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draft-ietf-calsch-itip-01.txt
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Network Working Group Steve Silverberg, Microsoft
INTERNET-DRAFT Steve Mansour, Netscape
Calendaring and Scheduling Working Group Frank Dawson, Lotus
<draft-ietf-calsch-itip-01.txt> Ross Hopson, ON Technologies
Expires in six months from October 24,1997
iCalendar Transport-Independent Interoperability Protocol
(iTIP)
Scheduling Events, BusyTime, To-dos and Journal Entries
Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups MAY also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months. Internet-Drafts MAY be updated, replaced, or made obsolete by
other documents at any time. It is not appropriate to use Internet-
Drafts as reference material or to cite them other than as a "working
draft" or "work in progress".
To learn the current status of any Internet-Draft, please check the
1id-abstracts.txt listing contained in the Internet-Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net
(Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific
Rim).
Distribution of this document is unlimited.
Copyright (C) The Internet Society 1997. All Rights Reserved.
Abstract
This document specifies how calendaring systems use iCalendar objects
to interoperate with other calendar systems. It does so in a general
way so as to allow multiple methods of communication between systems.
Subsequent documents specify interoperable methods of communications
between systems that use this protocol.
The document outlines a model for calendar exchange that defines both
static and dynamic event, to-do, journal and free/busy objects.
Static objects are used to transmit information from one entity to
another without the expectation of continuity or referential
integrity with the original item. Dynamic objects are a superset of
static objects and will gracefully degrade to their static
counterparts for clients that only support static objects.
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Table of Contents
1 7
Introduction 8
1.1 Formatting Conventions 8
1.2 Related Documents 9
1.3 Calendar Roles9
1.4 iTIP Transactions 10
2 Interoperability Models 11
2.1 Application Protocol 11
2.1.1 Calendar Entry State 12
3 Application Protocol Elements 12
3.1 Methods For "VEVENT" Calendar Component13
3.1.1 PUBLISH 14
3.1.2 REQUEST 15
3.1.2.1 REQUEST for Rescheduling an Event 16
3.1.2.2 REQUEST for Update or Reconfirmation of an Event 16
3.1.2.3 REQUEST for Delegating an Event from an "Attendee" to
another CU17
3.1.2.4 REQUEST for Delegating role of "Organizer" to another CU 17
3.1.2.5 REQUEST for Changing the "Organizer" from one CU to another
18
3.1.2.6 REQUEST for Changing the "Owner"18
3.1.2.7 REQUEST Forwarded To An Uninvited Calendar User18
3.1.2.8 REQUEST Updated Attendee Status 18
3.1.3 REPLY 18
3.1.4 CANCEL19
3.1.5 REFRESH 20
3.1.6 COUNTER 21
3.1.7 DECLINECOUNTER 22
3.2 Methods For VFREEBUSY Component 23
3.2.1 PUBLISH 24
3.2.2 REQUEST 25
3.2.3 REPLY 26
3.3 Methods For VTODO Component 27
3.3.1 PUBLISH 28
3.3.2 REQUEST 29
3.3.2.1 REQUEST for Rescheduling a VTODO30
3.3.2.2 REQUEST for Update or Reconfirmation of a VTODO30
3.3.2.3 REQUEST for Delegating a VTODO 31
3.3.2.4 REQUEST Forwarded To An Uninvited Calendar User31
3.3.2.5 REQUEST Updated Attendee Status 32
3.3.3 REPLY 32
3.3.4 CANCEL33
3.3.5 REFRESH 34
3.3.6 COUNTER 35
3.3.7 DECLINECOUNTER 36
3.4 Methods For VJOURNAL Component 37
3.4.1 PUBLISH 37
3.4.2 CANCEL38
3.4.3 REFRESH 39
3.5 Status Replies39
3.6 Implementation Considerations41
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3.6.1 Working With Recurrence Instances 41
3.6.2 Attendee Property Considerations 42
3.6.3 When To Refresh An Event 43
3.6.4 Timezones 43
3.6.5 Alarms43
3.6.6 SUMMARY Property43
3.6.7 X-Tokens 43
4 Examples 44
4.1 Published Event Examples44
4.1.1 A Minimal Published Event 44
4.1.2 Changing A Published Event45
4.1.3 Canceling A Published Event 45
4.1.4 A Rich Published Event 46
4.1.5 Anniversaries or Events attached to entire days 47
4.2 Group Event Examples 48
4.2.1 A Group Event Request48
4.2.2 Reply To A Group Event Request 49
4.2.3 Update An Event 49
4.2.4 Countering an Event Proposal 50
4.2.5 Delegate An Event 51
4.2.6 Delegate Accepts the Meeting 54
4.2.7 Delegate Declines the Meeting 54
4.2.8 Forwarding an Event Request 55
4.2.9 Cancel A Group Event 55
4.3 Busy Time Examples 56
4.3.1 Request Busy Time 56
4.3.2 Reply To A Busy Time Request 57
4.4 Recurring Event and Time Zone Examples 57
4.4.1 A Recurring Event Spanning Time Zones 57
4.4.2 Modify A Recurring Instance 59
4.4.3 Cancel A Recurring Instance 60
4.4.4 Cancel An Exception 60
4.4.5 Cancel Recurring Event 61
4.4.6 Change All Future Instances 61
4.4.7 Add A New Instance To A Recurring Event 62
4.4.8 Counter An Instance Of A Recurring Event 62
4.4.9 Error Reply To A request 63
4.5 Group To-do Examples 64
4.5.1 A VTODO Request 65
4.5.2 A VTODO Reply 65
4.5.3 A VTODO Refresh 65
4.5.4 A Refresh Reply: Percent-Complete 66
4.5.5 A Refresh Reply: Completed66
4.5.6 An Updated VTODO Request 66
4.5.7 A Recurring VTODOs 67
4.5.7.1 Request for a Recurring VTODO 67
4.5.7.2 Calculating due dates in recurring VTODOs 68
4.5.7.3 Replying to an instance of a recurring VTODO 68
4.6 Journal Examples 68
4.7 Other Examples69
4.7.1 Event Refresh 69
4.7.2 Bad RECURRENCE-ID 69
5 Application Protocol Fallbacks 70
5.1 Partial Implementation 70
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5.1.1 Event-Related Fallbacks 70
5.1.2 To-Do-Related Fallbacks 72
5.1.3 Journal-Related Fallbacks 74
5.2 Latency Issues75
5.2.1 Cancellation of an Unknown Calendar Component.75
5.2.2 Unexpected Reply from an Unknown Delegate75
5.3 Sequence Number 76
6 Security Considerations 76
6.1 Security Threats 76
6.1.1 Spoofing the "Organizer" 76
6.1.2 Spoofing the "Attendee" 76
6.1.3 Eavesdropping 77
6.1.4 Flooding a Calendar 77
6.1.5 Procedural Alarms 77
6.2 Recommendations 77
6.2.1 Use of [RFC1847] to secure iTIP transactions 77
6.2.2 Implementation Controls 77
7 Acknowledgments 78
8 Bibliography 78
9 Authors Addresses 79
10 Full Copyright Statement 80
1
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Introduction
This document specifies how calendaring systems use iCalendar objects
to interoperate with other calendar systems. In particular, it
specifies how to schedule events, to-dos, or daily journal entries.
It further specifies how to search for available busy time
information. It does so in a general way so as to allow multiple
methods of communication between systems. Subsequent documents
specify interoperable methods of communications between systems that
use this protocol.
This protocol is based on requests sent from an originator and
conveyed to one or more recipients. A recipient of a request MAY
reply, in order to update their status and MAY also return
transaction/request status information. The protocol also supports
the ability for the entry originator to modify or cancel the original
entry. The elements of the protocol also include the notion of user
roles.
1.1 Formatting Conventions
In order to refer to elements of the calendaring and scheduling
model, core object or interoperability protocol defined in [ICMS],
[ICAL] and [ITIP] several formatting conventions have been utilized.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this
document are to be interopreted as described in [RFC 2119].
Calendaring and scheduling roles defined by [ICMS] are referred to in
quoted-strings of text with the first character of each word in upper
case. For example, "Organizer" refers to a role of a "Calendar User"
within the scheduling protocol defined by [ITIP] Calendar components
defined by [ICAL] are referred to with capitalized, quoted-strings of
text. All calendar components start with the letter "V". For example,
"VEVENT" refers to the event calendar component, "VTODO" refers to
the to-do calendar component and "VJOURNAL" refers to the daily
journal calendar component. Scheduling methods defined by [ITIP] are
referred to with capitalized, quoted-strings of text. For example,
"REQUEST" refers to the method for requesting a scheduling calendar
component be created or modified, "REPLY" refers to the method a
recipient of a request uses to update their status with the
"Organizer" of the calendar component.
Properties defined by [ICAL] are referred to with capitalized,
quoted-strings of text, followed by the word "property". For example,
"ATTENDEE" property refers to the iCalendar property used to convey
the calendar address of a "Calendar User". Property parameters
defined by this memo are referred to with lower case, quoted-strings
of text, followed by the word "parameter". For example, "value"
parameter refers to the iCalendar property parameter used to override
the default data type for a property value. Enumerated values defined
by this memo are referred to with capitalized text, either alone or
followed by the word "value".
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In tables, the quoted-string text is specified without quotes in
order to minimize the table length.
1.2 Related Documents
Implementers will need to be familiar with several other memos that,
along with this one, describe the Internet calendaring and scheduling
standards. This document, [ITIP], specifies an interoperability
protocol for scheduling between different implementations;
[ICMS] - describes the abstract model and defines common terms and
concepts;
[ICAL] - specifies the objects, data types, properties and property
parameters used in the protocols, along with the methods for
representing and encoding them;
[IRIP] - specifies an Internet real time protocol binding for
[ITIP].
[IMIP] specifies an Internet email binding for [ITIP].
This memo does not attempt to repeat the specification of concepts or
definitions from these other memos. Where possible, references are
made to the memo that provides for the specification of these
concepts or definitions.
1.3 Calendar Roles
Roles are a behavior or set of activities performed by particular
groups of users or agents at a given state of the calendar
transaction. This specification describes 4 roles that determine a
range of actions and responsibilities specific to each role.
+=====================================================================+
| Role Name | Description |
|=====================================================================|
| Owner | The calendar entry owner is the only Calendar User |
| | allowed to directly modify an entry using the iTIP |
| | protocol. However, the Owner MAY delegate or |
| | assign an Organizer to manage the entry on their |
| | behalf. Usually, a calendar entry Owner is also the |
| | Organizer. |
| | |
| Organizer | The Organizer controls manipulation of the calendar |
| | entry. In most cases, the Owner and the Organizer |
| | are the same Calendar User. |
| | |
| Attendee | An Attendee is a Calendar User associated with |
| | a calendar entry via a Request method issued by an |
| | Organizer or another Attendee. Attendees are not |
| | capable of directly manipulating calendar entries, |
| | but MUST act through the Organizer. |
| | |
| Delegate | A Delegate is a proxy that acts on behalf of another |
| | Calendar User. ITIP addresses two forms of |
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| | delegation: |
| | 1) An Owner MAY delegate or re-assign an Organizer |
| | to manage a calendar entry |
| | 2) An Attendee MAY delegate a calendar entry request |
| | to another Calendar User. |
+=====================================================================+
1.4 iTIP Transactions
This protocol defines seven methods for exchanging [ICAL] objects for
the purposes of group calendaring and scheduling between "Calendar
Users". The methods are defined below and their usage and semantics
are outlined in section 3 of this document.
+================+==================================================+
| Method | Description |
|================+==================================================|
| PUBLISH | Used to publish a calendar entry to one or more |
| | Calendar Users. There is no interactivity |
| | between the publisher and any other calendar |
| | user. An example might include a baseball team |
| | publishing its schedule to the public. |
| | |
| REQUEST | Used to schedule a calendar entry with other |
| | Calendar Users. Requests are interactive in that |
| | they MAY require the receiver to respond using |
| | the the Reply methods. Meeting Requests, Busy |
| | Time requests and the assignment of VTODOs to |
| | other Calendar Users are all examples. |
| | Requests are also used by the "Organizer" to |
| | update the status of a calendar entry. |
| REPLY | A Reply is used in response to a Request to |
| | convey "Attendee" status to the "Organizer". |
| | Replies are commonly used to respond to meeting |
| | and task requests. |
| | |
| CANCEL | The Cancel method is used to cancel an existing |
| | calendar entry such as a VEVENT or VTODO. |
| | |
| REFRESH | The Refresh method is used by an "Attendee" to |
| | request the latest version of a calendar entry |
| | |
| COUNTER | The Counter method is used by an "Attendee" to |
| | negotiate a change in the calendar entry. |
| | Examples include the request to change a |
| | proposed Event time or change the due date for a |
| | VTODO. |
| DECLINE- | |
| COUNTER | Used by the "Organizer" to decline the proposed |
| | counter-proprosal by an "Attendee" |
+================+==================================================+
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2 Interoperability Models
There are two distinct protocols relevant to interoperability: an
"Application Protocol" and a "Transport Protocol". The Application
Protocol defines the content of the iCalendar objects sent between
sender and receiver to accomplish the scheduling transactions listed
in section 1.4. The Transport Protocol defines how the iCalendar
objects are sent between the sender and receiver. This document
focuses on the Application Protocol.
The connection between Sender and Receiver in the diagram below
refers to the Application Protocol. In particular, the iCalendar
objects passed from the Sender to the Receiver which conform to those
presented in Section 3, Application Protocol Elements.
+----------+ +----------+
| | iTIP | |
| Sender |<-------------------->| Receiver |
| | | |
+----------+ +----------+
There are several variations of this diagram in which the Sender and
Receiver take on various roles of "CUA" or CS. These variants are
detailed in the Model document [ICMS]
The architecture of iTIP is depicted in the diagram below. An
application written to this specification MAY work with bindings for
the store-and-forward transport, the real time transport, or both.
Also note that iTIP could be bound to other transports. If a
capability is not available on a particular transport binding, iTIP
provides a mechanism for indicating so.
+------------------------------------------+
| iTIP |
+------------------------------------------+
|Real-time | Store-and-Fwd | Other |
|Transport | Transport | Transports... |
+------------------------------------------+
2.1 Application Protocol
The model for the application protocol is centered with the
"Organizer" of the calendar entry. That is, the "Organizer" of a
Calendar entry sends a request to one or more "Attendees". The
"Attendees" then reply to the "Organizer". The "Organizer" maintains
the status of the event.
The "Owner" is usually the "Organizer" of the calendar entry.
However, the "Owner" MAY delegate or assign an "Organizer" to manage
the calendar entry on their behalf. In cases where the "Owner" has
delegated to another "Organizer", the "Owner" must still be specified
in associated "REQUEST" and "COUNTER" methods.
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The data sources for the application protocol are the "Calendar
Users". Examples of these users are the "Organizer" and "Attendees"
of an iCalendar event. The data objects are the iCalendar objects
that are exchanged between "Calendar Users".
2.1.1 Calendar Entry State
There are two distinct states relevant to calendar entries: the
overall state of the entry and the state associated with an
"Attendee" to that entry.
The state of an entry is defined by the "STATUS" property and is
controlled by the "Organizer." There is no default value for the
"STATUS" property. The "Organizer" MAY either set the "STATUS"
property to TENTATIVE or CONFIRMED values. The "Organizer" MAY also
set the "STATUS" property to CANCELLED value by sending a "CANCEL"
method to each "Attendee".
The state of a particular "Attendee" relative to an entry is defined
by the "STATUS" property parameter in the "ATTENDEE" property for
that "Attendee". When an "Organizer" sends out an entry, the state
associated with each "Attendee" is NEEDS-ACTION. Each "Attendee" MAY
modify their "ATTENDEE" property "STATUS" parameter to an appropriate
value and send it back to the "Organizer" in a "REPLY" message.
3 Application Protocol Elements
Messages are "text/calendar" MIME entities that contain calendaring
and scheduling information. The particular type of [ICAL] message is
referred to as the "method type". Each method type is identified by a
"METHOD" property specified as part of the "text/calendar" content
type. The table below shows various combinations of calendar
components and the method types that this memo supports.
+=================================================+
| | VEVENT | VTODO | VJOURNAL | VFREEBUSY |
|=================================================|
|Publish | Yes | Yes | Yes | Yes |
|Request | Yes | Yes | No | Yes |
|Refresh | Yes | Yes | Yes | No |
|Cancel | Yes | Yes | Yes | No |
|Reply | Yes | Yes | No | Yes |
|Counter | Yes | Yes | No | No |
|Decline- | | | | |
|Counter | Yes | Yes | No | No |
+=================================================+
Each method type is defined in terms of its associated properties.
