV:view-free-busy privilege is aggregated in the DAV:read
privilege. Clients can discover support for various privileges using
the DAV:supported-privilege-set property defined in RFC3744 [7].
7.1.2 Privilege aggregation and the DAV:supported-privilege-set
property
In the WebDAV ACL standard, servers MUST support the DAV:supported-
privilege-set property to show which privileges are abstract, which
privileges are supported, how the privileges relate to another, and
to provide text descriptions (particularly useful for custom
privileges). The relationships between privileges involves showing
which privilege is a subset or a superset of another privilege. For
example, because reading the ACL property is considered a more
specific privilege than the DAV:read privilege (a subset of the total
set of actions are allowed), it is aggregated under the DAV:read
privilege. Although the list of supported privileges MAY vary
somewhat from server to server (the WebDAV ACL specification leaves
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room for a fair amount of diversity in server implementations), some
relationships MUST hold for a CalDAV server:
o The server MUST support the CALDAV:view-free-busy privilege. The
CALDAV:view-free-busy privilege MUST be non-abstract, and MUST be
aggregated under the DAV:read privilege.
7.1.2.1 Partial example of DAV:supported-privilege-set property
This is a partial example of how the DAV:supported-privilege-set
property could look on a server supporting CalDAV. Note that
aggregation is shown in the structure of the DAV:supported-privilege
elements containing each other.
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<D:supported-privilege-set xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:supported-privilege>
<D:privilege><D:all/></D:privilege>
<D:abstract/>
<D:description xml:lang="en">Any operation
</D:description>
<D:supported-privilege>
<D:privilege><D:read/></D:privilege>
<D:description xml:lang="en">Read any object
</D:description>
<D:supported-privilege>
<D:privilege><D:read-acl/></D:privilege>
<D:description xml:lang="en">Read ACL
</D:description>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege><D:read-current-user-privilege-set/>
</D:privilege>
<D:description xml:lang="en">Read current user privilege
set</D:description>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege>
<C:view-free-busy/>
</D:privilege>
<D:description xml:lang="en">View free-busy rollup
</D:description>
</D:supported-privilege>
</D:supported-privilege>
<D:supported-privilege>
<D:privilege><D:write/></D:privilege>
<D:description xml:lang="en">Write any object</D:description>
...
</D:supported-privilege>
</D:supported-privilege-set>
7.2 Additional Principal Properties
This section defines a new property for WebDAV principal resources as
defined in RFC3744 [7].
7.2.1 CALDAV:calendar-URL Property
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Name: calendar-URL
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identify the URL of any calendar collections owned by the
associated principal resource.
Description:
<!ELEMENT calendar-URL (DAV:href*) >
Support for this property is RECOMMENDED.
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8. Calendaring Reports
This section defines the reports which a CalDAV server MUST support
on calendar collections and calendar resources.
CalDAV servers MUST advertise support for those reports with the DAV:
supported-report-set property defined in DeltaV [5].
Some of these reports allow calendar data (from possibly multiple
resources) to be returned. Clients SHOULD request the DAV:getetag
property whenever executing reports that return calendar data, to
ensure that any local cache used for synchronization is kept up to
date with the latest changes on the server
8.1 REPORT Method
The REPORT method (defined in Section 3.6 of RFC3253 [5]) provides an
extensible mechanism for obtaining information about a resource.
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.
A server that supports calendar-access MUST support the DAV:expand-
property report (defined in Section 3.8 of RFC3253 [5]).
8.2 Reports on collections containing calendar collections
A WebDAV collection which contains one or more calendar collections
is not a new type of resource, but it may support these new REPORT.
If so, then the REPORT is expected to have the semantics of including
information from all the calendar data contained in the collection,
and its children, recursively. These collections may contain more
than only calendar related resources. It's up to the server, if it
supports this REPORT on a normal WebDAV collection, to find calendar
resources and decide what to do with non-calendar resources and
whether those may also appear in the collection or its children.
If these reports are supported on ordinary collections the server
advertises the capability with the DAV:supported-report-set property
as already described.
8.3 CALDAV:calendar-query Report
The CALDAV:calendar-query REPORT performs a search for all calendar
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resources (e.g., iCalendar objects) that match a specified search
filter. The response of this report will contain all the WebDAV
properties and calendar 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 resource data that matches the search
filter.
The format of this report is modeled on the PROPFIND method. The
request and response bodies of the CALDAV:calendar-query report use
XML elements that are also used by PROPFIND. In particular the
request can include XML elements to request WebDAV properties to be
returned. When that occurs the response should follow the same
behavior as PROPFIND with respect to the DAV:multistatus response
elements used to return specific property results. For instance, a
request to retrieve the value of a property which does not exist is
an error and MUST be noted with a response XML element which contains
a 404 (Not Found) status value.
