Network Working Group C. Daboo
Internet-Draft ISAMET
Expires: August 14, 2005 B. Desruisseaux
Oracle
L. Dusseault
OSAF
February 10, 2005
Calendaring Extensions to WebDAV (CalDAV)
draft-dusseault-caldav-05
Status of this Memo
This document is an Internet-Draft and is subject to all provisions
of Section 3 of RFC 3667. By submitting this Internet-Draft, each
author represents that any applicable patent or other IPR claims of
which he or she is aware have been or will be disclosed, and any of
which he or she become aware will be disclosed, in accordance with
RFC 3668.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 14, 2005.
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
Daboo, et al. Expires August 14, 2005 [Page 1]
Internet-Draft CalDAV February 2005
WebDAV-based calendaring and scheduling an interoperable standard
that supports single-user calendar access, calendar sharing, and
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. Required CalDAV features . . . . . . . . . . . . . . . . . . . 7
3. Calendaring Data Model . . . . . . . . . . . . . . . . . . . . 8
3.1 Calendar Server . . . . . . . . . . . . . . . . . . . . . 8
3.2 Recurrence and the Data Model . . . . . . . . . . . . . . 9
3.3 Timezones . . . . . . . . . . . . . . . . . . . . . . . . 9
4. New Resource Types . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Calendar Collection . . . . . . . . . . . . . . . . . . . 11
4.2 iCalendar Components within the Calendar Collection . . . 11
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 CALDAV:timezone-collection-set OPTIONS request . . . . 17
5.2.5 Example - OPTIONS . . . . . . . . . . . . . . . . . . 18
5.3 Creating calendar resources . . . . . . . . . . . . . . . 18
6. Calendaring Properties . . . . . . . . . . . . . . . . . . . . 21
6.1 CALDAV:calendar-description Property . . . . . . . . . . . 21
7. Calendaring Access Control . . . . . . . . . . . . . . . . . . 22
7.1 Calendaring Privileges . . . . . . . . . . . . . . . . . . 22
7.1.1 CALDAV:view-free-busy Privilege . . . . . . . . . . . 22
7.1.2 Privilege aggregation and the
DAV:supported-privilege-set property . . . . . . . . . 22
7.1.2.1 Partial example of DAV:supported-privilege-set
property . . . . . . . . . . . . . . . . . . . . . 23
7.2 Additional Principal Properties . . . . . . . . . . . . . 24
7.2.1 CALDAV:calendar-URL Property . . . . . . . . . . . . . 24
8. Calendaring Reports . . . . . . . . . . . . . . . . . . . . . 25
8.1 REPORT Method . . . . . . . . . . . . . . . . . . . . . . 25
8.2 Reports on collections containing calendars . . . . . . . 25
8.3 CALDAV:calendar-query Report . . . . . . . . . . . . . . . 25
8.3.1 Example: Partial retrieval of events by time range . . 26
Daboo, et al. Expires August 14, 2005 [Page 2]
Internet-Draft CalDAV February 2005
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
8.3.5 Example: Retrieval of events only . . . . . . . . . . 31
8.3.6 Timezone Examples . . . . . . . . . . . . . . . . . . 32
8.3.6.1 Example: List all available timezones on the
server . . . . . . . . . . . . . . . . . . . . . . 32
8.4 CALDAV:calendar-multiget Report . . . . . . . . . . . . . 34
8.4.1 Example: CALDAV:calendar-multiget Report . . . . . . . 35
8.5 CALDAV:free-busy-query Report . . . . . . . . . . . . . . 37
8.5.1 Example: CALDAV:free-busy-query Report . . . . . . . . 38
9. Synchronization Operations . . . . . . . . . . . . . . . . . . 40
9.1 Use of Reports . . . . . . . . . . . . . . . . . . . . . . 40
9.1.1 Restrict the Time Range . . . . . . . . . . . . . . . 40
9.1.2 Synchronize by Time Range . . . . . . . . . . . . . . 40
9.1.3 Synchronization Process . . . . . . . . . . . . . . . 40
9.2 Restrict the Properties Returned . . . . . . . . . . . . . 42
9.3 Use the Server Timezone Collection . . . . . . . . . . . . 43
10. XML Element Definitions . . . . . . . . . . . . . . . . . . 44
10.1 CALDAV:calendar-query XML Element . . . . . . . . . . . . 44
10.2 CALDAV:calendar-data XML Element . . . . . . . . . . . . . 44
10.2.1 CALDAV:comp XML Element . . . . . . . . . . . . . . . 44
10.2.2 CALDAV:allcomp XML Element . . . . . . . . . . . . . . 45
10.2.3 CALDAV:allprop XML Element . . . . . . . . . . . . . . 45
10.2.4 CALDAV:prop XML Element . . . . . . . . . . . . . . . 45
10.2.5 CALDAV:expand-recurrence-set XML Element . . . . . . . 46
10.3 CALDAV:filter XML Element . . . . . . . . . . . . . . . . 46
10.3.1 CALDAV:comp-filter XML Element . . . . . . . . . . . . 46