Some properties are required, some are optional and others are
excluded. The property restrictions are expressed in this memo using
the following formal notation:
prop-restriction = "(" description component method
1*MUST-component *MAY-component *not-component ")"
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description = "DESCRIPTION" *ws text
component = "COMPONENT" *ws ("CALPROPOS" / "VEVENT" /
"VTODO" / "VJOURNAL")
method = "METHOD" *ws <any of the methods defined in this
memo for the associated calendar component>
MUST-component = "MUST COMPONENT =" *ws ("VEVENT" / "VTODO" /
"VJOURNAL" / "VTIMEZONE" / "VALARM" /
"VFREEBUSY" / "X-TOKEN")
*ws "(" [ws] 1*MUST-props *ws
*MAY-props *ws *not-props *ws ")"
MAY-component = "MAY COMPONENT =" *ws ("VEVENT" / "VTODO" /
"VJOURNAL" / "VTIMEZONE" / "VALARM" /
"VFREEBUSY" / "X-TOKEN")
*ws "(" [ws] ((*MUST-props *ws
*MAY-props *ws *not-props *ws) / any) ")"
not-component = "NOT COMPONENT =" *ws ("VEVENT" / "VTODO" /
"VJOURNAL" / "VTIMEZONE" / "VALARM" /
"VFREEBUSY" /"X-TOKEN")
MUST-props = "MUST PROPERTY =" *ws restriction-list
MAY-props = "MAY PROPERTY =" *ws (restriction-list / any)
not-props = "NOT PROPERTY =" *ws (restriction-list)
restriction-list = restriction
/ restriction *ws "," *ws restriction
restriction = property-name
[*ws "{" parm-or-val-restriction "}"]
property-name = <any of the valid properties for the component>
parm-or-val-restriction = <a text string description of a
constraint on the property parameters
or values>
any = "ANY" -- Specifies that any permissible
properties are allowed - -
ws = HTAB / SPACE
HTAB = <Horizontal TAB character>
SPACE = <Required Space character>
3.1 Methods For "VEVENT" Calendar Component
This section defines the property set restrictions for the method
types that are applicable to the "VEVENT" calendar component. Each of
the methods is defined using a grammar that clarifies the property
constraints that define the particular method.
The following summarizes the methods that are defined for the
"VEVENT" calendar component.
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+================+==================================================+
| Method | Description |
|================+==================================================|
| PUBLISH | Post notification of an event. Used primarily as |
| | a method of advertising the existence of an |
| | event. |
| REQUEST | Make a request for an event. This is an explicit |
| | invitation to one or more "Attendees". Event |
| | Requests are also used to update or change an |
| | existing event. Clients that cannot handle |
| | REQUEST MAYdegrade the event to view it as an |
| | PUBLISH. |
| REPLY | Reply to an event request. Clients MAYset their |
| | status to |
| | ACCEPTED, DECLINED, TENTATIVE, DELEGATED. |
| CANCEL | Cancel an existing event request. |
| REFRESH | A request sent to an by an "Attendee" |
| | "Organizer" asking |
| | for the latest version of an event to be resent |
| | to the requester. |
| COUNTER | Counter a REQUEST with an alternative proposal. |
| DECLINECOUNTER | Decline a counter proposal by an "Attendee". |
+================+==================================================+
3.1.1 PUBLISH
The "PUBLISH" method in a "VEVENT" calendar component provides an
unsolicited posting of an iCalendar object. Any "Calendar User" MAY
add the published components to their calendar. It requires and
accepts no responses to the "Organizer". Its expected usage is for
encapsulating an arbitrary event or to-do as an iCalendar object. The
"Organizer" MAY subsequently update (with another "PUBLISH" method)
or cancel (with a "CANCEL" method) a previously published "VEVENT"
calendar component.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Event - Publish" COMPONENT "VEVENT" METHOD "PUBLISH
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"PUBLISH"})
MUST COMPONENT = VEVENT (
MUST PROPERTY = ATTENDEE{ROLE=OWNER and ORGANIZER if
different}, DESCRIPTION{MAY BE NULL},DTSTAMP, DTSTART,
SEQUENCE{IF NE 0}, UID
MAY PROPERTY = ATTACH, ATTENDEE{other than ROLE=OWNER |
ORGANIZER}, CATEGORIES, CLASS, COMMENT, CONTACT
CREATED, DTEND, EXDATE, EXRULE, GEO, LAST-MODIFIED,
LOCATION,PRIORITY, RELATED-TO, RDATE, RECURRENCE-ID,
RESOURCES, RRULE, SEQUENCE{IF EQ 0},
STATUS{TENTATIVE/CONFIRMED/CANCELLED},
SUMMARY{MAYBE NULL}, URL
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NOT PROPERTY = REQUEST-STATUS, TRANSP)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME,
NOT PROPERTY = CREATED)
MAY COMPONENT = VALARM (
MUST PROPERTY = CATEGORIES, DTSTART, DURATION, REPEAT
MAY PROPERTY = ATTACH, DESCRIPTION, SUMMARY
NOT PROPERTY = COMMENT, CREATED, LAST-MODIFIED, RELATED-TO,
URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
)
3.1.2 REQUEST
The "REQUEST" method in a "VEVENT" calendar component provides the
following scheduling functions:
╖ Invite "Attendees" to an event;
╖ Reschedule an existing event;
╖ Update the details of an existing event, without rescheduling
it;
╖ Update the status of "Attendees" of an existing event, without
rescheduling it;
╖ Reconfirm an existing event, without rescheduling it;
╖ For an existing "VEVENT" calendar component, delegate the role
of "Attendee" to another "Calendar User";
╖ For an existing "VEVENT" calendar component, delegate the role
of "Organizer" to another "Calendar User".
The originator of the "REQUEST" method is the "Organizer" of the
event. Normally this is the "Owner" of the event. The recipient of
the "REQUEST" method is the "Calendar User" invited to the event,
called the "Attendee". The "Attendee" uses the "REPLY" method to
convey their attendance status to the "Organizer" of a VEVENT
"REQUEST".
The "UID" and "SEQUENCE" properties are used to distinguish the
various uses of the "REQUEST" method. If the "UID" property value in
the "REQUEST" is not found on the recipient's calendar, then the
"REQUEST" is for a new "VEVENT" calendar component. If the "UID"
property value is found on the recipient's calendar, then the
"REQUEST"' is for either a rescheduling, an update, or a reconfirm of
the "VEVENT" calendar component.
If the "Organizer" of the "REQUEST" method is not authorized to make
an event request on the "Attendee's" calendar system, then an
exception is returned in the "REQUEST-STATUS" property of a
subsequent "REPLY" method, but no scheduling action is performed.
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This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Event - Request" COMPONENT "VEVENT" METHOD "REQUEST"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REQUEST"})
MUST COMPONENT = VEVENT (
MUST PROPERTY = ATTENDEE{ ROLE=OWNER and ORGANIZER if
different and "STATUS parameter absent or
STATUS=NEEDS-ACTION on Attendees}, DESCRIPTION{MAYBE
NULL}, DTSTAMP,DTSTART,SEQUENCE{IF NE 0}, UID
MAY PROPERTY = ATTACH, CATEGORIES, CLASS, COMMENT, CONTACT,
CREATED, DTEND, EXDATE, EXRULE, GEO, LAST-MODIFIED,
LOCATION, PRIORITY, RDATE, RECURRENCE-ID, RELATED-TO,
RESOURCES, RRULE, SEQUENCE{IF EQ 0},
STATUS{TENTATIVE/CONFIRMED /CANCELLED}, SUMMARY {MAYBE
NULL}, TRANSP, URL
NOT PROPERTY = REQUEST-STATUS)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT = VALARM (
MUST PROPERTY = CATEGORIES, DTSTART, DURATION, REPEAT
MAY PROPERTY = ATTACH, DESCRIPTION, SUMMARY
NOT PROPERTY = COMMENT, CREATED, LAST-MODIFIED, RELATED-TO,
URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
)
3.1.2.1 REQUEST for Rescheduling an Event
The "REQUEST" method MAY be used to reschedule an event.
A rescheduled event involves a change to the existing event in terms
of it's time or recurrence intervals and possibly the location or
description. If the recipient "CUA" of a "REQUEST" method finds that
the "UID" property value already exists on the calendar, but that the
"SEQUENCE" property value in the "REQUEST" method is greater than the
value for the existing event, then the "REQUEST" method describes a
rescheduling of the event.
3.1.2.2 REQUEST for Update or Reconfirmation of an Event
The "REQUEST" method MAY be used to update or reconfirm an event.
An update to an existing event does not involve changes to the time
or recurrence intervals, and might not involve a change to the
location or description for the event. If the recipient "CUA" of a
"REQUEST" method finds that the "UID" property value already exists
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on the calendar and that the "SEQUENCE" property value in the
"REQUEST" is the same as the value for the existing event, then the
"REQUEST" method describes an update of the event details, but no
rescheduling of the event.
The update "REQUEST" method is the appropriate response to a
"REFRESH" method sent from an "Attendee" to the "Organizer" of an
event.
Unsolicited "REQUEST" methods MAY also be sent by the "Organizer" of
an event. The unsolicited "REQUEST" methods MAY be used to either
update the details of the event, without rescheduling it, to update
the "STATUS" property parameter of "Attendees", or to reconfirm the
event.
3.1.2.3 REQUEST for Delegating an Event from an "Attendee" to another
CU
The "REQUEST" method MAY be used to delegate an event to another
"Calendar User". The method is used to delegate the "Attendee's" role
(i.e., "Organizer" or "Attendee") for an event. The "REQUEST" method
for delegation is sent by one of the "Attendees" of an existing event
request to some other "Calendar User". In order to avoid scheduling
loops, the method MUST NOT be sent from an "Attendee" back to the
"Organizer" of the event. An "Attendee" MAY NOT delegate to the
"Organizer" of the event.
For the purposes of this description, the "Attendee" delegating the
event is referred to as the "delegator". The "Attendee" receiving the
delegation request is referred to as the "delegatee".
The "delegator" of an event MUST forward the existing "REQUEST"
method for an event to the "delegatee". The event description MUST
include the "delegator's" up-to-date event definition. The "REQUEST"
method MUST also include an "ATTENDEE" property with the calendar
address of the "delegatee". The "delegator" MUST also send a "REPLY"
method back to the "Organizer" with the "delegator's" "Attendee"
property "STATUS" parameter value set to DELEGATED. In addition, the
"DELEGATED-TO" parameter SHOULD be included with the calendar address
of the "delegatee". A response to the delegation "REQUEST" is sent
from the "delegatee" to the "Organizer" and optionally, to the
"delegator". The "REPLY" method from the "delegatee" SHOULD include
their "ATTENDEE" property with the "DELEGATED-FROM" parameter value
of the "delegator's"calendar address.
The delegation "REQUEST" method MUST assign the values of the "RSVP"
and "EXPECT" property parameters associated with the "delegator's"
"ATTENDEE" property to that of the "delegatee's" "ATTENDEE" property.
For example if the "delegator's" "ATTENDEE" property specifies
"RSVP=TRUE;EXPECT=REQUEST", then the "delegatee's" "ATTENDEE"
property MUST specify "RSVP=TRUE;EXPECT=REQUEST".
3.1.2.4 REQUEST for Delegating role of "Organizer" to another CU
If the "Owner" of an existing "VEVENT" calendar component wishes to
delegate the role of "Organizer" to another CU, they MAY issue
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another "REQUEST" method that notifies all "Attendees" and the new
"Organizer" of this change. The "Owner MUST modify several property
parameters of the "ATTENDEE" property including the "ROLE", where the
role of "Owner" and "Organizer" MUST be specified. Additionally, the
"DELEGATED-TO" and "DELEGATED-FROM" parameters MUST specify the
"Organizer" and "Owner" calendar addresses. The "Owner" MAY request
reconfirmation by incrementing the "SEQUENCE" property and setting
the "RSVP" property parameter to TRUE. This will cause a
reconfirmation to be sent to the new organizer.
3.1.2.5 REQUEST for Changing the "Organizer" from one CU to another
An "Owner" of an existing "VEVENT" calendar component MAY change the
"Organizer" from one "CU" to another by sending a "REQUEST" method.
The "ROLE" property parameter value of ORGANIZER MUST be assigned to
the new "Organizer". If the old "Organizer" is still an "Attendee"
then "ROLE" property parameter for that "CU" MUST be set to ATTENDEE.
3.1.2.6 REQUEST for Changing the "Owner"
This memo does not support the notion of changing ownership of a
"VEVENT" calendar component.
3.1.2.7 REQUEST Forwarded To An Uninvited Calendar User
An "Attendee" invited to an event MAY invite another uninvited
"Calendar User" to the event. The invited "Attendee" accomplishes
this scheduling action by forwarding the original "REQUEST" method to
the uninvited "Calendar User". The forwarded "REQUEST" method need
not include a new "ATTENDEE" property for the uninvited "Attendee".
Whether the uninvited "Calendar User" is added to the attendee list,
and thus informed of changes to the "VEVENT" calendar component is an
implementation issue.
3.1.2.8 REQUEST Updated Attendee Status
An "Organizer" of an event MAY also request an updated status from
one of the "Attendees". This is achieved by the "Organizer" sending a
"REQUEST" method to the "Attendee" with the "ATTENDEE;RSVP=TRUE"
property sequence. The "SEQUENCE" property for the event is not
changed from its previous value. A recipient will determine that the
only change in the "REQUEST" is that their "RSVP" property parameter
indicates a request for an updated status. The recipient SHOULD
respond with a "REPLY" method indicating their current status with
respect to the "REQUEST".
This capability MAY also be achieved by the "Organizer" sending the
"REFRESH" method to the "Attendees".
3.1.3 REPLY
The "REPLY" method in a "VEVENT" calendar component is used to
respond (e.g., accept or decline) to a request or to reply to a
delegation request. When used in to provide a delegation response,
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the "delegator" SHOULD include the calendar address of the
"delegatee" on the "DELEGATED-TO" property parameter of the
"delegator's" "ATTENDEE" property. The "delegatee" SHOULD include the
calendar address of the "delegator" on the "DELEGATED-FROM" property
parameter of the "delegatee's" "ATTENDEE" property.
The "REPLY" method MAY also be used to respond to an unsuccessful
"REQUEST" method. Depending on the value of the "REQUEST-STATUS"
property no scheduling action MAY have been performed.
The "Organizer" of an event MAY receive the "REPLY" method from a
"Calendar User" not in the original "REQUEST". For example, a "REPLY"
method MAY be received from a "delegatee" to an event. In addition,
the "REPLY" method MAY be received from an unknown "Calendar User",
forwarded the "REQUEST" from an invited "Attendee". This uninvited
"Attendee" MAY be accepted, or the "Organizer" MAY cancel the event
for the uninvited "Attendee" by sending them a "CANCEL" method to the
univited "Attendee".
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Event - Reply" COMPONENT "VEVENT" METHOD "REPLY"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REPLY"})
MUST COMPONENT = VEVENT (
MUST PROPERTY = ATTENDEE{MUST be address of ATTENDEE
replying}, DTSTAMP, SEQUENCE{IF NE 0}, UID{UID
associated with original REQUEST}
MAY PROPERTY = COMMENT{provides comment from ATTENDEE to
"Organizer"}, EXDATE, EXRULE, RECURRENCE-ID, REQUEST-
STATUS, SEQUENCE{IF EQ 0}, SUMMARY {MAYBE NULL}, URL
NOT PROPERTY = ATTACH, CATEGORIES, CLASS, CONTACT, CREATED,
DESCRIPTION, DTSTART, DTEND, GEO, LAST-MODIFIED,
PRIORITY, RELATED-TO, RESOURCES, RDATE, RRULE, STATUS,
SUMMARY, TRANSP)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.1.4 CANCEL
The "CANCEL" method in a "VEVENT" calendar component is used to send
a cancellation notice of an existing event request to the
"Attendees". The message is sent by the "Organizer" of an event to
the "Attendees" of the event. For a recurring event, either the whole
event or instances of an event MAY be cancelled. To cancel the
complete range of recurring event, the "UID" property value for the
event MUST be specified in the "CANCEL" method. In order to cancel an
individual instance of the event, the "RECURRENCE-ID" property value
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for the event MUST be specified in the "CANCEL" method. In order to
cancel a sequence of recurring events, either the"RECURRENCE-ID"
property for the first event instance in the sequence MUST be
specified with the "RANGE" property parameter value of THISANDPRIOR
or THISANDFUTURE to indicate cancellation of the event instances
before and after the first event instance, respectively. Lastly,
individual recurrence instances MAY be cancelled by specifying
multiple"RECURRENCE-ID" properties corresponding to the instances to
be cancelled.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Event - Cancel" COMPONENT "VEVENT" METHOD "CANCEL"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"CANCEL"})
MUST COMPONENT = VEVENT (
MUST PROPERTY = DTSTAMP, SEQUENCE{IF NE 0}, UID{UID
associated with original REQUEST}
MAY PROPERTY = COMMENT{provides comment from "Organizer" to
ATTENDEE}, EXDATE, EXRULE, RECURRENCE-ID, SEQUENCE{IF EQ
0}, STATUS{CANCELLED}
NOT PROPERTY = ATTACH, ATTENDEE, CATEGORIES, CLASS, CONTACT,
CREATED, DESCRIPTION, DTSTART, DTEND, GEO, LAST-
MODIFIED, PRIORITY, RDATE, RELATED-TO, RESOURCES,
REQUEST-STATUS, RRULE, SUMMARY, TRANSP, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.1.5 REFRESH
The "REFRESH" method in a "VEVENT" calendar component is used by
"Attendees" of an existing event to request an updated description
from the event "Organizer". The "REFRESH" method MUST specify the
"UID" property corresponding to the event needing update. A
recurrence instance of an event MAY be requested by specifying the
"RECURRENCE-ID" property corresponding to the associated event. The
"Organizer" MUST respond with the latest description and version of
the event. This method is intended to facilitate machine processing
of event update requests by an "Attendee".