Support for the calendar-query REPORT is REQUIRED.
Marshalling:
The request body MUST be a CALDAV:calendar-query XML element as
defined in Section 10.1.
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 multistatus XML element is empty.
The response body for a successful calendar-query REPORT request
MUST contain a DAV:response element for each iCalendar object that
matched the search filter. The declaration of the DAV:response
element from Section 12.9.1 of RFC2518 [3] has been modified as
follow to allow the CALDAV:calendar-data element within the DAV:
response element, see Section 10.5
[[Comment.1: We need to define the role of the Depth request header
when applied to a collection resource. We need to specify
preconditions and postconditions. (e.g., DAV:number-of-matches-
within-limits). --desruisseaux]]
8.3.1 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 September 2nd, 2004 at 00:00:00 am UTC to September
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2nd, 2004 at 11:59:59 pm UTC. In addition the DAV:getetag property
is also requested and returned as part of the response.
>> Request <<
REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop>
<D:getetag/>
</D:prop>
<C:calendar-data>
<C:comp name="VCALENDAR">
<C:allprop/>
<C:comp name="VEVENT">
<C:prop name="X-ABC-GUID"/>
<C:prop name="UID"/>
<C:prop name="DTSTART"/>
<C:prop name="DTEND"/>
<C:prop name="DURATION"/>
<C:prop name="EXDATE"/>
<C:prop name="EXRULE"/>
<C:prop name="RDATE"/>
<C:prop name="RRULE"/>
<C:prop name="LOCATION"/>
<C:prop name="SUMMARY"/>
</C:comp>
<C:comp name="VTIMEZONE">
<C:allprop/>
<C:allcomp/>
</C:comp>
</C:comp>
</C:calendar-data>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VEVENT">
<C:time-range start="20040902T000000Z"
end="20040902T235959Z"/>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>
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>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:response>
<D:href
>http://cal.example.com/bernard/calendar/ev102.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"23ba4d-ff11fb"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
DTSTART:20040902T100000Z
DTEND:20040902T120000Z
SUMMARY:Design meeting
UID:34222-232@example.com
X-ABC-GUID:E1CX4zp-0005Ld-21@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
</D:response>
<D:response>
<D:href
>http://cal.example.com/bernard/calendar/mtg103.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"ff11fb-23ba4d"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
DTSTART:20040902T130000Z
DTEND:20040902T150000Z
SUMMARY:Design meeting - Part II
UID:63409-868@example.com
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X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
</D:response>
</D:multistatus>
8.3.2 Example: Retrieval of todos 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.
>> Request <<
REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop xmlns:D="DAV:">
<D:getetag/>
</D:prop>
<C:calendar-data/>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VTODO">
<C:comp-filter name="VALARM">
<C:time-range start="20041121T000000Z"
end="20041121T235959Z"/>
</C:comp-filter>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>
8.3.3 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
"20041121-FEEBDAED@foo.org".
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>> Request <<
REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop xmlns:D="DAV:">
<D:getetag/>
</D:prop>
<C:calendar-data/>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VEVENT">
<C:prop-filter name="UID">
<C:text-match
caseless="no">20041121-FEEBDAED@foo.org</C:text-match>
</C:prop-filter>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>
8.3.4 Example: Retrieval of events by participation status
In this example, the client requests the server to return the VEVENT
components that have the ATTENDEE property with the value
"mailto:jsmith@example.org" and for which the PARTSTAT parameter is
set to "NEEDS-ACTION".
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>> Request <<
REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop xmlns:D="DAV:">
<D:getetag/>
</D:prop>
<C:calendar-data/>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VEVENT">
<C:prop-filter name="ATTENDEE"/>
<C:text-match
caseless="yes">mailto:jsmith@foo.org</C:text-match>
<C:param-filter name="PARTSTAT"/>
<C:text-match caseless="no">NEEDS-ACTION</C:text-match>
</C:param-filter>
</C:prop-filter>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>
8.3.5 Example: Retrieval of events only
In this example, the client requests the server to return all VEVENT
components.
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>> Request <<
REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop xmlns:D="DAV:">
<D:getetag/>
</D:prop>
<C:calendar-data/>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VEVENT">
<C:is-defined/>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>
8.4 CALDAV:calendar-multiget Report
The CALDAV:calendar-multiget REPORT is used to retrieve specific
calendar resources from within a collection, if the Request-URI is a
collection, or to retrieve a specific calendar resource, if the
Request-URI is a calendar resource. This report is similar to the
CALDAV:calendar-query REPORT (see Section 8.3), except that it takes
a list of DAV:href elements instead of a CALDAV:filter element to
determine which calendar resources to return.
Support for the calendar-multiget REPORT is REQUIRED.
