| Rfc | 6638 |
|---|
| Title | Scheduling Extensions to CalDAV |
|---|
| Author | C. Daboo, B. Desruisseaux |
|---|
| Date | June
2012 |
|---|
| Format: | TXT, HTML |
|---|
| Updates | RFC4791, RFC5546 |
|---|
| Updated by | RFC7953 |
|---|
| Status: | PROPOSED STANDARD |
|---|
|
Internet Engineering Task Force (IETF) C. Daboo
Request for Comments: 6638 Apple Inc.
Updates: 4791, 5546 B. Desruisseaux
Category: Standards Track Oracle
ISSN: 2070-1721 June 2012
Scheduling Extensions to CalDAV
Abstract
This document defines extensions to the Calendaring Extensions to
WebDAV (CalDAV) "calendar-access" feature to specify a standard way
of performing scheduling operations with iCalendar-based calendar
components. This document defines the "calendar-auto-schedule"
feature of CalDAV.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6638.
Copyright Notice
Copyright (c) 2012 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
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described in the Simplified BSD License.
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Contributions published or made publicly available before November
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material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
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than English.
Table of Contents
1. Introduction ....................................................5
1.1. Terminology ................................................6
1.2. Notational Conventions .....................................7
1.3. XML Namespaces and Processing ..............................7
2. Scheduling Support ..............................................8
2.1. Scheduling Outbox Collection ...............................9
2.1.1. CALDAV:schedule-outbox-URL Property ................10
2.2. Scheduling Inbox Collection ...............................10
2.2.1. CALDAV:schedule-inbox-URL Property .................11
2.3. Calendaring Reports Extensions ............................12
2.4. Additional Principal Properties ...........................12
2.4.1. CALDAV:calendar-user-address-set Property ..........12
2.4.2. CALDAV:calendar-user-type Property .................13
3. Scheduling Operations ..........................................14
3.1. Identifying Scheduling Object Resources ...................14
3.2. Handling Scheduling Object Resources ......................15
3.2.1. Organizer Scheduling Object Resources ..............15
3.2.1.1. Create ....................................16
3.2.1.2. Modify ....................................17
3.2.1.3. Remove ....................................18
3.2.2. Attendee Scheduling Object Resources ...............18
3.2.2.1. Allowed "Attendee" Changes ................18
3.2.2.2. Create ....................................19
3.2.2.3. Modify ....................................20
3.2.2.4. Remove ....................................21
3.2.3. HTTP Methods .......................................21
3.2.3.1. PUT .......................................22
3.2.3.2. DELETE ....................................22
3.2.3.3. COPY ......................................23
3.2.3.4. MOVE ......................................24
3.2.4. Additional Method Preconditions ....................24
3.2.4.1. CALDAV:unique-scheduling-object-resource
Precondition ..............................24
3.2.4.2. CALDAV:same-organizer-in-all-components
Precondition ..............................25
3.2.4.3. CALDAV:allowed-organizer-scheduling-
object-change Precondition .............25
3.2.4.4. CALDAV:allowed-attendee-scheduling-
object-change Precondition .............26
3.2.5. DTSTAMP and SEQUENCE Properties ....................26
3.2.6. Restrict Recurrence Instances Sent to "Attendees" ..27
3.2.7. Forcing the Server to Send a Scheduling Message ....27
3.2.8. "Attendee" Participation Status ....................28
3.2.9. Schedule Status Values .............................29
3.2.10. Avoiding Conflicts when Updating Scheduling Object
Resources .........................................31
3.2.10.1. PUT .....................................33
3.2.10.2. DELETE, COPY, or MOVE ...................33
4. Processing Incoming Scheduling Messages ........................34
4.1. Processing "Organizer" Requests, Additions, and
Cancellations .............................................34
4.2. Processing "Attendee" Replies .............................35
4.3. Default Calendar Collection ...............................35
4.3.1. Additional Method Preconditions ....................36
4.3.1.1. CALDAV:default-calendar-needed
Precondition ..............................36
4.3.1.2. CALDAV:valid-schedule-default-calendar-URL
Precondition ..............................36
5. Request for Busy Time Information ..............................37
5.1. Status Codes ..............................................38
5.2. Additional Method Preconditions ...........................38
5.2.1. CALDAV:valid-scheduling-message Precondition .......38
5.2.2. CALDAV:valid-organizer Precondition ................39
6. Scheduling Privileges ..........................................39
6.1. Privileges on Scheduling Inbox Collections ................39
6.1.1. CALDAV:schedule-deliver Privilege ..................40
6.1.2. CALDAV:schedule-deliver-invite Privilege ...........40
6.1.3. CALDAV:schedule-deliver-reply Privilege ............40
6.1.4. CALDAV:schedule-query-freebusy Privilege ...........40
6.2. Privileges on Scheduling Outbox Collections ...............40
6.2.1. CALDAV:schedule-send Privilege .....................41
6.2.2. CALDAV:schedule-send-invite Privilege ..............41
6.2.3. CALDAV:schedule-send-reply Privilege ...............41
6.2.4. CALDAV:schedule-send-freebusy Privilege ............41
6.3. Aggregation of Scheduling Privileges ......................42
Appendix A. Scheduling Privileges Summary .........................59
A.1. Scheduling Inbox Privileges ................................59
A.2. Scheduling Outbox Privileges ...............................60
Appendix B. Example Scheduling Operations .........................60
B.1. Example: "Organizer" Inviting Multiple "Attendees" .........61
B.2. Example: "Attendee" Receiving an Invitation ................63
B.3. Example: "Attendee" Replying to an Invitation ..............64
B.4. Example: "Organizer" Receiving a Reply to an Invitation ....66
B.5. Example: "Organizer" Requesting Busy Time Information ......69
B.6. Example: User Attempting to Invite "Attendee" on
Behalf of "Organizer" ......................................71
B.7. Example: "Attendee" Declining an Instance of a
Recurring Event ............................................72
B.8. Example: "Attendee" Removing an Instance of a
Recurring Event ............................................75
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 operations
such as schedule, reschedule, respond to scheduling request, or
cancel calendar components, as well as search for busy time
information. However, 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. It is expected that future extensions will
be developed to address these.