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Event - Refresh" COMPONENT "VEVENT" METHOD "REFRESH"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REFRESH"})
MUST COMPONENT = VEVENT (
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MUST PROPERTY = ATTENDEE{address of requestor}, DTSTAMP,
SEQUENCE{IF NE 0}, UID{UID associated with original
REQUEST}
MAY PROPERTY = COMMENT{provides comment from ATTENDEE to
"Organizer"}, RECURRENCE-ID, SEQUENCE{IF EQ 0}
NOT PROPERTY = ATTACH, CATEGORIES, CLASS, CONTACT, CREATED,
DESCRIPTION, DTSTART, DTEND, EXDATE, EXRULE, GEO,
LAST-MODIFIED, PRIORITY, RDATE,RELATED-TO, RESOURCES,
REQUEST-STATUS, RRULE,SUMMARY, STATUS, TRANSP, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.1.6 COUNTER
The "COUNTER" method in a "VEVENT" calendar component is used by an
"Attendee" of an existing event to submit to the "Organizer" a
counter proposal to the event description. The "Attendee" MUST send
the message to the "Organizer" of the event.
The counter proposal is an iCalendar object consisting of a VEVENT
calendar component describing the complete description of the
alternate event.
The "Organizer" rejects the counter proposal by sending the
"Attendee" a VEVENT "DECLINECOUNTER" method. The "Organizer" accepts
the counter proposal by sending all of the "Attendees" to the event a
VEVENT "REQUEST" method rescheduling the event. In the later case,
the "Organizer" SHOULD reset the individual "RSVP" property parameter
values to TRUE on each "ATTENDEE" property in order to force a
response by the "Attendees".
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Event - Counter Proposal" COMPONENT "EVENT"
METHOD "COUNTER"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"COUNTER"})
MUST COMPONENT = VEVENT (
MUST PROPERTY = ATTENDEE{STATUS parameter absent or
STATUS=NEEDS ACTION, Owner and Organizer if different,
MAY also be used to propose other "Attendees"},
DESCRIPTION{MAYBE NULL}, DTSTAMP, DTSTART,
SEQUENCE{IF NE 0}, UID{MUST be the UID associated with
the REQUEST being countered}
MAY PROPERTY = ATTACH, CATEGORIES, CLASS, COMMENT{provides a
comment from the ATTENDEE to the "Organizer"}, CONTACT,
CREATED, DTEND, EXDATE, EXRULE, GEO, LAST-
MODIFIED, LOCATION, PRIORITY, RDATE, RECURRENCE-ID,
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RELATED-TO, RESOURCES, RRULE, SEQUENCE{IF EQ 0},
STATUS{TENTATIVE/CONFIRMED/CANCELLED} , SUMMARY {MAYBE
NULL}, TRANSP, URL
NOT PROPERTY = COMPLETED, DUE, DURATION, REQUEST-STATUS)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT = VALARM (IF COMPONENT EXISTS
MUST PROPERTY = CATEGORIES, DTSTART, DURATION, REPEAT
MAY PROPERTY = ATTACH, DESCRIPTION, SUMMARY
NOT PROPERTY = COMMENT, CREATED, LAST-MODIFIED, RELATED-TO, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
)
3.1.7 DECLINECOUNTER
The "DECLINECOUNTER" method in a "VEVENT" calendar component is used
by the "Organizer" of an event to reject a counter proposal submitted
by an "Attendee". The "Organizer" MUST send the "DECLINECOUNTER"
message to the "Attendee" that sent the "COUNTER" method to the
"Organizer".
The counter proposal is an iCalendar object consisting of a VEVENT
calendar component describing the complete description of the
alternate event.
The "Organizer" rejects the counter proposal by sending the
"Attendee" a "DECLINECOUNTER" method. The "Organizer" accepts the
counter proposal by sending all of the "Attendees" to the event a
"REQUEST" method; rescheduling the event. Since this is a rescheduled
event, the "SEQUENCE" property value will be incremented. In the
later case, the "Organizer" SHOULD reset the individual "RSVP"
parameter values to TRUE on all of the "ATTENDEE" properties; in
order to force a response by the "Attendees".
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Event - Cancel" COMPONENT "VEVENT" METHOD
"DECLINECOUNTER"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"},METHOD{
"DECLINECOUNTER"})
MUST COMPONENT = VEVENT (
MUST PROPERTY = DTSTAMP, SEQUENCE{IF NE 0}, UID{same UID
specified In Original REQUEST and subsequent COUNTER}
MAY PROPERTY = COMMENT{provides comment from "Organizer" to
ATTENDEE}, RECURRENCE-ID, REQUEST-STATUS, SEQUENCE{IF EQ
0}
NOT PROPERTY = ATTACH, ATTENDEE, CATEGORIES, CLASS, CONTACT,
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CREATED, DESCRIPTION, DTSTART, DTEND, EXDATE, EXRULE,
GEO, LAST-MODIFIED, PRIORITY, RDATE, RELATED-TO,
RESOURCES, RRULE,STATUS, SUMMARY, TRANSP, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.2 Methods For VFREEBUSY Component
This section defines the property set for the methods that are
applicable to the "VFREEBUSY" calendar component. Each of the methods
is defined using a grammar that specifies the property constraints
that define the particular method.
This memo only addresses the transfer of busy time information.
Applications desiring free time information MUST infer this from
available busy time information.
The busy time information within the iCalendar object MAY be grouped
into more than one "VFREEBUSY" calendar component. This capability
allows busy time periods to be grouped according to some common
periodicity, such as a calendar week, month, or year. In this case,
each "VFREEBUSY" calendar component MUST include the "ATTENDEE",
"DTSTART" and "DTEND" properties in order to specify the source of
the busy time information and the date and time interval over which
the busy time information covers.
The "FREEBUSY" property value MAY include a list of values, separated
by the COMMA character (ASCII decimal 44). Alternately, multiple busy
time periods MAY be specified with multiple instances of the
"FREEBUSY" property. Both forms MUST be supported by implementations
conforming to this document. Duplicate busy time periods SHOULD NOT
be specified in an iCalendar object. However, two different busy time
periods MAY overlap.
"FREEBUSY" properties SHOULD be sorted such that their values are in
ascending order, based on the start time, and then the end time, with
the earliest periods first. For example, today's busy time
information SHOULD appear after yesterday's busy time information.
And the busy time for this half hour SHOULD appear after the busy
time for earlier today.
Since events MAY span a day boundary, free busy time period MAY also
span a day boundary. Individual "A" requests busy time from
individuals "B", "C" and "D". Individual "B" and "C" replies with
busy time data to individual "A". Individual "D" does not support
busy time requests and does not reply with any data. If the transport
binding supports exception messages, then a "unsupported capability"
message is returned by individual "D" to individual "A".
The following summarizes the methods that are defined for the
"VFREEBUSY" calendar component.
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|================|==================================================|
| Method | Description |
|================|==================================================|
| PUBLISH | Publish unsolicited busy time data. |
| REQUEST | Request busy time data. |
| REPLY | Reply to a busy time request. |
|================|==================================================|
3.2.1 PUBLISH
The "PUBLISH" method in a "VFREEBUSY" calendar component is used to
publish busy time data. The method MAY be sent from one "Calendar
User" to any other. The purpose of the method is to provide a message
for sending unsolicited busy time data. That is, the busy time data
is not being sent as a "REPLY" to the receipt of a "REQUEST" method.
Busy time intervals are represented by individual instances of the
"FREEBUSY" property. There is one occurrence of the property for each
busy time interval. Duplicate busy time periods SHOULD NOT be
returned. However, two different busy time periods MAY overlap.
The "FREEBUSY" property value MAY include a list of values, separated
by the COMA character (ASCII decimal 44).
"FREEBUSY" properties SHOULD be sorted such that their values are in
ascending order, from the most recent to past. For example, today's
busy time information SHOULD appear after yesterday's busy time
information. And the busy time for this half hour SHOULD appear after
the busy time for earlier today.
Since events MAY span a day boundary, free busy time period MAY also
span a day boundary.
The busy time periods MAY be grouped into more than one "VFREEBUSY"
calendar component. This capability allows busy time periods to be
grouped according to some common periodicity, such as a calendar
week, month, or year. In this case, each "VFREEBUSY" calendar
component MUST include the "ATTENDEE", "DTSTART" and "DTEND"
properties in order to specify the originator and date and time
interval for the busy time information.
The "ATTENDEE" property MUST be specified in the busy time
information. The value is the "Calendar User" address of the
originator of the busy time information.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Busy - Busy Time Publish" COMPONENT "VFREEBUSY"
METHOD "PUBLISH"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"PUBLISH"})
MUST COMPONENT = VFREEBUSY (
MUST PROPERTY = ATTENDEE{address of originator of busy time
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data},FREEBUSY{values MUST all be of the same data type.
Multiple instances are allowed. Multiple instances MUST
be sorted in ascending order. Values MAY NOT overlap},
RELATED-TO{refers to another related VFREEBUSY
component},
MAY PROPERTY = COMMENT{comment from attendee to originator of
request}, CREATED{specifies when the busy time data was
created}, DTSTART{represents start of interval for busy
time data}, DTEND{represents end of interval for busy
time data},LAST-MODIFIED{specifies when busy time data
was last modified}, SEQUENCE{IF EQ 0}, URL{specifies busy
time URL}
NOT PROPERTY = DTSTAMP, DURATION, REQUEST-STATUS, SEQUENCE,
UID)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VALARM
)
3.2.2 REQUEST
The "REQUEST" method in a "VFREEBUSY" calendar component is used to
ask a "Calendar User" for their busy time information. The request
MAY be for a busy time information bounded by a specific date and
time interval.
This message only permits requests for busy time information. The
message is sent from a "Calendar User" requesting the busy time
information to one or more intended recipients.
An "ATTENDEE" property MUST be included for the originator of the
request and each of the intended recipients that the method is sent
to. The originator is indicated with an "ATTENDEE" property parameter
sequence of ";ROLE=ORGANIZER". The recipients are indicated with an
"ATTENDEE" property parameter sequence of ";ROLE=ATTENDEE". The
requests MAY be fanned out in separate messages to the recipients,
with each "REQUEST" method only including the associated "ATTENDEE"
properties for the recipients of the message.
If the originator of the "REQUEST" method is not authorized to make a
busy time request on the recipient's calendar system, then an
exception message is returned in a "REPLY" method, but no busy time
data need be returned.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "FREEBUSY - Request For Busy Time" COMPONENT
"VFREEBUSY" METHOD "REQUEST"
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MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REQUEST"})
MUST COMPONENT = VFREEBUSY (
MUST PROPERTY = ATTENDEE{Attendee instances for the Owner and
Organizer if different and the intended recipient of the
request}, DTSTAMP, DTSTART, DTEND,SEQUENCE{IF NE 0}, UID
MAY PROPERTY = SEQUENCE{IF EQ 0}
NOT PROPERTY = COMMENT, CREATED, DURATION, FREEBUSY,
LAST-MODIFIED, RELATED-TO, URL, REQUEST-STATUS)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VALARM
)
3.2.3 REPLY
The "REPLY" method in a "VFREEBUSY" calendar component is used to
respond to an existing busy time request. The method is sent from a
recipient of a busy time request back to the originator of the
request. The originator of the request is specified by the "ATTENDEE"
property parameter sequence of ";ROLE=ORGANIZER".
The "REPLY" method MAY also be used to respond to an unsuccessful
"REQUEST" method. Depending on the "REQUEST-STATUS" value, no busy
time information MAY be returned.
Busy time intervals are represented by individual instances of the
"FREEBUSY" property. There is one occurrence of the property for each
busy time interval. Duplicate busy time periods SHOULD NOT be
returned. However, two different busy time periods MAY overlap.
The "FREEBUSY" property value MAY include a list of values, separated
by the COMA character (ASCII decimal 44).
"FREEBUSY" properties SHOULD be sorted such that their values are in
ascending order, from the most recent to past. For example, today's
busy time information SHOULD appear after yesterday's busy time
information. And the busy time for this half hour SHOULD appear after
the busy time for earlier today.
Since events MAY span a day boundary, free busy time period MAY also
span a day boundary.
The busy time periods MAY be grouped into more than one "VFREEBUSY"
calendar component. This capability allows busy time periods to be
grouped according to some common periodicity, such as a calendar
week, month, or year. In this case, each "VFREEBUSY" calendar
component MUST include the "ATTENDEE", "DTSTART" and "DTEND"
properties in order to identify the source and date and time range
for the busy time data.
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The "ATTENDEE" property MUST be specified in the busy time reply. The
value is the fully qualified RFC 822 address of the recipient
replying to the busy time request.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "FreeBusy - Busy Time Reply" COMPONENT "VFREEBUSY"
METHOD "REPLY"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REPLY"})
MUST COMPONENT = VFREEBUSY (
MUST PROPERTY = ATTENDEE{address of recipient replying},
DTSTAMP, DTSTART, DTEND, FREEBUSY{values MUST all be of
the same data type. Multiple instances are allowed.
Multiple instances MUST be sorted in ascending order.
Values MAY NOT overlap}, RELATED-TO{refers to another
related VFREEBUSY component}, REQUEST-STATUS, UID
MAY PROPERTY = COMMENT{comment from attendee to originator of
request}, CREATED{specifies when the busy time data was
created}, DTSTART{represents start of interval for busy
time data}, DTEND{represents end of interval for busy
time data},LAST-MODIFIED{specifies when busy time data
was last modified}, SEQUENCE{IF EQ 0}, URL{specifies busy
time URL}
NOT PROPERTY = DURATION, SEQUENCE)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY CREATED)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VTODO
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VALARM
)
3.3 Methods For VTODO Component
This section defines the property set for the methods that are
applicable to the "VTODO" calendar component . Each of the methods is
defined using a grammar that specifies the property constraints that
define the particular method.
The following summarizes the methods that are defined for the "VTODO"
calendar component .
+================+==================================================+
| Method | Description |
|================+==================================================|
| PUBLISH | Post notification of a VTODO. Used primarily as |
| | a method of advertising the existence of a VTODO.|
| REQUEST | Assign a VTODO. This is an explicit assignment to|
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| | one or more Calendar Users.VTODO REQUEST method |
| | is also used to update or change an existing |
| | VTODO. Clients that cannot handle REQUEST MAY |
| | degrade the method to view it as a PUBLISH. |
| REPLY | Reply to a VTODO request. Attendees MAY set |
| | status to ACCEPTED, DECLINED, TENTATIVE, |
| | DELEGATED, PARTIAL, and COMPLETED. |
| CANCEL | Cancel an existing VTODO assignment. |
| REFRESH | A request sent to a VTODO "Organizer" asking for |
| | the latest version of a |
| COUNTER | Counter a REQUEST with an alternative proposal. |
| DECLINECOUNTER | Decline a counter proposal by an attendee. |
+================+==================================================+
3.3.1 PUBLISH
The "PUBLISH" method in a "VTODO" calendar component has no reply
response associated with it. Instead, it is simply a posting of an
iCalendar object that MAY be added to a calendar by a "Calendar
User". It requires and accepts no responses to the "Organizer". It's
expected usage is for encapsulating an arbitrary "VTODO" calendar
component as an iCalendar object. The "Organizer" MAY subsequently
update (with another "PUBLISH" method) or cancel (with a "CANCEL"
method) a previously published "VTODO" calendar component .
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "VTODO - Publish" COMPONENT "VTODO" METHOD "PUBLISH
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"PUBLISH"})
MUST COMPONENT = VTODO(
MUST PROPERTY = ATTENDEE{only Owner and Organizer if
different}, DESCRIPTION{MAYBE NULL}, DTSTAMP, DTSTART,
PRIORITY, SEQUENCE{IF NE 0}, UID
MAY PROPERTY = ATTACH, ATTENDEE{other than ROLE=OWNER |
ORGANIZER}, CATEGORIES, CLASS, COMMENT, COMPLETED,
CONTACT, CREATED, DUE, EXDATE, EXRULE, GEO, LAST-
MODIFIED, LOCATION,PERCENT-COMPLETE, RELATED-TO, RDATE,
RECURRENCE-ID, RESOURCES, RRULE, SEQUENCE{IF EQ 0},
STATUS{TENTATIVE/CONFIRMED/CANCELLED}, SUMMARY{MAYBE
NULL}, URL
NOT PROPERTY = REQUEST-STATUS)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT = VALARM (
MUST PROPERTY = CATEGORIES, DTSTART, DURATION, REPEAT
MAY PROPERTY = ATTACH, DESCRIPTION, SUMMARY
NOT PROPERTY = COMMENT, CREATED, LAST-MODIFIED, RELATED-TO, URL)
MAY COMPONENT = X-TOKENS (ANY)
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NOT COMPONENT = VEVENT
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
)
3.3.2 REQUEST
The "REQUEST" method in a "VTODO" calendar component provides the
following scheduling functions:
╖ Assign a to-do to one or more "Calendar Users";
╖ Reschedule an existing to-do;
╖ Update the details of an existing to-do, without rescheduling
it;
╖ Update the completion status of "Attendees" of an existing to-
do, without rescheduling it;
╖ Reconfirm an existing to-do, without rescheduling it;
╖ Delegate/reassign an existing to-do to another "Calendar User".