10.3.2 CALDAV:prop-filter XML Element . . . . . . . . . . . . 47
10.3.3 CALDAV:param-filter XML Element . . . . . . . . . . . 47
10.3.4 CALDAV:is-defined XML Element . . . . . . . . . . . . 48
10.3.5 CALDAV:text-match XML Element . . . . . . . . . . . . 48
10.4 CALDAV:time-range XML Element . . . . . . . . . . . . . . 49
10.5 DAV:response XML Element . . . . . . . . . . . . . . . . . 49
10.6 CALDAV:calendar-multiget XML Element . . . . . . . . . . . 50
10.7 CALDAV:free-busy-query XML Element . . . . . . . . . . . . 50
11. Internationalization Considerations . . . . . . . . . . . . 51
12. Security Considerations . . . . . . . . . . . . . . . . . . 52
12.1 Authentication of Clients . . . . . . . . . . . . . . . . 52
12.2 Denial of Service . . . . . . . . . . . . . . . . . . . . 52
13. IANA Consideration . . . . . . . . . . . . . . . . . . . . . 53
13.1 Namespace Registration . . . . . . . . . . . . . . . . . . 53
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 54
15. Normative References . . . . . . . . . . . . . . . . . . . . 54
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 55
A. CalDAV Method Privilege Table (Normative) . . . . . . . . . . 56
B. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Daboo, et al. Expires August 14, 2005 [Page 3]
Internet-Draft CalDAV February 2005
B.1 Changes in -05 . . . . . . . . . . . . . . . . . . . . . . 57
B.2 Changes in -04 . . . . . . . . . . . . . . . . . . . . . . 57
B.3 Changes in -03 . . . . . . . . . . . . . . . . . . . . . . 57
B.4 Changes in -02 . . . . . . . . . . . . . . . . . . . . . . 57
B.5 Changes in -01 . . . . . . . . . . . . . . . . . . . . . . 58
Intellectual Property and Copyright Statements . . . . . . . . 59
Daboo, et al. Expires August 14, 2005 [Page 4]
Internet-Draft CalDAV February 2005
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 identiqual 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.
Daboo, et al. Expires August 14, 2005 [Page 5]
Internet-Draft CalDAV February 2005
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.
Daboo, et al. Expires August 14, 2005 [Page 6]
Internet-Draft CalDAV February 2005
2. Required CalDAV features
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.
o MAY support WebDAV Class 2 (i.e., locking).
o [[Comment.1: CalDAV should provide some guidelines to use locking
in the context of calendaring applications. --desruisseaux]]
o MAY support WebDAV DeltaV [5] or some of its components.
Daboo, et al. Expires August 14, 2005 [Page 7]
Internet-Draft CalDAV February 2005
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 areas, and
non-calendaring data in other areas.
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.
Daboo, et al. Expires August 14, 2005 [Page 8]
Internet-Draft CalDAV February 2005
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 calendars 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.
Consider the outcome if recurrence were handled through the creation
of many nearly-identical WebDAV resources. With this model, it
becomes hard to keep synchronized data consistent. Even worse, some
features like LOCK become difficult -- it's hard to lock the right
set of resources so that the user can change the title of all
recurrences of an appointment. Due to these considerations, this
proposal does not model recurrences as separate resources.
Instead, this proposal models recurrence patterns as properties of
calendar resources. This makes for much less data to synchronize,
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.
The drawback of the recurrence-is-a-property approach is that it
becomes harder to see what events occur in a given time interval.
It's a very common function for calendar views to display all events
happening between midnight yesterday and midnight tonight, or all
events happening within one week. In these views, each recurrence
appears as if it were an individual appointment. The
CALDAV:calendar-query REPORT defined in this document make these
views possible.
Because of this choice, clients MUST NOT create separate resources to
represent a recurring event when the recurrence pattern is known.
Otherwise, it makes it more difficult for other clients to
interoperate and modify the recurring event. Most importantly,
clients MUST NOT duplicate events represented through recurrence
patterns with manually created events, which would appear as
duplicates to the server and to other clients.