This specification defines a client/server scheduling protocol, where
the server is made responsible for sending scheduling messages and
processing incoming scheduling messages. The client operations of
creating, modifying, or deleting a calendar component in a calendar
are enough to trigger the server to deliver the necessary scheduling
messages to the appropriate calendar users. This approach is
sometimes referred to as "implicit scheduling".
This specification only addresses how scheduling occurs with users on
a single system (i.e., scheduling between CalDAV servers, or some
other calendaring and scheduling system, is not defined). However,
this specification is compatible with servers being able to send or
receive scheduling messages with "external" users (e.g., using the
iCalendar Message-Based Interoperability Protocol (iMIP) [RFC6047]).
Section 3 defines the automated "Scheduling Operations" that allow a
client to store iCalendar data on a CalDAV server, with the server
taking specific actions in response. One of three scheduling
operations can take place -- "create", "modify", or "remove", based
on the HTTP method used for the request -- in addition to a
comparison between any existing and any new iCalendar data.
Section 4 defines how the server processes scheduling messages sent
as the result of a scheduling operation.
Section 5 defines how freebusy requests with an immediate response
are accomplished.
Section 6 defines access control privileges for the scheduling
operations defined in this specification.
For the majority of the following discussion, scheduling of events
will be discussed. However, scheduling of to-dos is also fully
supported by this specification.
This specification has been under development for a number of years,
and most current implementations of CalDAV support it. With the
publication of this document, it is expected that all new CalDAV
implementations will support it by default. Interoperability tests
have been performed regularly. Significant issues with incompatible
CalDAV implementations are not anticipated.
1.1. Terminology
This specification reuses much of the same terminology as iCalendar
[RFC5545], iTIP [RFC5546], WebDAV [RFC4918], and CalDAV [RFC4791].
Additional terms used by this specification are as follows:
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 the "Organizer".
Attendee scheduling object resource: A scheduling object resource
owned by an "Attendee".
Scheduling operation: Add, change, or remove operations on a
scheduling object resource for which the server will deliver
scheduling messages to other calendar users.
Scheduling message: A calendar object that describes a scheduling
operation 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. 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 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].
Calendaring and scheduling roles are referred to in quoted-strings of
text with the first character of each word in uppercase. For
example, "Organizer" refers to a role of a calendar user within the
scheduling protocol defined by [RFC5546].
1.3. 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) can be added anywhere, except when explicitly stated
otherwise, and
4. extension attributes (attributes not already defined as valid for
this element) can 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
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 needs to be
taken not to confuse the two sets of names.
2. Scheduling Support
A server that supports the features described in this document is
REQUIRED to support the CalDAV "calendar-access" [RFC4791] feature.
Servers include "calendar-auto-schedule" as a field in the DAV
response header from an OPTIONS request on any resource that supports
any scheduling operations, properties, privileges, or methods.
This specification introduces new collection resource types that are
used to manage scheduling object resources, and scheduling privileges
(as per Section 6), 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.
2.1. 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>
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 and
apply to scheduling messages submitted to the scheduling Outbox
collection with the POST method:
o CALDAV:supported-calendar-component-set
o CALDAV:supported-calendar-data
o CALDAV:max-resource-size
o CALDAV:min-date-time
o CALDAV:max-date-time
o CALDAV:max-attendees-per-instance
The use of child resources in a scheduling Outbox collection is
reserved for future revisions or extensions of this specification.
The following WebDAV property is defined on principal resources and
used to locate the corresponding Outbox collection for the associated
principal.
2.1.1. 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 DAV: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)>
2.2. Scheduling Inbox Collection
A scheduling Inbox collection contains copies of incoming scheduling
messages. These can 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].
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., Unique Identifier ("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).
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 and
apply to scheduling messages delivered to the collection:
o CALDAV:supported-calendar-component-set
o CALDAV:supported-calendar-data
o CALDAV:max-resource-size
o CALDAV:min-date-time
o CALDAV:max-date-time
o CALDAV:max-instances
o CALDAV:max-attendees-per-instance
o CALDAV:calendar-timezone
The following WebDAV property is defined on principal resources and
used to locate the corresponding Inbox collection for the associated
principal.
2.2.1. 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 DAV: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 allows 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)>
2.3. 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.