Marshalling:
The request body MUST be a CALDAV:calendar-multiget XML element
(see Section 10.6, which MUST contain at least one DAV:href XML
element, and one optional CALDAV:calendar-data element as defined
in Section 10.2. If the Request-URI is a collection resource,
then the DAV:href elements MUST refer to resources within that
collection, and they MAY refer to 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 equal to the Request-URI.
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The response body for a successful request MUST be a DAV:
multistatus XML element. In the case where there are no response
elements, the returned multistatus XML element is empty.
The response body for a successful CALDAV:calendar-multiget REPORT
request MUST contain a DAV:response element for each calendar
resource referenced by the provided set of DAV:href elements. The
DAV:response element is as defined in Section 10.5.
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.
8.4.1 Example: CALDAV:calendar-multiget Report
In this example, the client requests the server to return specific
properties of the VEVENT components references 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/calendar/mtg1.ics does not exist,
resulting in an error status response.
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>> Request <<
REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-multiget xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop>
<D:getetag/>
</D:prop>
<C:calendar-data>
<C:comp name="VCALENDAR">
<C:allprop/>
<C:comp name="VEVENT">
<C:prop name="UID"/>
<C:prop name="DTSTART"/>
<C:prop name="DTEND"/>
<C:prop name="DURATION"/>
<C:prop name="EXDATE"/>
<C:prop name="EXRULE"/>
<C:prop name="RDATE"/>
<C:prop name="RRULE"/>
<C:prop name="LOCATION"/>
<C:prop name="SUMMARY"/>
</C:comp>
<C:comp name="VTIMEZONE">
<C:allprop/>
<C:allcomp/>
</C:comp>
</C:comp>
</C:calendar-data>
<D:href>http://cal.example.com/bernard/calendar/ev102.ics</D:href>
<D:href>http://cal.example.com/bernard/calendar/mtg1.ics</D:href>
</C:calendar-multiget>
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>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:response>
<D:href>http://cal.example.com/bernard/calendar/ev102.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"23ba4d-ff11fb"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
DTSTART:20040902T100000Z
DTEND:20040902T120000Z
SUMMARY:Design meeting
UID:34222-232@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
</D:response>
<D:response>
<D:href>http://cal.example.com/bernard/calendar/mtg1.ics</D:href>
<D:status>HTTP/1.1 404 Resource not found</D:status>
</D:response>
</D:multistatus>
8.5 CALDAV:free-busy-query Report
The CALDAV:free-busy-query REPORT generates an iCalendar VFREEBUSY
component containing free busy information for all relevant
components within calendar collections which have the CALDAV:view-
free-busy or DAV:read privilege granted for the current authenticated
user.
Only the VEVENT components, with the TRANSP property set to a value
different from "TRANSPARENT", and the VFREEBUSY components will be
considered to generate the free busy time information.
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Support for the CALDAV:free-busy-query REPORT is REQUIRED.
Marshalling:
The request body MUST be a CALDAV:free-busy-query XML element (see
Section 10.7, which MUST contain at least one CALDAV:time-range
XML element, as defined in Section 10.4.
The response body for a successful request MUST be a DAV:
multistatus XML element. In the case where there are no response
elements, the returned multistatus XML element is empty.
The response body for a successful CALDAV:free-busy-query REPORT
request MUST contains a DAV:response element for each calendar
collection for which free-busy information has been computed.
Each DAV:response element contains a single CALDAV:calendar-data
XML element as defined in Section 10.2. The CALDAV:calendar-data
XML element MUST contain an iCalendar object with a single
VFREEBUSY component, with zero or more FREEBUSY property values
that describe the busy time intervals for the calendar resources
being targeted, and with other properties set according to the
rules of iCalendar. This report only returns busy time
information. Applications desiring free time information MUST
infer this from available busy time information.
When the Request-URI for a CALDAV:free-busy-query REPORT is a
calendar collection, the free-busy data is implicitly determined from
the "text/calendar" VEVENT resources within the calendar collection,
irrespective of the value of any Depth header included in the REPORT
request. Only calendar resources containing VEVENT or VFREEBUSY
components that have the CALDAV:view-free-busy privilege granted to
the current authenticated user will be computed in the response.
When the Request-URI for a CALDAV:free-busy-query REPORT is a non-
calendar collection, the scope of the report is governed by the value
of the Depth header in the request as follows:
'Depth: 0' - an empty VFREEBUSY component will be returned as
there is no valid calendar data to be scanned on the collection.
'Depth: 1' - free-busy data for any calendar collections
immediately within the target collection is returned.
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'Depth: infinity' - free-busy data for all calendar collections
within any sub-collections of the target collection is returned.
8.5.1 Example: CALDAV:free-busy-query Report
In this example, the client requests the server to return free-busy
information on the calendar collection /bernard/calendar/, between
9:00 AM and 5:00 PM on 2nd September 2004. The server responds
indicating three busy time intervals of one hour, two hours and 30
minutes during the course of the time interval being examined.
