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Network Working Group C. Daboo
Internet-Draft Apple Inc.
Updates: 4791 (if approved) B. Desruisseaux
Intended status: Standards Track Oracle
Expires: March 10, 2012 September 7, 2011
CalDAV Scheduling Extensions to WebDAV
draft-desruisseaux-caldav-sched-10
Abstract
This document defines extensions to the CalDAV "calendar-access"
feature to specify a standard way of performing scheduling
transactions with iCalendar-based calendar components. This document
defines the "calendar-auto-schedule" feature of CalDAV.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on March 10, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
1.2. Approach . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3. Limitations . . . . . . . . . . . . . . . . . . . . . . . 7
1.4. Notational Conventions . . . . . . . . . . . . . . . . . . 8
1.5. XML Namespaces and Processing . . . . . . . . . . . . . . 8
2. Scheduling Process . . . . . . . . . . . . . . . . . . . . . . 10
3. Scheduling Support . . . . . . . . . . . . . . . . . . . . . . 11
3.1. Example OPTIONS Request . . . . . . . . . . . . . . . . . 11
4. Scheduling Collections . . . . . . . . . . . . . . . . . . . . 12
4.1. Scheduling Outbox Collection . . . . . . . . . . . . . . . 12
4.2. Scheduling Inbox Collection . . . . . . . . . . . . . . . 13
4.3. Calendaring Reports Extensions . . . . . . . . . . . . . . 15
5. Scheduling Transactions . . . . . . . . . . . . . . . . . . . 16
5.1. Identifying Scheduling Object Resources . . . . . . . . . 16
5.2. Handling Scheduling Object Resources . . . . . . . . . . . 16
5.2.1. Organizer Scheduling Object Resources . . . . . . . . 16
5.2.1.1. Create . . . . . . . . . . . . . . . . . . . . . . 17
5.2.1.2. Modify . . . . . . . . . . . . . . . . . . . . . . 18
5.2.1.3. Remove . . . . . . . . . . . . . . . . . . . . . . 20
5.2.2. Attendee Scheduling Object Resources . . . . . . . . . 20
5.2.2.1. Allowed Attendee Changes . . . . . . . . . . . . . 20
5.2.2.2. Create . . . . . . . . . . . . . . . . . . . . . . 21
5.2.2.3. Modify . . . . . . . . . . . . . . . . . . . . . . 22
5.2.2.4. Remove . . . . . . . . . . . . . . . . . . . . . . 23
5.2.3. HTTP Methods . . . . . . . . . . . . . . . . . . . . . 24
5.2.3.1. PUT . . . . . . . . . . . . . . . . . . . . . . . 24
5.2.3.2. COPY . . . . . . . . . . . . . . . . . . . . . . . 24
5.2.3.3. MOVE . . . . . . . . . . . . . . . . . . . . . . . 25
5.2.3.4. DELETE . . . . . . . . . . . . . . . . . . . . . . 26
5.2.4. Additional Method Preconditions . . . . . . . . . . . 26
5.2.4.1. CALDAV:unique-scheduling-object-resource
Precondition . . . . . . . . . . . . . . . . . . . 26
5.2.4.2. CALDAV:same-organizer-in-all-components
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Precondition . . . . . . . . . . . . . . . . . . . 26
5.2.4.3. CALDAV:allowed-organizer-scheduling-object-chan
Precondition . . . . . . . . . . . . . . . . . . . 27
5.2.4.4. CALDAV:allowed-attendee-scheduling-object-chang
Precondition . . . . . . . . . . . . . . . . . . . 28
5.2.5. DTSTAMP and SEQUENCE Properties . . . . . . . . . . . 28
5.2.6. Restrict Recurrence Instances Sent to Attendees . . . 28
5.2.7. Forcing the Server to Send a Scheduling Message . . . 29
6. Processing Incoming Scheduling Messages . . . . . . . . . . . 30
6.1. Processing Organizer Requests, Additions, and
Cancellations . . . . . . . . . . . . . . . . . . . . . . 30
6.2. Processing Attendee Replies . . . . . . . . . . . . . . . 31
6.3. Scheduling Messages as Notifications . . . . . . . . . . . 31
6.4. Default Calendar Collection . . . . . . . . . . . . . . . 31
6.4.1. Additional Method Preconditions . . . . . . . . . . . 32
6.4.1.1. CALDAV:default-calendar-needed Precondition . . . 32
6.4.1.2. CALDAV:valid-schedule-default-calendar-URL
Precondition . . . . . . . . . . . . . . . . . . . 33
7. Request for Busy Time Information . . . . . . . . . . . . . . 34
7.1. Status Codes . . . . . . . . . . . . . . . . . . . . . . . 34
7.2. Additional Method Preconditions . . . . . . . . . . . . . 34
7.2.1. DAV:need-privileges Precondition . . . . . . . . . . . 34
7.2.2. CALDAV:supported-collection Precondition . . . . . . . 35
7.2.3. CALDAV:supported-calendar-data Precondition . . . . . 36
7.2.4. CALDAV:valid-calendar-data Precondition . . . . . . . 36
7.2.5. CALDAV:valid-scheduling-message Precondition . . . . . 37
7.2.6. CALDAV:valid-organizer Precondition . . . . . . . . . 37
7.2.7. CALDAV:max-resource-size Precondition . . . . . . . . 38
7.3. Response to a POST request . . . . . . . . . . . . . . . . 38
8. Avoiding Conflicts when Updating Scheduling Object
Resources . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.1. PUT . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
8.2. DELETE, COPY or MOVE . . . . . . . . . . . . . . . . . . . 42
9. Other Scheduling Considerations . . . . . . . . . . . . . . . 44
9.1. Attendee Participation Status . . . . . . . . . . . . . . 44
9.2. Schedule Status Values . . . . . . . . . . . . . . . . . . 45
10. Additional iCalendar Property Parameters . . . . . . . . . . . 49
10.1. Schedule Agent Parameter . . . . . . . . . . . . . . . . . 49
10.2. Schedule Force Send Parameter . . . . . . . . . . . . . . 50
10.3. Schedule Status Parameter . . . . . . . . . . . . . . . . 51
11. Additional Message Header Fields . . . . . . . . . . . . . . . 53
11.1. Schedule-Reply Request Header . . . . . . . . . . . . . . 53
11.2. Schedule-Tag Response Header . . . . . . . . . . . . . . . 53
11.3. If-Schedule-Tag-Match Request Header . . . . . . . . . . . 54
12. Additional WebDAV Properties . . . . . . . . . . . . . . . . . 55
12.1. CALDAV:schedule-calendar-transp Property . . . . . . . . . 55
12.2. CALDAV:schedule-default-calendar-URL Property . . . . . . 56
12.3. CALDAV:schedule-tag Property . . . . . . . . . . . . . . . 57
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13. Scheduling Access Control . . . . . . . . . . . . . . . . . . 58
13.1. Scheduling Privileges . . . . . . . . . . . . . . . . . . 58
13.1.1. Privileges on Scheduling Inbox Collections . . . . . . 58
13.1.1.1. CALDAV:schedule-deliver Privilege . . . . . . . . 58
13.1.1.2. CALDAV:schedule-deliver-invite Privilege . . . . . 59
13.1.1.3. CALDAV:schedule-deliver-reply Privilege . . . . . 59
13.1.1.4. CALDAV:schedule-query-freebusy Privilege . . . . . 59
13.1.2. Privileges on Scheduling Outbox Collections . . . . . 59
13.1.2.1. CALDAV:schedule-send Privilege . . . . . . . . . . 59
13.1.2.2. CALDAV:schedule-send-invite Privilege . . . . . . 60
13.1.2.3. CALDAV:schedule-send-reply Privilege . . . . . . . 60
13.1.2.4. CALDAV:schedule-send-freebusy Privilege . . . . . 60
13.1.3. Aggregation of Scheduling Privileges . . . . . . . . . 60
13.2. Additional Principal Properties . . . . . . . . . . . . . 61
13.2.1. CALDAV:schedule-inbox-URL Property . . . . . . . . . . 61
13.2.2. CALDAV:schedule-outbox-URL Property . . . . . . . . . 62
13.2.3. CALDAV:calendar-user-address-set Property . . . . . . 62
13.2.4. CALDAV:calendar-user-type Property . . . . . . . . . . 63
14. XML Element Definitions . . . . . . . . . . . . . . . . . . . 65
14.1. CALDAV:schedule-response XML Element . . . . . . . . . . . 65
14.2. CALDAV:response XML Element . . . . . . . . . . . . . . . 65
14.3. CALDAV:recipient XML Element . . . . . . . . . . . . . . . 65
14.4. CALDAV:request-status XML Element . . . . . . . . . . . . 66
15. Security Considerations . . . . . . . . . . . . . . . . . . . 67
15.1. Verifying Scheduling Transactions . . . . . . . . . . . . 67
15.2. Verifying Busy Time Information Requests . . . . . . . . . 67
15.3. Privacy Issues . . . . . . . . . . . . . . . . . . . . . . 68
16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 69
16.1. Message Header Field Registrations . . . . . . . . . . . . 69
16.1.1. Schedule-Reply . . . . . . . . . . . . . . . . . . . . 69
16.1.2. Schedule-Tag . . . . . . . . . . . . . . . . . . . . . 69
16.1.3. If-Schedule-Tag-Match . . . . . . . . . . . . . . . . 69
16.2. iCalendar Property Parameter Registrations . . . . . . . . 70
16.3. iCalendar REQUEST-STATUS Value Registrations . . . . . . . 70
16.4. Additional iCalendar Elements Registries . . . . . . . . . 70
16.4.1. Schedule Agent Values Registry . . . . . . . . . . . . 70
16.4.2. Schedule Force Send Values Registry . . . . . . . . . 71
17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 72
18. References . . . . . . . . . . . . . . . . . . . . . . . . . . 73
18.1. Normative References . . . . . . . . . . . . . . . . . . . 73
18.2. Informative References . . . . . . . . . . . . . . . . . . 74
Appendix A. Scheduling Privileges Summary . . . . . . . . . . . . 75
A.1. Scheduling Inbox Privileges . . . . . . . . . . . . . . . 75
A.2. Scheduling Outbox Privileges . . . . . . . . . . . . . . . 75
Appendix B. Example Scheduling Transactions . . . . . . . . . . . 77
B.1. Example: Organizer Inviting Multiple Attendees . . . . . . 77
B.2. Example: Attendee Receiving an Invitation . . . . . . . . 79
B.3. Example: Attendee Replying to an Invitation . . . . . . . 81
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B.4. Example: Organizer Receiving a Reply to an Invitation . . 83
B.5. Example: Organizer Requesting Busy Time Information . . . 85
B.6. Example: User Attempting to Invite Attendee on behalf
of Organizer . . . . . . . . . . . . . . . . . . . . . . . 87
B.7. Example: Attendee Declining an Instance of a Recurring
Event . . . . . . . . . . . . . . . . . . . . . . . . . . 88
B.8. Example: Attendee Removing an Instance of a Recurring
Event . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Appendix C. Changes (to be removed by RFC Editor prior to
publication) . . . . . . . . . . . . . . . . . . . . 95
C.1. Changes in -10 . . . . . . . . . . . . . . . . . . . . . . 95
C.2. Changes in -09 . . . . . . . . . . . . . . . . . . . . . . 95
C.3. Changes in -08 . . . . . . . . . . . . . . . . . . . . . . 96
C.4. Changes in -07 . . . . . . . . . . . . . . . . . . . . . . 97
C.5. Changes in -06 . . . . . . . . . . . . . . . . . . . . . . 97
C.6. Changes in -05 . . . . . . . . . . . . . . . . . . . . . . 98
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1. Introduction
This document specifies extensions to the CalDAV "calendar-access"
[RFC4791] feature to enable scheduling of iCalendar-based [RFC5545]
calendar components between Calendar Users. This extension leverages
the scheduling methods defined in the iCalendar Transport-independent
Interoperability Protocol (iTIP) [RFC5546] to permit Calendar Users
to perform scheduling transactions such as schedule, reschedule,
respond to scheduling request or cancel calendar components, as well
as search for busy time information.
Discussion of this Internet-Draft is taking place on the mailing list
<https://www.ietf.org/mailman/listinfo/caldav>.
1.1. Terminology
This specification uses much of the same terminology as iCalendar
[RFC5545], iTIP [RFC5546], WebDAV [RFC4918], and CalDAV [RFC4791].
The following definitions are provided to aid the reader in
understanding this specification.
Calendar User (CU): An entity (often a human) that accesses calendar
information [RFC3283].
Calendar collection: A resource that acts as a container of
references to child calendar object resources [RFC4791].
Calendar object resource: A resource representing a calendar object
(event, to-do, journal entry, or other calendar components)
[RFC4791].
Scheduling object resource: A calendar object resource contained in
a calendar collection for which the server will take care of
sending scheduling messages on behalf of the owner of the calendar
collection.
Organizer scheduling object resource: A scheduling object resource
owned by an Organizer.
Attendee scheduling object resource: A scheduling object resource
owned by an Attendee.
Automatic scheduling transaction: Add, change or remove operations
on a scheduling object resource for which the server will deliver
scheduling messages to other Calendar Users.
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Scheduling message: A calendar object that describes a scheduling
transaction such as schedule, reschedule, reply, or cancel.
Scheduling Outbox collection: A resource at which busy time
information requests are targeted.
Scheduling Inbox collection: A collection in which incoming
scheduling messages are delivered.
1.2. Approach
iTIP [RFC5546] outlines a model where Calendar Users exchange
scheduling messages with one another. Often times, clients are made
responsible for generating and sending scheduling messages as well as
processing incoming scheduling messages. This approach yields a
number of problems, including:
o For most updates to a calendar component, clients are responsible
for sending appropriate scheduling messages to the Organizer or
the Attendees.
o The handling of incoming scheduling messages and the updates to
calendars impacted by those messages only occurs when clients are
active.
o Due to the update latency, it is possible for calendars of
different Calendar Users to reflect different, inaccurate states.
This specification uses an alternative approach where the server is
made responsible for sending scheduling messages and processing
incoming scheduling messages. This approach frees the clients from
the submission and processing of scheduling messages and ensures
better consistency of calendar data across users' calendars. The
operation of creating, modifying or deleting a calendar component in
a calendar is enough to trigger the server to deliver the necessary
scheduling messages to the appropriate Calendar Users.
1.3. Limitations
While the scheduling features described in this specification are
based on iTIP [RFC5546], some of its more advanced features have
deliberately been left out in order to keep this specification
simple. In particular, the following iTIP [RFC5546] features are not
covered: publishing, countering, delegating, refreshing and
forwarding calendar components, as well as replacing the Organizer of
a calendar component.
The goal of this specification is to provide the essential scheduling
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features needed. It is expected that future extensions will be
developed to address the more advanced features.
1.4. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The Augmented BNF (ABNF) syntax used by this document to specify the
format definition of new iCalendar elements is defined in [RFC5234].
The Augmented BNF (ABNF) syntax used by this document to specify the
format definition of new message header fields to be used with the
HTTP/1.1 protocol is described in Section 2.1 of [RFC2616]. Since
this Augmented BNF uses the basic production rules provided in
Section 2.2 of [RFC2616], these rules apply to this document as well.
The term "protected" is used in the Conformance field of WebDAV
property definitions as defined in Section 15 of [RFC4918].
1.5. XML Namespaces and Processing
This document uses XML DTD fragments ([W3C.REC-xml-20081126], Section
3.2) as a purely notational convention. WebDAV request and response
bodies cannot be validated by a DTD due to the specific extensibility
rules defined in Section 17 of [RFC4918] and due to the fact that all
XML elements defined by that specification use the XML namespace name
"DAV:". In particular:
1. element names use the "DAV:" namespace,
2. element ordering is irrelevant unless explicitly stated,
3. extension elements (elements not already defined as valid child
elements) may be added anywhere, except when explicitly stated
otherwise,
4. extension attributes (attributes not already defined as valid for
this element) may be added anywhere, except when explicitly
stated otherwise.