2.4. 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.
2.4.1. CALDAV:calendar-user-address-set Property
Name: calendar-user-address-set
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 DAV: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 his calendar user address, the URI of his 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>
2.4.2. 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.
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 DAV: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 look
up "Attendees" available on the server. When doing this, it is
useful to know, or restrict the query to, certain types of
calendar users (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>
3. Scheduling Operations
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.
3.1. Identifying Scheduling Object Resources
Calendar object resources on which the server performs scheduling
operations 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 if 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 4.3).
3.2. 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.
3.2.1. Organizer Scheduling Object Resources
An "Organizer" can create, modify, or remove a scheduling object
resource, subject to access privileges, preconditions, and the
restrictions defined in Section 4.1 of [RFC4791]. These operations
are each described next, and how they are invoked via HTTP requests
is described in Section 3.2.3.
The "Organizer" of a calendar component can 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".
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".
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".
3.2.1.1. Create
When an "Organizer" creates a scheduling object resource, the server
MUST inspect each "ATTENDEE" property to determine whether to send a
scheduling message. The table below indicates the appropriate iTIP
method used by the server, taking into account any "SCHEDULE-AGENT"
property parameter (see Section 7.1) specified on each "ATTENDEE"
property.
+------------------+-------------+
| SCHEDULE-AGENT | iTIP METHOD |
+------------------+-------------+
| SERVER (default) | REQUEST |
| | |
| CLIENT | -- |
| | |
| NONE | -- |
+------------------+-------------+
"SCHEDULE-STATUS" iCalendar property parameters are added or changed
on "ATTENDEE" iCalendar properties in the scheduling object resource
being created as described in Section 7.3, with the value set as
described in Section 3.2.9. 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.
The server MUST add a "SCHEDULE-STATUS" iCalendar property parameter
(see Section 7.3) to the "ATTENDEE" iCalendar property in the
scheduling object resource being created, and set its value as
described in Section 3.2.9. 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.
The server MUST return an error with the CALDAV:allowed-organizer-
scheduling-object-change precondition code (Section 3.2.4.3) when the
"Organizer" attempts to change the iCalendar data in a manner that is
forbidden.
3.2.1.2. Modify
When an "Organizer" modifies a scheduling object resource, the server
MUST inspect each "ATTENDEE" property in both the original and
modified iCalendar data on a per-instance basis to determine whether
to send a scheduling message. The table below indicates the
appropriate iTIP method used by the server, taking into account any
"SCHEDULE-AGENT" property parameter (see Section 7.1) specified on
each "ATTENDEE" property. 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 (Original) or is being removed (Modified).
+---------------+-----------------------------------------------+
| | Modified |
| +-----------+-----------+-----------+-----------+
| | <Removed> | SERVER | CLIENT | NONE |
| | | (default) | | |
+===+===========+===========+===========+===========+===========+
| | <Absent> | -- | REQUEST / | -- | -- |
| O | | | ADD | | |
| r +-----------+-----------+-----------+-----------+-----------+
| i | SERVER | CANCEL | REQUEST | CANCEL | CANCEL |
| g | (default) | | | | |
| i +-----------+-----------+-----------+-----------+-----------+
| n | CLIENT | -- | REQUEST / | -- | -- |
| a | | | ADD | | |
| l +-----------+-----------+-----------+-----------+-----------+
| | NONE | -- | REQUEST / | -- | -- |
| | | | ADD | | |
+---+-----------+-----------+-----------+-----------+-----------+
"SCHEDULE-STATUS" iCalendar property parameters are added or changed
on "ATTENDEE" iCalendar properties in the scheduling object resource
being modified as described in Section 7.3, with the value set as
described in Section 3.2.9. 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.
The server MUST return an error with the CALDAV:allowed-organizer-
scheduling-object-change precondition code (Section 3.2.4.3) when the
"Organizer" attempts to change the iCalendar data in a manner that is
forbidden.
3.2.1.3. Remove
When an "Organizer" removes a scheduling object resource, the server
MUST inspect each "ATTENDEE" property to determine whether to send a
scheduling message. The table below indicates the appropriate iTIP
method used by the server, taking into account any "SCHEDULE-AGENT"
property parameter (see Section 7.1) specified on each "ATTENDEE"
property.
+------------------+-------------+
| SCHEDULE-AGENT | iTIP METHOD |
+------------------+-------------+
| SERVER (default) | CANCEL |
| | |
| CLIENT | -- |
| | |
| NONE | -- |
+------------------+-------------+
3.2.2. Attendee Scheduling Object Resources
An "Attendee" can create, modify, or remove a scheduling object
resource. These operations are each described next, and how they are
invoked via HTTP requests is described in Section 3.2.3.
3.2.2.1. 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".
Servers MUST allow "Attendees" to make the following iCalendar data
changes, subject to other restrictions, such as access privileges and
preconditions:
1. change their own "PARTSTAT" iCalendar property parameter value.
2. add, modify, or remove any "TRANSP" iCalendar properties.
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 3.2.4.4) when the
"Attendee" attempts to change the iCalendar data in a manner
forbidden by the server.