>> Request <<
REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:free-busy-query xmlns:C="urn:ietf:params:xml:ns:caldav">
<C:time-range start="20040902T090000Z"
end="20040902T170000Z"/>
</C:free-busy-query>
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>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:response>
<D:href>http://cal.example.com/bernard/calendar/</D:href>
<D:status>HTTP/1.1 200 OK</D:status>
<C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VFREEBUSY
DTSTAMP:20050125T090000Z
DTSTART:20040902T090000Z
DTEND:20040902T170000Z
FREEBUSY:20040902T090000Z/PT1H,
20040902T120000Z/PT2H,
20040902T160000Z/PT30M
END:VFREEBUSY
END:VCALENDAR
</C:calendar-data>
</D:response>
</D:multistatus>
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9. Guidelines
9.1 Client-to-client Interoperability
There are a number of actions clients can take which will be legal
(the server will not return errors) but which can degrade
interoperability with other client implementations accessing the same
data. For example, a recurrence rule could be replaced with a set of
recurrence dates, a single recurring event could be replaced with a
set of independent resources to represent each recurrence, or the
start/end time values can be translated from the original timezone to
another timezone. Although these are iCalendar interoperability best
practices and not limited only to CalDAV usage, interoperability
problems are likely to be more evident in CalDAV use cases.
9.2 Sychronization Operations
WebDAV already provides functionality required to synchronize a
collection or set of collections, make changes offline, and a simple
way to resolve conflicts when reconnected. Strong ETags are the key
to making this work, but these are not required of all WebDAV
servers. Since offline functionality is more important to Calendar
applications than to other WebDAV applications, CalDAV servers MUST
support strong ETags.
9.2.1 Use of Reports
9.2.1.1 Restrict the Time Range
The reports provided in CalDAV can be used by clients to optimize
their performance in terms of network bandwidth usage, and resource
consumption on the local client machine. Both of those issues are
certainly major considerations for mobile or handheld devices with
limited capacity, but they are also relevant to desktop client
applications in cases where the calendar collections contain large
amounts of data.
Typically clients present calendar data to users in views that span a
finite time interval, so whenever possible clients should only
retrieve calendar items from the server using CALDAV:calendar-query
report combined with a time-range element to limit the scope of
returned items to just those needed to populate the current view.
9.2.1.2 Synchronize by Time Range
Typically in a calendar, historical data (events, to-dos etc that
have completed prior to the current date) do not change, though they
may be deleted. As a result, a client can speed up the
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synchronization process by only considering data for the present time
and the future up to a reasonable limit (e.g., one week, one month).
If the user then tries to examine a portion of the calendar outside
of the range that has been synchronized, the client can perform
another synchronization operation on the new time interval being
examined. This 'just-in-time' synchronization can minimize bandwidth
for common user interaction behaviors.
9.2.1.3 Synchronization Process
If a client wants to support calendar data synchronization, as
opposed to downloading calendar data each time it is needed, it needs
to cache the component resources URI and ETag along with the actual
calendar data. Whilst the URI remains static for the lifetime of the
component, the ETag will change with each successive change to the
component data. Thus to synchronize a local data cache with the
server, the client can first fetch the URI/ETag pairs for the time
interval being considered, and compare those results with the cached
data. Any cached component whose ETag differs from that on the
server needs to be synchronized.
In order to properly detect the changes between the server and client
data, the client will need to keep a record of which items have been
created, changed or deleted since the last synchronization operation
so that it can reconcile those changes with the data on the server.
An example of how to do that would be the following:
The client issues a CALDAV:calendar-query REPORT request for a
specific time range, and asks for only the DAV:getetag property to
be returned:
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REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop>
<D:getetag/>
</D:prop>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VEVENT">
<C:time-range start="20040902T000000Z"
end="20040902T235959Z"/>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>
The client then uses the results to determine which components
have changed, been created or deleted on the server and how those
relate to locally cached components that may have changed, been
created or deleted. If the client determines that there are items
on the server that need to be fetched, the client issues a CALDAV:
calendar-multiget report to fetch the actual data:
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REPORT /bernard/calendar/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: text/xml
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-multiget xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:prop>
<D:getetag/>
</D:prop>
<C:calendar-data>
<C:comp name="VCALENDAR">
<C:allprop/>
<C:comp name="VEVENT">
<C:prop name="UID"/>
<C:prop name="DTSTART"/>
<C:prop name="DTEND"/>
<C:prop name="DURATION"/>
<C:prop name="EXDATE"/>
<C:prop name="EXRULE"/>
<C:prop name="RDATE"/>
<C:prop name="RRULE"/>
<C:prop name="LOCATION"/>
<C:prop name="SUMMARY"/>
</C:comp>
<C:comp name="VTIMEZONE">
<C:allprop/>
<C:allcomp/>
</C:comp>
</C:comp>
</C:calendar-data>
<D:href>http://cal.example.com/bernard/calendar/evt1.ics</D:href>
<D:href>http://cal.example.com/bernard/calendar/mtg1.ics</D:href>
</C:calendar-multiget>
9.2.2 Restrict the Properties Returned
Clients may not need all the properties in a calendar component when
presenting information to the user. Since some property data can be
large (e.g., 'ATTACH' or 'ATTENDEE' lists) clients can choose to
ignore those by only requesting the specific items it knows it will
use, through use of the CALDAV:calendar-data XML element in the
relevant reports.