The XML elements specified in this document are defined in the
"urn:ietf:params:xml:ns:caldav" XML namespace registered by CalDAV
[RFC4791].
When XML element types in the namespaces "DAV:" and
"urn:ietf:params:xml:ns:caldav" are referenced in this document
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outside of the context of an XML fragment, the strings "DAV:" and
"CALDAV:" will be prefixed to the element types, respectively.
This document inherits, and sometimes extends, DTD productions from
Section 14 of [RFC4918].
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.
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2. Scheduling Process
The process of scheduling an event between different parties often
involves a series of steps with different actors playing particular
roles during the whole process. Typically there is an event
"Organizer" whose role is to schedule an event between one or more
"Attendees", and this is done by sending out invitations and handling
responses from each Attendee.
This process can typically be broken down into two phases.
In the first phase, the Organizer will query the busy time
information of each Attendee to determine the most appropriate time
for the event. This request is sometimes called a "freebusy" lookup.
In the second phase, the Organizer sends out invitations to each
Attendee using the time previously determined from the freebusy
lookup. There then follows exchanges between Organizer and Attendees
regarding the invitation. Some Attendees may choose to attend at the
time proposed by the Organizer, others may decline to attend. The
Organizer needs to process each of the replies from the Attendees and
take appropriate action to confirm the event, reschedule it or
perhaps cancel it.
The user expectation as to how a calendaring and scheduling system
should respond in each of these two phases is somewhat different. In
the case of a freebusy lookup, users expect to get back results
immediately so that they can then move on to the invitation phase as
quickly as possible. In the case of invitations, it is expected that
each Attendee will reply with their participation status in their own
time, so delays in receiving replies are anticipated. Thus
calendaring and scheduling systems should treat these two operational
phases in different ways to accommodate the user expectations, which
is what this specification does.
While the scenario described above only covers the case of scheduling
events between Calendar Users, and requesting busy time information,
this specification also provides support for the scheduling of to-dos
between Calendar Users. For the majority of the following
discussion, scheduling of events and freebusy lookups will be
discussed, as these are the more common operations.
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3. Scheduling Support
A server that supports the features described in this document MUST
include "calendar-auto-schedule" as a field in the DAV response
header from an OPTIONS request on any resource that supports any
scheduling actions, properties, privileges or methods.
To advertise support for the CalDAV "calendar-auto-schedule" feature
a server is REQUIRED to support and advertise support for the CalDAV
"calendar-access" [RFC4791] feature.
3.1. Example OPTIONS Request
In this example, the OPTIONS response indicates that the server
supports the "calendar-access" and "calendar-auto-schedule" features
and that the resource "/home/cyrus/calendars/inbox/" supports the
scheduling actions, properties, privileges and methods defined in
this specification.
>> Request <<
OPTIONS /home/cyrus/calendars/inbox/ HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 204 No Content
Date: Thu, 31 Mar 2011 09:00:00 GMT
Allow: OPTIONS, GET, HEAD, DELETE, TRACE, PROPFIND
Allow: PROPPATCH, LOCK, UNLOCK, REPORT, ACL
DAV: 1, 2, 3, access-control
DAV: calendar-access, calendar-auto-schedule
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4. Scheduling Collections
This specification introduces new collection resource types that are
used to manage scheduling object resources, and scheduling
privileges, as well as provide scheduling functionality. It is the
server's responsibility to create these collection resources, and
clients have no way to create or delete them.
4.1. Scheduling Outbox Collection
A scheduling Outbox collection is used as the target for busy time
information requests, and to manage privileges that apply to outgoing
scheduling requests.
A scheduling Outbox collection MUST report the DAV:collection and
CALDAV:schedule-outbox XML elements in the value of the DAV:
resourcetype property. The element type declaration for CALDAV:
schedule-outbox is:
<!ELEMENT schedule-outbox EMPTY>
Example:
<D:resourcetype xmlns:D="DAV:">
<D:collection/>
<C:schedule-outbox xmlns:C="urn:ietf:params:xml:ns:caldav"/>
</D:resourcetype>
New WebDAV ACL [RFC3744] privileges can be set on the scheduling
Outbox collection to control who is allowed to send scheduling
messages on behalf of the Calendar User associated with the
scheduling Outbox collection. See Section 13.1 for more details.
A scheduling Outbox collection MUST NOT be a child (at any depth) of
a calendar collection resource.
The following WebDAV properties specified in CalDAV "calendar-access"
[RFC4791] MAY also be defined on scheduling Outbox collections:
CALDAV:supported-calendar-component-set - when present this
indicates the allowed calendar component types for scheduling
messages submitted to the scheduling Outbox collection with the
POST method.
CALDAV:supported-calendar-data - when present this indicates the
allowed media types for scheduling messages submitted to the
scheduling Outbox collection with the POST method.
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CALDAV:max-resource-size - when present this indicates the maximum
size in octets of a resource that the server is willing to accept
for scheduling messages submitted to the scheduling Outbox
collection with the POST method.
CALDAV:min-date-time - when present this indicates the earliest
date and time (in UTC) that the server is willing to accept for
any DATE or DATE-TIME value in scheduling messages submitted to
the scheduling Outbox collection with the POST method.
CALDAV:max-date-time - when present this indicates the latest date
and time (in UTC) that the server is willing to accept for any
DATE or DATE-TIME value in scheduling messages submitted to the
scheduling Outbox collection with the POST method.
CALDAV:max-attendees-per-instance - when present this indicates
the maximum number of ATTENDEE properties in any instance of
scheduling messages submitted to the scheduling Outbox collection
with the POST method. Specifically, this limits the total number
of Attendees whose freebusy information can be queried in a single
request.
The use of child resources in a scheduling Outbox collection is
reserved for future revisions or extensions of this specification.
4.2. Scheduling Inbox Collection
A scheduling Inbox collection contains copies of incoming scheduling
messages. These may be requests sent by an Organizer, or replies
sent by an Attendee in response to a request. The scheduling Inbox
collection is also used to manage scheduling privileges.
A scheduling Inbox collection MUST report the DAV:collection and
CALDAV:schedule-inbox XML elements in the value of the DAV:
resourcetype property. The element type declaration for CALDAV:
schedule-inbox is:
<!ELEMENT schedule-inbox EMPTY>
Example:
<D:resourcetype xmlns:D="DAV:">
<D:collection/>
<C:schedule-inbox xmlns:C="urn:ietf:params:xml:ns:caldav"/>
</D:resourcetype>
Scheduling Inbox collections MUST only contain calendar object
resources that obey the restrictions specified in iTIP [RFC5546].
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Consequently, scheduling Inbox collections MUST NOT contain any types
of collection resources. Restrictions defined in Section 4.1 of
CalDAV "calendar-access" [RFC4791] on calendar object resources
contained in calendar collections (e.g., "UID" uniqueness) do not
apply to calendar object resources contained in a scheduling Inbox
collection. Thus, multiple calendar object resources contained in a
scheduling Inbox collection can have the same "UID" property value
(i.e., multiple scheduling messages for the same calendar component).
New WebDAV ACL [RFC3744] privileges can be set on the scheduling
Inbox collection to control from whom the Calendar User associated
with the scheduling Inbox collection will accept scheduling messages
from. See Section 13.1 for more details.
A scheduling Inbox collection MUST NOT be a child (at any depth) of a
calendar collection resource.
The following WebDAV properties specified in CalDAV "calendar-access"
[RFC4791] MAY also be defined on scheduling Inbox collections:
CALDAV:calendar-timezone - when present this contains a time zone
that the server can use when calendar date-time operations are
carried out, for example when a time-range CALDAV:calendar-query
REPORT is targeted at a scheduling Inbox collection.
CALDAV:supported-calendar-component-set - when present this
indicates the allowed calendar component types for scheduling
messages delivered to the scheduling Inbox collection.
CALDAV:supported-calendar-data - when present this indicates the
allowed media types for scheduling messages delivered to the
scheduling Inbox collection.
CALDAV:max-resource-size - when present this indicates the maximum
size in octets of a resource that the server is willing to accept
for scheduling messages delivered to the scheduling Inbox
collection.
CALDAV:min-date-time - when present this indicates the earliest
date and time (in UTC) that the server is willing to accept for
any DATE or DATE-TIME value in scheduling messages delivered to
the scheduling Inbox collection.
CALDAV:max-date-time - when present this indicates the latest date
and time (in UTC) that the server is willing to accept for any
DATE or DATE-TIME value in scheduling messages delivered to the
scheduling Inbox collection.
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CALDAV:max-instances - when present this indicates the maximum
number of recurrence instances in scheduling messages delivered to
the scheduling Inbox collection.
CALDAV:max-attendees-per-instance - when present this indicates
the maximum number of ATTENDEE properties in any instance of
scheduling messages delivered to the scheduling Inbox collection.
4.3. Calendaring Reports Extensions
This specification extends the CALDAV:calendar-query and CALDAV:
calendar-multiget REPORTs to return results for calendar object
resources in scheduling Inbox collections.
When a CALDAV:calendar-query REPORT includes a time-range query and
targets a scheduling Inbox collection, if any calendar object
resources contain "VEVENT" calendar components that do not include a
"DTSTART" iCalendar property (as allowed by iTIP [RFC5546]) then such
components MUST always match the time-range query test.
Note that the CALDAV:free-busy-query REPORT is not supported on
scheduling Inbox collections.
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5. Scheduling Transactions
When a calendar object resource is created, modified or removed from
a calendar collection, the server examines the calendar data and
checks to see whether the data represents a scheduling object
resource. If it does, the server will automatically attempt to
deliver a scheduling message to the appropriate Calendar Users.
Several types of scheduling operations can occur in this case,
equivalent to iTIP "REQUEST", "REPLY", "CANCEL", and "ADD"
operations.
5.1. Identifying Scheduling Object Resources
Calendar object resources on which the server performs automatic
scheduling transactions are referred to as scheduling object
resources. There are two types of scheduling object resources:
organizer scheduling object resources, and attendee scheduling object
resources.
A calendar object resource is considered to be a valid organizer
scheduling object resource if the "ORGANIZER" iCalendar property is
present and set in all the calendar components to a value that
matches one of the calendar user addresses of the owner of the
calendar collection.
A calendar object resource is considered to be a valid attendee
scheduling object resource if the "ORGANIZER" iCalendar property is
present and set in all the calendar components to the same value and
doesn't match one of the calendar user addresses of the owner of the
calendar collection, and at least one of the "ATTENDEE" iCalendar
property values matches one of the calendar user addresses of the
owner of the calendar collection.
The creation of attendee scheduling object resources is typically
done by the server, with the resource being created in an appropriate
calendar collection (see Section 6.4).
5.2. Handling Scheduling Object Resources
The server's behavior when processing a scheduling object resource
depends on whether it is owned by the Organizer or an Attendee
specified in the calendar data.
5.2.1. Organizer Scheduling Object Resources
An Organizer can create, modify or remove a scheduling object
resource. The create, modify and remove behaviors for the server are
each described next, and the way these are invoked via HTTP requests
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is described in Section 5.2.3.
The Organizer of a calendar component may also be an Attendee of that
calendar component. In such cases the server MUST NOT send a
scheduling message to the Attendee that matches the Organizer.
5.2.1.1. Create
When a scheduling object resource is created by the Organizer, the
server will inspect each "ATTENDEE" property to determine if a
scheduling message should be delivered to this Attendee according to
the value of the "SCHEDULE-AGENT" property parameter (see
Section 10.1) as described in the table below:
+------------------+-------------+
| SCHEDULE-AGENT | iTIP METHOD |
+==================+=============+
| SERVER (default) | REQUEST |
+------------------+-------------+
| CLIENT | -- |
+------------------+-------------+
| NONE | -- |
+------------------+-------------+
The attempt to deliver the scheduling message will either succeed or
fail. In all cases, the server MUST add a "SCHEDULE-STATUS"
iCalendar property parameter (see Section 10.3) to the "ATTENDEE"
iCalendar property in the scheduling object resource being created,
and set its value as described in Section 9.2. This will result in
the created calendar object resource differing from the calendar data
sent in the HTTP request. As a result clients MAY reload the
calendar data from the server in order to update to the new server
generated state information. Servers MUST NOT set the "SCHEDULE-
STATUS" property parameter on the "ATTENDEE" property of Attendees
for which it did not attempt to deliver a scheduling message.
Restrictions:
1. The server SHOULD reject any attempt to set the "PARTSTAT"
iCalendar property parameter value of the "ATTENDEE" iCalendar
property of other users in the calendar object resource to a
value other than "NEEDS-ACTION" if the "SCHEDULE-AGENT" property
parameter value is not present or set to the value "SERVER".
2. The server MAY reject attempts to create a scheduling object
resource that specifies a "UID" property value already specified
in a scheduling object resource contained in another calendar
collection of the Organizer.
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3. The server MUST take into account scheduling privileges as
described in Section 13.1 when handling the creation of a
scheduling object resource.
4. Restrictions on calendar object resources defined in Section 4.1
of [RFC4791] MUST also be enforced.
The server MUST return an error with the CALDAV:allowed-organizer-
scheduling-object-change precondition code (Section 5.2.4.3) when the
Organizer attempts to change the iCalendar data in a manner that is
forbidden.
5.2.1.2. Modify
When a scheduling object resource is modified by the Organizer, the
server will inspect each "ATTENDEE" property in the new calendar data
to determine which ones have the "SCHEDULE-AGENT" iCalendar property
parameter. It will then need to compare this with the "ATTENDEE"
properties in the existing calendar object resource that is being
modified.
For each Attendee in the old and new calendar data on a per-instance
basis, and taking into account the addition or removal of Attendees,
the server will determine whether to deliver a scheduling message to
the Attendee. The following table determines whether the server
needs to deliver a scheduling message, and if so which iTIP
scheduling method to use. The values "SERVER", "CLIENT", and "NONE"
in the top and left titles of the table refer to the "SCHEDULE-AGENT"
parameter value of the "ATTENDEE" property, and the values "<Absent>"
and "<Removed>" are used to cover the cases where the "ATTENDEE"
property is not present (Old) or is being removed (New).
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+---------------+-----------------------------------------------+
| | New |
| ATTENDEE +-----------+-----------+-----------+-----------+
| | <Removed> | SERVER | CLIENT | NONE |
| | | (default) | | |
+===+===========+===========+===========+===========+===========+
| | <Absent> | -- | REQUEST / | -- | -- |
| | | | ADD | | |
| +-----------+-----------+-----------+-----------+-----------+
| | SERVER | CANCEL | REQUEST | CANCEL | CANCEL |
| O | (default) | | | | |
| l +-----------+-----------+-----------+-----------+-----------+
| d | CLIENT | -- | REQUEST / | -- | -- |
| | | | ADD | | |
| +-----------+-----------+-----------+-----------+-----------+
| | NONE | -- | REQUEST / | -- | -- |
| | | | ADD | | |
+---+-----------+-----------+-----------+-----------+-----------+
The attempt to deliver the scheduling message will either succeed or
fail. In all cases, the server MUST add a "SCHEDULE-STATUS"
iCalendar property parameter to the "ATTENDEE" iCalendar property in
the scheduling object resource being modified, and set its value as
described in Section 9.2. This will result in the created calendar
object resource differing from the calendar data sent in the HTTP
request. As a result clients MAY reload the calendar data from the
server in order to update to the new server generated state
information.
Restrictions:
1. The server MAY reject any attempt to set the "PARTSTAT" iCalendar
property parameter value of the "ATTENDEE" iCalendar property of
other users in the calendar object resource to a value other than
"NEEDS-ACTION" if the "SCHEDULE-AGENT" property parameter value
is not present or set to the value "SERVER".
2. The server MUST take into account scheduling privileges as
described in Section 13.1 when handling the modification of a
scheduling object resource.