The assigned "Calendar Users" are identified in the "VTODO" calendar
component by individual "ATTENDEE;ROLE=ATTENDEE" property value
sequences.
The originator of a "REQUEST" is the "Organizer" of the to-do. The
recipient of a "REQUEST" is the "Calendar User" assigned the to-do,
called the Attendee. The "Attendee" uses the "REPLY" method to convey
their acceptance and completion status to the "Organizer" of the
"REQUEST".
The "UID" and "SEQUENCE" properties are used to distinguish the
various uses of the "REQUEST" method. If the "UID" property value in
the "REQUEST" is not found on the recipient's calendar, then the
"REQUEST" is for a new to-do. If the "UID" property value is found on
the recipient's calendar, then the "REQUEST" is for either a
rescheduling, an update, or a reconfirm of the "VTODO" calendar
object.
If the "Organizer" of the "REQUEST" method is not authorized to make
a to-do request on the "Attendee's" calendar system, then an
exception is returned in the "REQUEST-STATUS" property of a
subsequent "REPLY" method, but no scheduling action is performed.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "VTODO - Request" COMPONENT "VTODO" METHOD "REQUEST"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REQUEST"})
MUST COMPONENT = VTODO(
MUST PROPERTY = ATTENDEE{For Owner and Organizer if different
and each Attendee},DESCRIPTION{MAYBE NULL}, DTSTAMP,
DTSTART, PRIORITY, SEQUENCE{IF NE 0}, UID
MAY PROPERTY = ATTACH, CATEGORIES, CLASS, COMMENT, CONTACT,
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CREATED, DUE, EXDATE, EXRULE, GEO, LAST-MODIFIED,
LOCATION, PERCENT-COMPLETE, RELATED-TO, RDATE,
RECURRENCE-ID, RESOURCES, RRULE, SEQUENCE{IF EQ 0},
STATUS{TENTATIVE/CONFIRMED/CANCELLED}, SUMMARY{MAYBE
NULL}, URL
NOT PROPERTY = COMPLETED, REQUEST-STATUS)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT = VALARM (
MUST PROPERTY = CATEGORIES, DTSTART, DURATION, REPEAT
MAY PROPERTY = ATTACH, DESCRIPTION, SUMMARY
NOT PROPERTY = COMMENT, CREATED, LAST-MODIFIED, RELATED-TO,
URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
)
3.3.2.1 REQUEST for Rescheduling a VTODO
The "REQUEST" method MAY be used to reschedule a "VTODO" calendar
component .
A rescheduled "VTODO" calendar component involves a change to the
existing "VTODO" calendar component in terms of it's start or due
time or recurrence intervals and possibly the description. If the
recipient "CUA" of a "REQUEST" method finds that the "UID" property
value already exists on the calendar, but that the "SEQUENCE"
property value in the "REQUEST" is greater than the value for the
existing VTODO, then the "REQUEST" method describes a rescheduling of
the "VTODO" calendar component.
3.3.2.2 REQUEST for Update or Reconfirmation of a VTODO
The "REQUEST" method MAY be used to update or reconfirm a "VTODO"
calendar component. Reconfirmation is merely an update of "Attendee"
completion status or overall "VTODO" calendar component status.
An update to an existing "VTODO" calendar component does not involve
changes to the start or due time or recurrence intervals, nor
generally to the description for the "VTODO" calendar component. If
the recipient "CUA" of a "REQUEST" method finds that the "UID"
property value already exists on the calendar and that the "SEQUENCE"
property value in the "REQUEST" is the same as the value for the
existing event, then the "REQUEST" method describes an update of the
"VTODO" calendar component details, but no rescheduling of the
"VTODO" calendar component.
The update "REQUEST" is the appropriate response to a "REFRESH"
method sent from an "Attendee" to the "Organizer" of a "VTODO"
calendar component.
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Unsolicited "REQUEST" methods MAY also be sent by the "Organizer" of
a "VTODO" calendar component. The unsolicited "REQUEST" methods MAY
be used to either update the details of the VTODO, without
rescheduling it or to update the completion status of "Attendees" or
the "VTODO" calendar component itself (i.e., reconfirm the VTODO).
3.3.2.3 REQUEST for Delegating a VTODO
The "REQUEST" method MAY be used to delegate or reassign ownership of
a "VTODO" calendar component to another "Calendar User". The
"REQUEST" method is used to delegate the "Attendee's" role (i.e. "
"Organizer", or "Attendee") for a "VTODO" calendar component. The
"REQUEST" method is sent by one of the "Attendees" of an existing
"VTODO" calendar component request to some other individual. In order
to avoid scheduling loops, the method MUST NOT be sent from an
"Attendee" back to the "Organizer" of the "VTODO" calendar component.
An "Attendee" of a "VTODO" calendar component MAY NOT delegate to the
"Organizer" of the event.
For the purposes of this description, the "Attendee" delegating the
"VTODO" calendar component is referred to as the "delegator". The
"Attendee" receiving the delegation request is referred to as the
"delegatee".
The "delegator" of a "VTODO" calendar component MUST forward the
existing "REQUEST" method for a "VTODO" calendar component to the
"delegatee". The "VTODO" calendar component description MUST include
the "delegator's" up-to-date "VTODO" calendar component definition.
The "REQUEST" method MUST also include an "ATTENDEE" property with
the calendar address of the "delegatee". The "delegator" MUST also
send a "REPLY" method back to the "Organizer" with the "delegator's"
"Attendee" property "STATUS" parameter value set to DELEGATED. In
addition, the "DELEGATED-TO" parameter SHOULD be included with the
calendar address of the "delegatee". A response to the delegation
"REQUEST" is sent from the "delegatee" to the "Organizer" and
optionally, to the "delegator". The "REPLY" method from the
"delegatee" SHOULD include the "ATTENDEE" property with their
calendar address and the "DELEGATED-FROM" parameter with the value of
the "delegator's"calendar address.
The delegation "REQUEST" method MUST assign the values of the "RSVP"
and "EXPECT" property parameters associated with the "delegator's"
"Attendee" property to that of the "delegatee's" "Attendee" property.
For example if the "delegator's" "Attendee" property specifies
"RSVP=TRUE;EXPECT=REQUEST", then the "delegatee's" "Attendee"
property MUST specify "RSVP=TRUE;EXPECT=REQUEST".
3.3.2.4 REQUEST Forwarded To An Uninvited Calendar User
An "Attendee" assigned a "VTODO" calendar component MAY also assign
the "VTODO" calendar component to another new "Calendar User", not
previously associated with the "VTODO" calendar component. The
current "Attendee" assigned the "VTODO" calendar component
accomplishes this scheduling action by forwarding the original
"REQUEST" method to the new "Calendar User".
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An "Organizer" of a "VTODO" calendar component MAY also request an
updated completion status from one of the "Attendees". This is
achieved by the "Organizer" sending a "REQUEST" method to the
"Attendee" with the "ATTENDEE;RSVP=TRUE" property sequence. The
"SEQUENCE" property for the "VTODO" calendar component is not changed
from its previous value. A recipient will determine that the only
change in the "REQUEST" is that their "RSVP" property parameter
indicates a request for an updated status. The recipient SHOULD
respond with a "REPLY" method indicating their current status with
respect to the "REQUEST".
3.3.2.5 REQUEST Updated Attendee Status
An "Organizer" of a to-do MAY also request an updated status from one
of the "Attendees". This is achieved by the "Organizer" sending a
"REQUEST" method to the "Attendee" with the "ATTENDEE;RSVP=TRUE"
property sequence. The "SEQUENCE" property for the to-do is not
changed from its previous value. A recipient will determine that the
only change in the "REQUEST" is that their "RSVP" property parameter
indicates a request for an updated status. The recipient SHOULD
respond with a "REPLY" method indicating their current status with
respect to the "REQUEST".
This capability MAY also be achieved by the "Organizer" sending the
"REFRESH" method to the "Attendees".
3.3.3 REPLY
The "REPLY" method in a "VTODO" calendar component is used to respond
(e.g., accept or decline) to a request or to reply to a delegation
request. It is also used by an "Attendee" to update their completion
status. When used to provide a delegation response, the "delegator"
SHOULD include the calendar address of the "delegatee" in the
"DELEGATED-TO" parameter of the "delegator's" "ATTENDEE" property.
The "delegatee" SHOULD include the calendar address of the
"delegator" on the "DELEGATED-FROM" parameter of the "delegatee's"
"ATTENDEE" property.
The "REPLY" method MAY also be used to respond to an unsuccessful
"VTODO" calendar component "REQUEST" method. Depending on the
"REQUEST-STATUS" value, no scheduling action MAY have been performed.
The "Organizer" of a "VTODO" calendar component MAY receive a "REPLY"
method from a "Calendar User" not in the original "REQUEST". For
example, a "REPLY" method MAY be received from a "delegatee" of a
"VTODO" calendar component. In addition, the "REPLY" method MAY be
received from an unknown "Calendar User"; forwarded the "REQUEST"
from an original "Attendee" assigned the "VTODO" calendar component.
This uninvited "Attendee" MAY be accepted, or the "Organizer" MAY
cancel the "VTODO" calendar component for the uninvited "Attendee" by
sending them a "CANCEL" method.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "VTODO - Reply" COMPONENT "VTODO" METHOD "REPLY"
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MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REPLY"})
MUST COMPONENT = VTODO(
MUST PROPERTY = ATTENDEE{MUST be address of ATTENDEE
replying}, DTSTAMP, SEQUENCE{IF NE 0}, UID{UID
associated with original REQUEST}
MAY PROPERTY = COMMENT{provides comment from ATTENDEE to
"Organizer"}, COMPLETED, EXDATE, EXRULE, RECURRENCE-ID,
REQUEST-STATUS, PERCENT-COMPLETE, SEQUENCE{IF EQ 0},
SUMMARY {MAYBE NULL}, URL
NOT PROPERTY = ATTACH, CATEGORIES, CLASS, CONTACT, CREATED,
DESCRIPTION, DTSTART, DUE, GEO, LAST-MODIFIED, PRIORITY,
RELATED-TO, RESOURCES, RDATE, RRULE, STATUS, SUMMARY,
TRANSP)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.3.4 CANCEL
The "CANCEL" method in a "VTODO" calendar component is used to send a
cancellation notice of an existing "VTODO" calendar request request
to the "Attendees". The message is sent by the "Organizer" of a
"VTODO" calendar component to the "Attendees" of the "VTODO" calendar
component. For a recurring "VTODO" calendar component, either the
whole "VTODO" calendar component or instances of a "VTODO" calendar
component MAY be cancelled. To cancel the complete range of a
recurring "VTODO" calendar component, the "UID" property value for
the "VTODO" calendar component MUST be specified in the "CANCEL"
method. In order to cancel an individual instance of a recurring
"VTODO" calendar component, the "RECURRENCE-ID" property value for
the "VTODO" calendar component MUST be specified in the "CANCEL"
method. In order to cancel a sequence of instances of a recurring
"VTODO" calendar component, either the "RECURRENCE-ID" property for
the first instance in the sequence MUST be specified with the "RANGE"
property parameter value of THISANDPRIOR or THISANDFUTURE; to
indicate cancellation of the "VTODO" calendar component instances
before and after the first instance, respectively. Lastly, individual
recurrence instances MAY be cancelled by specifying multiple
"RECURRENCE-ID" properties corresponding to the instances to be
cancelled.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "VTODO - Cancel" COMPONENT "VTODO" METHOD "CANCEL"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"CANCEL"})
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MUST COMPONENT = VTODO(
MUST PROPERTY = DTSTAMP, SEQUENCE{IF NE 0}, UID{UID
associated with original REQUEST}
MAY PROPERTY = COMMENT{provides comment from "Organizer" to
ATTENDEE}, EXDATE, EXRULE, RECURRENCE-ID, SEQUENCE{IF EQ
0}, STATUS{CANCELLED}
NOT PROPERTY = ATTACH, ATTENDEE, CATEGORIES, CLASS,
COMPLETED, CONTACT, CREATED, DESCRIPTION, DTSTART, DUE,
GEO, LAST-MODIFIED, PRIORITY, RDATE, RELATED-TO,
RESOURCES, REQUEST-STATUS, RRULE, SUMMARY, TRANSP, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.3.5 REFRESH
The "REFRESH" method in a "VTODO" calendar component is used by
"Attendees" of an existing "VTODO" calendar component to request an
updated description from the "Organizer" of the "VTODO" calendar
component. The "Organizer" of the "VTODO" calendar component MAY also
use this method to request an updated status from the "Attendees".
The "REFRESH" method MUST specify the "UID" property corresponding to
the "VTODO" calendar component needing update.
A refresh of a recurrence instance of a "VTODO" calendar component
MAY be requested by specifying the "RECURRENCE-ID" property
corresponding to the associated "VTODO" calendar component. The
"Organizer" MUST respond with the latest description and rendition of
the "VTODO" calendar component. This method is intended to facilitate
machine processing of requests for updates to a "VTODO" calendar
component.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "VTODO - Refresh" COMPONENT "VTODO" METHOD "REFRESH"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REFRESH"})
MUST COMPONENT = VTODO(
MUST PROPERTY = ATTENDEE{address of requestor}, DTSTAMP,
SEQUENCE{IF NE 0}, UID{UID associated with original
REQUEST} MAY PROPERTY = COMMENT{provides comment from
ATTENDEE to "Organizer"}, RECURRENCE-ID, SEQUENCE{IF EQ
0}
NOT PROPERTY = ATTACH, CATEGORIES, CLASS, COMPLETED, CONTACT,
CREATED, DESCRIPTION, DTSTART, DUE, EXDATE, EXRULE, GEO,
LAST-MODIFIED, PRIORITY, RDATE,RELATED-TO, RESOURCES,
REQUEST-STATUS, RRULE,SUMMARY, STATUS, TRANSP, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
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NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.3.6 COUNTER
The "COUNTER" method in a "VTODO" calendar component is used by an
"Attendee" of an existing "VTODO" calendar component to submit to the
"Organizer" a counter proposal for the "VTODO" calendar component.
The "Attendee" MUST send the message to the "Organizer" of the
"VTODO" calendar component.
The counter proposal is an iCalendar object consisting of a "VTODO"
calendar component describing the complete description of the
alternate "VTODO" calendar component.
The "Organizer" rejects the counter proposal by sending the
"Attendee" a "DECLINECOUNTER" method. The "Organizer" accepts the
counter proposal by sending all of the "Attendees" of the "VTODO"
calendar component a "REQUEST" method rescheduling the "VTODO"
calendar component. In the later case, the "Organizer" SHOULD reset
the individual "RSVP" property parameter values to TRUE on each
"ATTENDEE" property; in order to force a response by the "Attendees".
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "VTODO- Request" COMPONENT "VTODO" METHOD "REQUEST"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REQUEST"})
MUST COMPONENT = VTODO(
MUST PROPERTY = ATTENDEE{For Owner and Orginator if different
and Attendees}, DESCRIPTION{MAYBE NULL}, DTSTAMP,
DTSTART, PRIORITY, SEQUENCE{IF NE 0}, UID
MAY PROPERTY = ATTACH, CATEGORIES, CLASS, COMMENT, COMPLETED,
CONTACT, CREATED, DUE, EXDATE, EXRULE, GEO, LAST-
MODIFIED,LOCATION,RELATED-TO, RDATE, RECURRENCE-ID,
RESOURCES, RRULE, SEQUENCE{IF EQ 0},
STATUS{TENTATIVE/CONFIRMED/CANCELLED}, SUMMARY{MAYBE
NULL}, URL
NOT PROPERTY = REQUEST-STATUS)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT = VALARM (
MUST PROPERTY = CATEGORIES, DTSTART, DURATION, REPEAT
MAY PROPERTY = ATTACH, DESCRIPTION, SUMMARY
NOT PROPERTY = COMMENT, CREATED, LAST-MODIFIED, RELATED-TO, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VJOURNAL
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NOT COMPONENT = VFREEBUSY
)
3.3.7 DECLINECOUNTER
The "DECLINECOUNTER" method in a "VTODO" calendar component is used
by an "Organizer" of "VTODO" calendar component to reject a counter
proposal offered by one of the "Attendees". The "Organizer" MUST send
the message to the "Attendee" that sent the "COUNTER" method to the
"Organizer".
The counter proposal is an iCalendar object consisting of a "VTODO"
calendar component describing the complete description of the
alternate "VTODO" calendar component.
The "Organizer" rejects the counter proposal by sending the
"Attendee" a "DECLINECOUNTER" method. The "Organizer" accepts the
counter proposal by sending all of the "Attendees" of the "VTODO"
calendar component a "REQUEST" method rescheduling the "VTODO"
calendar component. Since this is a rescheduled "VTODO", the
"SEQUENCE" property value will be incremented. In the later case, the
"Organizer" SHOULD reset the individual "RSVP" property parameter
values to TRUE on all of the "ATTENDEE" properties in order to force
a response by the "Attendees".