3.3 Timezones
Calendar resources in CalDAV MUST be valid iCalendar objects. As
such, an individual VTIMEZONE calendar component MUST be specified
for each unique TZID parameter value specified in an iCalendar
object. Unfortunately this mean that the same VTIMEZONE component
will get sent or retrieved multiple times for each iCalendar object
Daboo, et al. Expires August 14, 2005 [Page 9]
Internet-Draft CalDAV February 2005
that uses the timezone. This is not efficient in terms of bandwidth
usage.
[[Comment.2: Not clear how big an issue that really is. CalDAV
already allows clients to retrieve iCalendar objects without their
VTIMEZONE component with the CALDAV:calendar-query REPORT. It is
still not clear whether a client could rely only on the value of the
TZID parameter, or should it always requests a VTIMEZONE component
with at least the TZID and TZURL properties and rely on the TZURL as
a unique identifier for a given time zone. CalDAV servers have no
choice but to return complete VTIMEZONE components in iCalendar
object retrieve with the GET method as their is no way to know if the
client is a CalDAV client or a simple HTTP client. On a PUT request
perhaps a CalDAV server could accept an iCalendar object with a
VTIMEZONE object that has at least TZURL that points to a calendar
resource that defines a time zone on the server. --desruisseaux]]
The timezone collection is a calendar collection that contains only
VTIMEZONE components as separate resources within that collection.
There MUST be only one VTIMEZONE component per calendar resource in
the timezone collection. Clients can discover the location of the
timezone collection with the CALDAV:timezone-collection-set OPTIONS
request (see Section 5.2.4) and can list the supported timezones and
retrieve specific timezone component data by using the
CALDAV:calendar-query REPORT defined in Section 8.3.
Daboo, et al. Expires August 14, 2005 [Page 10]
Internet-Draft CalDAV February 2005
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 calendars are for, users must rely on non-standard cues to
find out what a calendar 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 calendars 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 iCalendar Components within the Calendar Collection
Each top-level iCalendar component within the VCALENDAR component is
represented as a separate WebDAV resource, with the following
exceptions
o sets of recurring items (i.e., components with the same UID
iCalendar property value, but differing RECURRENCE-ID values) are
all stored in the same resource. That is, each WebDAV resource
MUST only contain iCalendar components with the same iCalendar UID
Daboo, et al. Expires August 14, 2005 [Page 11]
Internet-Draft CalDAV February 2005
property value, and all iCalendar components with the same
iCalendar UID property value MUST be stored in the same WebDAV
resource.
o any top-level component that references a timezone via a "TZID"
property MUST include the VTIMEZONE component corresponding to
that timezone id, as required by iCalendar, unless the timezone is
one included in the server's timezone collection, as described in
Section 3.3.
For example, given the following iCalendar object:
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 with UID value "1@example.com", would be stored in its own
unique WebDAV resource. The two VEVENTs with UID value
"2@example.com", which represent a set of recurring events where one
instance has been overridden, would be stored in a single unique
WebDAV resource.
Daboo, et al. Expires August 14, 2005 [Page 12]
Internet-Draft CalDAV February 2005
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 calendars 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 calendars 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 calendars 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>
Daboo, et al. Expires August 14, 2005 [Page 13]
Internet-Draft CalDAV February 2005
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
method.
Daboo, et al. Expires August 14, 2005 [Page 14]
Internet-Draft CalDAV February 2005
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
supports CalDAV in this namespace, therefore the '/calendars/users/'
collection may be used as a parent for calendar collections as the
Daboo, et al. Expires August 14, 2005 [Page 15]
Internet-Draft CalDAV February 2005
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:
If an XML request body is included, it MUST be a DAV:options XML
element.
<!ELEMENT options ANY>
Daboo, et al. Expires August 14, 2005 [Page 16]
Internet-Draft CalDAV February 2005
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.
[[Comment.3: We should probably put a note that one needs to be
authenticated before issuing this OPTIONS request. Obviously.
--desruisseaux]]
5.2.4 CALDAV:timezone-collection-set OPTIONS request
A CALDAV:timezone-collection-set element MAY be included in the
request body to identify the calendar collections that contains the
set of calendar resources that defines the timezone supported by the
server.
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
timezone-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
timezone-collection-set element.
<!ELEMENT timezone-collection-set (href*)>
If CALDAV:timezone-collection-set is included in the request body,
the response body for a successful request MUST contain a
Daboo, et al. Expires August 14, 2005 [Page 17]
Internet-Draft CalDAV February 2005
CALDAV:timezone-collection-set element identifying calendar
collections containing the set of calendar resources that defines
the timezone supported by the server.