3. Restrictions on calendar object resources defined in Section 4.1
of [RFC4791] MUST also be enforced.
The server MUST return an error with the CALDAV:allowed-organizer-
scheduling-object-change precondition code (Section 5.2.4.3) when the
Organizer attempts to change the iCalendar data in a manner that is
forbidden.
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5.2.1.3. Remove
When a scheduling object resource is removed by the Organizer, the
server will inspect each "ATTENDEE" property in the scheduling object
resource being removed to determine which ones have the "SCHEDULE-
AGENT" iCalendar property parameter.
For each Attendee the server will determine whether to attempt to
deliver a scheduling message into the Attendee's scheduling Inbox
collection, based on the table below:
+------------------+-------------+
| SCHEDULE-AGENT | iTIP METHOD |
+==================+=============+
| SERVER (default) | CANCEL |
+------------------+-------------+
| CLIENT | -- |
+------------------+-------------+
| NONE | -- |
+------------------+-------------+
Restrictions:
1. The server MUST take into account scheduling privileges as
described in Section 13.1 when handling the deletion of a
scheduling object resource.
5.2.2. Attendee Scheduling Object Resources
An Attendee can create, modify or remove a scheduling object resource
by issuing HTTP requests with an appropriate method. The create,
modify and remove behaviors for the server are each described next,
and the way these are invoked via HTTP requests is described in
Section 5.2.3.
5.2.2.1. Allowed Attendee Changes
Attendees are allowed to make some changes to a scheduling object
resource, though key properties such as start time, end time,
location, and summary are typically under the control of the
Organizer.
The server MUST allow Attendees to:
1. change their own "PARTSTAT" iCalendar property parameter value.
2. add, modify or remove any "TRANSP" iCalendar properties.
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3. add, modify or remove any "PERCENT-COMPLETE" iCalendar
properties.
4. add, modify or remove any "COMPLETED" iCalendar properties.
5. add, modify or remove any "VALARM" iCalendar components.
6. add, modify or remove the "CALSCALE" iCalendar property within
the top-level "VCALENDAR" component.
7. modify the "PRODID" iCalendar property within the top-level
"VCALENDAR" component.
8. add "EXDATE" iCalendar properties and possibly remove components
for overridden recurrence instances.
9. add, modify or remove any "CREATED", "DTSTAMP" and "LAST-
MODIFIED" iCalendar properties.
10. add, modify or remove "SCHEDULE-STATUS" iCalendar property
parameters on "ATTENDEE" properties that have a "SCHEDULE-AGENT"
parameter set to "CLIENT".
11. add new components to represent overridden recurrence instances,
provided the only changes to the recurrence instance follow the
rules above.
The server MUST return an error with the CALDAV:allowed-attendee-
scheduling-object-change precondition code (Section 5.2.4.4) when the
Attendee attempts to change the iCalendar data in a manner forbidden
by the server.
5.2.2.2. Create
Typically an Attendee does not create scheduling object resources, as
scheduling messages delivered to them on the server are automatically
processed by the server and placed on one of their calendars (see
Section 6). However, in some cases a scheduling message may get
delivered directly to the client, and the Attendee may wish to store
that on the server. In that case the client creates a scheduling
object resource in a suitable calendar belonging to the Attendee. It
can then set the "SCHEDULE-AGENT" iCalendar property parameter on all
"ORGANIZER" iCalendar properties in the resource to determine how the
server treats the resource. The value of the "SCHEDULE-AGENT"
iCalendar property parameter on all "ORGANIZER" iCalendar properties
MUST be the same.
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+----------------+--------------------------------------------------+
| SCHEDULE-AGENT | Action |
+----------------+--------------------------------------------------+
| SERVER | The server will attempt to process changes to |
| (default) | the resource using the normal rules for attendee |
| | scheduling object resources. |
| | |
| CLIENT | The server does no special processing of the |
| | resource. The client is assumed to be handling |
| | Attendee replies etc. |
| | |
| NONE | The server does no special processing of the |
| | resource. |
+----------------+--------------------------------------------------+
In some cases a server may not be able to process an Attendee
scheduling object resource that originated from another system (i.e.,
where the server is unable to deliver scheduling messages to the
Organizer). In such cases the server MUST add a "SCHEDULE-STATUS"
iCalendar property parameter to all "ORGANIZER" iCalendar properties
in the resource with a suitable value indicating a error.
5.2.2.3. Modify
When a scheduling object resource is modified by an Attendee, the
server behavior depends on the value of the "SCHEDULE-AGENT"
iCalendar property parameter on the "ORGANIZER" iCalendar properties:
+----------------+--------------------------------------------------+
| SCHEDULE-AGENT | Action |
+----------------+--------------------------------------------------+
| SERVER | The server will attempt to process the removal |
| (default) | using the behavior listed below. |
| | |
| CLIENT | The server does no special processing of the |
| | resource. The client is assumed to be handling |
| | any Attendee replies etc. |
| | |
| NONE | The server does no special processing of the |
| | resource. |
+----------------+--------------------------------------------------+
The server will inspect the changes by comparing the new scheduling
object resource with the existing scheduling object resource.
If the Attendee changes one or more "PARTSTAT" iCalendar property
values on any component, or adds an overridden component with a
changed "PARTSTAT" property, then the server MUST deliver an iTIP
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"REPLY" scheduling message to the Organizer to indicate the new
participation status of the Attendee.
If the Attendee adds an "EXDATE" property value to effectively remove
a recurrence instance, the server MUST deliver an iTIP "REPLY"
scheduling message to the Organizer to indicate that the Attendee has
declined the instance (i.e., the Attendee's "PARTSTAT" iCalendar
property parameter value is set to "DECLINED").
The attempt to deliver the scheduling message will either succeed or
fail. In all cases, the server MUST add a "SCHEDULE-STATUS"
iCalendar property parameter to the "ORGANIZER" iCalendar property in
the scheduling object resource being created, and set its value as
described in Section 9.2. This will result in the created calendar
object resource differing from the calendar data sent in the HTTP
request. As a result clients MAY reload the calendar data from the
server in order to update to the new server generated state
information.
5.2.2.4. Remove
When a scheduling object resource is removed by an Attendee, the
server behavior depends on the value of the "SCHEDULE-AGENT"
iCalendar property parameter on the "ORGANIZER" iCalendar properties:
+----------------+--------------------------------------------------+
| SCHEDULE-AGENT | Action |
+----------------+--------------------------------------------------+
| SERVER | The server will attempt to process the removal |
| (default) | using either behaviors (1) or (2) listed below. |
| | |
| CLIENT | The server does no special processing of the |
| | resource. The client is assumed to be handling |
| | any Attendee replies etc. |
| | |
| NONE | The server does no special processing of the |
| | resource. |
+----------------+--------------------------------------------------+
1. If the HTTP request contains a "Schedule-Reply" request header
set to the value "T" or there is no "Schedule-Reply" request
header, then the server MUST attempt to deliver a scheduling
message to the Organizer indicating that the Attendee has a
"PARTSTAT" iCalendar property parameter value set to "DECLINED".
That is, the Attendee has chosen not to attend any instances. If
the server is unable to deliver the scheduling message, the
remove action MUST fail, and an appropriate "SCHEDULE-STATUS"
iCalendar property parameter set on the "ORGANIZER" property in
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the scheduling object resource stored by the server.
2. If the HTTP request contains a "Schedule-Reply" request header
set to the value "F", the server MUST NOT attempt to deliver a
scheduling message. The resource is simply removed. This
provides the client a way to silently remove unwanted scheduling
messages.
5.2.3. HTTP Methods
This section describes how use of various HTTP methods on a
scheduling object resource will cause a create, modify or remove
action on that resource as described above. The use of these methods
is subject to the restrictions in [RFC4791], in addition to what is
described below.
5.2.3.1. PUT
When a PUT method request is received, the server will execute the
following actions, provided all appropriate preconditions are met:
+--------------------------+--------------------------+-------------+
| Existing Destination | Resulting Destination | Server |
| Resource | Resource | Action |
+--------------------------+--------------------------+-------------+
| None | Calendar object resource | None |
| | | |
| None | Scheduling object | Create |
| | resource | |
| | | |
| Calendar object resource | Calendar object resource | None |
| | | |
| Calendar object resource | Scheduling object | Create |
| | resource | |
| | | |
| Scheduling object | Calendar object resource | Remove |
| resource | | |
| | | |
| Scheduling object | Scheduling object | Modify |
| resource | resource | |
+--------------------------+--------------------------+-------------+
5.2.3.2. COPY
When a COPY method request is received, the server will execute the
following actions based on the source and destination collections in
the request:
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+-------------------------+-------------------------+---------------+
| Source Collection | Destination Collection | Server Action |
+-------------------------+-------------------------+---------------+
| Non-calendar collection | Non-calendar collection | None |
| | | |
| Non-calendar collection | Calendar collection | (1) |
| | | |
| Calendar collection | Non-calendar collection | None |
| | | |
| Calendar collection | Calendar collection | (2) |
+-------------------------+-------------------------+---------------+
Note 1. The same rules as used for PUT above are applied for the
destination of the COPY request.
Note 2. The server MAY reject this as per Section 5.2.4.1, otherwise
None.
The behavior of a COPY method request on a calendar collection is
undefined.
5.2.3.3. MOVE
When a MOVE method request is received, the server will execute the
following actions based on the source and destination collections in
the request:
+-------------------------+-------------------------+---------------+
| Source Collection | Destination Collection | Server Action |
+-------------------------+-------------------------+---------------+
| Non-calendar collection | Non-calendar collection | None |
| | | |
| Non-calendar collection | Calendar collection | (1) |
| | | |
| Calendar collection | Non-calendar collection | (2) |
| | | |
| Calendar collection | Calendar collection | None |
+-------------------------+-------------------------+---------------+
Note 1. The same rules as used for PUT above are applied for the
destination of the MOVE request.
Note 2. The same rules as used for DELETE below are applied for the
source of the MOVE request.
The behavior of a MOVE method request on a calendar collection is
undefined.
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5.2.3.4. DELETE
When a DELETE method is targeted at a scheduling object resource the
server will execute the Remove action.
When a DELETE method is targeted at a calendar collection the server
will execute the Remove action on all scheduling object resources
contained in the calendar collection.
5.2.4. Additional Method Preconditions
This specification defines method preconditions (see Section 16 of
WebDAV [RFC4918]), in addition to the ones in [RFC4791], to provide
machine-parsable information in error responses.
5.2.4.1. CALDAV:unique-scheduling-object-resource Precondition
Name: unique-scheduling-object-resource
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: PUT, COPY, and MOVE
Use with: 403 Forbidden
Purpose: (precondition) -- Servers MAY reject requests to create a
scheduling object resource with an iCalendar "UID" property value
already in use by another scheduling object resource owned by the
same user in other calendar collections. Servers SHOULD report
the URL of the scheduling object resource that is already making
use of the same "UID" property value in the DAV:href element.
Definition:
<!ELEMENT unique-scheduling-object-resource (DAV:href?)>
Example:
<C:unique-scheduling-object-resource xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:href>/home/bernard/calendars/personal/abc123.ics</D:href>
</C:unique-scheduling-object-resource>
5.2.4.2. CALDAV:same-organizer-in-all-components Precondition
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Name: same-organizer-in-all-components
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: PUT, COPY, and MOVE
Use with: 403 Forbidden
Purpose: (precondition) -- All the calendar components in a
scheduling object resource MUST contain the same "ORGANIZER"
property value when present.
Definition:
<!ELEMENT same-organizer-in-all-components EMPTY>
Example:
<C:same-organizer-in-all-components
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
5.2.4.3. CALDAV:allowed-organizer-scheduling-object-change Precondition
Name: allowed-organizer-scheduling-object-change
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: PUT, COPY, and MOVE
Use with: 403 Forbidden
Purpose: (precondition) -- Servers MAY impose restrictions on
modifications allowed by an Organizer. For instance, servers MAY
prevent the Organizer setting the "PARTSTAT" property parameter to
a value other than "NEEDS-ACTION" if the corresponding "ATTENDEE"
property has the "SCHEDULE-AGENT" property parameter set to
"SERVER", or has no "SCHEDULE-AGENT" property parameter. See
Section 5.2.1.
Definition:
<!ELEMENT allowed-organizer-scheduling-object-change EMPTY>
Example:
<C:allowed-organizer-scheduling-object-change
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
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5.2.4.4. CALDAV:allowed-attendee-scheduling-object-change Precondition
Name: allowed-attendee-scheduling-object-change
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: PUT, COPY, and MOVE
Use with: 403 Forbidden
Purpose: (precondition) -- Servers MAY impose restrictions on
modifications allowed by an Attendee. Attendee modifications that
servers MUST allow are specified in Section 5.2.2.1.
Definition:
<!ELEMENT allowed-attendee-scheduling-object-change EMPTY>
Example:
<C:allowed-attendee-scheduling-object-change
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
5.2.5. DTSTAMP and SEQUENCE Properties
Whenever the server generates a scheduling message for delivery to a
Calendar User, it MUST ensure that a "DTSTAMP" iCalendar property is
present and MUST set the value to the UTC time that the scheduling
message was generated (as required by iCalendar).
iTIP [RFC5546] places certain requirements on how the "SEQUENCE"
iCalendar property value in scheduling messages changes. The server
MUST ensure that for each type of scheduling operation, the
"SEQUENCE" iCalendar property value is appropriately updated. If the
client does not update the "SEQUENCE" iCalendar property itself when
that is required, the server MUST update the property.
5.2.6. Restrict Recurrence Instances Sent to Attendees
When delivering scheduling messages for recurring calendar components
to Attendees, servers MUST ensure that Attendees only get information
about recurrence instances that explicitly include them as an
Attendee.
For example, if an Attendee is invited to a single recurrence
instance of a recurring event, and no others, the scheduling object
resource contained in the Organizer's calendar collection will
contain an overridden instance in the form of a separate calendar
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component. That separate calendar component will include the
"ATTENDEE" property referencing the "one-off" Attendee. That
Attendee will not be listed in any other calendar components in the
scheduling object resource. Any scheduling messages delivered to the
Attendee will only contain information about this overridden
instance.
As another example, an Attendee could be excluded from one instance
of a recurring event. In that case the scheduling object resource
contained in the calendar collection of the Organizer will include an
overridden instance with an "ATTENDEE" list that does not include the
Attendee being excluded. The scheduling message that will be
delivered to the Attendee will not specify the overridden instance
but rather include an "EXDATE" property in the master recurring
component defining the recurrence set.
5.2.7. Forcing the Server to Send a Scheduling Message
The iCalendar property parameter "SCHEDULE-FORCE-SEND" defined in
Section 10.2 can be used by a Calendar User to force the server to
send a scheduling message to an Attendee or the Organizer in a
situation where the server would not normally send a scheduling
message. For instance, an Organizer could use this property
parameter to request an Attendee, that previously declined an
invitation, to reconsider their participation status without being
forced to modify the event.
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6. Processing Incoming Scheduling Messages
Scheduling operations can cause the delivery of a scheduling message
into an Organizer's or Attendee's scheduling Inbox collection. In
the former case the scheduling messages are replies from Attendees,
in the latter case the scheduling messages are requests,
cancellations or additions from the Organizer.
Servers MUST automatically process incoming scheduling messages using
the rules defined by [RFC5546], by creating or updating the
corresponding scheduling object resources on calendars owned by the
owner of the scheduling Inbox collection. In addition, the
scheduling message is stored in the scheduling Inbox collection as an
indicator to the client that a scheduling operation has taken place.
The server MUST take into account privileges on the scheduling Inbox
collection when processing incoming scheduling messages, to determine
whether delivery of the scheduling message is allowed. Privileges on
calendars containing any matching scheduling object resource are not
considered in this case (i.e., a schedule message from another user
can cause modifications to resources in calendar collections that the
other user would not normally have read or write access to).