3.2.2.2. Create
Typically, an "Attendee" does not create scheduling object resources,
as scheduling messages delivered to him on the server are
automatically processed by the server and placed on one of his
calendars (see Section 4). However, in some cases, a scheduling
message can get delivered directly to the client (e.g., via email
[RFC6047]), and the "Attendee" might wish to store that on the
server. In that case, the client creates a scheduling object
resource in a 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.
+----------------+--------------------------------------------------+
| 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. |
+----------------+--------------------------------------------------+
"SCHEDULE-STATUS" iCalendar property parameters are added or changed
on "ORGANIZER" iCalendar properties in the scheduling object resource
being created as described in Section 7.3, with the value set as
described in Section 3.2.9.
3.2.2.3. Modify
When a scheduling object resource is modified by an "Attendee", the
server's 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 update |
| (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
"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.
"SCHEDULE-STATUS" iCalendar property parameters are added or changed
on "ORGANIZER" iCalendar properties in the scheduling object resource
being modified as described in Section 7.3, with the value set as
described in Section 3.2.9. This will result in the updated 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.
3.2.2.4. Remove
When a scheduling object resource is removed by an "Attendee", the
server's 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) | taking into account any "Schedule-Reply" request |
| | header as per Section 8.1. |
| | |
| 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. |
+----------------+--------------------------------------------------+
3.2.3. HTTP Methods
This section describes how the use of various HTTP [RFC2616] and
WebDAV [RFC4918] methods on a scheduling object resource will cause a
create, modify, or remove operation 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.
3.2.3.1. PUT
When the server receives a PUT method request, it MUST execute the
following operations, provided all appropriate preconditions are met:
+------------------------+--------------------------+---------------+
| Existing Destination | Resulting Destination | Server |
| Resource | Resource | Operation |
+------------------------+--------------------------+---------------+
| None | Calendar object resource | None |
| | | |
| None | Scheduling object | Create |
| | resource | |
| | | |
| Calendar object | Calendar object resource | None |
| resource | | |
| | | |
| Calendar object | Scheduling object | Create |
| resource | resource | |
| Scheduling object | Calendar object resource | Remove |
| resource | | |
| | | |
| Scheduling object | Scheduling object | Modify |
| resource | resource | |
+------------------------+--------------------------+---------------+
3.2.3.2. DELETE
When the server receives a DELETE method request targeted at a
scheduling object resource, it MUST execute the Remove operation.
When the server receives a DELETE method request targeted at a
calendar collection, it MUST execute the Remove operation on all
scheduling object resources contained in the calendar collection.
3.2.3.3. COPY
When the server receives a COPY method request, it MUST execute the
following operations based on the source and destination collections
in the request:
+-----------------------+------------------------+------------------+
| Source Collection | Destination Collection | Server Operation |
+-----------------------+------------------------+------------------+
| Non-calendar | Non-calendar | None |
| collection | collection | |
| | | |
| Non-calendar | Calendar collection | (1) |
| collection | | |
| | | |
| Calendar collection | Non-calendar | None |
| | collection | |
| | | |
| Calendar collection | Calendar collection | (2) |
+-----------------------+------------------------+------------------+
Note (1): The rules in Section 3.2.3.1 are applied for the
destination of the COPY request.
Note (2): The server MAY reject this as per Section 3.2.4.1;
otherwise, None.
The behavior of a COPY method request on a calendar collection is
undefined.
3.2.3.4. MOVE
When the server receives a MOVE method request, it MUST execute the
following operations based on the source and destination collections
in the request:
+-----------------------+------------------------+------------------+
| Source Collection | Destination Collection | Server Operation |
+-----------------------+------------------------+------------------+
| Non-calendar | Non-calendar | None |
| collection | collection | |
| | | |
| Non-calendar | Calendar collection | (1) |
| collection | | |
| | | |
| Calendar collection | Non-calendar | (2) |
| | collection | |
| | | |
| Calendar collection | Calendar collection | None |
+-----------------------+------------------------+------------------+
Note (1): The rules in Section 3.2.3.1 are applied for the
destination of the MOVE request.
Note (2): The rules in Section 3.2.3.2 are applied for the source of
the MOVE request.
The behavior of a MOVE method request on a calendar collection is
undefined.
3.2.4. Additional Method Preconditions
This specification defines method preconditions (see Section 16 of
WebDAV [RFC4918]), in addition to those in [RFC4791], to provide
machine-parseable information in error responses.
3.2.4.1. 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>
3.2.4.2. CALDAV:same-organizer-in-all-components Precondition
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>
3.2.4.3. 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" from 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 does not have the
"SCHEDULE-AGENT" property parameter. See Section 3.2.1.
Definition:
<!ELEMENT allowed-organizer-scheduling-object-change EMPTY>
3.2.4.4. 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", subject to the allowed
changes specified in Section 3.2.2.1.
Definition:
<!ELEMENT allowed-attendee-scheduling-object-change EMPTY>
3.2.5. DTSTAMP and SEQUENCE Properties
The server MUST ensure that a "DTSTAMP" iCalendar property is present
and set the value to the UTC time that the scheduling message was
generated (as required by iCalendar).
The server MUST ensure that for each type of scheduling operation,
the "SEQUENCE" iCalendar property value is updated as per iTIP
[RFC5546].