5.2.5 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>
>> 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.
5.3 Creating calendar resources
Clients typically populate calendars 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.
Daboo, et al. Expires August 14, 2005 [Page 18]
Internet-Draft CalDAV February 2005
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.
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
Location: http://cal.example.com/lisa/calendar/ev1234.ics
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
Daboo, et al. Expires August 14, 2005 [Page 19]
Internet-Draft CalDAV February 2005
"If-None-Match" header.
As mentionned in Section 3.10 of RFC 2445 [2], the URI of calendar
resources containing (an arbitrary set of) calendaring and scheduling
information may be suffixed by ".ics", and the URI of calendar
resources containing free or busy time information may be suffixed by
".ifb".
A CalDAV server MAY return the Location header in a 201 (Created)
response to a PUT request if the server created the resource at a
different URI than the Request-URI. CalDAV clients MUST be able to
handle the URI returned by the server in the Location header, by
adjusting their original resource URI to the new one returned by the
server.
Daboo, et al. Expires August 14, 2005 [Page 20]
Internet-Draft CalDAV February 2005
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.
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) >
Daboo, et al. Expires August 14, 2005 [Page 21]
Internet-Draft CalDAV February 2005
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
Daboo, et al. Expires August 14, 2005 [Page 22]
Internet-Draft CalDAV February 2005
specification leaves 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.
<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>
Daboo, et al. Expires August 14, 2005 [Page 23]
Internet-Draft CalDAV February 2005
</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
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.
Daboo, et al. Expires August 14, 2005 [Page 24]
Internet-Draft CalDAV February 2005
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 calendars
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
Daboo, et al. Expires August 14, 2005 [Page 25]
Internet-Draft CalDAV February 2005
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.4: 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
2nd, 2004 at 11:59:59 pm UTC. In addition the DAV:getetag property
is also requested and returned as part of the response.
Daboo, et al. Expires August 14, 2005 [Page 26]
Internet-Draft CalDAV February 2005
>> 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>
>> Response <<
Daboo, et al. Expires August 14, 2005 [Page 27]
Internet-Draft CalDAV February 2005
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
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
Daboo, et al. Expires August 14, 2005 [Page 28]
Internet-Draft CalDAV February 2005
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".
Daboo, et al. Expires August 14, 2005 [Page 29]
Internet-Draft CalDAV February 2005
>> 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".
Daboo, et al. Expires August 14, 2005 [Page 30]
Internet-Draft CalDAV February 2005
>> 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.
Daboo, et al. Expires August 14, 2005 [Page 31]
Internet-Draft CalDAV February 2005
>> 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>
8.3.6 Timezone Examples
The following examples illustrate two common operations a client may
want to perform on the CalDAV server's timezone collection. These
examples assume that the client has already got the URI for the
server's timezone calendar collection.
8.3.6.1 Example: List all available timezones on the server
In this example, the client requests the server to return all
VTIMEZONE components, with just their TZID property, and without the
embedded DAYLIGHT and STANDARD components.
[[Comment.5: A client might also want to get a human-readable display
name for the VTIMEZONE components. Unfortunately, there is no such
property defined in iCalendar. The TZNAME property is defined in the
DAYLIGHT and STANDARD components and would have a value such as "US
Eastern Standard Time" or "US Eastern Daylight Time". What a client
would need here, is a time zone name irrespective of the "Standard"
or "Daylight" observance, e.g., "US Eastern Time". Perhaps we should
recommend the use of the DAV:displayname property on timezone
resources. --desruisseaux]]
Daboo, et al. Expires August 14, 2005 [Page 32]
Internet-Draft CalDAV February 2005
>> Request <<
REPORT /calendar/timezones/ 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:comp name="VCALENDAR">
<C:allprop/>
<C:comp name="VTIMEZONE">
<C:prop name="TZID"/>
</C:comp>
</C:comp>
</C:calendar-data>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VTIMEZONE">
<C:is-defined/>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>
>> 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/calendar/timezones/tz1.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"tz1-20050125"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
Daboo, et al. Expires August 14, 2005 [Page 33]
Internet-Draft CalDAV February 2005
<C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
TZID:America/New_York
END:VTIMEZONE
END:VCALENDAR
</C:calendar-data>
</D:response>
<D:response>
<D:href
>http://cal.example.com/calendar/timezones/tz2.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"tz2-20050125"</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:VTIMEZONE
TZID:America/Los_Angeles
END:VTIMEZONE
END:VCALENDAR
</C:calendar-data>
</D:response>
</D:multistatus>
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
Daboo, et al. Expires August 14, 2005 [Page 34]
Internet-Draft CalDAV February 2005
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.