Additionally, servers MUST take into account any scheduling Inbox
collection preconditions (see Section 4.2) when delivering the
scheduling message, and it MUST take into account the similar
preconditions on any calendar collection which contains, or would
contain, the corresponding scheduling object resource.
6.1. Processing Organizer Requests, Additions, and Cancellations
For a scheduling message sent by an Organizer, the server first tries
to locate a corresponding scheduling object resource belonging to the
Attendee. If no matching scheduling object resource exists, the
server treats the scheduling message as a new message, otherwise it
is treated as an update.
In the case of a new message, the server MUST process the scheduling
message and create a new scheduling object resource in an appropriate
calendar collection for the Attendee.
In the case of an update, the server MUST process the scheduling
message and update the matching scheduling object resource belonging
to the Attendee to reflect the changes sent by the Organizer.
In each case, the scheduling message MUST only appear in the
Attendee's scheduling Inbox collection once all automatic processing
has been done.
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6.2. Processing Attendee Replies
For a scheduling message reply sent by an Attendee, the server first
locates the corresponding scheduling object resource belonging to the
Organizer.
The server MUST then update the "PARTSTAT" iCalendar property
parameter value of each "ATTENDEE" iCalendar property in the
scheduling object resource to match the changes indicated in the
reply (taking into account the fact that an Attendee could have
created a new overridden iCalendar component to indicate different
participation status on one or more recurrence instances of a
recurring event).
The server MUST also update or add the "SCHEDULE-STATUS" property
parameter on each matching "ATTENDEE" iCalendar property and set its
value to that of the "REQUEST-STATUS" property in the reply, or to
"2.0" if "REQUEST-STATUS" is not present (also taking into account
recurrence instances). If there are multiple "REQUEST-STATUS"
properties in the reply, the "SCHEDULE-STATUS" property parameter
value is set to a comma-separated list of status codes, one from each
"REQUEST-STATUS" property.
The server SHOULD send scheduling messages to all the other Attendees
indicating the change in participation status of the Attendee
replying, subject to the recurrence requirements of Section 5.2.6.
The scheduling message MUST only appear in the Organizer's scheduling
Inbox collection once all automatic processing has been done.
6.3. Scheduling Messages as Notifications
Once the processing of an incoming scheduling message is completed by
the server, the message is made available as a child resource in the
scheduling Inbox collection of the Calendar User that received the
message, to serve as a notification that a change has been made to
the corresponding scheduling object resource. Scheduling messages
are typically removed from the scheduling Inbox collection by the
client once the calendar user has acknowledged the change.
6.4. Default Calendar Collection
The server is REQUIRED to process scheduling messages received for an
Attendee by creating a new scheduling object resource in a calendar
collection belonging to the Attendee, when one does not already
exist. A Calendar User that is an Attendee in a scheduling operation
MUST have at least one valid calendar collection available. If there
is no valid calendar collection, then the server MUST reject the
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attempt to deliver the scheduling message to the Attendee.
Servers MAY provide support for a default calendar collection, that
is, the calendar collection in which new scheduling object resources
will be created. The CALDAV:schedule-default-calendar-URL WebDAV
property, which can be present on the scheduling Inbox collection of
a Calendar User, specifies if this Calendar User has a default
calendar collection. See Section 12.2.
Servers SHOULD create new scheduling object resources in the default
calendar collection, if the CALDAV:schedule-default-calendar-URL
WebDAV property is set.
Servers MAY allow clients to change the default calendar collection
by changing the value of the CALDAV:schedule-default-calendar-URL
WebDAV property on the scheduling Inbox collection. However, the
servers MUST ensure that any new value for that property refers to a
valid calendar collection belonging to the owner of the scheduling
Inbox collection.
Servers MUST reject any attempt to delete the default calendar
collection.
6.4.1. Additional Method Preconditions
This specification defines additional method preconditions (see
Section 16 of WebDAV [RFC4918]) to provide machine-parsable
information in error responses.
6.4.1.1. CALDAV:default-calendar-needed Precondition
Name: default-calendar-needed
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: DELETE
Use with: 403 Forbidden
Purpose: (precondition) -- The client attempted to delete the
calendar collection currently referenced by the CALDAV:schedule-
default-calendar-URL property, or attempted to remove the CALDAV:
schedule-default-calendar-URL property on the scheduling Inbox
collection on a server that doesn't allow such operations.
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Definition:
<!ELEMENT default-calendar-needed EMPTY>
Example:
<C:default-calendar-needed
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
6.4.1.2. CALDAV:valid-schedule-default-calendar-URL Precondition
Name: valid-schedule-default-calendar-URL
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: PROPPATCH
Use with: 403 Forbidden
Purpose: (precondition) -- The client attempted to set the CALDAV:
schedule-default-calendar-URL property to a DAV:href element that
doesn't reference a valid calendar collection. Note: Servers that
do not allow clients to change the CALDAV:schedule-default-
calendar-URL property would simply return the DAV:cannot-modify-
protected-property precondition defined in Section 16 of WebDAV
[RFC4918].
Definition:
<!ELEMENT valid-schedule-default-calendar-URL EMPTY>
Example:
<C:valid-schedule-default-calendar-URL
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
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7. Request for Busy Time Information
The POST method is used to request busy time information of one or
more Calendar Users by submitting a request at the scheduling Outbox
collection of the Calendar User requesting the information (the
Organizer). To accomplish this, the request body of a POST method
MUST contain a "VFREEBUSY" calendar component with the "METHOD"
iCalendar property set to the value "REQUEST" as specified in Section
3.3.2 of iTIP [RFC5546]. The resource identified by the Request-URI
MUST be a resource collection of type CALDAV:schedule-outbox
(Section 4.1). The "ORGANIZER" property in the "VFREEBUSY" component
MUST match that of the Calendar User who "owns" the Outbox
collection.
7.1. Status Codes
The following are examples of response codes one would expect to be
used for this method. However, unless explicitly prohibited, any
2/3/4/5xx series response code can be used in a response.
200 (OK) - The command succeeded.
204 (No Content) - The command succeeded.
400 (Bad Request) - The client has provided an invalid scheduling
message.
403 (Forbidden) - The client cannot submit a scheduling message to
the specified Request-URI.
404 (Not Found) - The URL in the Request-URI was not present.
423 (Locked) - The specified resource is locked and the client
either is not a lock owner or the lock type requires a lock token
to be submitted and the client did not submit it.
7.2. Additional Method Preconditions
This specification defines additional method preconditions for the
POST method. Preconditions defined in WebDAV ACL [RFC3744] and
CalDAV [RFC4791] that applies to the POST method are also listed here
for completeness.
7.2.1. DAV:need-privileges Precondition
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Name: need-privileges
Namespace: DAV:
Apply to: POST
Use with: 403 Forbidden
Purpose: (precondition) -- The currently authenticated user MUST be
granted the CALDAV:schedule-send-freebusy privilege on the
scheduling Outbox collection being targeted by the request.
Definition:
<!ELEMENT DAV:need-privileges (DAV:resource)* >
<!ELEMENT DAV:resource (DAV:href, DAV:privilege) >
Example:
<D:need-privileges xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
<D:resource>
<D:href>/home/bernard/calendars/outbox/</D:href>
<D:privilege><C:schedule-send-freebusy/></D:privilege>
</D:resource>
</D:need-privileges>
7.2.2. CALDAV:supported-collection Precondition
Name: supported-collection
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: POST
Use with: 400 Bad Request
Purpose: (precondition) -- The Request-URI MUST identify the
location of a scheduling Outbox collection.
Definition:
<!ELEMENT supported-collection EMPTY >
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Example:
<C:supported-collection xmlns:C="urn:ietf:params:xml:ns:caldav"/>
7.2.3. CALDAV:supported-calendar-data Precondition
Name: supported-calendar-data
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: POST
Use with: 400 Bad Request
Purpose: (precondition) -- The resource body submitted in the POST
request MUST be a supported media type (e.g., text/calendar).
Definition:
<!ELEMENT supported-calendar-data EMPTY >
Example:
<C:supported-calendar-data
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
7.2.4. CALDAV:valid-calendar-data Precondition
Name: valid-calendar-data
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: POST
Use with: 400 Bad Request
Purpose: (precondition) -- The resource submitted in the POST
request MUST be valid data for the media type being specified
(e.g., a valid iCalendar object).
Definition:
<!ELEMENT valid-calendar-data EMPTY>
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Example:
<C:valid-calendar-data xmlns:C="urn:ietf:params:xml:ns:caldav"/>
7.2.5. CALDAV:valid-scheduling-message Precondition
Name: valid-scheduling-message
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: POST
Use with: 400 Bad Request
Purpose: (precondition) -- The resource submitted in the POST
request MUST obey all restrictions specified for the POST request
(e.g., the scheduling message follow the restrictions of iTIP).
Definition:
<!ELEMENT valid-scheduling-message EMPTY >
Example:
<C:valid-scheduling-message
xmlns:C="urn:ietf:params:xml:ns:caldav"/>
7.2.6. CALDAV:valid-organizer Precondition
Name: valid-organizer
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: POST
Use with: 403 Forbidden
Purpose: (precondition) -- The Calendar User identified by the
"ORGANIZER" property in the POST request's scheduling message MUST
be the Calendar User (or one of the Calendar Users) associated
with the scheduling Outbox collection being targeted by the
request;
Definition:
<!ELEMENT valid-organizer EMPTY >
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Example:
<C:valid-organizer xmlns:C="urn:ietf:params:xml:ns:caldav"/>
7.2.7. CALDAV:max-resource-size Precondition
Name: max-resource-size
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: POST
Use with: 403 Forbidden
Purpose: (precondition) -- The resource submitted in the POST
request MUST have a size in octets less than or equal to the value
of the CALDAV:max-resource-size property (defined in Section 5.2.5
of [RFC4791]) specified on the scheduling Outbox collection
targeted by the request.
Definition:
<!ELEMENT max-resource-size EMPTY >
Example:
<C:max-resource-size xmlns:C="urn:ietf:params:xml:ns:caldav"/>
7.3. Response to a POST request
A POST request can return freebusy information for one or more
Calendar Users. Thus the response needs to contain separate status
information for each recipient. This specification defines a new XML
response body to convey multiple recipient status.
A response to a POST method that indicates status for one or more
recipients MUST be an XML document with a CALDAV:schedule-response
XML element as its root element. This element MUST contain one
CALDAV:response element for each recipient, with each of those
containing elements that indicate which recipient they correspond to,
the scheduling status for that recipient, any error codes and an
optional description. See Section 14.1 for the detail on the child
elements.
In the case of a successful freebusy request, the CALDAV:response
elements can also contain CALDAV:calendar-data elements which contain
freebusy information (e.g., an iCalendar VFREEBUSY component)
indicating the busy state of the corresponding recipient. See
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Appendix B.5 for an example freebusy request and response.
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8. Avoiding Conflicts when Updating Scheduling Object Resources
Because replies from Attendees and updates from Organizers are
automatically processed by the server, clients might be in a
situation where their copy of a calendar resource is different from
the one currently on the server. When an Attendee or Organizer makes
a change to the client's copy of the calendar resource, if the client
writes the data to the server it could overwrite the changes already
made there. Typically, clients use the ETag value and If-Match
request headers to avoid the "lost update problem".
Clients can also use ETag and If-Match to avoid this problem.
However, when doing so the client will likely have to resolve the
differences between the new resource and the original one, and the
changes made by the Attendee or Organizer in the client. This can be
a complicated comparison particularly when recurring components are
present.
Additionally, the data on the server may change frequently as
Attendees change their participation status, triggering updates to
the Organizer, and consequently other Attendees' copies of the
scheduling object resource. If the ETag/If-Match behavior were used,
clients would be forced to reconcile their cached copy of a
scheduling object resource with the updated one on the server in
order to attempt to write the user's changes back. This could lead
to a race condition that can effectively result in a temporary denial
of service when, for example, there is an event with a large Attendee
list. A "storm" of updates will occur if Attendees all start
responding at the same time, and this would prevent Attendees and the
Organizer from being able to update their own copies of the
scheduling object resource as the server copy is changing frequently.
A solution is to have the server determine the best way to merge
changes made on the server with changes being made by the client.
For example, if an Attendee changes their participation status and
triggers an update to the Organizer's copy of the event, but the
Organizer also updates their cached copy of the event and attempts to
write it back, rather than failing on a conditional If-Match when the
Organizer writes their data, the server would instead take the
changes made by the Organizer and apply the Attendee changes and
store the result. Thus a form of "weak" ETag matching behavior is
needed such that scheduling changes made automatically on the server
do not invalidate the tag, so that when clients store data
conditionally based on the tag value, the server knows it can apply
the merge behavior.
In order to do that, this specification introduces a new WebDAV
resource property CALDAV:schedule-tag with a corresponding response
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header "Schedule-Tag", and a new "If-Schedule-Tag-Match" request
header to allow client changes to be appropriately merged with server
changes in the case where the changes on the server were the result
of an "inconsequential" scheduling message update. An
"inconsequential" scheduling message is one which simply updates the
status information of Attendees due to a reply from an Attendee.
Servers MUST support requests targeted at scheduling object resources
using the "If-Schedule-Tag-Match" request header. Consequently, the
server MUST support the "Schedule-Tag" response header and CALDAV:
schedule-tag property for scheduling object resources. Servers MUST
automatically resolve conflicts with "inconsequential" changes done
to scheduling object resources when the "If-Schedule-Tag-Match"
request header is specified.
The If-Schedule-Tag-Match request header applies only to the Request-
URI, and not to the Destination of a COPY or MOVE in the same way as
the If-Match request header.
Clients SHOULD use the If-Schedule-Tag-Match header on requests that
update scheduling object resources.
A response to any successful GET or PUT request targeting a
scheduling object resource MUST include a Schedule-Tag response
header with the value set to the same value as the CALDAV:schedule-
tag WebDAV property of the resource.
A response to any successful COPY or MOVE request that specifies a
Destination request header targeting a scheduling object resource
MUST include a Schedule-Tag response header with the value set to the
same value as the CALDAV:schedule-tag WebDAV property of the resource
identified in the Request-URI.
The Schedule-Tag feature is designed to be used to address the
problem of "inconsequential" changes on the server only. Normal ETag
operations are used in all other cases, e.g., for synchronization.
The value of the CALDAV:schedule-tag property changes according to
these rules:
o For an Organizer's copy of a scheduling object resource:
1. The server MUST NOT change the CALDAV:schedule-tag property
value when the scheduling object resource is updated as the
result of automatically processing a scheduling message reply
from an Attendee. For instance, when an Attendee replies to
the Organizer, the CALDAV:schedule-tag property is unchanged
after the Organizer's scheduling object resource has been
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automatically updated by the server with the Attendee's new
participation status.
2. The server MUST change CALDAV:schedule-tag property value when
the scheduling object resource is changed directly via an HTTP
request (e.g., PUT, COPY or MOVE).
o For an Attendee's copy of a scheduling object resource:
1. The server MUST change the CALDAV:schedule-tag property value
when the scheduling object resource is changed as the result
of processing a scheduling message update from an Organizer
that contains changes other than just the participation status
of Attendees.
2. The server MUST NOT change the CALDAV:schedule-tag property
value when the scheduling object resource is changed as the
result of processing a scheduling message update from an
Organizer that only specify changes in the participation
status of Attendees. For instance, when Attendee "A" replies
to Organizer "O", and Attendee "B" receives a scheduling
message update from Organizer "O" with the new participation
status of Attendee "A", the CALDAV:schedule-tag property of
Attendee "B"s scheduling object resource MUST NOT be changed.
3. The server MUST change the CALDAV:schedule-tag property value
when the scheduling object resource is changed directly via an
HTTP request (e.g., PUT, COPY or MOVE).