3.2.6. Restrict Recurrence Instances Sent to "Attendees"
Servers MUST ensure that "Attendees" only get information about
recurrence instances that explicitly include them as an "Attendee",
when delivering scheduling messages for recurring calendar
components.
For example, if an "Attendee" is invited to only a single instance of
a recurring event, the organizer scheduling object resource will
contain an overridden instance in the form of a separate calendar
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 organizer scheduling object
resource will include an overridden instance with an "ATTENDEE" list
that does not include the "Attendee" being excluded. Any scheduling
messages delivered to the "Attendee" will not specify the overridden
instance but rather will include an "EXDATE" property in the "master"
component that defines the recurrence set.
3.2.7. Forcing the Server to Send a Scheduling Message
The iCalendar property parameter "SCHEDULE-FORCE-SEND", defined in
Section 7.2, 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 his participation status without being
forced to modify the event.
3.2.8. "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.
A reschedule 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. Servers MUST reset the
"PARTSTAT" property parameter value of all "ATTENDEE" properties,
except the one that corresponds to the "Organizer", to "NEEDS-ACTION"
for each calendar component change that causes any instance to be
rescheduled.
+-----------+-------------------------------------------------------+
| Property | Server Action |
+-----------+-------------------------------------------------------+
| DTSTART, | Any change to these properties results in "PARTSTAT" |
| DTEND, | 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 |
| | results 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 |
| | results in "PARTSTAT" being reset to "NEEDS-ACTION" |
| | on each affected component. |
| | |
| EXDATE | A change to or removal of this property that results |
| | in the reinstatement of recurring instances results |
| | 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 might be impacted
by the change).
3.2.9. Schedule Status Values
When scheduling with an "Attendee", there are two types of status
information that can be returned during the operation. 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 7.3). The status code value for "delivery"
status can be one of the following:
+----------+--------------------------------------------------------+
| Delivery | Description |
| Status | |
| Code | |
+----------+--------------------------------------------------------+
| 1.0 | The scheduling message is pending. That is, 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 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. |
| | |
| 5.2 | The scheduling message was not delivered because the |
| | server was not able to find a way to deliver the |
| | message. This is likely a permanent failure, and the |
| | originator ought 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 ought 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:
3.2.9.1. Status Code 1.0
Status Code: 1.0
Status Description: Pending.
Status Exception Data: None.
Description: Delivery of the iTIP message is pending.
3.2.9.2. 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.
3.2.9.3. Status Code 1.2
Status Code: 1.2
Status Description: Delivered.
Status Exception Data: None.
Description: The iTIP message has been sent and delivered.
3.2.10. Avoiding Conflicts when Updating Scheduling Object Resources
Scheduling object resources on the server might change frequently as
"Attendees" change their participation status, triggering updates to
the "Organizer", and refreshes of other "Attendees'" copies of the
scheduling object resource. This can lead to an "inconsequential"
change to a calendar user's data -- one that does not directly impact
the user's own participation status. When this occurs, clients have
to reload calendar data and reconcile with changes being made by
calendar users. To avoid the need for this, the server can instead
merge calendar data changes from a client with changes made as a
result of a scheduling operation carried out by some other calendar
user.
This specification introduces a new WebDAV resource property CALDAV:
schedule-tag with a corresponding response 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 (one that simply updates the status
information of "Attendees" due to a reply from another "Attendee").
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.
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
destination resource.
Clients SHOULD use the If-Schedule-Tag-Match header on requests that
update scheduling object resources, instead of HTTP ETag-based
precondition tests (e.g., If-Match). Normal ETag-based precondition
tests 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 automatically updated by the server with the
"Attendee's" new participation status.
2. 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).
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 specifies 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
would remain the same.
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).
3.2.10.1. PUT
Clients MAY 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.
3.2.10.2. DELETE, COPY, or MOVE
Clients MAY 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
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.
4. Processing Incoming Scheduling Messages
Scheduling operations can cause the delivery of a scheduling message
into an "Organizer's" or "Attendee's" scheduling Inbox collection.
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.
Scheduling messages are typically removed from the scheduling Inbox
collection by the client once the calendar user has acknowledged the
change.
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 2.2) when delivering the
scheduling message, and MUST take into account the similar
preconditions on any calendar collection that contains, or would
contain, the corresponding scheduling object resource.
4.1. 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 processes the scheduling
message and creates a new scheduling object resource as per
Section 4.3.
In the case of an update, the server processes the scheduling message
and updates 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.
4.2. 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". If the corresponding scheduling object resource
cannot be found, the server SHOULD ignore the scheduling message.
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 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 3.2.6.
The scheduling message MUST only appear in the "Organizer's"
scheduling Inbox collection once all automatic processing has been
done.
4.3. Default Calendar Collection
The server processes 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 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 whether this calendar user has a default
calendar collection. See Section 9.2.
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
server 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.
4.3.1. Additional Method Preconditions
This specification defines additional method preconditions (see
Section 16 of WebDAV [RFC4918]) to provide machine-parseable
information in error responses.
4.3.1.1. 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.
Definition:
<!ELEMENT default-calendar-needed EMPTY>
4.3.1.2. 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>
5. Request for Busy Time Information
Busy time information of one or more calendar users can be determined
by submitting a POST request targeted at the scheduling Outbox
collection of the calendar user requesting the information (the
"Organizer"). To accomplish this, the request body 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 2.1).