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "VTODO - Cancel" COMPONENT "VTODO" METHOD
"DECLINECOUNTER"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD
{"DECLINECOUNTER"})
MUST COMPONENT = VTODO(
MUST PROPERTY = DTSTAMP, SEQUENCE{IF NE 0}, UID{same UID
specified In Original REQUEST and subsequent COUNTER}
MAY PROPERTY = COMMENT{provides comment from "Organizer" to
ATTENDEE}, RECURRENCE-ID, REQUEST-STATUS, SEQUENCE{IF EQ
0}
NOT PROPERTY = ATTACH, ATTENDEE, CATEGORIES, CLASS,
COMPLETED, CONTACT, CREATED, DESCRIPTION, DTSTART, DUE,
EXDATE, EXRULE, GEO, LAST-MODIFIED, PRIORITY, RDATE,
RELATED-TO, RESOURCES, RRULE, STATUS, SUMMARY, TRANSP,
URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VJOURNAL
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
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3.4 Methods For VJOURNAL Component
This section defines the property set for the methods that are
applicable to the "VJOURNAL" calendar component. Each of the methods
is defined using a grammar that clarifies the property constraints
that define the particular method.
The following summarizes the methods that are defined for the
"VJOURNAL" calendar component.
+================+==================================================+
| Method | Description |
|================+==================================================|
| PUBLISH | Post a journal entry. Used primarily as a method |
| | of advertising the existence of a journal entry |
| CANCEL | Cancel an existing journal entry request. |
| REFRESH | A request sent to the journal "Organizer" for |
| | the latest version of the journal entry to be |
| | resent the requester. |
+================+==================================================+
3.4.1 PUBLISH
The "PUBLISH" method in a "VJOURNAL" calendar component has no reply
response associated with it. Instead, it is simply a posting of an
iCalendar object that MAY be added to a calendar by a "Calendar User"
agent. It requires and accepts no responses to the "Organizer". The
expected usage is for encapsulating an arbitrary journal entry as an
iCalendar object. The "Organizer" MAY subsequently update (with
another "PUBLISH" method) or cancel (with a "CANCEL" method) a
previously published journal entry.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Journal - Publish" COMPONENT "VJOURNAL" METHOD
"PUBLISH
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"PUBLISH"})
MUST COMPONENT = VJOURNAL (
MUST PROPERTY = DESCRIPTION{MAYBE NULL}, DTSTAMP,
DTSTART{VALUE=DATE}, SEQUENCE{IF NE 0}, UID
MAY PROPERTY = ATTACH, ATTENDEE{only ROLE=ORGANIZER and
OWNER if different}, CATEGORIES, CLASS, COMMENT,
CONTACT, CREATED, EXDATE, EXRULE, LAST-MODIFIED,
RELATED-TO, RDATE, RECURRENCE-ID, RRULE, SEQUENCE{IF EQ
0}, SUMMARY{MAYBE NULL}, URL
NOT PROPERTY = REQUEST-STATUS)
MAY COMPONENT = VTIMEZONE (
MUST PROPERTY = DTSTART, TZOFFSET
MAY PROPERTY = COMMENT, DAYLIGHT, (RDATE / RRULE), TZNAME
NOT PROPERTY = CREATED)
MAY COMPONENT = X-TOKENS (ANY)
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NOT COMPONENT = VEVENT
NOT COMPONENT = VTODO
NOT COMPONENT = VALARM
NOT COMPONENT = VFREEBUSY
)
3.4.2 CANCEL
The "CANCEL" method in a "VJOURNAL" calendar component is used to
send a cancellation notice of an existing journal entry request to
the "Attendees". The message is sent by the "Organizer" of a journal
entry to the "Attendees" of the journal entry. For a recurring
journal entry, either the whole journal entry or instances of a
journal entry MAY be cancelled. To cancel the complete range of a
recurring journal entry, the "UID" property value for the journal
entry MUST be specified in the "CANCEL" method. In order to cancel an
individual instance of the journal entry, the "RECURRENCE-ID"
property value for the journal entry MUST be specified in the
"CANCEL" method. In order to cancel a sequence of instances in a
recurring journal entry, the "RECURRENCE-ID" property for the first
journal entry instance in the sequence MUST be specified with the
"RANGE" property parameter value of THISANDPRIOR or THISANDFUTURE; to
indicate cancellation of the journal entry instances before and after
the first journal entry instance, respectively. Lastly, individual
recurrence instances MAY be cancelled by specifying multiple
"RECURRENCE-ID" properties corresponding to the instances to be
cancelled.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Journal - Cancel" COMPONENT "VJOURNAL" METHOD
"CANCEL"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"CANCEL"})
MUST COMPONENT = VJOURNAL (
MUST PROPERTY = DTSTAMP, SEQUENCE{IF NE 0}, UID{UID
associated with original REQUEST}
MAY PROPERTY = COMMENT{provides comment from "Organizer" to
ATTENDEE}, EXDATE, EXRULE, RECURRENCE-ID, SEQUENCE{IF EQ
0}, STATUS{CANCELLED}
NOT PROPERTY = ATTACH, ATTENDEE, CATEGORIES, CLASS, CONTACT,
CREATED, DESCRIPTION, DTSTART, LAST-MODIFIED, RDATE,
RELATED-TO, REQUEST-STATUS, RRULE, SUMMARY, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VTODO
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
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3.4.3 REFRESH
The "REFRESH" method in a "VJOURNAL" calendar component is used by
"Attendees" of an existing journal entry to request an updated
description from the journal entry "Organizer". The "REFRESH" method
MUST specify the "UID" property corresponding to the journal entry
needing update. A recurrence instance of a journal entry MAY be
requested by specifying the"RECURRENCE-ID" property corresponding to
the associated journal entry. The "Organizer" MUST respond with the
latest description and version of the journal entry. This method is
intended to facilitate machine processing of the "REFRESH" response.
This method type is an iCalendar object that conforms to the
following property constraints:
(DESCRIPTION "Journal - Refresh" COMPONENT "VJOURNAL" METHOD
"REFRESH"
MUST COMPONENT = CALPROPS (
MUST PROPERTY = PRODID, VERSION{"2.0"}, METHOD{"REFRESH"})
MUST COMPONENT = VJOURNAL (
MUST PROPERTY = ATTENDEE{address of requestor}, DTSTAMP,
SEQUENCE{IF NE 0}, UID{UID associated with original
REQUEST}
MAY PROPERTY = COMMENT{provides comment from ATTENDEE to
"Organizer"}, RECURRENCE-ID, SEQUENCE{IF EQ 0}
NOT PROPERTY = ATTACH, CATEGORIES, CLASS, CONTACT, CREATED,
DESCRIPTION, DTSTART, EXDATE, EXRULE, LAST-MODIFIED,
PRIORITY, RDATE, RELATED-TO, REQUEST-STATUS, RRULE,
SUMMARY, URL)
MAY COMPONENT = X-TOKENS (ANY)
NOT COMPONENT = VEVENT
NOT COMPONENT = VTODO
NOT COMPONENT = VFREEBUSY
NOT COMPONENT = VTIMEZONE
NOT COMPONENT = VALARM
)
3.5 Status Replies
The "REQUEST-STATUS" property MAY include the following values:
|==============+============================+=========================|
| Short Return | Longer Return Status | Offending Data |
| Status Code | Description | |
|==============+============================+=========================|
| 2.0 | Success. | None. |
|==============+============================+=========================|
| 2.1 | Success but fallback taken | Property name and value |
| | on one or more property | MAY be specified. |
| | values. | |
|==============+============================+=========================|
| 2.2 | Success, invalid property | Property name MAY be |
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| | ignored. | specified. |
|==============+============================+=========================|
| 2.3 | Success, invalid property | Property parameter name |
| | parameter ignored. | and value MAY be |
| | | specified. |
|==============+============================+=========================|
| 2.4 | Success, unknown non- | Non-standard property |
| | standard property ignored. | name MAY be specified. |
|==============+============================+=========================|
| 2.5 | Success, unknown non | Property and non- |
| | standard property value | standard value MAY be |
| | ignored. | specified. |
|==============+============================+=========================|
| 2.6 | Success, invalid calendar | Calendar component |
| | component ignored. | sentinel (e.g., "BEGIN: |
| | | ALARM") MAY be |
| | | specified. |
|==============+============================+=========================|
| 2.7 | Success, request forwarded | Original and forwarded |
| | to Calendar User. | caluser addresses MAY |
| | | be specified. |
|==============+============================+=========================|
| 2.8 | Success, repeating event | RRULE or RDATE property |
| | ignored. Scheduled as a | name and value MAY be |
| | single event. | specified. |
|==============+============================+=========================|
| 2.9 | Success, truncated end date| DTEND property value |
| | time to date boundary. | MAY be specified. |
|==============+============================+=========================|
| 2.10 | Success, repeating VTODO | RRULE or RDATE property |
| | ignored. Scheduled as a | name and value MAY be |
| | single VTODO. | specified. |
|==============+============================+=========================|
| 3.0 | Invalid property name. | Property name MAY be |
| | | specified. |
|==============+============================+=========================|
| 3.1 | Invalid property value. | Property name and value |
| | | MAY be specified. |
|==============+============================+=========================|
| 3.2 | Invalid property parameter.| Property parameter name |
| | | and value MAY be |
| | | specified. |
|==============+============================+=========================|
| 3.3 | Invalid property parameter | Property parameter name |
| | value. | and value MAY be |
| | | specified. |
|==============+============================+=========================|
| 3.4 | Invalid calendar component | Calendar component |
| | sequence. | sentinel MAY be |
| | | specified (e.g., BEGIN: |
| | | VTIMEZONE). |
|==============+============================+=========================|
| 3.5 | Invalid date or time. | Date/time value(s) MAY |
| | | be specified. |
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|==============+============================+=========================|
| 3.6 | Invalid rule. | Rule value MAY be |
| | | specified. |
|==============+============================+=========================|
| 3.7 | Invalid Calendar User. | Attendee property value |
| | |MAY be specified. |
|==============+============================+=========================|
| 3.8 | No authority. | PROFILE and ATTENDEE |
| | | property values MAY be |
| | | specified. |
|==============+============================+=========================|
| 3.9 | Unsupported version. | VERSION property name |
| | | and value MAY be |
| | | specified. |
|==============+============================+=========================|
| 3.10 | Request entity too large. | None. |
|==============+============================+=========================|
| 4.0 | Event conflict. Date/time | DTSTART and DTEND |
| | is busy. | property name and values|
| | | MAY be specified. |
|==============+============================+=========================|
| 5.0 | Request not supported. | Method property value |
| | | MAY be specified. |
|==============+============================+=========================|
| 5.1 | Service unavailable. | ATTENDEE property value |
| | | MAY be specified. |
|==============+============================+=========================|
| 5.2 | Invalid calendar service. | ATTENDEE property value |
| | | MAY be specified. |
|==============+============================+=========================|
| 5.3 | No scheduling support for | ATTENDEE property value |
| | user. | MAY be specified. |
|==============+============================+=========================|
3.6 Implementation Considerations
3.6.1 Working With Recurrence Instances
iCalendar includes a recurrence grammar to represent recurring
events. The benefit of such a grammar is the ability to represent a
number of events in a single object. However, while this simplifies
creation of a recurring event, meeting instances MAY still need to be
referenced. For instance, an "Attendee" MAY decline the third
instance of a recurring Friday event. Similarly, the "Organizer" MAY
change the time or location to a single instance of the recurring
event.
Since implementations MAY elect to store recurring events as either a
single event object or a collection of discreet, related event
objects, the protocol is designed so that each recurring instance MAY
be both referenced and versioned. Hence, implementations that choose
to maintain per-instance properties (such as "ATTENDEE" property
"STATUS" parameter) MAY do so. However, the protocol does not require
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per-instance recognition unless the instance itself MUST be
renegotiated.
The scenarios for recurrence instance referencing are listed below.
For purposes of simplification a change to an event refers to a
"trigger property." That is, a property that has a substantive
affect on the meeting itself such as start time, location, due date
(for "VTODO" calendar component components) and possibly description.
╖ "Organizer" initiated actions:
╖ "Organizer" deletes or changes a single instance of a recurring
event
╖ "Organizer" makes changes that affect all future instances
╖ "Organizer" makes changes that affect all previous instances
╖ "Organizer" deletes or modifies a previously changed instance
╖ Attendee initiated actions:
╖ Attendee changes status for a particular recurrence instance
╖ Attendee sends Event-Counter for a particular recurrence
instance
An instance of a recurring event is assigned a unique identification,
"RECURRENCE-ID" property, when that instance MUST be renegotiated.
Negotiation is necessary when the start time, end time, due date or
location are modified. If the "Organizer" wishes to identify a
specific recurrence instance it is done using the "RECURRENCE-ID"
property. The property value is equal to the date/time of the
instance. If the "Organizer" wishes to change the"DTSTART", the
original "DTSTART" value is used for"RECURRENCE-ID" property and the
new "DTSTART" and "DTEND" values reflect the change. If the
"Organizer" wishes to add a new instance to the recurring event then
a "REQUEST" is issued with an "RDATE" property equal to the new
instance date. It is recommended that the "Organizer" include the
"RECURRENCE-ID" property[SS1]. Since the creation of a new event
instance requires negotiation, the sequence number is also
incremented.
3.6.2 Attendee Property Considerations
The "ATTENDEE" property for the "Organizer" is required on published
events, to-dos, and journal entries for two reasons. First, a
published only the "Organizer" is allowed to update an event, to-do,
or journal entry component. The "Organizer" "ATTENDEE" property MUST
be present in the event, to-do, or journal entry component so that
the "CUA" has a basis for authorizing an update. Second, it is
prudent to provide a point of contact for anyone who receives a
published component in case of problems.
There are valid RFC 822 addresses that represent groups. Sending
email to such an address results in mail being sent to multiple
recipients. Such an address MAY be used as the value of an "ATTENDEE"
property. Thus, it is possible that the recipient of a "REQUEST" does
not appear explicitly in the list list.
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It is recommended that the general approach to finding a "Calendar
User" in an attendee list be as follows:
1. Search for the "Calendar User" in the attendee list where
"TYPE=INDIVIDUAL"
2. Failing (1) look for attendees where "TYPE=GROUP" or
'TYPE=UNKNOWN". The "CUA" MUST then determine if the "CU" is a
member of one of these groups. If so, the "REPLY" method sent to
the "Organizer" MUST contain a new "ATTENDEE" property in which
the "TYPE" property parameter is set to INDIVIDUAL and the
"GROUP" property parameter is set to the name of the group.
3. Failing (2) the "CUA" MAY ignore or accept the request as the
"Calendar User" wishes.
3.6.3 When To Refresh An Event
An "VEVENT" or "VTODO" calendar component SHOULD be resent to all
"Attendees" whenever the "SEQUENCE" property is incremented or any
other substantive change is made.
3.6.4 Timezones
If a recurring event has any instance where "DTSTART" and "DTEND"
fall on different sides of a time zone shift, the "VTIMEZONE"
components are required.
The threat of duplicate time zone definitions exists. SHOULD an
iCalendar object contain multiple conflicting time zone components,
the one with the latest "DTSTART" property supersedes the others.
3.6.5 Alarms
It is recommended that application software ask the user whether or
not they want alarms included when they read the event.
3.6.6 SUMMARY Property
The minimum support for the "SUMMARY" property in a recipient MUST be
for a 255 byte value. Implementations MAY truncate longer length
values.
3.6.7 X-Tokens
To make iCalendar objects extensible, new property types MAY be
inserted into components. These properties are called X-Tokens as
they are prefixed with "X-". A client is not required to make sense
of X-Tokens. Clients are not required to save X-Tokens or use them in
event replies.
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4 Examples
4.1 Published Event Examples
In the calendaring and scheduling context, publication refers to the
one way transfer of event information. Consumers of published events
simply incorporate the event into a calendar. No reply is expected.
Individual "A" publishes an event. Individual "B" reads the event and
incorporates it into their calendar. Events MAY be published in
several ways including: embedding the event as an object in a web
page, e-mailing the event to a distribution list, and posting the
event to a newsgroup.
The table below illustrates the sequence of events between the
publisher and the consumers of a published event.
+-------------------------------------------------------------------+
| Action | "Organizer" |
+---------------------------------+---------------------------------+
| Publish an event | "A" sends or posts a PUBLISH |
| | message |
+---------------------------------+---------------------------------+
| "B" reads a published event | |
+---------------------------------+---------------------------------+
| Publish an updated event | "A" sends or posts a PUBLISH |
| | message |
+---------------------------------+---------------------------------+
| "B" reads the updated event | |
+---------------------------------+---------------------------------+
| Cancel a published event | "A" sends or posts a CANCEL |
| | message |
+---------------------------------+---------------------------------+
| "B" reads the canceled event | |
| publication | |
+---------------------------------+---------------------------------+
4.1.1 A Minimal Published Event
The iCalendar object below describes a single event that begins on
July 1, 1997 at 20:00 UTC. This event contains the minimum set of
properties for a "PUBLISH" for a "VEVENT" calendar component.
BEGIN:VCALENDAR
METHOD:PUBLISH
PRODID:-//ACME/DesktopCalendar//EN
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER:a@host.com
DTSTART:19970701T200000Z
DTSTAMP:19970611T190000Z
SUMMARY:ST. PAUL SAINTS -VS- DULUTH-SUPERIOR DUKES
UID:0981234-1234234-23@host.com
END:VEVENT
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END:VCALENDAR
4.1.2 Changing A Published Event
The iCalendar object below describes an update to the event described
in 4.1.1, the time has been changed, an end time has been added, and
the sequence number has been adjusted.