8.1. PUT
Clients can use the If-Schedule-Tag-Match request header to do a PUT
request that ensures that "inconsequential" changes on the server do
not result in a precondition error. The value of the request header
is set to the last Schedule-Tag value received for the resource being
modified. If the value of the If-Schedule-Tag-Match header matches
the current value of the CALDAV:schedule-tag property the server MUST
take any "ATTENDEE" property changes for all Attendees other than the
owner of the scheduling object resource and apply those to the new
resource being stored. Otherwise, the server MUST fail the request
with a 412 Precondition Failed status code.
8.2. DELETE, COPY or MOVE
Clients can use the If-Schedule-Tag-Match request header to do a
DELETE, COPY or MOVE request that ensures that "inconsequential"
changes on the server do not result in a precondition error. The
value of the request header is set to the last Schedule-Tag value
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received for the resource being deleted. If the value of the If-
Schedule-Tag-Match header matches the current value of the CALDAV:
schedule-tag property the server performs the normal DELETE, COPY or
MOVE request processing for the resource. Otherwise, the server MUST
fail the request with a 412 Precondition Failed status code.
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9. Other Scheduling Considerations
9.1. Attendee Participation Status
This section specifies additional requirements on the handling of the
"PARTSTAT" property parameter when the "SCHEDULE-AGENT" property
parameter on the corresponding "ATTENDEE" property is set to the
value "SERVER" or is not present.
Clients SHOULD, and servers MUST reset the "PARTSTAT" property
parameter value of all "ATTENDEE" properties, except the one that
corresponds to the Organizer, to "NEEDS-ACTION" when the Organizer
reschedules an event.
A reschedule of an event occurs when any "DTSTART", "DTEND",
"DURATION", "DUE", "RRULE", "RDATE", or "EXDATE" property changes in
a calendar component such that existing recurrence instances are
impacted by the changes, as shown in the table below.
+-----------+-------------------------------------------------------+
| Property | Server Action |
+-----------+-------------------------------------------------------+
| DTSTART, | Any change to these properties MUST result in |
| DTEND, | "PARTSTAT" being set to "NEEDS-ACTION" |
| DURATION, | |
| DUE | |
| | |
| | |
| | |
| RRULE | A change to or addition of this property that results |
| | in the addition of new recurring instances or a |
| | change in time for existing recurring instances MUST |
| | result in "PARTSTAT" being reset to "NEEDS-ACTION" on |
| | each affected component. |
| | |
| | |
| | |
| RDATE | A change to or addition of this property that results |
| | in the addition of new recurring instances or a |
| | change in time for existing recurring instances MUST |
| | result in "PARTSTAT" being reset to "NEEDS-ACTION" on |
| | each affected component. |
| | |
| | |
| | |
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| EXDATE | A change to or removal of this property that results |
| | in the re-instatement of recurring instances MUST |
| | result in "PARTSTAT" being set to "NEEDS-ACTION" on |
| | each affected component. |
+-----------+-------------------------------------------------------+
The server MAY allow the Organizer's client to change an Attendee's
"PARTSTAT" property parameter value to "NEEDS-ACTION" at any other
time (e.g., when the "LOCATION" property value changes, an Organizer
might wish to re-invite Attendees who may be impacted by the change).
9.2. Schedule Status Values
When scheduling with an Attendee there are two types of status
information that can be returned during the transaction. The first
type of status information is a "delivery" status that indicates
whether the scheduling message from the Organizer to the Attendee was
delivered or not, or what the current status of delivery is. The
second type of status information is a "reply" status corresponding
to the Attendee's own "REQUEST-STATUS" information from the
scheduling message reply that is sent back to the Organizer.
Similarly, when an Attendee sends a reply back to the Organizer,
there will be "delivery" status information for the scheduling
message sent to the Organizer. However, there is no "REQUEST-STATUS"
sent back by the Organizer, so there is no equivalent of the "reply"
status as per scheduling messages to Attendees.
The "delivery" status information on an "ORGANIZER" or "ATTENDEE"
iCalendar property is conveyed in the "SCHEDULE-STATUS" property
parameter value (Section 10.3). The status code value for "delivery"
status can be one of the following:
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+----------+--------------------------------------------------------+
| Delivery | Description |
| Status | |
| Code | |
+----------+--------------------------------------------------------+
| 1.0 | The scheduling message is pending. i.e. the server is |
| | still in the process of sending the message. The |
| | status code value can be expected to change once the |
| | server has completed its sending and delivery |
| | attempts. |
| | |
| | |
| | |
| 1.1 | The scheduling message has been successfully sent. |
| | However, the server does not have explicit information |
| | about whether the scheduling message was successfully |
| | delivered to the recipient. This state can occur with |
| | "store and forward" style scheduling protocols such as |
| | iMIP [RFC6047] (iTIP using email). |
| | |
| | |
| | |
| 1.2 | The scheduling message has been successfully |
| | delivered. |
| | |
| | |
| | |
| 3.7 | The scheduling message was not delivered because the |
| | server did not recognize the calendar user address as |
| | a valid calendar user. Note that this code applies to |
| | both Organizer and Attendee calendar user addresses. |
| | |
| | |
| | |
| 3.8 | The scheduling message was not delivered due to |
| | insufficient privileges. Note that this code applies |
| | to both privileges granted by both the Organizer and |
| | Attendee calendar users. |
| | |
| | |
| | |
| 5.1 | The scheduling message was not delivered because the |
| | server could not complete delivery of the message. |
| | This is likely due to a temporary failure, and the |
| | originator can try to send the message again at a |
| | later time. |
| | |
| | |
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| 5.2 | The scheduling message was not delivered because the |
| | server was not able to find a suitable way to deliver |
| | the message. This is likely a permanent failure, and |
| | the originator should not try to send the message |
| | again, at least without verifying/correcting the |
| | calendar user address of the recipient. |
| | |
| | |
| | |
| 5.3 | The scheduling message was not delivered and was |
| | rejected because scheduling with that recipient is not |
| | allowed. This is likely a permanent failure, and the |
| | originator should not try to send the message again. |
+----------+--------------------------------------------------------+
The status code for "reply" status can be any of the valid iTIP
[RFC5546] "REQUEST-STATUS" values.
The 1.xx "REQUEST-STATUS" codes are new. This specification modifies
item (2) of Section 3.6 of [RFC5546] by adding the following
restriction:
For a 1.xx code, all components MUST have exactly the same code.
Definition of the new 1.xx codes is as follows:
9.2.1. Status Code 1.0
Status Code: 1.0
Status Description: Pending.
Status Exception Data: None.
Description: Delivery of the iTIP message is pending.
9.2.2. Status Code 1.1
Status Code: 1.1
Status Description: Sent.
Status Exception Data: None.
Description: The iTIP message has been sent, though no information
about successful delivery is known.
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9.2.3. Status Code 1.2
Status Code: 1.2
Status Description: Delivered.
Status Exception Data: None.
Description: The iTIP message has been sent and delivered.
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10. Additional iCalendar Property Parameters
This specification defines additional iCalendar property parameters
to support the CalDAV scheduling extensions.
10.1. Schedule Agent Parameter
Parameter Name: SCHEDULE-AGENT
Purpose: To specify the agent expected to deliver scheduling
messages to the corresponding Organizer or Attendee.
Format Definition: This property parameter is defined by the
following notation:
scheduleagentparam = "SCHEDULE-AGENT" "="
("SERVER" ; The server handles scheduling
/ "CLIENT" ; The client handles scheduling
/ "NONE" ; No scheduling
/ x-name ; Experimental type
/ iana-token) ; Other IANA registered type
;
; Default is SERVER
Description: This property parameter MAY be specified on "ORGANIZER"
or "ATTENDEE" iCalendar properties. In the absence of this
parameter, the value "SERVER" MUST be used for the default
behavior. The value determines whether or not an automatic
scheduling transaction on a server will cause a scheduling message
to be sent to the corresponding Calendar User identified by the
"ORGANIZER" or "ATTENDEE" property value. When the value "SERVER"
is specified, or the parameter is absent, then it is the server's
responsibility to send a scheduling message as part of an
automatic scheduling transaction. When the value "CLIENT" is
specified, that indicates that the client is handling scheduling
messages with the Calendar User itself. When "NONE" is specified,
no scheduling messages are being sent to the Calendar User.
Servers MUST NOT include this parameter in any scheduling messages
sent as the result of an automatic scheduling transaction.
Clients MUST NOT include this parameter in any scheduling messages
that they themselves send.
The parameter value MUST be the same on every "ORGANIZER" property
in a scheduling object resource.
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The parameter value MUST be the same on each "ATTENDEE" property
whose values match in a scheduling object resource.
Servers and clients MUST treat x-name and iana-token values they
do not recognize the same way as they would the "NONE" value.
Example:
ORGANIZER;SCHEDULE-AGENT=SERVER:mailto:bernard@example.com
ATTENDEE;SCHEDULE-AGENT=NONE:mailto:cyrus@example.com
10.2. Schedule Force Send Parameter
Parameter Name: SCHEDULE-FORCE-SEND
Purpose: To force a scheduling message to be sent to the Calendar
User specified by the property.
Format Definition: This property parameter is defined by the
following notation:
scheduleforcesendparam = "SCHEDULE-FORCE-SEND" "="
("REQUEST" ; Force a "REQUEST"
/ "REPLY" ; Force a "REPLY"
/ iana-token) ; IANA registered method
Description: This property parameter MAY be specified on "ATTENDEE"
and "ORGANIZER" properties on which the "SCHEDULE-AGENT" property
parameter is set to the value "SERVER" or is not specified. This
property parameter is used to force a server to send a scheduling
message to a specific Calendar User in situations where the server
would not send a scheduling message otherwise (e.g., when no
change that warrants the delivery of a new scheduling message was
performed on the scheduling object resource). An Organizer MAY
specify this parameter on an "ATTENDEE" property with the value
"REQUEST" to force a "REQUEST" scheduling message to be sent to
this Attendee. An Attendee MAY specify this parameter on the
"ORGANIZER" with the value "REPLY" to force a "REPLY" scheduling
message to be sent to the Organizer.
Servers MUST NOT preserve this property parameter in scheduling
object resources, nor include it in any scheduling messages sent
as the result of an automatic scheduling transaction.
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Clients MUST NOT include this parameter in any scheduling messages
that they themselves send.
Servers MUST set the "SCHEDULE-STATUS" parameter of the "ATTENDEE"
or "ORGANIZER" to 2.3 (i.e., "Success, invalid property parameter
ignored", see Section 3.6 of [RFC5546]) when the "SCHEDULE-FORCE-
SEND" parameter is set to a x-name or iana-token value they do not
recognize.
Example:
ATTENDEE;SCHEDULE-FORCE-SEND=REQUEST:mailto:bernard@example.com
ORGANIZER;SCHEDULE-FORCE-SEND=REPLY:mailto:cyrus@example.com
10.3. Schedule Status Parameter
Parameter Name: SCHEDULE-STATUS
Purpose: To specify the status codes returned from processing of the
most recent scheduling message sent to the corresponding Attendee,
or received from the corresponding Organizer.
Format Definition: This property parameter is defined by the
following notation:
schedulestatusparam = "SCHEDULE-STATUS" "="
( statcode
/ DQUOTE statcode *("," statcode) DQUOTE)
; "statcode" is defined in Section 3.8.8.3 of
; [RFC5545]. Value is a single
; "statcode" or a comma-separated list of "statcode" values.
Description: This property parameter MAY be specified on the
"ATTENDEE" and "ORGANIZER" properties.
Servers MUST add this property parameter to any "ATTENDEE"
properties corresponding to Calendar Users who were sent a
scheduling message via an automatic scheduling transaction.
Clients SHOULD NOT change or remove this parameter if it was
provided by the server. In the case where the client is handling
the scheduling, the client MAY add, change or remove this
parameter to indicate the last scheduling message status it
received.
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Servers MUST add this parameter to any "ORGANIZER" properties
corresponding to Calendar Users who were sent a scheduling message
reply by an Attendee via an automatic scheduling transaction.
Clients SHOULD NOT change or remove this parameter if it was
provided by the server. In the case where the client is handling
the scheduling, the client MAY add, change or remove this
parameter to indicate the last scheduling message status it
received.
Servers MUST NOT include this parameter in any scheduling messages
sent as the result of an automatic scheduling transaction.
Clients MUST NOT include this parameter in any scheduling messages
that they themselves send.
Suitable values for this property parameter are described in
Section 9.2.
Example:
ATTENDEE;SCHEDULE-STATUS="2.0":mailto:bernard@example.com
ATTENDEE;SCHEDULE-STATUS="2.0,2.4":mailto:cyrus@example.com
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11. Additional Message Header Fields
This specification defines additional HTTP request and response
headers for use with CalDAV.
11.1. Schedule-Reply Request Header
Schedule-Reply = "Schedule-Reply" ":" ("T" | "F")
Example:
Schedule-Reply: F
When an Attendee removes a scheduling object resource, and the
Schedule-Reply header is not present, or present and set to the value
"T", the server MUST send an appropriate reply scheduling message
with the Attendee's "PARTSTAT" iCalendar property parameter value set
to "DECLINED" as part of its normal automatic scheduling transaction
processing.
When the Schedule-Reply header is set to the value "F", the server
MUST NOT send a scheduling message as part of its normal automatic
scheduling transaction processing.
The Schedule-Reply request header is used by a client to indicate to
a server whether or not an automatic scheduling transaction should
occur when an Attendee deletes a scheduling object resource. In
particular it controls whether a reply scheduling message is sent to
the Organizer as a result of the removal. There are situations in
which unsolicited scheduling messages need to be silently removed (or
ignored) for security or privacy reasons. This request header allows
the scheduling object resource to be removed if such a need arises.
All scheduling object resources MUST support the Schedule-Reply
request header.
11.2. Schedule-Tag Response Header
The Schedule-Tag response header provides the current value of the
CALDAV:schedule-tag property value. The behavior of this response
header is described in Section 8.
All scheduling object resources MUST support the Schedule-Tag header.
Schedule-Tag = "Schedule-Tag" ":" opaque-tag
; "opaque-tag" is defined in Section 3.11 of [RFC2616]
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Example:
Schedule-Tag: "12ab34-cd56ef"
11.3. If-Schedule-Tag-Match Request Header
The If-Schedule-Tag-Match request header field is used with a method
to make it conditional. Clients can set this header to the value
returned in the Schedule-Tag response header, or the CALDAV:schedule-
tag property, of a scheduling object resource previously retrieved
from the server to avoid overwriting "consequential" changes to the
scheduling object resource.
All scheduling object resources MUST support the If-Schedule-Tag-
Match header.
If-Schedule-Tag-Match = "If-Schedule-Tag-Match" ":" opaque-tag
; "opaque-tag" is defined in Section 3.11 of [RFC2616]
Example:
If-Schedule-Tag-Match: "12ab34-cd56ef"
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12. Additional WebDAV Properties
This specification defines the following new WebDAV properties for
use with CalDAV.
12.1. CALDAV:schedule-calendar-transp Property
Name: schedule-calendar-transp
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Determines whether the calendar object resources in a
calendar collection will affect the owner's freebusy.
Protected: This property MAY be protected and SHOULD NOT be returned
by a PROPFIND allprop request (as defined in Section 14.2 of
[RFC4918]).
COPY/MOVE behavior: This property value SHOULD be kept during a MOVE
operation, and SHOULD be copied and preserved in a COPY.
Description: This property SHOULD be defined on all calendar
collections. If present, it contains one of two XML elements that
indicate whether the calendar object resources in the calendar
collection should contribute to the owner's freebusy or not. When
the CALDAV:opaque element is used, all calendar object resources
in the corresponding calendar collection MUST contribute to
freebusy, assuming access privileges and other iCalendar
properties allow it to. When the CALDAV:transparent XML element
is used, the calendar object resources in the corresponding
calendar collection MUST NOT contribute to freebusy.
If this property is not present on a calendar collection, then the
default value CALDAV:opaque MUST be assumed.