However, if a client needs to make a change to a component, it can
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only change the entire component data via a PUT request. There is no
way to incrementally make a change to a set of properties within a
calendar component resource. As a result the client will have to
cache the entire set of properties on a resource that is being
changed.
9.3 Use of Locking
WebDAV locks can be used to prevent two clients modifying the same
resource from either overwriting each others' changes (though that
problem can also be solved by using ETags) and also to prevent the
user from making changes that will conflict with another set of
changes. In a multi-user calendar system, the calendar client could
lock an event while the user is editing the event, and unlock the
event when the user finishes or cancels. Locks can also be used to
prevent changes while data is being reorganized. For example, a
calendar client might lock two calendar collections prior to moving a
bunch of calendar resources from one to another.
Clients may request a lock timeout period that is appropriate to the
use case. When the user explicitly decides to reserve a resource and
prevent other changes, a long timeout might be appropriate, but in
cases when the client automatically decides to lock the resource the
timeout should be short (and the client can always refresh the lock
should it need to). A short lock timeout means that if the client is
unable to remove the lock, the other calendar users aren't prevented
from making changes.
9.4 Finding calendars
Much of the time a calendar client (or agent) will discover a new
calendar's location by being provided directly with the URL. E.g. a
user will type his or her own calendar location into client
configuration information, or cut and paste a URL from email into the
calendar application. The client need only confirm that the URL
points to a resource which is a calendar. The client may also be
able to browse WebDAV collections to find calendar collections.
The choice of HTTP URLs means that calendar resources are backward
compatible with existing software, but does have the disadvantage
that existing software does not usually know to look at the OPTIONS
response to that URL to determine what can be done with it. This is
somewhat of a barrier for WebDAV usage as well as with CalDAV usage.
This specification does not offer a way through this other than
making the information available in the OPTIONS response should this
be requested.
For calendar sharing and scheduling use cases, one might wish to find
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the calendar belonging to another user. If the other user has a
calendar in the same repository, that calendar can be found by using
the principal namespace required by WebDAV ACL support. For other
cases, the authors have no universal solution but implementors can
consider whether to use vCard [11] or LDAP [10] standards together
with calendar attributes [12].
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10. XML Element Definitions
10.1 CALDAV:calendar-query XML Element
Name: calendar-query
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Defines a report for querying calendar data
Description See Section 8.3.
<!ELEMENT calendar-query (DAV:allprop | DAV:propname | DAV:prop)?
calendar-data? filter>
10.2 CALDAV:calendar-data XML Element
Name: calendar-data
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Used to define which parts of a calendar component object
should be returned by the report that uses this element.
Description: When used in a request, the CALDAV:calendar-data element
specifies the iCalendar components and properties to be returned
in the iCalendar objects part of the response. If this element
doesn't contain any CALDAV:comp element, iCalendar objects will be
returned with all their components and properties.
Value: When used inside a response, the CALDAV:calendar-data element
contains an iCalendar object that matched the search filter
specified in the request.
<!ELEMENT calendar-data ((comp?, expand-recurrence-set?) |
#PCDATA)?>
<!ATTLIST calendar-data return-content-type CDATA
"text/calendar">
10.2.1 CALDAV:comp XML Element
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Name: comp
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Defines which component types to return
Description: The name value is an iCalendar component name (e.g.,
"VEVENT")
NOTE: The CALDAV:prop and CALDAV:allprop elements used here have the
same name as elements defined in WebDAV. However, the elements used
here have the "urn:ietf:params:xml:ns:caldav" namespace, as opposed
to the "DAV:" namespace used for elements defined in WebDAV.
<!ELEMENT comp ((allcomp, (allprop | prop*)) |
(comp*, (allprop | prop*)))>
<!ATTLIST comp name CDATA #REQUIRED>
10.2.2 CALDAV:allcomp XML Element
Name: allcomp
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies that all components shall be returned
Description: This element can be used when the client wants all types
of components returned by a report.
<!ELEMENT allcomp EMPTY>
10.2.3 CALDAV:allprop XML Element
Name: allprop
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies that all properties shall be returned.