The "ORGANIZER" property value in the "VFREEBUSY" component MUST
match one of the calendar user addresses of the owner of the Outbox
collection.
A response to a busy time request that indicates status for one or
more calendar users 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 calendar user, with each such
element in turn containing elements that indicate which calendar user
they correspond to, the scheduling status for that calendar user, any
error codes, and an optional description. For a successful busy time
request, a CALDAV:calendar-data element is also present for each
calendar user, containing the actual busy time information (i.e., an
iCalendar "VFREEBUSY" component). See Section 10 for details on the
child elements. See Appendix B.5 for an example busy time request
and response.
5.1. Status Codes
The list below summarizes the most common status codes used for this
method. However, clients need to be prepared to handle other
2/3/4/5xx series status codes as well.
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.
5.2. Additional Method Preconditions
The following are existing preconditions that are reused for the POST
method on an Outbox collection.
o DAV:need-privileges [RFC3744]
o CALDAV:supported-calendar-data [RFC4791]
o CALDAV:valid-calendar-data [RFC4791]
o CALDAV:max-resource-size [RFC4791]
The following are new method preconditions for the POST method on an
Outbox collection.
5.2.1. 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 the restrictions specified in Section 3.3.2
of iTIP [RFC5546].
Definition:
<!ELEMENT valid-scheduling-message EMPTY>
5.2.2. CALDAV:valid-organizer Precondition
Name: valid-organizer
Namespace: urn:ietf:params:xml:ns:caldav
Apply to: POST
Use with: 403 Forbidden
Purpose: (precondition) -- The "ORGANIZER" property value in the
POST request's scheduling message MUST match one of the calendar
user addresses of the owner of the scheduling Outbox collection
being targeted by the request.
Definition:
<!ELEMENT valid-organizer EMPTY>
6. Scheduling Privileges
New scheduling privileges are 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.
6.1. Privileges on Scheduling Inbox Collections
This section defines new WebDAV Access Control List (ACL) [RFC3744]
privileges that are defined 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.
6.1.1. CALDAV:schedule-deliver Privilege
CALDAV:schedule-deliver is an aggregate privilege as per Section 6.3.
<!ELEMENT schedule-deliver EMPTY>
6.1.2. 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>
6.1.3. 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>
6.1.4. 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>
6.2. Privileges on Scheduling Outbox Collections
This section defines new WebDAV ACL [RFC3744] 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 (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.
6.2.1. CALDAV:schedule-send Privilege
CALDAV:schedule-send is an aggregate privilege as per Section 6.3.
<!ELEMENT schedule-send EMPTY>
6.2.2. 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 the
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 scheduling messages to "Attendees".
<!ELEMENT schedule-send-invite EMPTY>
6.2.3. 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 the
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 scheduling message replies to the
"Organizer".
<!ELEMENT schedule-send-reply EMPTY>
6.2.4. 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>
6.3. Aggregation of Scheduling Privileges
Server implementations MUST aggregate the scheduling privileges as
follows:
DAV:all contains CALDAV:schedule-deliver and CALDAV:schedule-send;
CALDAV:schedule-deliver contains CALDAV:schedule-deliver-invite,
CALDAV:schedule-deliver-reply, and CALDAV:schedule-query-freebusy;
CALDAV:schedule-send contains CALDAV:schedule-send-invite, CALDAV:
schedule-send-reply, and CALDAV:schedule-send-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]
7. Additional iCalendar Property Parameters
This specification defines additional iCalendar property parameters
to support the CalDAV scheduling extensions.
7.1. 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
;
; If the parameter is not present, its value defaults to SERVER.
; "x-name" and "iana-token" are defined in Section 3.1 of
; [RFC5545].
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 a scheduling
operation 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 a
scheduling operation. 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 a scheduling operation.
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.
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
7.2. 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-token" is defined in Section 3.1 of [RFC5545]. Its value
; MUST be an IANA-registered iCalendar "METHOD" property value.
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 a scheduling operation.
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 an iana-token value they do not
recognize.
Example:
ORGANIZER;SCHEDULE-FORCE-SEND=REPLY:mailto:cyrus@example.com
ATTENDEE;SCHEDULE-FORCE-SEND=REQUEST:mailto:bernard@example.com
7.3. 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]. The
; 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 only add or change this property parameter on any
"ATTENDEE" properties corresponding to calendar users who were
sent a scheduling message via a scheduling operation. 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 add this parameter to any "ORGANIZER" properties
corresponding to calendar users who were sent a scheduling message
reply by an "Attendee" via a scheduling operation. 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 a scheduling operation.
Clients MUST NOT include this parameter in any scheduling messages
that they themselves send.
Values for this property parameter are described in Section 3.2.9.
Example:
ATTENDEE;SCHEDULE-STATUS="2.0":mailto:bernard@example.com
ATTENDEE;SCHEDULE-STATUS="2.0,2.4":mailto:cyrus@example.com
8. Additional Message Header Fields
This specification defines additional HTTP request and response
headers for use with CalDAV.