Definition:
<!ELEMENT schedule-calendar-transp (opaque | transparent) >
<!ELEMENT opaque EMPTY>
<!-- Affect busy time searches -->
<!ELEMENT transparent EMPTY>
<!-- Invisible to busy time searches -->
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Example:
<C:schedule-calendar-transp
xmlns:C="urn:ietf:params:xml:ns:caldav">
<C:opaque/>
</C:schedule-calendar-transp>
12.2. CALDAV:schedule-default-calendar-URL Property
Name: schedule-default-calendar-URL
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a default calendar for an Attendee where new
scheduling object resources are created.
Protected: This property MAY be protected in the case where a server
does not support changing the default calendar, or does not
support a default calendar.
COPY/MOVE behavior: This property is only defined on a scheduling
Inbox collection which cannot be moved or copied.
Description: This property MAY be defined on a scheduling Inbox
collection. If present, it contains zero or one DAV:href XML
elements. When a DAV:href element is present, its value indicates
a URL to a calendar collection that is used as the default
calendar. When no DAV:href element is present, it indicates that
there is no default calendar. In the absence of this property
there is no default calendar. When there is no default calendar
the server is free to choose the calendar in which a new
scheduling object resource is created. See Section 6.4.
Definition:
<!ELEMENT schedule-default-calendar-URL (DAV:href?) >
Example:
<C:schedule-default-calendar-URL xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:href>/home/cyrus/calendars/work/</D:href>
</C:schedule-default-calendar-URL>
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12.3. CALDAV:schedule-tag Property
Name: schedule-tag
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Indicates whether a scheduling object resource has had a
"consequential" change made to it.
Value: opaque-tag (defined in Section 3.11 of [RFC2616])
Protected: This property MUST be protected as only the server can
update the value.
COPY/MOVE behavior: This property is only defined on scheduling
object resources. It MUST be preserved when a scheduling object
resource is copied or moved and the resulting resource is also a
scheduling object resource. If the source resource is not a
scheduling object resource but the destination resource is, this
property MUST be added to the destination resource.
Description: The CALDAV:schedule-tag property MUST be defined on all
scheduling object resources. This property is described in
Section 8.
Definition:
<!ELEMENT schedule-tag (#PCDATA) >
Example:
<C:schedule-tag xmlns:C="urn:ietf:params:xml:ns:caldav"
>"12345-67890"</C:schedule-tag>
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13. Scheduling Access Control
13.1. Scheduling Privileges
CalDAV servers MUST support and adhere to the requirements of WebDAV
ACL [RFC3744]. Furthermore, CalDAV servers that advertise support
for the "calendar-auto-schedule" feature MUST also support the
scheduling privileges defined in this section.
All the scheduling privileges MUST be non-abstract and MUST appear in
the DAV:supported-privilege-set property of scheduling Outbox and
Inbox collections on which they are defined.
The tables specified in Appendix A clarify which scheduling methods
(e.g., "REQUEST", "REPLY", etc.) are controlled by each scheduling
privilege defined in this section.
13.1.1. Privileges on Scheduling Inbox Collections
This section defines new WebDAV ACL privileges that are for use on
scheduling Inbox collections. These privileges determine whether
delivery of scheduling messages from a calendar user is allowed by
the calendar user who "owns" the scheduling Inbox collection. This
allows calendar users to choose which other calendar users can
schedule with them.
Note that when a scheduling message is delivered to a calendar user,
in addition to a scheduling object resource being created in the
calendar user's scheduling Inbox collection, a new scheduling object
resource might be created or an existing one updated in a calendar
belonging to the calendar user. In that case, the ability to create
or update the scheduling object resource in the calendar is
controlled by the privileges assigned to the scheduling Inbox
collection.
The privileges defined in this section are ignored if applied to a
resource other than a scheduling Inbox collection.
13.1.1.1. CALDAV:schedule-deliver Privilege
CALDAV:schedule-deliver is an aggregate privilege that contains all
the scheduling privileges that control the processing and delivery of
incoming scheduling messages, that is, CALDAV:schedule-deliver-invite
and CALDAV:schedule-deliver-reply, as well as freebusy requests
targeted at the owner of the scheduling Inbox collection, that is,
CALDAV:schedule-query-freebusy.
<!ELEMENT schedule-deliver EMPTY >
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13.1.1.2. CALDAV:schedule-deliver-invite Privilege
The CALDAV:schedule-deliver-invite privilege controls the processing
and delivery of scheduling messages coming from an Organizer.
<!ELEMENT schedule-deliver-invite EMPTY >
13.1.1.3. CALDAV:schedule-deliver-reply Privilege
The CALDAV:schedule-deliver-reply privilege controls the processing
and delivery of scheduling messages coming from an Attendee.
<!ELEMENT schedule-deliver-reply EMPTY >
13.1.1.4. CALDAV:schedule-query-freebusy Privilege
The CALDAV:schedule-query-freebusy privilege controls freebusy
requests targeted at the owner of the scheduling Inbox collection.
<!ELEMENT schedule-query-freebusy EMPTY >
13.1.2. Privileges on Scheduling Outbox Collections
This section defines new WebDAV ACL privileges that are defined for
use on scheduling Outbox collections. These privileges determine
which calendar users are allowed to send scheduling messages on
behalf of the calendar user who "owns" the scheduling Outbox
collection. This allows calendar users to choose other calendar
users who can act on their behalf to send schedule messages to other
calendar users (e.g. assistants working on behalf of their boss).
The privileges defined in this section are ignored if applied to a
resource other than a scheduling Outbox collection.
13.1.2.1. CALDAV:schedule-send Privilege
CALDAV:schedule-send is an aggregate privilege that contains all the
scheduling privileges that control the use of methods that will cause
scheduling messages to be delivered to other users, that is, CALDAV:
schedule-send-invite and CALDAV:schedule-send-reply, as well as
freebusy requests to be targeted at other users, that is, CALDAV:
schedule-send-freebusy.
<!ELEMENT schedule-send EMPTY >
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13.1.2.2. CALDAV:schedule-send-invite Privilege
The CALDAV:schedule-send-invite privilege controls the sending of
scheduling messages by Organizers.
Users granted the DAV:bind privilege on a calendar collection, or
DAV:write privilege on scheduling object resources, will also need
the CALDAV:schedule-send-invite privilege granted on the scheduling
Outbox collection of the owner of the calendar collection or
scheduling object resource in order to be allowed to create, modify
or delete scheduling object resources in a way that will trigger the
CalDAV server to deliver organizer scheduling messages to other
calendar users.
<!ELEMENT schedule-send-invite EMPTY >
13.1.2.3. CALDAV:schedule-send-reply Privilege
The CALDAV:schedule-send-reply privilege controls the sending of
scheduling messages by Attendees.
Users granted the DAV:bind privilege on a calendar collection, or
DAV:write privilege on scheduling object resources, will also need
the CALDAV:schedule-send-reply privilege granted on the scheduling
Outbox collection of the owner of the calendar collection or
scheduling object resource in order to be allowed to create, modify
or delete scheduling object resources in a way that will trigger the
CalDAV server to deliver attendee scheduling messages to other
calendar users.
<!ELEMENT schedule-send-reply EMPTY >
13.1.2.4. CALDAV:schedule-send-freebusy Privilege
The CALDAV:schedule-send-freebusy privilege controls the use of the
POST method to submit scheduling messages that specify the scheduling
method "REQUEST" with a "VFREEBUSY" calendar component.
<!ELEMENT schedule-send-freebusy EMPTY >
13.1.3. Aggregation of Scheduling Privileges
Server implementations MUST aggregate the scheduling privileges as
follows:
DAV:all MUST contain CALDAV:schedule-send and CALDAV:schedule-
deliver;
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CALDAV:schedule-send MUST contain CALDAV:schedule-send-invite,
CALDAV:schedule-send-reply, and CALDAV:schedule-send-freebusy;
CALDAV:schedule-deliver MUST contain CALDAV:schedule-deliver-
invite, CALDAV:schedule-deliver-reply, and CALDAV:schedule-query-
freebusy.
The following diagram illustrates how scheduling privileges are
aggregated according to the above requirements.
[DAV:all] (aggregate)
|
+-- [CALDAV:schedule-deliver] (aggregate)
| |
| +-- [CALDAV:schedule-deliver-invite]
| +-- [CALDAV:schedule-deliver-reply]
| +-- [CALDAV:schedule-query-freebusy]
|
+-- [CALDAV:schedule-send] (aggregate)
|
+-- [CALDAV:schedule-send-invite]
+-- [CALDAV:schedule-send-reply]
+-- [CALDAV:schedule-send-freebusy]
13.2. Additional Principal Properties
This section defines new properties for WebDAV principal resources as
defined in [RFC3744]. These properties are likely to be protected
but the server MAY allow them to be written by appropriate users.
13.2.1. CALDAV:schedule-inbox-URL Property
Name: schedule-inbox-URL
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identify the URL of the scheduling Inbox collection owned
by the associated principal resource.
Protected: This property MAY be protected.
PROPFIND behavior: This property SHOULD NOT be returned by a
PROPFIND allprop request (as defined in Section 14.2 of
[RFC4918]).
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COPY/MOVE behavior: This property value SHOULD be preserved in COPY
and MOVE operations.
Description: This property is needed for a client to determine where
the scheduling Inbox collection of the current user is located so
that processing of scheduling messages can occur. If not present,
then the associated calendar user is not enabled for reception of
scheduling messages on the server.
Definition:
<!ELEMENT schedule-inbox-URL (DAV:href)>
13.2.2. CALDAV:schedule-outbox-URL Property
Name: schedule-outbox-URL
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identify the URL of the scheduling Outbox collection owned
by the associated principal resource.
Protected: This property MAY be protected.
PROPFIND behavior: This property SHOULD NOT be returned by a
PROPFIND allprop request (as defined in Section 14.2 of
[RFC4918]).
COPY/MOVE behavior: This property value SHOULD be preserved in COPY
and MOVE operations.
Description: This property is needed for a client to determine where
the scheduling Outbox collection of the current user is located so
that sending of scheduling messages can occur. If not present,
then the associated calendar user is not enabled for the sending
of scheduling messages on the server.
Definition:
<!ELEMENT schedule-outbox-URL DAV:href>
13.2.3. CALDAV:calendar-user-address-set Property
Name: calendar-user-address-set
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Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identify the calendar addresses of the associated principal
resource.
Protected: This property MAY be protected.
PROPFIND behavior: This property SHOULD NOT be returned by a
PROPFIND allprop request (as defined in Section 14.2 of
[RFC4918]).
COPY/MOVE behavior: This property value SHOULD be preserved in COPY
and MOVE operations.
Description: Support for this property is REQUIRED. This property
is needed to map calendar user addresses in iCalendar data to
principal resources and their associated scheduling Inbox and
Outbox collections. In the event that a user has no well defined
identifier for their calendar user address, the URI of their
principal resource can be used. This property SHOULD be
searchable using the DAV:principal-property-search REPORT. The
DAV:principal-search-property-set REPORT SHOULD identify this
property as such. If not present, then the associated calendar
user is not enabled for scheduling on the server.
Definition:
<!ELEMENT calendar-user-address-set (DAV:href*)>
Example:
<C:calendar-user-address-set xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:href>mailto:bernard@example.com</D:href>
<D:href>mailto:bernard.desruisseaux@example.com</D:href>
</C:calendar-user-address-set>
13.2.4. CALDAV:calendar-user-type Property
Name: calendar-user-type
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Identifies the calendar user type of the associated
principal resource.
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Value: Same values allowed for the iCalendar "CUTYPE" property
parameter defined in Section 3.2.3 of [RFC5545].
Protected: This property MAY be protected.
PROPFIND behavior: This property SHOULD NOT be returned by a
PROPFIND allprop request (as defined in Section 14.2 of
[RFC4918]).
COPY/MOVE behavior: This property value SHOULD be preserved in COPY
and MOVE operations.
Description: Clients can query principal resources in order to
lookup attendees available on the server. When doing this, it is
useful to know, or restrict the query to, certain types of
calendar user (e.g., only search for "people", or only search for
"rooms"). This property MAY be defined on principal resources to
indicate the type of calendar user associated with the principal
resource. Its value is the same as the iCalendar "CUTYPE"
property parameter that can be used on "ATTENDEE" properties.
This property SHOULD be searchable using the DAV:principal-
property-search REPORT. The DAV:principal-search-property-set
REPORT SHOULD identify this property as such.
Definition:
<!ELEMENT calendar-user-type (#PCDATA) >
Example:
<C:calendar-user-type
xmlns:C="urn:ietf:params:xml:ns:caldav">INDIVIDUAL<
/C:calendar-user-type>
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14. XML Element Definitions
14.1. CALDAV:schedule-response XML Element
Name: schedule-response
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Contains the set of responses for a POST method request.
Description: See Section 7.3.
Definition:
<!ELEMENT schedule-response (response*)>
14.2. CALDAV:response XML Element
Name: response
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Contains a single response for a POST method request.
Description: See Section 7.3.
Definition:
<!ELEMENT response (recipient,
request-status,
calendar-data?,
DAV:error?,
DAV:responsedescription?)>
<!-- CALDAV:calendar-data is defined in Section 9.6 of
RFC 4791 and when used here uses the definition with
content (#PCDATA) only -->
14.3. CALDAV:recipient XML Element
Name: recipient
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: The calendar user address that the enclosing response for a
POST method request is for.
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Description: See Section 7.3.
Definition:
<!ELEMENT recipient (DAV:href)>
14.4. CALDAV:request-status XML Element
Name: request-status
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: The iTIP "REQUEST-STATUS" property value for this response.
Description: See Section 7.3.
Definition:
<!ELEMENT request-status (#PCDATA) >
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15. Security Considerations
The process of scheduling involves the sending and receiving of
scheduling messages. As a result, the security problems related to
messaging in general are relevant here. In particular the
authenticity of the scheduling messages needs to be verified.
Servers and clients MUST use an HTTP connection protected with TLS as
defined in [RFC2818] for all scheduling transactions.
15.1. Verifying Scheduling Transactions
When handling a scheduling transaction:
Servers MUST verify that the principal associated with the DAV:
owner of the calendar collection in which a scheduling object
resource is being manipulated contains a CALDAV:schedule-outbox-
URL property value.
Servers MUST verify that the currently authenticated user has the
CALDAV:schedule-send privilege, or a suitable sub-privilege
aggregated under this privilege, on the scheduling Outbox
collection of the DAV:owner of the calendar collection in which a
scheduling object resource is being manipulated.
Servers MUST only deliver scheduling messages to recipients when
the CALDAV:schedule-deliver privilege, or a suitable sub-privilege
aggregated under this privilege, is granted on the recipient's
scheduling Inbox collection for the principal associated with the
DAV:owner of the calendar collection in which a scheduling object
resource is being manipulated.
To prevent impersonation of calendar users, the server MUST verify
that the "ORGANIZER" property in an organizer scheduling object
resource matches one of the calendar user addresses of the DAV:
owner of the calendar collection in which the resource is stored.
To prevent spoofing of an existing scheduling object resource,
servers MUST verify that the "UID" iCalendar property value in a
new scheduling object resource does not match that of an existing
scheduling object resource with a different "ORGANIZER" property
value.
15.2. Verifying Busy Time Information Requests
When handling a POST request on a scheduling Outbox collection:
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Servers MUST verify that the principal associated with the
calendar user address specified in the "ORGANIZER" property of the
scheduling message data in the request contains a CALDAV:schedule-
outbox-URL property value that matches the scheduling Outbox
collection targeted by the request.
Servers MUST verify that the currently authenticated user has the
CALDAV:schedule-send privilege, or a sub-privilege aggregated
under this privilege, on the scheduling Outbox collection targeted
by the request.