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.
Daboo, et al. Expires August 14, 2005 [Page 35]
Internet-Draft CalDAV February 2005
>> 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>
Daboo, et al. Expires August 14, 2005 [Page 36]
Internet-Draft CalDAV February 2005
>> 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.
Daboo, et al. Expires August 14, 2005 [Page 37]
Internet-Draft CalDAV February 2005
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.
'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
Daboo, et al. Expires August 14, 2005 [Page 38]
Internet-Draft CalDAV February 2005
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>
>> 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>
Daboo, et al. Expires August 14, 2005 [Page 39]
Internet-Draft CalDAV February 2005
9. Synchronization Operations
WebDAV already provides functionality required to synchronize a
collection or set of collections, make changes offline, and a simple
way to resolve conflicts when reconnected. 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.
9.1 Use of Reports
9.1.1 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 calendars 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.
9.1.2 Synchronize by Time Range
Typically in a calendar, historical data (events, to-dos etc that
have completed prior to the current date) do not change, though they
may be deleted. As a result, a client can speed up the
synchronization process by only considering data for the present time
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.
9.1.3 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
Daboo, et al. Expires August 14, 2005 [Page 40]
Internet-Draft CalDAV February 2005
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:
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:
Daboo, et al. Expires August 14, 2005 [Page 41]
Internet-Draft CalDAV February 2005
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 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
Daboo, et al. Expires August 14, 2005 [Page 42]
Internet-Draft CalDAV February 2005
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 the Server Timezone Collection
Clients should use the set of timezone components in the server's
timezone collection advertises in the namespace report, for any
timezones for calendar components that it creates. This avoids the
need for the client or server to send the timezone data along with
the component data and thus reduces network bandwidth usage.
Daboo, et al. Expires August 14, 2005 [Page 43]
Internet-Draft CalDAV February 2005
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
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.
Daboo, et al. Expires August 14, 2005 [Page 44]
Internet-Draft CalDAV February 2005
<!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
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'
Daboo, et al. Expires August 14, 2005 [Page 45]
Internet-Draft CalDAV February 2005
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
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
Daboo, et al. Expires August 14, 2005 [Page 46]
Internet-Draft CalDAV February 2005
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")
<!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.
Daboo, et al. Expires August 14, 2005 [Page 47]
Internet-Draft CalDAV February 2005
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) >
<!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)>
Daboo, et al. Expires August 14, 2005 [Page 48]
Internet-Draft CalDAV February 2005
10.4 CALDAV:time-range XML Element
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>
10.5 DAV:response XML Element
Daboo, et al. Expires August 14, 2005 [Page 49]
Internet-Draft CalDAV February 2005
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+ >
Daboo, et al. Expires August 14, 2005 [Page 50]
Internet-Draft CalDAV February 2005
11. Internationalization Considerations
Daboo, et al. Expires August 14, 2005 [Page 51]
Internet-Draft CalDAV February 2005
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.6: 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]]
Daboo, et al. Expires August 14, 2005 [Page 52]
Internet-Draft CalDAV February 2005
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.
Daboo, et al. Expires August 14, 2005 [Page 53]
Internet-Draft CalDAV February 2005
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, 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.
15. 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/>.
Daboo, et al. Expires August 14, 2005 [Page 54]
Internet-Draft CalDAV February 2005
ISBN 0321185781
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/
Daboo, et al. Expires August 14, 2005 [Page 55]
Internet-Draft CalDAV February 2005
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) |
+---------------------------------+---------------------------------+
Daboo, et al. Expires August 14, 2005 [Page 56]
Internet-Draft CalDAV February 2005
Appendix B. Changes
B.1 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.
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.2 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.3 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.4 Changes in -02
Basically still adding major sections of content:
a. Defined new field values to the OPTIONS "DAV:" response header
b. Added new resource properties
Daboo, et al. Expires August 14, 2005 [Page 57]
Internet-Draft CalDAV February 2005
c. Added new principal properties
d. Added new SCHEDULE method and related headers
e. Added new privileges for scheduling
B.5 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
Daboo, et al. Expires August 14, 2005 [Page 58]
Internet-Draft CalDAV February 2005
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Daboo, et al. Expires August 14, 2005 [Page 59]