8.1. Schedule-Reply Request Header
Schedule-Reply = "Schedule-Reply" ":" ("T" | "F")
Example:
Schedule-Reply: F
When an "Attendee" removes a scheduling object resource as per
Section 3.2.2.4, and the Schedule-Reply header is set to the value
"T" (true) or is not present, 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
scheduling operation processing.
When the Schedule-Reply header is set to the value "F" (false), the
server MUST NOT send a scheduling message as part of its normal
scheduling operation processing.
The Schedule-Reply request header is used by a client to indicate to
a server whether or not a scheduling operation ought to 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.
8.2. 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 3.2.10.
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].
Example:
Schedule-Tag: "12ab34-cd56ef"
8.3. 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"
9. Additional WebDAV Properties
This specification defines the following new WebDAV properties for
use with CalDAV.
9.1. 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 busy time information.
Protected: This property MAY be protected and SHOULD NOT be returned
by a PROPFIND DAV: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 ought to contribute to the owner's busy time. When the
CALDAV:opaque element is used, all calendar object resources in
the corresponding calendar collection MUST contribute to busy
time, assuming that 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 busy time.
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>
<!-- Affects busy time searches -->
<!ELEMENT transparent EMPTY>
<!-- Invisible to busy time searches -->
Example:
<C:schedule-calendar-transp
xmlns:C="urn:ietf:params:xml:ns:caldav">
<C:opaque/>
</C:schedule-calendar-transp>
9.2. 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 that 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 4.3.
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>
9.3. 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 value is determined by the server
and MAY be different from the value on the source resource.
Description: The CALDAV:schedule-tag property MUST be defined on all
scheduling object resources. This property is described in
Section 3.2.10.
Definition:
<!ELEMENT schedule-tag (#PCDATA)>
Example:
<C:schedule-tag xmlns:C="urn:ietf:params:xml:ns:caldav"
>"12345-67890"</C:schedule-tag>
10. XML Element Definitions
10.1. 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 5.
Definition:
<!ELEMENT schedule-response (response*)>
10.2. 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 5.
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. -->
10.3. 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.
Description: See Section 5.
Definition:
<!ELEMENT recipient (DAV:href)>
10.4. 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 5.
Definition:
<!ELEMENT request-status (#PCDATA)>
11. 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
Transport Layer Security (TLS) as defined in [RFC2818] for all
scheduling operations. Clients MUST use the procedures detailed in
Section 6 of [RFC6125] to verify the authenticity of the server.
Servers MUST make use of HTTP authentication [RFC2617] to verify the
authenticity of the calendar user for whom the client is sending
requests.
11.1. Preventing Denial-of-Service Attacks
Servers MUST ensure that clients cannot consume excessive server
resources by carrying out "large" scheduling operations. In
particular, servers SHOULD enforce CALDAV:max-resource-size, CALDAV:
max-instances, and CALDAV:max-attendees-per-instance preconditions as
applicable for scheduling Inbox and Outbox collections.
11.2. Verifying Scheduling Operations
When handling a scheduling operation:
1. 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.
2. 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 of the
DAV:owner of the calendar collection in which a scheduling object
resource is being manipulated.
3. Servers MUST only deliver scheduling messages to 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 calendar collection in which a scheduling object
resource is being manipulated.
4. 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.
5. 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.
11.3. Verifying Busy Time Information Requests
When handling a POST request on a scheduling Outbox collection:
1. 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.
2. 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.
3. 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.
11.4. Privacy Issues
This specification only defines how calendar users on the same server
are able to schedule with each other -- unauthenticated users have no
way to carry out scheduling operations. Access control privileges
(as per Section 6) can control which of those users can schedule with
others. Calendar users not wishing to expose their calendar
information to other users can do so by denying privileges to
specific users, or all users, for all scheduling operations, or
perhaps only freebusy.
"Attendees" can also use the Schedule-Reply request header
(Section 8.1) 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".
Servers MUST NOT expose any private iCalendar data, or WebDAV
resource state information (URLs, WebDAV properties, etc.) for one
calendar user to another via scheduling messages or error responses
to scheduling operations. In particular, as per Section 8.1 of
[RFC4918], authorization errors MUST take preference over other
errors.
11.5. Mitigation of iTIP Threats
Section 6.1 of iTIP [RFC5546] defines a set of potential threats in a
scheduling system, and Section 6.2 of [RFC5546] defines
recommendations on how those can be addressed in protocols using
iTIP. This specification addresses the iTIP threats in the following
manner:
Spoofing the "Organizer": Addressed by item 4 in Section 11.2.
Spoofing the "Attendee": Addressed by Section 3.2.2.1 and item 2 in
Section 11.2.
Unauthorized Replacement of the "Organizer": Addressed by item 5 in
Section 11.2.
Eavesdropping and Data Integrity: Addressed by requiring TLS.
Flooding a Calendar: Addressed by requirements in Section 11.1.
Unauthorized REFRESH Requests: This specification does not support
the REFRESH method.
12. IANA Considerations
12.1. Message Header Field Registrations
The message header fields below have been added to the Permanent
Message Header Field Registry (see [RFC3864]).