Servers MUST only return valid freebusy information for recipients
when the CALDAV:schedule-deliver privilege, or a sub-privilege
aggregated under this privilege, is granted on the recipient's
scheduling Inbox collection for the principal associated with the
DAV:owner of the scheduling Outbox collection targeted by the
request.
15.3. Privacy Issues
As noted in Section 11.1, Attendees can use the Schedule-Reply
request header with the value set to "F" to prevent notification to
an Organizer that a scheduling object resource was deleted. This
allows Attendees to remove unwanted scheduling messages without any
response to the Organizer.
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16. IANA Considerations
16.1. Message Header Field Registrations
The message header fields below should be added to the Permanent
Message Header Field Registry (see [RFC3864]).
16.1.1. Schedule-Reply
Header field name: Schedule-Reply
Applicable protocol: http
Status: standard
Author/Change controller: IETF
Specification document(s): this specification (Section 11.1)
Related information: none
16.1.2. Schedule-Tag
Header field name: Schedule-Tag
Applicable protocol: http
Status: standard
Author/Change controller: IETF
Specification document(s): this specification (Section 11.2)
Related information: none
16.1.3. If-Schedule-Tag-Match
Header field name: If-Schedule-Tag-Match
Applicable protocol: http
Status: standard
Author/Change controller: IETF
Specification document(s): this specification (Section 11.3)
Related information: none
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16.2. iCalendar Property Parameter Registrations
The following iCalendar property parameters should be added to the
iCalendar Property Parameter Registry defined in Section 8.3.3 of
[RFC5545].
+---------------------+---------+-----------------------+
| Parameter | Status | Reference |
+---------------------+---------+-----------------------+
| SCHEDULE-AGENT | Current | RFCXXXX, Section 10.1 |
| | | |
| SCHEDULE-STATUS | Current | RFCXXXX, Section 10.3 |
| | | |
| SCHEDULE-FORCE-SEND | Current | RFCXXXX, Section 10.2 |
+---------------------+---------+-----------------------+
16.3. iCalendar REQUEST-STATUS Value Registrations
The following iCalendar "REQUEST-STATUS" values should be added to
the iCalendar REQUEST-STATUS Value Registry defined in Section 7.3 of
[RFC5546].
+-------------+---------+-------------------------+
| Status Code | Status | Reference |
+-------------+---------+-------------------------+
| 1.0 | Current | RFC XXXX, Section 9.2.1 |
| | | |
| 1.1 | Current | RFC XXXX, Section 9.2.2 |
| | | |
| 1.2 | Current | RFC XXXX, Section 9.2.3 |
+-------------+---------+-------------------------+
16.4. Additional iCalendar Elements Registries
This specification adds two new IANA registries for iCalendar
elements. Additional codes MAY be used, provided the process
described in Section 8.2.1 of [RFC5545] is used to register them.
16.4.1. Schedule Agent Values Registry
The following table has been used to initialize the schedule agent
values registry.
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+----------------+---------+------------------------+
| Schedule Agent | Status | Reference |
+----------------+---------+------------------------+
| SERVER | Current | RFC XXXX, Section 10.1 |
| | | |
| CLIENT | Current | RFC XXXX, Section 10.1 |
| | | |
| NONE | Current | RFC XXXX, Section 10.1 |
+----------------+---------+------------------------+
16.4.2. Schedule Force Send Values Registry
The following table has been used to initialize the schedule send
values registry.
+---------------------+---------+------------------------+
| Schedule Force Send | Status | Reference |
+---------------------+---------+------------------------+
| REQUEST | Current | RFC XXXX, Section 10.2 |
| | | |
| REPLY | Current | RFC XXXX, Section 10.2 |
+---------------------+---------+------------------------+
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17. Acknowledgements
The authors would like to thank the following individuals for
contributing their ideas and support for writing this specification:
Mike Douglass, Lisa Dusseault, Helge Hess, Arnaud Quillaud, Julian F.
Reschke, Wilfredo Sanchez Vega, 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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18. References
18.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14,
RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk,
H., Masinter, L., Leach, P., and T. Berners-
Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
May 2000.
[RFC3744] Clemm, G., Reschke, J., Sedlar, E., and J.
Whitehead, "Web Distributed Authoring and
Versioning (WebDAV) Access Control Protocol",
RFC 3744, May 2004.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul,
"Registration Procedures for Message Header
Fields", BCP 90, RFC 3864, September 2004.
[RFC4791] Daboo, C., Desruisseaux, B., and L.
Dusseault, "Calendaring Extensions to WebDAV
(CalDAV)", RFC 4791, March 2007.
[RFC4918] Dusseault, L., "HTTP Extensions for Web
Distributed Authoring and Versioning
(WebDAV)", RFC 4918, June 2007.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF
for Syntax Specifications: ABNF", STD 68,
RFC 5234, January 2008.
[RFC5545] Desruisseaux, B., "Internet Calendaring and
Scheduling Core Object Specification
(iCalendar)", RFC 5545, September 2009.
[RFC5546] Daboo, C., "iCalendar Transport-Independent
Interoperability Protocol (iTIP)", RFC 5546,
December 2009.
[W3C.REC-xml-20081126] Paoli, J., Yergeau, F., Bray, T., Sperberg-
McQueen, C., and E. Maler, "Extensible Markup
Language (XML) 1.0 (Fifth Edition)", World
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Wide Web Consortium Recommendation REC-xml-
20081126, November 2008,
<http://www.w3.org/TR/2008/REC-xml-20081126>.
18.2. Informative References
[RFC3283] Mahoney, B., Babics, G., and A. Taler, "Guide
to Internet Calendaring", RFC 3283,
June 2002.
[RFC6047] Melnikov, A., "iCalendar Message-Based
Interoperability Protocol (iMIP)", RFC 6047,
December 2010.
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Appendix A. Scheduling Privileges Summary
A.1. Scheduling Inbox Privileges
The following tables specify which scheduling privileges grant the
right to a calendar user to deliver a scheduling message to the
scheduling Inbox collection of another calendar user. The
appropriate behavior depends on the calendar component type as well
as the scheduling "METHOD" specified in the scheduling message.
+--------------------------------+
| METHOD for VEVENT and VTODO |
+-----------------------------+---------+-------+-----+--------+
| Scheduling Inbox Privilege | REQUEST | REPLY | ADD | CANCEL |
+-----------------------------+---------+-------+-----+--------+
| schedule-deliver | * | * | * | * |
| schedule-deliver-invite | * | | * | * |
| schedule-deliver-reply | | * | | |
| schedule-query-freebusy | | | | |
+-----------------------------+---------+-------+-----+--------+
+----------------------+
| METHOD for VFREEBUSY |
+-----------------------------+----------------------+
| Scheduling Inbox Privilege | REQUEST |
+-----------------------------+----------------------+
| schedule-deliver | * |
| schedule-deliver-invite | |
| schedule-deliver-reply | |
| schedule-query-freebusy | * |
+-----------------------------+----------------------+
A.2. Scheduling Outbox Privileges
The following tables specify which scheduling privileges grant the
right to a Calendar User to perform busy time information requests
and to submit scheduling messages to other Calendar Users as the
result of a scheduling transaction. The appropriate behavior depends
on the calendar component type as well as the scheduling "METHOD"
specified in the scheduling message.
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+--------------------------------+
| METHOD for VEVENT and VTODO |
+-----------------------------+---------+-------+-----+--------+
| Scheduling Outbox Privilege | REQUEST | REPLY | ADD | CANCEL |
+-----------------------------+---------+-------+-----+--------+
| schedule-send | * | * | * | * |
| schedule-send-invite | * | | * | * |
| schedule-send-reply | | * | | |
| schedule-send-freebusy | | | | |
+-----------------------------+---------+-------+-----+--------+
+----------------------+
| METHOD for VFREEBUSY |
+-----------------------------+----------------------+
| Scheduling Outbox Privilege | REQUEST |
+-----------------------------+----------------------+
| schedule-send | * |
| schedule-send-invite | |
| schedule-send-reply | |
| schedule-send-freebusy | * |
+-----------------------------+----------------------+
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Appendix B. Example Scheduling Transactions
This section describes some example scheduling transactions that give
a general idea of how scheduling is carried out between CalDAV
clients and servers from the perspective of meeting Organizers and
Attendees.
In the following examples the requests and responses are incomplete
and are only for illustrative purposes. In particular, HTTP
authentication headers and behaviors are not shown, even though they
are required in normal operation.
B.1. Example: Organizer Inviting Multiple Attendees
In the following example, Cyrus invites Wilfredo, Bernard and Mike to
a single instance event by simply creating a new scheduling object
resource in one of his calendar collection by using the PUT method.
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>> Request <<
PUT /home/cyrus/calendars/work/9263504FD3AD.ics HTTP/1.1
Host: cal.example.com
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
If-None-Match: *
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T185254Z
DTSTART:20090602T160000Z
DTEND:20090602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";CUTYPE=INDIVIDUAL;PARTSTAT
=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:wilfredo@
example.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@ex
ample.net
ATTENDEE;CN="Mike Douglass";CUTYPE=INDIVIDUAL;PARTSTAT=NEEDS-A
CTION;RSVP=TRUE:mailto:mike@example.org
END:VEVENT
END:VCALENDAR
>> Response <<
HTTP/1.1 201 Created
Content-Length: 0
Date: Tue, 02 Jun 2009 18:52:54 GMT
Last-Modified: Tue, 02 Jun 2009 18:52:54 GMT
ETag: "d85561cfe74a4e785eb4639451b434fb"
Schedule-Tag: "488177c8-2ea7-4176-a6cb-fab8cfccdea2"
Once the event creation has been completed, Cyrus's client will
retrieve the event back from the server to get the schedule status of
each Attendee. In this example, the server reports that a scheduling
message was delivered to Wilfredo, a scheduling message is still
pending for Bernard, and the server was unable to deliver a
scheduling message to Mike.
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>> Request <<
GET /home/cyrus/calendars/work/9263504FD3AD.ics HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 18:52:58 GMT
Last-Modified: Tue, 02 Jun 2009 18:52:58 GMT
ETag: "eb897deabc8939589da116714bc99265"
Schedule-Tag: "488177c8-2ea7-4176-a6cb-fab8cfccdea2"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T185300Z
DTSTART:20090602T160000Z
DTEND:20090602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";CUTYPE=INDIVIDUAL;PARTSTAT
=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE;SCHEDULE-STATUS=
1.2:mailto:wilfredo@e
xample.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE;SCHEDULE-STATUS=
1.0:mailto:bernard@example.net
ATTENDEE;CN="Mike Douglass";CUTYPE=INDIVIDUAL;PARTSTAT=NEEDS-A
CTION;RSVP=TRUE;SCHEDULE-STATUS=3.7:mailto:mike@example.org
END:VEVENT
END:VCALENDAR
B.2. Example: Attendee Receiving an Invitation
In the following example, Wilfredo's client retrieves and deletes the
new scheduling message that appeared in his scheduling Inbox
collection after the server automatically processed it and created a
new scheduling object resource in his default calendar collection.
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>> Request <<
GET /home/wilfredo/calendars/inbox/27d93fc0a58c.ics HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 18:59:58 GMT
Last-Modified: Tue, 02 Jun 2009 18:59:58 GMT
ETag: "da116714bc9926c89395895eb897deab"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
METHOD:REQUEST
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T185254Z
DTSTART:20090602T160000Z
DTEND:20090602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";CUTYPE=INDIVIDUAL;PARTSTAT
=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:wilfredo@
example.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@ex
ample.net
ATTENDEE;CN="Mike Douglass";CUTYPE=INDIVIDUAL;PARTSTAT=NEEDS-A
CTION;RSVP=TRUE:mailto:mike@example.org
END:VEVENT
END:VCALENDAR
>> Request <<
DELETE /home/wilfredo/calendars/inbox/27d93fc0a58c.ics HTTP/1.1
Host: cal.example.com
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>> Response <<
HTTP/1.1 204 No Content
Date: Tue, 02 Jun 2009 20:40:36 GMT
B.3. Example: Attendee Replying to an Invitation
In the following example, Wilfredo's accepts Cyrus's invitation and
sets a reminder on the event.
>> Request <<
PUT /home/wilfredo/calendars/work/BB64861C2228.ics HTTP/1.1
Host: cal.example.com
If-Schedule-Tag-Match: "e78f23ed-0188-4bab-938d-2aeb3324c7e8"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T185254Z
DTSTART:20090602T160000Z
DTEND:20090602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";CUTYPE=INDIVIDUAL;PARTSTAT
=ACCEPTED;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:wilfredo@exam
ple.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@ex
ample.net
ATTENDEE;CN="Mike Douglass";CUTYPE=INDIVIDUAL;PARTSTAT=NEEDS-A
CTION;RSVP=TRUE:mailto:mike@example.org
BEGIN:VALARM
TRIGGER:-PT15M
ACTION:DISPLAY
DESCRIPTION:Reminder
END:VALARM
END:VEVENT
END:VCALENDAR
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>> Response <<
HTTP/1.1 200 OK
Content-Length: 0
Date: Tue, 02 Jun 2009 18:57:54 GMT
Last-Modified: Tue, 02 Jun 2009 18:57:54 GMT
ETag: "eb4639451b434fbd85561cfe74a4e785"
Schedule-Tag: "8893ee45-eb9d-428f-b53c-c777daf19e41"
Once the event modification has been completed, Wilfredo's client
will retrieve the event back from the server to get the schedule
status of the Organizer.
>> Request <<
GET /home/wilfredo/calendars/work/BB64861C2228.ics HTTP/1.1
Host: cal.example.com
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>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 19:03:03 GMT
Last-Modified: Tue, 02 Jun 2009 19:02:21 GMT
ETag: "5eb897deabda116714bc9926c8939589"
Schedule-Tag: "8893ee45-eb9d-428f-b53c-c777daf19e41"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T190221Z
DTSTART:20090602T160000Z
DTEND:20090602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Cyrus Daboo";SCHEDULE-STATUS=1.2:mailto:cyrus@ex
ample.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";CUTYPE=INDIVIDUAL;PARTSTAT
=ACCEPTED;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:wilfredo@exam
ple.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@ex
ample.net
ATTENDEE;CN="Mike Douglass";CUTYPE=INDIVIDUAL;PARTSTAT=NEEDS-A
CTION;RSVP=TRUE:mailto:mike@example.org
BEGIN:VALARM
TRIGGER:-PT15M
ACTION:DISPLAY
DESCRIPTION:Reminder
END:VALARM
END:VEVENT
END:VCALENDAR
B.4. Example: Organizer Receiving a Reply to an Invitation
On reception of Wilfredo's reply, Cyrus's server will automatically
update Cyrus's scheduling object resource, make Wilfredo's scheduling
message available in Cyrus's scheduling Inbox collection, and deliver
an updated scheduling message to Bernard to share Wilfredo's updated
participation status. In this example, Cyrus's client retrieves and
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deletes this scheduling message in his scheduling Inbox collection.
>> Request <<
GET /home/cyrus/calendars/inbox/c0a58c27d93f.ics HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 19:05:02 GMT
Last-Modified: Tue, 02 Jun 2009 19:04:20 GMT
ETag: "9265eb897deabc8939589da116714bc9"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
METHOD:REPLY
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T185754Z
DTSTART:20090602T160000Z
DTEND:20090602T170000Z
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";PARTSTAT=ACCEPTED:mailto:w
ilfredo@example.com
REQUEST-STATUS:2.0;Success
END:VEVENT
END:VCALENDAR
>> Request <<
DELETE /home/cyrus/calendars/inbox/c0a58c27d93f.ics HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 204 No Content
Date: Tue, 02 Jun 2009 19:05:05 GMT
Cyrus's client then retrieves the event back from the server with
Wilfredo's updated participation status.