BEGIN:VCALENDAR
METHOD:PUBLISH
VERSION:2.0
PRODID:-//ACME/DesktopCalendar//EN
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER:a@acme.com
DTSTAMP:19970612T190000Z
DTSTART:19970701T210000Z
DTEND:19970701T230000Z
SEQUENCE:2
UID:0981234-1234234-23@host.com
SUMMARY:ST. PAUL SAINTS -VS- DULUTH-SUPERIOR DUKES
END:VEVENT
END:VCALENDAR
The "UID" property is used by the client to identify the event. The
"SEQUENCE" property indicates that this is the second change to the
event. Events with sequence numbers 0 and 1 are superseded by this
event.
The "SEQUENCE" property provides a reliable way to distinguish
different versions of the same event. Each time an event is
published, its sequence number is incremented. If a client receives
an event with a sequence number 5 and finds it has the same event
with sequence number 2, the event SHOULD be updated. However, if the
client received an event with sequence number 2 and finds it already
has sequence number 5 of the same event, the event SHOULD NOT be
updated.
4.1.3 Canceling A Published Event
The iCalendar object below cancels the event described in 4.1.1. This
cancels the event with "SEQUENCE" property of 0, 1, and 2.
BEGIN:VCALENDAR
METHOD:CANCEL
VERSION:2.0
PRODID:-//ACME/DesktopCalendar//EN
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER:a@acme.com
COMMENT:DUKES forfeit the game
SEQUENCE:2
UID:0981234-1234234-23@host.com
DTSTAMP:19970613T190000Z
STATUS:CANCELLED
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END:VEVENT
END:VCALENDAR
4.1.4 A Rich Published Event
This example describes the same event as in 4.1.1, but in much
greater detail.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:PUBLISH
CALSCALE:GREGORIAN
SOURCE:http://www.midwaystadium.com/stadium-cal/1997-events.or4
NAME:1997 GAME SCHEDULE
VERSION:2.0
BEGIN:VTIMEZONE
DAYLIGHT:TRUE
DTSTART:19970406T070000-0600
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZNAME:CDT
TZOFFSET:-0500
END:VTIMEZONE
BEGIN:VTIMEZONE
DAYLIGHT:FALSE
DTSTART:19971026T0200-0500
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZNAME:CST
TZOFFSET:-0600
END:VTIMEZONE
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER:a@acme.com
ATTACH:http://www.midwaystadium.com
CATEGORIES:SPORTS EVENT;ENTERTAINMENT
CLASS:PRIVATE
CREATED:19970415T194319Z
DESCRIPTION:MIDWAY STADIUM\n
Big time game. MUST see.\n
Expected duration:2 hours\n
DTEND:19970701T180000
DTSTART:19970702T160000
DTSTAMP:19970614T190000Z
STATUS:CONFIRMED
LAST-MODIFIED:19970416T162421Z
LOCATION;VALUE=URL:http://www.midwaystadium.com/
PRIORITY:2
RESOURCES:SCOREBOARD
SEQUENCE:3
SUMMARY:ST. PAUL SAINTS -VS- DULUTH-SUPERIOR DUKES
UID:0981234-1234234-23@host.com
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RELATED-TO:0981234-1234234-14@host.com
BEGIN:VALARM
DTSTART:19970701T190000Z
REPEAT:2
DURATION:PT2H
CATEGORIES:DISPLAY,AUDIO
DESCRIPTION:ItÆs almost game time
END:VALARM
BEGIN:VALARM
DTSTART:19970701T153000
CATEGORIES:DISPLAY,AUDIO
DESCRIPTION:You SHOULD leave now. Game starts in 30 min!
END:VALARM
END:VEVENT
END:VCALENDAR
The "CLASS" property is specified, though it is not really needed
here. Since this is a published event, a program that displays it
need not apply any content filtering based on the "CLASS" attribute.
If this event is copied into a userÆs calendar, the "CLASS" would be
included as part of the copy. The handling of the "CLASS" tag at
that point is implementation specific.
The "RELATED-TO" field contains the "UID" property of a related
calendar event. The handling of this property is application
dependent.
The "SEQUENCE" property 3 indicates that this event supersedes
versions 0, 1, and 2.
4.1.5 Anniversaries or Events attached to entire days
This example demonstrates the use of the "value" parameter to tie a
VEVENT to day rather than a specific time.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:PUBLISH
VERSION:2.0
BEGIN:VEVENT
DTSTAMP:19970614T190000Z
UID:0981234-1234234-23@host.com
DTSTART;VALUE=DATE:19970714
RRULE:FREQ=YEARLY;INTERVAL=1
SUMMARY: Bastille Day
END:VEVENT
END:VCALENDAR
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4.2 Group Event Examples
Group events are distinguished from published events in that they
have "Attendees" and that there is interaction between the
"Attendees" with respect to the event. Individual "A" requests a
meeting between individuals "A", "B", "C" and "D". Individual "B"
confirms attendance to the meeting. Individual "C" declines
attendance. Individual "D" tentatively confirms their attendance.
This is sometimes referred to as "penciling-in" the event on a
calendar. The following table illustrates the sequence of messages
that would be exchanged between these individuals. The table below
illustrates the message flow.
+--------------------------------------------------------------------+
| Action | "Organizer" | Attendee |
+--------------------------------------------------------------------+
| Initiate a meeting | "A" sends a REQUEST | |
| request | message to "B", "C",| |
| | and "D" | |
+--------------------------------------------------------------------+
| Accept the meeting | | "B" sends a REPLY |
| request | | message to "A" with its |
| | | ATTENDEE STATUS para- |
| | | set to "ACCEPTED" |
+--------------------------------------------------------------------+
| Decline the meeting| | "C" sends a REPLY |
| request | | message to "A" with its |
| | | ATTENDEE STATUS para- |
| | | set to "DECLINED" |
+--------------------------------------------------------------------+
| Tentatively accept | | "D" sends a REPLY |
| the meeting request| | message to "A" with its |
| | | ATTENDEE STATUS para- |
| | | set to "TENTATIVE" |
+--------------------------------------------------------------------+
| Confirm meeting | "A" sends a REQUEST | |
| status with | message to "B" and | |
| attendees | "C" with updated | |
| | information. | |
+--------------------------------------------------------------------+
4.2.1 A Group Event Request
A sample meeting request that "A" sends to "B", "C", and "D".
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
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ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:D@acme.com
ATTENDEE;RSVP=NO;EXPECT=REQUIRE;TYPE=ROOM:CR_Big_One@acme.com
DTSTAMP:19970611T190000Z
DTSTART:19970701T100000-0700
DTEND:19970701T103000-0700
SUMMARY:Phone Conference
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
4.2.2 Reply To A Group Event Request
Attendee "B" accepts the meeting.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;STATUS=ACCEPTED:B@acme.com
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
REQUEST-STATUS:2.0;Success
DTSTAMP:19970612T190000Z
END:VEVENT
END:VCALENDAR
"B" could have declined the meeting or indicated tentative acceptance
by setting the ATTENDEE;"STATUS" parameter to DECLINED or TENTATIVE,
respectively.
4.2.3 Update An Event
The event is moved to a different time. The combination of the "UID"
property(which remains the same) and the SEQUENCE (bumped to 1)
properties indicate the update.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:D@acme.com
ATTENDEE;RSVP=NO;EXPECT=REQUIRE;TYPE=ROOM:CR_Big_One@acme.com
DTSTART:19970701T110000-0700
DTEND:19970701T113000-0700
SUMMARY:Phone Conference
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UID:www.acme.com-873970198738777@host.com
SEQUENCE:1
DTSTAMP:19970613T190000Z
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
4.2.4 Countering an Event Proposal
Attendee A sends "REQUEST" to B and C. B makes a counter proposal to
A to change the time and location.
Attendee A sends "REQUEST":
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
DTSTART:19970701T190000Z
DTEND:19970701T200000Z
SUMMARY:Discuss the Merits of the election results
LOCATION:The Big Conference Room
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
DTSTAMP:19970611T190000Z
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
Attendee B sends "COUNTER" to A, requesting changes to time and
place:
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:COUNTER
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
DTSTART:19970701T160000Z
DTEND:19970701T190000Z
DTSTAMP:19970612T190000Z
SUMMARY:Discuss the Merits of the election results
LOCATION:The Small Conference Room
COMMENT:This time works much better and I think the big conference
room is too big
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
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DTSTAMP:19970611T190000Z
END:VEVENT
END:VCALENDAR
Attendee A accepts the changes from B
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
DTSTAMP:19970613T190000Z
DTSTART:19970701T160000Z
DTEND:19970701T190000Z
SUMMARY:Discuss the Merits of the election results - changed to
suite B's schedule
LOCATION:The Small Conference Room
UID:www.acme.com-873970198738777@host.com
SEQUENCE:1
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
A rejects B's counter proposal
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:COUNTERDECLINE
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
COMMENT:Sorry, I cannot change this meeting time
UID:www.acme.com-873970198738777@host.com
SEQUENCE:1
DTSTAMP:19970614T190000Z
END:VEVENT
4.2.5 Delegate An Event
When delegating an event request to another "Calendar User", the
"delegator" MUST both update the "Organizer" with a "REPLY" and send
a request to the "delegatee". There is currently no protocol
limitation to delegation depth. It is possible for the original
delegate to delegate the meeting to someone else, and so on. When a
request is delegated from one "CUA" to another there are a number of
responsibilities required of the "delegator". They MUST:
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╖ Send an REPLY to the "Organizer" with their attendee/status
property parameter set to "Delegated"
╖ Include the delegate as an additional attendee with the
"Delegated-From" property parameter set to the delegator
╖ Include the original UID of the REQUEST
╖ The delegator MUST also send a copy of the original REQUEST to
the delegate. The delegator modifies the request to include:
╖ The ATTENDEE/STATUS property parameter for the delegator
(sender in this case) is set to "DELEGATED"
╖ ATTENDEE/DELEGATED-TO parameter is set to the address of the
delegatee
╖ An ATTENDEE property is added for delegatee
As a rule, it is not required that the "delegatee" include the
"delegator" in their "REPLY" method. However, it is strongly advised
since this will inform the "delegator" whether their proxy plans to
attend the meeting. If the "delegatee" declines the meeting, the
"delegator" MAY elect to try and delegate the "REQUEST" to another
"CUA". The process is the same.
+---------------------------------------------------------------------+
| Action | "Organizer" | Attendee |
+---------------------------------------------------------------------+
| Initiate a meeting | "A" sends a REQUEST | |
| request | message to "B" and | |
+---------------------------------------------------------------------+
| Delegate: | | "C" sends a REPLY to "A" |
| "C" delegates to | | with the ATTENDEE.STATUS |
| "E" | | parameter set to |
| | | "DELEGATED" and with a |
| | | new ATTENDEE property |
| | | for "E". "E's" ATTENDEE |
| | | DELEGATED-FROM property |
| | | is set to "C". "C's" |
| | | ATTENDEE.DELEGATED-TO |
| | | property is set to "E". |
| | | "C" sends REQUEST message|
| | | to "E" with the original |
| | | meeting request |
| | | information. The |
| | | ATTENDEE/STATUS property |
| | | parameter for "C" is set |
| | | to "DELEGATED" and the |
| | | ATTENDEE/DELEGATED-TO |
| | | parameter is set to |
| | | the address of "E". An |
| | | ATTENDEE property is |
| | | added for "E" and the |
| | | ATTENDEE/DELEGATED-FROM |
| | | parameter is set to |
| | | the address of "C". |
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+---------------------------------------------------------------------+
| Confirm meeting | | "E" sends REPLY message |
| attendance | | to "A" and optionally "C"|
| | | with its ATTENDEE/STATUS |
| | | property parameter set |
| | | to "ACCEPTED" |
+---------------------------------------------------------------------+
| Optional: | "A" sends REQUEST | |
| Redistribute | message to "B", "C" | |
| meeting to | and "E". SEQUENCE | |
| attendees | number is now 1. | |
+---------------------------------------------------------------------+
Attendee "C" responds to meeting "Organizer" "A"
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=ATTENDEE;STATUS=DELEGATED;DELEGATED-
TO=E@acme.com:C@acme.com
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
REQUEST-STATUS:2.0;Success
DTSTAMP:19970611T190000Z
END:VEVENT
END:VCALENDAR
Attendee "C" delegates presence at the meeting to "E".
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=Organizer;STATUS=ACCEPTED:A@acme.com
ATTENDEE;ROLE=DELEGATE;RSVP=YES;EXPECT=REQUEST;
DELEGATED-FROM=C@acme.com:E@acme.com
ATTENDEE;ROLE=ATTENDEE;STATUS=DELEGATED;
DELEGATED-TO=E@acme.com:C@acme.com
DTSTART:19970701T110000-0700
DTEND:19970701T113000-0700
SUMMARY:Phone Conference
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
STATUS:CONFIRMED
DTSTAMP:19970611T190000Z
END:VEVENT
END:VCALENDAR
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4.2.6 Delegate Accepts the Meeting
To accept a delegated meeting, the delegate sends the following
message to "A" and "C"
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=ATTENDEE;STATUS=CONFIRMED;
DELEGATED-FROM=C@acme.com:E@acme.com
UID:www.acme.com-873970198738777@host.com
SEQUENCE:1
REQUEST-STATUS:2.0;Success
DTSTAMP:19970614T190000Z
END:VEVENT
END:VCALENDAR
4.2.7 Delegate Declines the Meeting
In this example the delegate declines the meeting request and sets
the "ATTENDEE" property "STATUS" parameter to DECLINED. The
"Organizer" SHOULD resend the "REQUEST" to "C" with the status of the
delegate set to DECLINED. This lets the "delegator" know that the
"delegate" has declined and provides an opportunity to the
"delegator" to either accept or delegate the request to another
"Calendar User".
Response from "E" to "A" and "C".
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=ATTENDEE;STATUS=DECLINED;
DELEGATED-FROM=C@acme.com:E@acme.com
UID:www.acme.com-873970198738777@host.com
SEQUENCE:1
REQUEST-STATUS:2.0;Success
DTSTAMP:19970614T190000Z
END:VEVENT
END:VCALENDAR
"A" resends the "REQUEST" method to "C". "A" MAY also wish to express
the fact that the item was delegated in the "COMMENT" property.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
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ATTENDEE;ROLE=ATTENDEE;STATUS=DECLINED;
DELEGATED-FROM=C@acme.com:E@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
UID:www.acme.com-873970198738777@host.com
SEQUENCE:2
REQUEST-STATUS:2.0;Success
DTSTAMP:19970614T200000Z
COMMENT:DELEGATE (ATTENDEE E@acme.com) DECLINED YOUR INVITATION
END:VEVENT
END:VCALENDAR
4.2.8 Forwarding an Event Request
The protocol does not prevent an "Attendee" from "forwarding" an
"VEVENT" calendar component to other "Calendar Users". Forwarding
differs from delegation in that the forwarded "Calendar User" (often
referred to as a "Party Crasher") does not replace the forwarding
"Calendar User". Implementations are not required to add the "Party
Crasher" to the "Attendee" list and hence there is no guarantee that
a "Party Crasher" will receive additional updates to the Event. The
forwarding "Calendar User" SHOULD NOT add the "Party Crasher" to the
attendee list.
4.2.9 Cancel A Group Event
Individual "A" requests a meeting between individuals "A", "B" and
"C". Individual "B" declines attendance to the meeting. Individual
"A" decides to cancel the meeting. The following table illustrates
the sequence of messages that would be exchanged between these
individuals.
Messages related to a previously canceled event ("SEQUENCE" property
value is less than the "SEQUENCE" property value of the "CANCEL"
message) or "VTODO" calendar component MUST be ignored.
+--------------------------------------------------------------------+
| Action | "Organizer" | Attendee |
+--------------------------------------------------------------------+
| Initiate a meeting | "A" sends a REQUEST | |
| request | message to "B" and | |
| | and "C" | |
+--------------------------------------------------------------------+
| Decline the meeting| | "B" sends a REPLY |
| request | | message to "A" with its |
| | | ATTENDEE STATUS para- |
| | | set to "DECLINED". |
+--------------------------------------------------------------------+
| Cancel the meeting | "A" sends a CANCEL | |
| | message to "B" and | |
| | "C" | |
+--------------------------------------------------------------------+
The example shows how "A" cancels the event.
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BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:CANCEL
VERSION:2.0
BEGIN:VEVENT
COMMENT:Mr. B cannot attend. IÆll reschedule the meeting later.
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
DTSTAMP:19970613T190000Z
STATUS:CANCELLED
END:VEVENT
END:VCALENDAR
The "Organizer" of a meeting MAY "uninvite" or remove "Attendees" by
sending a "CANCEL" method to only those "Attendees".
4.3 Busy Time Examples
Individual "A" requests busy time from individuals "B", "C" and "D".
Individual "B" and "C" replies with busy time data to individual "A".
Individual "D" does not support busy time requests and does not reply
with any data.
The following table illustrates the sequence of messages that would
be exchanged between these individuals.