Description: This element can be used when the client wants all
properties of components returned by a report.
NOTE: The 'allprop' element defined here has the same name as the
'allprop' element defined in WebDAV. However, the 'allprop' element
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defined here uses the "urn:ietf:params:xml:ns:caldav" namespace, as
opposed to the "DAV:" namespace used for the 'allprop' element
defined in WebDAV.
<!ELEMENT allprop EMPTY>
10.2.4 CALDAV:prop XML Element
Name: prop
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Defines which properties to return in the response.
Description: The "name" attribute specifies the name of the iCalendar
property to return (e.g., "ATTENDEE"). The "novalue" attribute
can be used by clients to request that the actual value of the
property not be returned (if the "novalue" attribute is set to
"yes"). In that case the server will return just the iCalendar
property name and any iCalendar parameters and a trailing ":"
without the subsequent value data.
NOTE: The 'prop' element defined here has the same name as the 'prop'
element defined in WebDAV. However, the 'prop' element defined here
uses the "urn:ietf:params:xml:ns:caldav" namespace, as opposed to the
"DAV:" namespace used for the 'prop' element defined in WebDAV.
<!ELEMENT prop EMPTY>
<!ATTLIST prop name CDATA #REQUIRED
novalue (yes|no) "no">
10.2.5 CALDAV:expand-recurrence-set XML Element
Name: expand-recurrence-set
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Forces the server to expand recurring components into
separate instances.
Description: The expand-recurrence-set element specifies that
recurring components shall be returned as multiple components with
no recurrence properties (i.e., EXDATE, EXRULE, RDATE and RRULE).
The required "start" and "end" attributes contain iCalendar format
DATE-TIME (always specified in UTC) or DATE values that define the
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time interval over which the recurrence expansion should take
place. The start value is inclusive and the end value is
exclusive of the interval as per iCalendar DTSTART and DTEND
properties. The server MUST return only those expanded components
whose time interval intersects the interval specified by the start
and end attributes.
<!ELEMENT expand-recurrence-set EMPTY>
<!ATTLIST expand-recurrence-set start CDATA #REQUIRED
end CDATA #REQUIRED>
10.3 CALDAV:filter XML Element
Name: filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Determines which matching components are returned.
Description: The "filter" element specifies the search filter used to
match components that should be returned by a report.
<!ELEMENT filter comp-filter>
10.3.1 CALDAV:comp-filter XML Element
Name: comp-filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Limits the search to only the chosen component types.
Description: The "name" attribute is an iCalendar component type
(e.g., "VEVENT"). When this element is present, the server should
only return a component if it matches the filter, which is to say:
("no is-defined element" OR "is-defined matches") AND
("no time-range element" OR "time-range matches") AND
("no sub-component filter" OR "all sub-component filters match") AND
("no property filter elements" OR "all property filters match")
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<!ELEMENT comp-filter (is-defined | time-range)?
comp-filter* prop-filter*>
<!ATTLIST comp-filter name CDATA #REQUIRED>
10.3.2 CALDAV:prop-filter XML Element
Name: prop-filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Limits the search to specific properties.
Description: The "name" attribute MUST contain an iCalendar property
name (e.g., "ATTENDEE"). When the 'prop-filter' executes, a
property matches if:
("no is-defined element" OR "is-defined matches") AND
("no time-range element" OR "time-range matches") AND
("no text match element" OR "text-match matches") AND
("no parameter filter elements" OR "all parameter filters match")
<!ELEMENT prop-filter (is-defined | time-range | text-match)?
param-filter*>
<!ATTLIST prop-filter name CDATA #REQUIRED>
10.3.3 CALDAV:param-filter XML Element
Name: param-filter
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Limits the search to specific parameters.
Description: The "param-filter" element limits the search result to
the set of resources containing properties with parameters that
meet the parameter filter rules. When this filter executes, a
parameter matches if:
("is-defined matches" OR "text-match matches")
<!ELEMENT param-filter (is-defined | text-match) >
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<!ATTLIST param-filter name CDATA #REQUIRED>
10.3.4 CALDAV:is-defined XML Element
Name: is-defined
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Causes a search to match a resource if a component type,
property or parameter name exists.
Description: The CALDAV:is-defined XML element limits the filter to
resources where the named component, property or parameter is
defined.
<!ELEMENT is-defined EMPTY>
10.3.5 CALDAV:text-match XML Element
Name: text-match
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a substring match on a property or parameter
value.
Description: The specified text is used for a substring match against
the property or parameter value specified in a report. The
"caseless" attribute indicates whether the match is case-sensitive
(value set to "no") or case-insensitive (value set to "yes"). The
default value is server-specified. Caseless matching SHOULD be
implemented as defined in section 5.18 of the Unicode Standard
([9]). Support for the "caseless" attribute is optional. A
server should respond with a status of 422 if it is used but
cannot be supported.