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>> Request <<
GET /home/cyrus/calendars/work/9263504FD3AD.ics HTTP/1.1
Host: cal.example.com
>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 19:05:02 GMT
Last-Modified: Tue, 02 Jun 2009 19:04:20 GMT
ETag: "eb897deabc8939589da116714bc99265"
Schedule-Tag: "132cab27-1fe3-67ab-de13-abd348d1dee3"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T190420Z
DTSTART:20090602T160000Z
DTEND:20090602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";CUTYPE=INDIVIDUAL;PARTSTAT
=ACCEPTED;ROLE=REQ-PARTICIPANT;RSVP=TRUE;SCHEDULE-STATUS=2.0:
mailto:wilfredo@example.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE;SCHEDULE-STATUS=1
.0:mailto:bernard@example.net
ATTENDEE;CN="Mike Douglass";CUTYPE=INDIVIDUAL;PARTSTAT=NEEDS-A
CTION;RSVP=TRUE;SCHEDULE-STATUS=3.7:mailto:mike@example.org
END:VEVENT
END:VCALENDAR
B.5. Example: Organizer Requesting Busy Time Information
In this example, Cyrus requests the busy time information of
Wilfredo, Bernard and Mike.
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>> Request <<
POST /home/cyrus/calendars/outbox/ HTTP/1.1
Host: cal.example.com
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
METHOD:REQUEST
BEGIN:VFREEBUSY
UID:4FD3AD926350
DTSTAMP:20090602T190420Z
DTSTART:20090602T000000Z
DTEND:20090604T000000Z
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega":mailto:wilfredo@example.com
ATTENDEE;CN="Bernard Desruisseaux":mailto:bernard@example.net
ATTENDEE;CN="Mike Douglass":mailto:mike@example.org
END:VFREEBUSY
END:VCALENDAR
>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 20:07:34 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:schedule-response xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<C:response>
<C:recipient>
<D:href>mailto:wilfredo@example.com</D:href>
</C:recipient>
<C:request-status>2.0;Success</C:request-status>
<C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
METHOD:REPLY
BEGIN:VFREEBUSY
UID:4FD3AD926350
DTSTAMP:20090602T200733Z
DTSTART:20090602T000000Z
DTEND:20090604T000000Z
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
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ATTENDEE;CN="Wilfredo Sanchez Vega":mailto:wilfredo@example.com
FREEBUSY;FBTYPE=BUSY:20090602T110000Z/20090602T120000Z
FREEBUSY;FBTYPE=BUSY:20090603T170000Z/20090603T180000Z
END:VFREEBUSY
END:VCALENDAR
</C:calendar-data>
</C:response>
<C:response>
<C:recipient>
<D:href>mailto:bernard@example.net</D:href>
</C:recipient>
<C:request-status>2.0;Success</C:request-status>
<C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
METHOD:REPLY
BEGIN:VFREEBUSY
UID:4FD3AD926350
DTSTAMP:20090602T200733Z
DTSTART:20090602T000000Z
DTEND:20090604T000000Z
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Bernard Desruisseaux":mailto:bernard@example.net
FREEBUSY;FBTYPE=BUSY:20090602T150000Z/20090602T160000Z
FREEBUSY;FBTYPE=BUSY:20090603T090000Z/20090603T100000Z
FREEBUSY;FBTYPE=BUSY:20090603T180000Z/20090603T190000Z
END:VFREEBUSY
END:VCALENDAR
</C:calendar-data>
</C:response>
<C:response>
<C:recipient>
<D:href>mailto:mike@example.org</D:href>
</C:recipient>
<C:request-status>3.7;Invalid calendar user</C:request-status>
</C:response>
</C:schedule-response>
B.6. Example: User Attempting to Invite Attendee on behalf of Organizer
In the following example, Cyrus attempts to create, on behalf of
Wilfredo, an event with Bernard specified as an Attendee. The
request fails since Wilfredo didn't grant Cyrus the right to invite
other Calendar Users on his behalf.
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>> Request <<
PUT /home/wilfredo/calendars/work/def456.ics HTTP/1.1
Host: cal.example.com
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
If-None-Match: *
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:3504F926D3AD
SEQUENCE:0
DTSTAMP:20090602T190221Z
DTSTART:20090602T230000Z
DTEND:20090603T000000Z
TRANSP:OPAQUE
SUMMARY:Dinner
ORGANIZER;CN="Wilfredo Sanchez Vega":mailto:wilfredo@example.com
ATTENDEE;CN="Wilfredo Sanchez Vega";CUTYPE=INDIVIDUAL;PARTSTAT=A
CCEPTED:mailto:wilfredo@example.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=NE
EDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@exampl
e.net
END:VEVENT
END:VCALENDAR
>> Response <<
HTTP/1.1 403 Forbidden
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
<D:error xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:need-privileges>
<D:resource>
<D:href>/home/wilfredo/calendars/outbox/</D:href>
<D:privilege><C:schedule-send-invite/></D:privilege>
</D:resource>
</D:need-privileges>
</D:error>
B.7. Example: Attendee Declining an Instance of a Recurring Event
In the following example, Bernard declines the second recurrence
instance of a daily recurring event he's been invited to by Cyrus.
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>> Request <<
PUT /home/bernard/calendars/work/4FD3AD926350.ics HTTP/1.1
Host: cal.example.com
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
If-Schedule-Tag-Match: "7775FB30-7534-489E-A79A-0EA147B933EB"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
TZID:America/Montreal
BEGIN:STANDARD
DTSTART:20071104T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20070311T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T185254Z
DTSTART;TZID=America/Montreal:20090601T150000
DTEND;TZID=America/Montreal:20090601T160000
RRULE:FREQ=DAILY;INTERVAL=1;COUNT=5
TRANSP:OPAQUE
SUMMARY:Review Internet-Draft
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
ACCEPTED;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@exampl
e.net
END:VEVENT
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090603T183823Z
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RECURRENCE-ID;TZID=America/Montreal:20090602T150000
DTSTART;TZID=America/Montreal:20090602T150000
DTEND;TZID=America/Montreal:20090602T160000
TRANSP:TRANSPARENT
SUMMARY:Review Internet-Draft
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
DECLINED;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@exampl
e.net
END:VEVENT
END:VCALENDAR
>> Response <<
HTTP/1.1 200 OK
Content-Length: 0
Date: Tue, 02 Jun 2009 18:52:54 GMT
Last-Modified: Tue, 02 Jun 2009 18:52:54 GMT
ETag: "d85561cfe74a4e785eb4639451b434fb"
Schedule-Tag: "488177c8-2ea7-4176-a6cb-fab8cfccdea2"
Bernard's participation status update will cause his server to
deliver a scheduling message to Cyrus. Cyrus's client will find the
following reply message from Bernard in Cyrus's scheduling Inbox
collection:
>> Request <<
GET /home/cyrus/calendars/inbox/9263504FD3AD.ics HTTP/1.1
Host: cal.example.com
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>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 18:52:58 GMT
Last-Modified: Tue, 02 Jun 2009 18:52:58 GMT
ETag: "eb897deabc8939589da116714bc99265"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
METHOD:REPLY
BEGIN:VTIMEZONE
TZID:America/Montreal
BEGIN:STANDARD
DTSTART:20071104T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20070311T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090603T183823Z
RECURRENCE-ID;TZID=America/Montreal:20090602T150000
DTSTART;TZID=America/Montreal:20090602T150000
DTEND;TZID=America/Montreal:20090602T160000
SUMMARY:Review Internet-Draft
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Bernard Desruisseaux";PARTSTAT=DECLINED:
mailto:bernard@example.net
REQUEST-STATUS:2.0;Success
END:VEVENT
END:VCALENDAR
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B.8. Example: Attendee Removing an Instance of a Recurring Event
In the following example, Bernard removes from his calendar the third
recurrence instance of a daily recurring event he's been invited to
by Cyrus. This is accomplished by the addition of an "EXDATE"
property to the scheduling object resource stored by Bernard.
>> Request <<
PUT /home/bernard/calendars/work/4FD3AD926350.ics HTTP/1.1
Host: cal.example.com
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
If-Schedule-Tag-Match: "488177c8-2ea7-4176-a6cb-fab8cfccdea2"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTIMEZONE
TZID:America/Montreal
BEGIN:STANDARD
DTSTART:20071104T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20070311T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090602T185254Z
DTSTART;TZID=America/Montreal:20090601T150000
DTEND;TZID=America/Montreal:20090601T160000
RRULE:FREQ=DAILY;INTERVAL=1;COUNT=5
EXDATE;TZID=America/Montreal:20090603T150000
TRANSP:OPAQUE
SUMMARY:Review Internet-Draft
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
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ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
ACCEPTED;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@exampl
e.net
END:VEVENT
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090603T183823Z
RECURRENCE-ID;TZID=America/Montreal:20090602T150000
DTSTART;TZID=America/Montreal:20090602T150000
DTEND;TZID=America/Montreal:20090602T160000
TRANSP:TRANSPARENT
SUMMARY:Review Internet-Draft
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Cyrus Daboo";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:cyrus@example.com
ATTENDEE;CN="Bernard Desruisseaux";CUTYPE=INDIVIDUAL;PARTSTAT=
DECLINED;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:bernard@exampl
e.net
END:VEVENT
END:VCALENDAR
Bernard's deletion of a recurrence instance will cause his server to
deliver a scheduling message to Cyrus. Cyrus's client will find the
following reply message from Bernard in Cyrus's scheduling Inbox
collection:
>> Request <<
GET /home/cyrus/calendars/inbox/6504923FD3AD.ics HTTP/1.1
Host: cal.example.com
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>> Response <<
HTTP/1.1 200 OK
Date: Tue, 02 Jun 2009 18:52:58 GMT
Last-Modified: Tue, 02 Jun 2009 18:52:58 GMT
ETag: "eb897deabc8939589da116714bc99265"
Content-Type: text/calendar; charset="utf-8"
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
METHOD:REPLY
BEGIN:VTIMEZONE
TZID:America/Montreal
BEGIN:STANDARD
DTSTART:20071104T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20070311T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
UID:9263504FD3AD
SEQUENCE:0
DTSTAMP:20090603T183823Z
RECURRENCE-ID;TZID=America/Montreal:20090603T150000
DTSTART;TZID=America/Montreal:20090603T150000
DTEND;TZID=America/Montreal:20090603T160000
SUMMARY:Review Internet-Draft
ORGANIZER;CN="Cyrus Daboo":mailto:cyrus@example.com
ATTENDEE;CN="Bernard Desruisseaux";PARTSTAT=DECLINED:
mailto:bernard@example.net
REQUEST-STATUS:2.0;Success
END:VEVENT
END:VCALENDAR
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Appendix C. Changes (to be removed by RFC Editor prior to publication)
C.1. Changes in -10
a. Updated to RFC 6047 reference.
b. Various minor clarifications to behavior and terminology done.
c. Clarified that Inbox/Outbox are the server's responsibility to
create.
d. Changed MAY to SHOULD for server rejecting organizer PARTSTAT
changes of attendees.
e. Allow COMPLETED as a valid attendee change.
f. Allow SCHEDULE-STATUS as a valid attendee change on SCHEDULE-
AGENT=CLIENT attendee properties.
g. COPY or MOVE on a calendar collection now declared to be
undefined.
h. Changed pre-condition error codes from 409 to 403.
i. Clarified that rules 5546 must be used when server processes
incoming scheduling messages.
j. default-calendar-delete-allowed -> default-calendar-needed.
k. Clarified that SCHEDULE-AGENT must be the same on all matching
properties.
l. Added more text justifying the need for calendar-user-type
property.
C.2. Changes in -09
a. Fixed some examples.
b. Tweaked XML conventions.
c. Removed description in SCHEDULE-STATUS example values.
d. Tweaked 3.7 and 3.8 SCHEDULE-STATUS description to indicate it
applies to the Organizer as well as Attendee.
e. Updated to RFC 5545 reference.
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f. AD Review: clarified text about inbox resource deletion being
acknowledgment of change.
g. AD Review: clarified description of freebusy Outbox POST.
h. AD Review: registered new 1.xx request-status codes and added new
restriction on usage as per iTIP.
i. AD Review: changes SHOULD NOT to MUST NOT for new property
parameters when clients send scheduling messages.
j. AD Review: CALDAV:schedule-calendar-transp now preserved during
COPY.
k. AD Review: changed CALDAV- to CALDAV: in acl descriptions.
l. AD Review: fixed various minor typos.
m. AD Review: Added text to new principal properties to indicate
that if they are not present, then the user is not enabled for
the various scheduling operations.
n. AD Review: clarified use of CALDAV:calendar-data element in
CALDAV:response element.
o. AD Review: made reference to 5545 IANA registry procedures for
the two new element registries.
p. AD Review: Fixed description of B5. example.
q. Fixed SCHEDULE-AGENT/SCHEDULE-STATUS behavior for Attendee
replies.
C.3. Changes in -08
a. Added "Updates 4791".
b. XML conventions changed to match that in CardDAV spec.
c. Reworded child response behavior for Outbox.
d. Reworded "octet size".
e. If-Schedule-Match descriptions changed to remove implication that
it is purely a conditional operation.
f. Schedule-Reply header descriptions generalized to resource
removal rather than just HTTP DELETE.
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g. Fixed various examples.
C.4. Changes in -07
a. Restructured document.
b. Clarified that CALDAV:schedule-calendar-transp only applies to
calendar collection.
c. Removed CALDAV:schedule-state property on scheduling messages in
the scheduling Inbox collection.
d. Added conditional requests on scheduling object resources.
e. Added section on handling of PARTSTAT.
f. Added SCHEDULE-FORCE-SEND iCalendar property parameter.
g. Added clarification on child resources in scheduling Outbox
collections.
h. Clarified Attendee changes that server MUST allow, and removed
restrictions on changes that Attendee MUST NOT do.
i. Added Example Scheduling Transactions appendix.
j. Scheduling privileges are no longer required to be non-abstract.
k. Removed handling of REFRESH requests.
l. Removed handling of VJOURNAL components.
m. Completed IANA Considerations section.
n. Added references to RFC3283 and RFC5234.
o. Updated references to iCalendar, iTIP and iMIP.
C.5. Changes in -06
a. Removed distinction between scheduling calendar collections and
basic calendar collections - now just have calendar collections.
b. Clients now "MAY" reload data rather than "SHOULD" reload data.
c. Fixed <C:recipient> in examples.
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d. Removed CALDAV:attachments-allowed precondition on POST to Outbox
as that is no longer relevant.
e. Added CALDAV:default-calendar-delete-allowed precondition for
DELETE.
f. Relaxed MUST->MAY for Organizer setting PARTSTAT value.
g. Tweaked restrictions on Create/Modify to emphasize that 4791
restrictions also apply.
h. Added comment that 'opaque' is the default when the CALDAV:
schedule-calendar-transp property is not present.
i. Description of Schedule-Reply header changed to reflect that it
is only relevant for Attendees.
j. Minor typos fixed.
C.6. Changes in -05
This draft has changed substantially since the -04 version. The
primary reason for this change was implementation experience from a
number of vendors who implemented products based on the earlier
drafts. Experience showed that the client/server interaction was not
reliable in keeping scheduling messages synchronized between
organizer and attendees. In addition the latency in updates due to
clients being offline proved unacceptable to users. These issues led
to the redesign of this specification to support a server-based
processing model that eliminates all the problems seen previously.
Whilst this adds significant complexity to the server in that it
needs to be a full blown iTIP processing agent, it does remove a lot
of the same complexity from clients, opening up the possibility of
supporting complex scheduling behaviors even with "thin" clients.
In the judgement of the authors, we consider this new specification
to be a substantial improvement over the old one and believe it
represents a stronger protocol that will lead to better
interoperability.
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Authors' Addresses
Cyrus Daboo
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
USA
EMail: cyrus@daboo.name
URI: http://www.apple.com/
Bernard Desruisseaux
Oracle Corporation
600 Blvd. de Maisonneuve West
Suite 1900
Montreal, QC H3A 3J2
CANADA
EMail: bernard.desruisseaux@oracle.com
URI: http://www.oracle.com/
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