+--------------------------------------------------------------------+
| Action | "Organizer" | Attendee |
+--------------------------------------------------------------------+
| Initiate a busy | "A" sends a REQUEST | |
| time request | message to "B" and | |
| | and "C" | |
+--------------------------------------------------------------------+
| Reply to the busy | | "B" sends a REPLY |
| request with busy | | message to "A" with |
| time data | | busy time data |
+--------------------------------------------------------------------+
4.3.1 Request Busy Time
"A" sends a BUSY-"REQUEST" to "B" and "C" for busy time
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VFREEBUSY
ATTENDEE;ROLE=OWNER:A@acme.com
ATTENDEE:B@acme.com
ATTENDEE:C@acme.com
DTSTAMP:19970613T190000Z
DTSTART:19970701T080000-0700
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DTEND:19970701T200000-0700
UID:www.acme.com-873970198738777@host.com
END:VFREEBUSY
END:VCALENDAR
4.3.2 Reply To A Busy Time Request
"B" sends a "REPLY" method type of a "VFREEBUSY" calendar component
to "A"
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VFREEBUSY
ATTENDEE:B@acme.com
DTSTART:19970701T080000-0700
DTEND:19970701T200000-0700
UID:www.acme.com-873970198738777@host.com
FREEBUSY:19970701T090000-0700/PT1H,19970701T140000-0700/PT30H
DTSTAMP:19970613T190030Z
END:VFREEBUSY
END:VCALENDAR
B is busy from 09:00 to 10:00 and from 14:00 to 14:30.
4.4 Recurring Event and Time Zone Examples
4.4.1 A Recurring Event Spanning Time Zones
This event describes a weekly phone conference. The "Attendees" are
each in a different time zone.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VTIMEZONE
DAYLIGHT:TRUE
DTSTART:19970406T200000-0800
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZNAME:PDT
TZOFFSET:-0700
END:VTIMEZONE
BEGIN:VTIMEZONE
DAYLIGHT:FALSE
DTSTART:19971026T200000-0700
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZNAME:PST
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TZOFFSET:-0800
END:VTIMEZONE
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:sman@mcom.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:gb@mcom.fr
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:kimiko@mcom.jp
DTSTAMP:19970613T190030Z
DTSTART:19970701T140000
DTEND:19970701T150000
RRULE:FREQ=WEEKLY;INTERVAL=20;WKST=SU;BYDAY=TU
RDATE:19970910T140000
EXDATE:19970909T140000
EXDATE:19971028T150000
SUMMARY:Weekly Phone Conference
UID:www.acme.com-873970198738777@host.com
SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
The "VTIMEZONE" components SHOULD appear in an iCalendar object
containing recurring events. This is especially important if a
recurring event has "Attendees" in different time zones. There MAY be
multiple VTIMEZONE components in an iCalendar object, however, they
MUST be used to define the same time zone. That is, there cannot be
VTIMEZONE components describing both PST/PDT and EST/EDT at the
component level in the same iCalendar object.
The first two components of this iCalendar object are the time zone
components. The "DTSTART" date coincides with the first instance of
the RRULE property.
The recurring meeting is defined in a particular time zone,
presumably that of the originator. The client for each "Attendee" has
the responsibility of determining the recurrence time in the
"Attendee's" time zone.
The repeating event starts on Tuesday, July 1, 1997 at 2:00pm. Since
no time zone is specified in the "DTSTART" property, the time zone
component of PDT applies to the start and end times. "Attendee"
gb@mcom.fr is in France where the local time on this date is 7 hours
later than PDT or 21:00. "Attendee" kimiko@mcom.jp is in Japan where
local time is 9 hours ahead of than UTC or Wednesday, July 2 at
07:00. The event repeats weekly on Tuesdays (in PST/PDT). The "RRULE"
property results in 20 instances. The last instance falls on Tuesday,
November 11, 1997 2:00pm PST. The "RDATE" property adds another
instance: WED, 10-SEP-1997 21:00 GMT.
There are two exceptions to this recurring appointment. The first one
is:
TUE, 09-SEP-1997 21:00 GMT
TUE, 09-SEP-1997 14:00 PDT
WED, 10-SEP-1997 07:00 JDT
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and the second is:
TUE, 28-OCT-1997 22:00 GMT
TUE, 28-OCT-1997 14:00 PST
WED, 29-OCT-1997 07:00 JST
4.4.2 Modify A Recurring Instance
In this example the "Organizer" issues a recurring meeting. Later the
"Organizer" changes an instance of the event by changing the
"DTSTART" property. Note the use of "RECURRENCE-ID" property and
"SEQUENCE" property in the second request.
Original Request:
BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:19970526T083000
UID:guid-1@host1.com
SEQUENCE:0
RRULE:FREQ=MONTHLY;BYMONTHDAY=1;UNTIL=19980901T210000Z
ATTENDEE;EXPECT=REQUEST:Sman@netscape.com
ATTENDEE;EXPECT=REQUEST:Frank_Dawson@Lotus.com
ATTENDEE;EXPECT=REQUEST:Deriks@Microsoft.com
ATTENDEE;EXPECT=REQUEST:Alecd@Microsoft.com
DESCRIPTION:IETF-C&S Conference Call
CLASS:PUBLIC
SUMMARY:IETF Calendaring Working Group Meeting
DTSTART:19970601T210000Z
DTEND:19970601T220000Z
LOCATION:Conference Call
DTSTAMP:19970526T083000
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
The event request below is to change a time and create an exception.
This creates an exception on July 3rd.
BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:19970526T083000
UID:guid-1@host1com
RECURRENCE-ID:19970701T210000Z
SEQUENCE:1
RRULE:FREQ=MONTHLY;BYMONTHDAY=1;UNTIL=19980901T210000Z
ATTENDEE;EXPECT=REQUEST:Sman@netscape.com
ATTENDEE;EXPECT=REQUEST:Frank_Dawson@Lotus.com
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ATTENDEE;EXPECT=REQUEST:Deriks@Microsoft.com
ATTENDEE;EXPECT=REQUEST:Alecd@Microsoft.com
DESCRIPTION:IETF-C&S Conference Call
CLASS:PUBLIC
SUMMARY:IETF Calendaring Working Group Meeting
DTSTART:19970703T210000Z
DTEND:19970703T220000Z
LOCATION:Conference Call
DTSTAMP:19970626T093000
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
4.4.3 Cancel A Recurring Instance
In this example the "Organizer" of a recurring event wishes to delete
an instance. This is referred to as an "exception" to the recurring
event.
BEGIN:VCALENDAR
METHOD:CANCEL
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
UID:guid-1@host1.com
RECURRENCE-ID:19970801T210000Z
SEQUENCE:2
DTSTAMP:19970721T093000
STATUS:CANCELLED
END:VEVENT
END:VCALENDAR
4.4.4 Cancel An Exception
In the following example, the "Organizer" has created an exception
(as in 4.4.3) and now wishes to cancel it. In this case a "CANCEL"
method is sent with the specific "RECURRENCE-ID", "UID" and
"SEQUENCE" properties of the exception. This same sequence MAY be
used to decline a previously accepted modification to a recurring
event (as in 4.4.2).
BEGIN:VCALENDAR
METHOD:CANCEL
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
UID:guid-1@host1.com
RECURRENCE-ID:19970801T210000Z
SEQUENCE:2
DTSTAMP:19970721T103000
STATUS:CANCELLED
END:VEVENT
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END:VCALENDAR
4.4.5 Cancel Recurring Event
In this example the "Organizer" wishes to cancel the entire recurring
event and any child exceptions.
BEGIN:VCALENDAR
METHOD:CANCEL
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
UID:guid-1@host1.com
DTSTAMP:19970721T103000
SEQUENCE:2
STATUS:CANCELLED
END:VEVENT
END:VCALENDAR
4.4.6 Change All Future Instances
This example changes the meeting location from a conference call to
Seattle starting Sept 1 and extends to all future instances.
BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:19970526T083000
UID:guid-1@host1.com
RECURRENCE-ID;THISANDFUTURE:19970901T210000Z
SEQUENCE:3
RRULE:FREQ=MONTHLY;BYMONTHDAY=1;UNTIL=19980901T210000Z
ATTENDEE;EXPECT=REQUEST:Sman@netscape.com
ATTENDEE;EXPECT=REQUEST:Frank_Dawson@Lotus.com
ATTENDEE;EXPECT=REQUEST:Deriks@Microsoft.com
ATTENDEE;EXPECT=REQUEST:Alecd@Microsoft.com
DESCRIPTION:IETF-C&S Conference Call
CLASS:PUBLIC
SUMMARY:IETF Calendaring Working Group Meeting
DTSTART:19970901T210000Z [SS2][SS3]
DTEND:19970901T220000Z
LOCATION:Building 32, Microsoft, Seattle, WA
DTSTAMP:19970526T083000
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
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4.4.7 Add A New Instance To A Recurring Event
This example adds a one-time additional instance to the recurring
event. "Organizer" adds a second July meeting on the 15th.
BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:19970526T083000
UID:guid-1@host1.com
RECURRENCE-ID:19970715T210000Z
SEQUENCE:4
RRULE:FREQ=MONTHLY;BYMONTHDAY=1;UNTIL=19980901T210000Z
RDATE;VALUE=PERIOD:19970715T210000Z/19970715T220000Z
ATTENDEE;EXPECT=REQUEST:Sman@netscape.com
ATTENDEE;EXPECT=REQUEST:Frank_Dawson@Lotus.com
ATTENDEE;EXPECT=REQUEST:Deriks@Microsoft.com
ATTENDEE;EXPECT=REQUEST:Alecd@Microsoft.com
DESCRIPTION:IETF-C&S Conference Call
CLASS:PUBLIC
SUMMARY:IETF Calendaring Working Group Meeting
DTSTART:19970715T210000Z
DTEND:19970715T220000Z
LOCATION:Conference Call
DTSTAMP:19970629T093000
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
4.4.8 Counter An Instance Of A Recurring Event
In this example one of the "Attendees" counters the "DTSTART"
property of the proposed second July meeting.
BEGIN:VCALENDAR
METHOD:COUNTER
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:19970526T083000
UID:guid-1@host1.com
RECURRENCE-ID:19970715T210000Z
SEQUENCE:4
RRULE:FREQ=MONTHLY;BYMONTHDAY=1;UNTIL=19980901T210000Z
ATTENDEE;EXPECT=REQUEST:Sman@netscape.com
ATTENDEE;EXPECT=REQUEST:Frank_Dawson@Lotus.com
ATTENDEE;EXPECT=REQUEST:Deriks@Microsoft.com
ATTENDEE;EXPECT=REQUEST:Alecd@Microsoft.com
DESCRIPTION:IETF-C&S Conference Call
CLASS:PUBLIC
SUMMARY:IETF Calendaring Working Group Meeting
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DTSTART:19970715T220000Z
DTEND:19970715T230000Z
LOCATION:Conference Call
COMMENT:May we bump this by an hour? I have a conflict
DTSTAMP:19970629T094000
END:VEVENT
END:VCALENDAR
4.4.9 Error Reply To A request
The following example illustrates a scenario where a meeting is
proposed that contains a property that is not supported (in this
case, the "RRULE" property).
Original Request:
BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:19970526T083000
UID:guid-1@host1.com
SEQUENCE:0
RRULE:FREQ=MONTHLY;BYMONTHDAY=1
ATTENDEE;EXPECT=REQUEST:Sman@netscape.com
ATTENDEE;EXPECT=REQUEST:Frank_Dawson@Lotus.com
ATTENDEE;EXPECT=REQUEST:Deriks@Microsoft.com
ATTENDEE;EXPECT=REQUEST:Alecd@Microsoft.com
DESCRIPTION:IETF-C&S Conference Call
CLASS:PUBLIC
SUMMARY:IETF Calendaring Working Group Meeting
DTSTART:19970601T210000Z
DTEND:19970601T220000Z
DTSTAMP:19970602T094000
LOCATION:Conference Call
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
Response to indicate that RRULE is not supported:
BEGIN:VCALENDAR
PRODID:-//RDU Software//NONSGML HandCal//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
REQUEST-STATUS:2.8;Repeating event ignored. Scheduled as a single
event;RRULE
UID:guid-1@host1.com
SEQUENCE:0
DTSTAMP:19970603T094000
END:VEVENT
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END:VCALENDAR
4.5 Group To-do Examples
Individual "A" creates a group task in which individuals "A", "B",
"C" and "D" will participate. Individual "B" confirms acceptance of
the task. Individual "C" declines the task. Individual "D"
tentatively accepts the task. The following table illustrates the
sequence of messages that would be exchanged between these
individuals. Individual "A" then issues a "REFRESH" method to obtain
the status of the to-do from each participant. The response indicates
the individual "Attendee's" completion status. The table below
illustrates the message flow.
+--------------------------------------------------------------------+
| Action | "Organizer" | Attendee |
+--------------------------------------------------------------------+
| Initiate a to-do | "A" sends a REQUEST | |
| request | message to "B", "C",| |
| | and "D" | |
+--------------------------------------------------------------------+
| Accept the to-do | | "B" sends a REPLY |
| request | | message to "A" with its |
| | | ATTENDEE STATUS para- |
| | | set to "ACCEPTED". |
+--------------------------------------------------------------------+
| Decline the to-do | | "C" sends a REPLY |
| request | | message to "A" with its |
| | | ATTENDEE STATUS para- |
| | | set to "DECLINED". |
+--------------------------------------------------------------------+
| Tentatively accept | | "D" sends a REPLY |
| the to-do request | | message to "A" with its |
| | | ATTENDEE STATUS para- |
| | | set to "TENTATIVE". |
+--------------------------------------------------------------------+
| Check attendee | "A" sends a REFRESH | |
| completion status | message to "B" and | |
| | "C" with current | |
| | information. | |
+--------------------------------------------------------------------+
| Attendee indicates | | "B" sends a REPLY |
| percent complete | | message indicating |
| | | percent complete |
+--------------------------------------------------------------------+
| Attendee indicates | | "C" sends a REPLY |
| completion | | message indicating |
| | | completion |
+--------------------------------------------------------------------+
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4.5.1 A VTODO Request
A sample "REQUEST" with for a "VTODO" calendar component that "A"
sends to "B", "C", and "D".
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VTODO
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:D@acme.com
DTSTART:19970701T100000-0700
DUE:19970722T100000-0700
SUMMARY:Create the requirements document
UID:www.acme.com-873970198738777-00@host.com
SEQUENCE:0
DTSTAMP:19970717T200000Z
STATUS:CONFIRMED
END:VTODO
END:VCALENDAR
4.5.2 A VTODO Reply
Attendee "B" accepts the meeting.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VTODO
ATTENDEE;STATUS=ACCEPTED:B@acme.com
UID:www.acme.com-873970198738777-00@host.com
COMMENT:I'll send you my input by e-mail
SEQUENCE:0
DTSTAMP:19970717T203000Z
REQUEST-STATUS:2.0;Success
END:VTODO
END:VCALENDAR
"B" could have declined the meeting or indicated tentative acceptance
by setting the "ATTENDEE;STATUS=" property parameter sequence to
DECLINED or TENTATIVE, respectively.
4.5.3 A VTODO Refresh
"A" requests status from all "Attendees".
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
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METHOD:REFRESH
VERSION:2.0
BEGIN:VTODO
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:D@acme.com
UID:www.acme.com-873970198738777-00@host.com
DTSTAMP:19970717T230000Z
END:VTODO
END:VCALENDAR
4.5.4 A Refresh Reply: Percent-Complete
A reply indicating that the task in being worked on and that "B" is
75% complete with "B's" part of the assignment.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VTODO
ATTENDEE;STATUS=IN-PROCESS:B@acme.com
PERCENT-COMPLETE:75
UID:www.acme.com-873970198738777-00@host.com
DTSTAMP:19970717T233000Z
SEQUENCE:0
END:VTODO
END:VCALENDAR
4.5.5 A Refresh Reply: Completed
A reply indicating that "C" finished with "C's" part of the
assignment.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VTODO
ATTENDEE;STATUS=COMPLETED:C@acme.com
UID:www.acme.com-873970198738777-00@host.com
DTSTAMP:19970717T233000Z
SEQUENCE:0
END:VTODO
END:VCALENDAR
4.5.6 An Updated VTODO Request
Owner "A" resends the "VTODO" calendar component. "A" set's the
overall completion for the to-do at 40%.
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BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VTODO
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;STATUS=ACCEPTED;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;STATUS=COMPLETED;TYPE=INDIVIDUAL:C@acme.com
ATTENDEE;STATUS=TENTATIVE;TYPE=INDIVIDUAL:D@acme.com
DTSTART:19970701T100000-0700
DUE:19970722T100000-0700
SUMMARY:Create the requirements document
UID:www.acme.com-873970198738777-00@host.com
SEQUENCE:1
DTSTAMP:19970718T100000Z
STATUS:IN-PROGRESS
PERCENT-COMPLETE:40
END:VTODO
END:VCALENDAR
4.5.7 A Recurring VTODOs
The following examples relate to recurring "VTODO" calendar
components.
4.5.7.1 Request for a Recurring VTODO
In this example "A" sends a recurring "VTODO" calendar component to
"B" and "C".