<!ELEMENT text-match #PCDATA>
<!ATTLIST text-match caseless (yes|no)>
10.4 CALDAV:time-range XML Element
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Name: time-range
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a time interval for testing components against.
Description: The CALDAV:time-range element allows for a single time
range to be defined, in order to limit all the results of the
search to the set of resources that contain a component which
falls into that time range. The value of the "start" and "end"
attributes MUST follow the syntax of the DATE or DATE-TIME
iCalendar value type, with any time specified in UTC.
A VEVENT component falls in a given time-range if:
(DTSTART <= start AND DTEND > start) OR
(DTSTART <= start AND DTSTART+DURATION > start) OR
(DTSTART >= start AND DTSTART < end) OR
(DTEND > start AND DTEND <= end)
A VTODO component falls in a given time-range if:
(DTSTART <= start AND DUE >= start) OR
(DTSTART <= start AND DTSTART+DURATION > start) OR
(DTSTART >= start AND DTSTART < end) OR
(DUE >= start AND DUE < end)
A VJOURNAL component falls in a given time-range if:
DTSTART >= start AND DTSTART < end
A VALARM component falls in a given time-range if:
trigger-time >= start AND trigger-time < end
Any property of value type DATE-TIME or DATE (e.g., DTSTAMP) will
match a given time-range if:
value >= start AND value < end
<!ELEMENT time-range EMPTY>
<!ATTLIST time-range start CDATA
end CDATA>
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10.5 DAV:response XML Element
Name: response
Namespace: DAV:
Purpose: Response that includes calendar data.
Description: Modifies the standard WebDAV response element to include
calendar data in the response if required by the report type.
<!ELEMENT DAV:response (DAV:href,
((DAV:href*, DAV:status)|(DAV:propstat+)),
calendar-data?,
DAV:responsedescription?) >
10.6 CALDAV:calendar-multiget XML Element
Name: calendar-multiget
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: CalDAV report used to retrieve specific calendar component
items via their URIs.
Description: See Section 8.4.
<!ELEMENT calendar-multiget (DAV:allprop | DAV:propname | DAV:prop)?
calendar-data? DAV:href+>
10.7 CALDAV:free-busy-query XML Element
Name: free-busy-query
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: CalDAV report used to generate a VFREEBUSY to determine busy
time over a specific set of time ranges.
Description: See Section 8.5.
<!ELEMENT free-busy-query time-range+ >
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11. Internationalization Considerations
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12. Security Considerations
12.1 Authentication of Clients
CalDAV relies on HTTP authentication to authenticate users to the
server. As a result the security considerations for use of HTTP
authentication also apply to CalDAV. In particular, the HTTP Basic
authentication method MUST NOT be used without adequate transport
layer security.
12.2 Denial of Service
Servers MUST take adequate precautions to ensure malicious clients
cannot consume excessive server resources (CPU, memory, disk, etc.)
through carefully crafted reports. For example, a client could
upload an event with a recurrence rule that specifies a recurring
event occurring every second for the next 100 years which would
result in approximately 3 x 10^9 instances! A report that asks for
recurrences to be expanded over that range would likely constitute a
denial-of-service attack on the server.
[[Comment.2: We should make an explicit reference to the security
considerations mentionned in iCalendar, iTIP and iMIP. We should
also specify if there is any semantic defined in CalDAV for the
iCalendar property CLASS (access classification). --desruisseaux]]
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13. IANA Consideration
In addition to the namespaces defined by RFC2518 [3] for XML
elements, this document uses a URN to describe a new XML namespace
conforming to a registry mechanism described in RFC3688 [6]. All
other IANA considerations mentioned in RFC2518 [3] also apply to this
document.
13.1 Namespace Registration
Registration request for the CalDAV namespace:
URI: urn:ietf:params:xml:ns:caldav
Registrant Contact: See the "Author's Address" section of this
document.
XML: None. Namespace URIs do not represent an XML specification.
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14. Acknowledgements
The authors would like to thank the following individuals for
contributing their ideas and support for writing this specification:
Michael Arick, Mario Bonin, Scott Carr, Mike Douglass, Helge Hess,
Dan Mosedale, Julian F. Reschke, Mike Shaver, Simon Vaillancourt, and
Jim Whitehead.
The authors would also like to thank the Calendaring and Scheduling
Consortium for advice with this specification, and for organizing
interoperability testing events to help refine it.
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15. References
15.1 Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Dawson, F. and Stenerson, D., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)", RFC 2445,
November 1998.
[3] Goland, Y., Whitehead, E., Faizi, A., Carter, S., and D. Jensen,
"HTTP Extensions for Distributed Authoring -- WEBDAV", RFC 2518,
February 1999.
[4] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999.