12.1.1. Schedule-Reply
Header field name: Schedule-Reply
Applicable protocol: http
Status: standard
Author/Change controller: IETF
Specification document(s): this specification (Section 8.1)
Related information: none
12.1.2. Schedule-Tag
Header field name: Schedule-Tag
Applicable protocol: http
Status: standard
Author/Change controller: IETF
Specification document(s): this specification (Section 8.2)
Related information: none
12.1.3. 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 8.3)
Related information: none
12.2. iCalendar Property Parameter Registrations
The following iCalendar property parameter names have been added to
the iCalendar Parameters Registry defined in Section 8.3.3 of
[RFC5545].
+---------------------+---------+-----------------------+
| Parameter | Status | Reference |
+---------------------+---------+-----------------------+
| SCHEDULE-AGENT | Current | RFC 6638, Section 7.1 |
| | | |
| SCHEDULE-STATUS | Current | RFC 6638, Section 7.3 |
| | | |
| SCHEDULE-FORCE-SEND | Current | RFC 6638, Section 7.2 |
+---------------------+---------+-----------------------+
12.3. iCalendar REQUEST-STATUS Value Registrations
The following iCalendar "REQUEST-STATUS" values have been added to
the iCalendar REQUEST-STATUS Value Registry defined in Section 7.3 of
[RFC5546].
+-------------+---------+---------------------------+
| Status Code | Status | Reference |
+-------------+---------+---------------------------+
| 1.0 | Current | RFC 6638, Section 3.2.9.1 |
| | | |
| 1.1 | Current | RFC 6638, Section 3.2.9.2 |
| | | |
| 1.2 | Current | RFC 6638, Section 3.2.9.3 |
+-------------+---------+---------------------------+
12.4. Additional iCalendar Elements Registries
Per this specification, two new IANA registries for iCalendar
elements have been added. Additional codes MAY be used, provided the
process described in Section 8.2.1 of [RFC5545] is used to register
them.
12.4.1. Schedule Agent Values Registry
The following table has been used to initialize the Schedule Agent
Values Registry.
+----------------+---------+-----------------------+
| Schedule Agent | Status | Reference |
+----------------+---------+-----------------------+
| SERVER | Current | RFC 6638, Section 7.1 |
| | | |
| CLIENT | Current | RFC 6638, Section 7.1 |
| | | |
| NONE | Current | RFC 6638, Section 7.1 |
+----------------+---------+-----------------------+
12.4.2. Schedule Force Send Values Registry
The following table has been used to initialize the Schedule Force
Send Values Registry.
+---------------------+---------+-----------------------+
| Schedule Force Send | Status | Reference |
+---------------------+---------+-----------------------+
| REQUEST | Current | RFC 6638, Section 7.2 |
| | | |
| REPLY | Current | RFC 6638, Section 7.2 |
+---------------------+---------+-----------------------+
13. Acknowledgements
The authors would like to thank the following individuals for
contributing their ideas and support for writing this specification:
Mike Douglass, Lisa Dusseault, Red Dutta, Jacob Farkas, Jeffrey
Harris, Helge Hess, Eliot Lear, Andrew McMillan, Alexey Melnikov,
Arnaud Quillaud, Julian F. Reschke, Wilfredo Sanchez Vega, and Simon
Vaillancourt.
The authors would also like to thank the Calendaring and Scheduling
Consortium for advice with this specification, and for organizing
interoperability testing events to help refine it.
14. References
14.1. Normative References
[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.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication",
RFC 2617, 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., Ed., "HTTP Extensions for Web Distributed
Authoring and Versioning (WebDAV)", RFC 4918, June 2007.
[RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234,
January 2008.
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 5545, September 2009.
[RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent
Interoperability Protocol (iTIP)", RFC 5546,
December 2009.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, March 2011.
[W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E.,
and F. Yergeau, "Extensible Markup Language (XML) 1.0
(Fifth Edition)", World Wide Web Consortium
Recommendation REC-xml-20081126, November 2008,
<http://www.w3.org/TR/2008/REC-xml-20081126>.
14.2. Informative References
[RFC6047] Melnikov, A., Ed., "iCalendar Message-Based
Interoperability Protocol (iMIP)", RFC 6047,
December 2010.
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 operation. 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 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 | * |
+-----------------------------+----------------------+
Appendix B. Example Scheduling Operations
This section describes some example scheduling operations that give a
general idea of how scheduling is carried out between CalDAV clients
and servers from the perspective of meeting "Organizers" and
"Attendees".
The server is assumed to be hosted in the "example.com" domain, and
users whose email addresses are at the "example.com" domain are
assumed to be hosted by the server. In addition, the email addresses
in the "example.net" domain are also valid email addresses for
calendar users hosted by the server. Calendar users with an email
address at the "example.org" domain are assumed to not be hosted by
the server.
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 collections by using the PUT method.
>> 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", as well as record the Schedule-Tag value for future
use. 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.
>> 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.
>> 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
>> 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 accepts Cyrus's invitation and
sets an alarm reminder on the event. It uses the If-Schedule-Tag-
Match precondition behavior to ensure it does not overwrite any
significant changes from the "Organizer" that might have occurred
after it retrieved the initial resource data.
>> 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
>> 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
>> 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
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.
>> 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.
>> 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
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.
>> 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
<?xml version="1.0" encoding="utf-8" ?>
<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.
>> 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
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
>> 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
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
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
>> 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
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/