[5] Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. Whitehead,
"Versioning Extensions to WebDAV (Web Distributed Authoring and
Versioning)", RFC 3253, March 2002.
[6] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[7] Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web
Distributed Authoring and Versioning (WebDAV) Access Control
Protocol", RFC 3744, May 2004.
[8] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F.
Yergeau, "Extensible Markup Language (XML) 1.0 (Third Edition)",
W3C REC-xml-20040204, February 2004,
<http://www.w3.org/TR/2004/REC-xml-20040204>.
[9] The Unicode Consortium, "The Unicode Standard - Version 4.0",
Addison-Wesley , August 2003,
<http://www.unicode.org/versions/Unicode4.0.0/>.
ISBN 0321185781
15.2 Informative References
[10] Wahl, M., Howes, T., and S. Kille, "Lightweight Directory
Access Protocol (v3)", RFC 2251, December 1997.
[11] Dawson, F. and T. Howes, "vCard MIME Directory Profile",
RFC 2426, September 1998.
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[12] Small, T., Hennessy, D., and F. Dawson, "Calendar Attributes
for vCard and LDAP", RFC 2739, January 2000.
Authors' Addresses
Cyrus Daboo
ISAMET Inc.
5001 Baum Blvd.
Suite 650
Pittsburgh, PA 15213
US
Email: daboo@isamet.com
URI: http://www.isamet.com/
Bernard Desruisseaux
Oracle Corporation
600 Blvd. de Maisonneuve West
10th Floor
Montreal, QC H3A 3J2
CA
Email: bernard.desruisseaux@oracle.com
URI: http://www.oracle.com/
Lisa Dusseault
Open Source Application Foundation
2064 Edgewood Dr.
Palo Alto, CA 94303
US
Email: lisa@osafoundation.org
URI: http://www.osafoundation.org/
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Appendix A. CalDAV Method Privilege Table (Normative)
The following table extend the WebDAV Method Privilege Table
specified in Appendix B of WebDAV ACL [7].
+---------------------------------+---------------------------------+
| METHOD | PRIVILEGES |
+---------------------------------+---------------------------------+
| MKCALENDAR | DAV:bind |
| | |
| REPORT | DAV:read or |
| | CALDAV:view-free-busy (on all |
| | referenced resources) |
+---------------------------------+---------------------------------+
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Appendix B. Changes
B.1 Changes in -06
a. Reworded section "Recurrence and the Data Model".
b. Removed timezone collection feature.
c. Removed ability for a server to return the Location header on a
successful PUT request.
d. Clarified restrictions on calendar resources contained in
calendar collections.
e. Added preconditions on PUT in calendar collections.
f. Added informative "Guidelines" section, with information on
locking and how to find calendar collections.
g. Moved "Sychronization Operations" section in the "Guidelines"
section.
B.2 Changes in -05
a. Removed a lot of non-normative text.
b. Removed property promotion/demotion requirements.
c. Removed calendar-owner and cal-scale properties.
d. Removed 'ical' prefix/text from element names.
e. Relaxed WebDAV Class 2 (locking) requirement to a MAY.
f. Relaxed MKCALENDAR requirement to a SHOULD.
g. Moved the XML Namespace section in the Introduction.
h. Added CALDAV: prefix to CalDAV XML elements in the text.
i. Added CALDAV:calendar-multiget report.
j. Added CALDAV:free-busy-query report.
k. Added CALDAV:calendar-description property.
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l. Changed CALDAV:calendar-query-result element name to CALDAV:
calendar-data
m. Added description and examples of handling timezones.
n. Added mandatory "start" and "end" attributes to the CALDAV:
expand-recurrence-set element.
o. Added three CalDAV OPTIONS requests.
p. Grouped XML Element declarations in a separate section.
B.3 Changes in -04
a. Added a note about the HTTP Location response header.
b. Added report calendar-query.
c. Removed reports calendar-property-search and calendar-time-range.
d. Removed section on CalDAV and timezones.
e. Added requirement to return ETag on creation.
f. Revised data model to remove sub-collections from calendar
collection.
g. Added informative references section.
h. Removed dependencies on DASL.
B.4 Changes in -03
a. Removed Calendar Containers (simplification that doesn't seem to
remove much functionality)
b. Added MKCALENDAR to create calendars and all sub-collections
c. Added cal-scale property to calendars
B.5 Changes in -02
Basically still adding major sections of content:
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a. Defined new field values to the OPTIONS "DAV:" response header
b. Added new resource properties
c. Added new principal properties
d. Added new SCHEDULE method and related headers
e. Added new privileges for scheduling
B.6 Changes in -01
a. Added section on privileges for calendaring, extending WebDAV ACL
privilege set
b. Defined what to do with unrecognized properties in the bodies of
iCalendar events, with respect to property promotion/demotion
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