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VTODO
ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:A@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:B@acme.com
ATTENDEE;RSVP=YES;EXPECT=REQUEST;TYPE=INDIVIDUAL:C@acme.com
RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR
DTSTART:19980101T100000-0700
DUE:19980103T100000-0700
SUMMARY:Send Status Reports to Area Managers
UID:www.acme.com-873970198738777-00@host.com
SEQUENCE:0
DTSTAMP:19970717T200000Z
STATUS:CONFIRMED
END:VTODO
END:VCALENDAR
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4.5.7.2 Calculating due dates in recurring VTODOs
The due date in a recurring "VTODO" calendar component is either a
fixed interval specified in the "REQUEST" method or specified
specifically using the "RECURRENCE-ID" property. The former is
calculated by applying the difference between "DTSTART" and "DUE"
properties and applying it to each of the start of each recurring
instance. Hence, if the initial "VTODO" calendar component specifies
a "DTSTART" property value of "19970701T190000Z" and a "DUE" property
value of "19970801T190000Z" the interval of one day which could be
applied to each recurring instance of the "VTODO" calendar component.
4.5.7.3 Replying to an instance of a recurring VTODO
In this example "B" updates "A" on a single instance of the "VTODO"
calendar component.
BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VTODO
ATTENDEE;STATUS=IN-PROCESS:B@acme.com
PERCENT-COMPLETE:75
UID:www.acme.com-873970198738777-00@host.com
DTSTAMP:19970717T233000Z
RECURRENCE-ID:19980101T100000-0700
SEQUENCE:0
END:VTODO
END:VCALENDAR
4.6 Journal Examples
The iCalendar object below describes a single journal entry for
October 2, 1997. The "RELATED-TO" property references the phone
conference event for which minutes were taken.
BEGIN:VCALENDAR
PROFILE:PUBLISH
PRODID:-//ACME/DesktopCalendar//EN
VERSION:2.0
BEGIN:VJOURNAL
DTSTART:19971002T200000Z
SUMMARY:Phone conference minutes
DESCRIPTION:The editors meeting was held on October 1, 1997.
Details are in the attached document.
UID:0981234-1234234-2410@host.com
RELATED-TO:0981234-1234234-2402-35@host.com
ATTACH:ftp\://ftp.example.com/pub/ed/minutes100197.txt
END:VJOURNAL
END:VCALENDAR
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4.7 Other Examples
4.7.1 Event Refresh
Refresh the event with "UID" property value of "guid-1-
12345@host1.com":
BEGIN:VCALENDAR
PRODID:-//RDU Software//NONSGML HandCal//EN
METHOD:REFRESH
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;ROLE=OWNER;EXPECT=REQUEST:Sman@netscape.com
ATTENDEE;EXPECT=REQUEST:Frank_Dawson@Lotus.com
ATTENDEE;EXPECT=REQUEST:Deriks@Microsoft.com
ATTENDEE;EXPECT=REQUEST:Alecd@Microsoft.com
UID: guid-1-12345@host1.com
DTSTAMP:19970603T094000
END:VEVENT
END:VCALENDAR
4.7.2 Bad RECURRENCE-ID
If an "Attendee" receives a request that references a "RECURRENCE-ID"
property that can not be found, the "Attendee" SHOULD send a
"REFRESH" method back to the "Organizer" for the latest copy of the
event.
+--------------------------------------------------------------------+
| Action | "Organizer" | Attendee |
+--------------------------------------------------------------------+
| Update an instance | "A" sends a REQUEST | |
| request | message to "B" | |
+--------------------------------------------------------------------+
| Attendee requests | | "B" sends a REFRESH |
| refresh because | | message to "A" |
| RecurrenceID was | | |
| not found | | |
+--------------------------------------------------------------------+
| Refresh the entire | "A" sends the | |
| Event | latest copy of the | |
| | Event to "B" | |
+--------------------------------------------------------------------+
| Attendee handles | | "B" updates to the |
| the request and | | latest copy of the |
| updates the | | meeting. |
| instance | | |
+--------------------------------------------------------------------+
Request from "A":
BEGIN:VCALENDAR
METHOD:REQUEST
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PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
UID:acme-12345@host1.com
SEQUENCE:3
RRULE:FREQ=WEEKLY
RDATE;VALUE=PERIOD:19970819T210000Z/199700819T220000Z
ATTENDEE;STATUS=ACCEPTED;ROLE=OWNER:sman@netscape.com
ATTENDEE;EXPECT=REQUEST:stevesil@microsoft.com
DESCRIPTION:IETF-C&S Conference Call
SUMMARY:IETF Calendaring Working Group Meeting
DTSTART:19970801T210000Z
DTEND:19970801T220000Z
DTSTAMP:19970726T083000
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR
"B" has the event with "UID" property"acme-12345@host1.com" but the
"SEQUENCE" property value is "1" and the event does not have an
instance at the specified recurrence time. This means that the
"Owner" is either adding a new instance or that the new instance was
added when "SEQUENCE" property value "2" of the event was generated.
In either case, "B" needs a new copy of the event.
BEGIN:VCALENDAR
PRODID:-//RDU Software//NONSGML HandCal//EN
METHOD:REFRESH
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;STATUS=ACCEPTED;ROLE=OWNER:sman@netscape.com
ATTENDEE;EXPECT=REQUEST:stevesil@microsoft.com
UID:acme-12345@host1.com
DTSTAMP:19970603T094000
END:VEVENT
END:VCALENDAR
5 Application Protocol Fallbacks
5.1 Partial Implementation
Applications that support this memo are not required to support the
entire protocol. The following describes how methods and properties
SHOULD "fallback" in applications that do not support the complete
protocol. If a method or property is not addressed in this section,
it MAY be ignored.
5.1.1 Event-Related Fallbacks
Method Fallback
-------------- -----------------------------------------------------
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PUBLISH Required.
CANCEL Required.
REQUEST PUBLISH
REPLY Required.
DELEGATE Reply with Not Supported.
REQUEST Reply with Not Supported.
REPLY Reply with Not Supported.
COUNTER Reply with Not Supported
DECLINECOUNTER Required if EVENT-COUNTER is implemented; otherwise
reply with Not Supported.
iCalendar
Property Fallback
-------------- -----------------------------------------------------
CALSCALE Ignore; assume GREGORIAN.
GEO Ignore.
PRODID Ignore.
METHOD Required as described in the Method list above.
SOURCE Ignore
NAME Ignore.
VERSION Ignore.
Event-Related
Components Fallback
-------------- -----------------------------------------------------
VFREEBUSY Reply with Not Supported.
VALARM Reply with Not Supported.
VTIMEZONE Required if RRULE or RDATE is implemented; otherwise
ignore and use local time.
Component
Property Fallback
-------------- -----------------------------------------------------
ATTACH Ignore.
ATTENDEE Required if EVENT-REQUEST is not implemented;
otherwise reply with Not Supported.
CATEGORIES Required if in VALARM and VALARM is implemented,
otherwise ignore.
CLASS Ignore.
COMMENT Ignore.
COMPLETED Ignore.
CREATED Ignore.
DAYLIGHT Required if VTIMEZONE is implemented; otherwise
Ignore.
DESCRIPTION Required.
DELEGATED-FROM Required if EVENT-DELEGATE is implemented; otherwise
Ignore.
DELEGATED-TO Required if EVENT-DELEGATE is implemented; otherwise
Ignore.
DUE Ignore.
DURATION Reply with Not Supported.
DTSTAMP Required.
DTSTART Required.
DTEND Required.
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EXDATE Ignore.
EXRULE Ignore.
FREEBUSY Reply with Not Supported.
LAST-MODIFIED Ignore.
LOCATION Required.
PRIORITY Ignore.
RELATED-TO Ignore.
RDATE Ignore. If implemented, VTIMEZONE MUST also be
implemented.
RRULE Ignore. The first instance occurs on the DTStart
property.
RECURRENCE-ID Required if RRULE is implemented; otherwise Ignore.
REQUEST-STATUS Required.
RESOURCES Ignore.
SEQUENCE Required.
STATUS Ignore.
SUMMARY Ignore.
TRANSP Required if FREEBUSY is implemented; otherwise Ignore.
TZNAME Required if VTIMEZONE is implemented; otherwise
Ignore.
TZOFFSET Required if VTIMEZONE is implemented; otherwise
Ignore.
URL Ignore.
UID Required.
X- Ignore.
5.1.2 To-Do-Related Fallbacks
Method Fallback
-------------- -----------------------------------------------------
PUBLISH Required.
CANCEL Required.
REQUEST TODO-PUBLISH
REPLY Required.
iCalendar
Property Fallback
-------------- -----------------------------------------------------
CALSCALE Ignore; assume GREGORIAN.
GEO Ignore.
PRODID Ignore.
METHOD Required as described in the Method list above.
SOURCE Ignore
NAME Ignore.
VERSION Ignore.
To-Do-Related
Components Fallback
-------------- -----------------------------------------------------
VALARM Reply with Not Supported.
VTIMEZONE Required if RRULE or RDATE is implemented;
otherwise ignore and use local time.
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Component
Property Fallback
-------------- -----------------------------------------------------
CALSCALE Ignore; assume GREGORIAN.
GEO Ignore.
PRODID Ignore.
PROFILE Required as described in the Method list above.
SOURCE Ignore
NAME Ignore.
VERSION Assume "2.0".
Property Fallback
ATTACH Ignore.
ATTENDEE Required if REQUEST is not implemented; otherwise
ignore.
CATEGORIES Ignore.
CLASS Ignore.
COMMENT Ignore.
COMPLETED Required.
CREATED Ignore.
DAYLIGHT Required if VTIMEZONE is implemented; otherwise
ignore.
DESCRIPTION Required.
DUE Required.
DURATION Ignore. Reply with Not Supported.
DTSTAMP Required.
DTSTART Required.
EXDATE Ignore. Reply with Not Supported.
EXRULE Ignore. Reply with Not Supported.
LAST-MODIFIED Ignore.
LOCATION Ignore.
PERCENT-COMPLETE Ignore
PRIORITY Required.
RELATED-TO Ignore.
RDATE Ignore. If implemented, VTIMEZONE MUST also be
implemented.
RRULE Ignore. The first instance occurs on the DTStart
property.
RESOURCES Ignore.
SEQUENCE Required.
STATUS Required.
SUMMARY Ignore.
TRANSP Required if FREEBUSY is implemented; otherwise Ignore.
TZNAME Required if VTIMEZONE is implemented; otherwise
Ignore.
TZOFFSET Required if VTIMEZONE is implemented; otherwise
Ignore.
URL Ignore.
UID Required.
X- Ignore.
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5.1.3 Journal-Related Fallbacks
Method Fallback
-------------- -----------------------------------------------------
PUBLISH Implementations MAY ignore the profile type. The
REQUEST-STATUS "302;Request not supported" MUST be
returned.
CANCEL Implementations MAY ignore the profile type. The
REQUEST-STATUS "302;Request not supported" MUST be
returned.
REFRESH Implementations MAY ignore the profile type. The
REQUEST-STATUS "302;Request not supported" MUST be
returned.
iCalendar
Property Fallback
-------------- -----------------------------------------------------
CALSCALE Ignore; assume GREGORIAN.
GEO Ignore.
PRODID Ignore.
METHOD Required as described in the Method list above.
SOURCE Ignore
NAME Ignore.
VERSION Ignore.
Journal-Related
Components Fallback
-------------- -----------------------------------------------------
VTIMEZONE Required if RRULE or RDATE is implemented; otherwise
ignore and use local time.
CALSCALE Ignore; assume GREGORIAN.
GEO Ignore.
PRODID Ignore.
METHOD Required as described in the Method section above.
SOURCE Ignore
NAME Ignore.
VERSION Assume "2.0".
Component
Property Fallback
-------------- -----------------------------------------------------
ATTACH Ignore.
ATTENDEE Required if JOURNAL-REQUEST is implemented; otherwise
ignore.
CATEGORIES Ignore.
CLASS Ignore.
COMMENT Ignore.
CREATED Ignore.
DAYLIGHT Required if VTIMEZONE is implemented; otherwise
Ignore.
DESCRIPTION Required.
DTSTAMP Required.
DTSTART Required.
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DTEND Required.
EXDATE Ignore.
EXRULE Ignore.
LAST-MODIFIED Ignore.
RELATED-TO Ignore.
RDATE Ignore. If implemented, VTIMEZONE MUST also be
implemented.
RRULE Ignore. The first instance occurs on the DTStart
property.
SEQUENCE Required.
STATUS Ignore.
TRANSP Required if FREEBUSY is implemented; otherwise ignore.
TZNAME Required if VTIMEZONE is implemented; otherwise
ignore.
TZOFFSET Required if VTIMEZONE is implemented; otherwise
ignore.
URL Ignore.
UID Required.
X- Ignore.
5.2 Latency Issues
With a store-and-forward transport, it is possible for events to
arrive out of sequence. That is, you MAY receive a "CANCEL" method
prior to receiving the associated "REQUEST" for the calendar
component. This section discusses a few of these scenarios.
5.2.1 Cancellation of an Unknown Calendar Component.
When a "CANCEL" method is received before the original "REQUEST"
method the calendar will be unable to correlate the "UID" property of
the cancellation with an existing calendar component. It is suggested
that messages that can not be correlated that also contain non-zero
sequence numbers be held and not discarded. Implementations MAY age
them out if no other messages arrive with the same "UID" property
value and a lower sequence number.
5.2.2 Unexpected Reply from an Unknown Delegate
When an "Attendee" delegates an item to another "Calendar User" they
MUST send a "REPLY" method to the "Organizer" using the "ATTENDEE"
properties to indicate the fact that the request was delegated and to
whom the item was delegated. Hence it is possible for an "Organizer"
to receive an "REPLY" from a "Calendar User" not listed as one of the
original "Attendees". The resolution is left to the implementation
but it is expected that the calendaring software will either accept
the reply or hold it until the related "REPLY" method is received
from the "delegator". If the version of the "REPLY" method is out of
date the "Organizer" SHOULD treat the message as a "STATUS-REQUEST"
and update the delegate with the correct version.
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5.3 Sequence Number
Under some conditions, a "CUA" MAY receive requests and replies with
the same "SEQUENCE" property value. The "DTSTAMP" property is
utilized as a tie-breaker when two items with the same "SEQUENCE"
property value are evaluated. Furthermore, the "SEQUENCE" property is
only incremented when one or more of the following properties
changes:
╖ DTSTART
╖ DTEND
╖ RDATE
╖ RRULE
╖ EXDATE
╖ EXRULE
╖ DUE (for VTODO components)
╖ and possibly LOCATION
6 Security Considerations
This memo outlines an abstract transport protocol which will be bound
to a real-time transport, a store-and-forward transport, and perhaps
other transports. The transport protocol will be responsible for
providing facilities for authentication and encryption using standard
Internet mechanisms that are mutually understood between the sender
and receiver.
6.1 Security Threats
6.1.1 Spoofing the "Organizer"
In this memo, the "Organizer" is the only person authorized to make
changes to an existing "VEVENT", "VTODO", "VJOURNAL" calendar
component and redistribute the updates to the "Attendees". An
iCalendar object that maliciously changes or cancels an existing
"VEVENT", "VTODO" or "VJOURNAL" calendar component MAY be constructed
by someone other than the "Organizer" and sent to the "Attendees".
6.1.2 Spoofing the "Attendee"
In this memo, an "Attendee" of a "VEVENT", "VTODO", "VJOURNAL"
calendar component is the only person authorized to update any
parameter associated with their "ATTENDEE" property and send it to
the "Organizer". An iCalendar object that maliciously changes the
"ATTENDEE" parameters MAY be constructed by someone other than the
real "Attendee" and sent to the "Organizer".
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6.1.3 Eavesdropping
The iCalendar object is constructed with human-readable clear text.
Any information contained in an iCalendar object MAY be read and/or
changed by unauthorized persons while the object is in transit.
6.1.4 Flooding a Calendar
Implementations MAY provide a means to automatically incorporate
"REQUEST" methods into a calendar. This presents the opportunity for
a calendar to be flooded with requests, which effectively block all
the calendar's free time.
6.1.5 Procedural Alarms
The "REQUEST" methods for "VEVENT" and "VTODO" calendar components
MAY contain "VALARM" calendar components. The "VALARM" calendar
component MAY be of type PROCEDURE and MAY have an attachment
containing some sort of executable program. Implementations that
incorporate these types of alarms are subject to any virus or
malicious attack that MAY occur as a result of executing the
attachment.
6.2 Recommendations
For an application where the information is sensitive or critical and
the network is subject is subject to a high probability of attack,
iTIP transactions SHOULD be secured. This MAY be accomplished using
public key technology, specifically Security Multiparts for MIME
[RFC1847] in the iTIP transport binding. This helps mitigate the
threats of spoofing, eavesdropping and malicious changes in transit.
6.2.1 Use of [RFC1847] to secure iTIP transactions
iTIP transport bindings SHOULD provide a mechanism based on Security
Multiparts for MIME [RFC1847] to enable authentication of the
senderÆs identity, and privacy and integrity of the data being
transmitted. This allows the receiver of a signed iCalendar object to
verify the identity of the sender. This sender MAY then be correlated
to an "ATTENDEE" property in the iCalendar object. If the correlation
is made and the sender is authorized to make the requested change or
update then the operation MAY proceed. It also allows the message to
be encrypted to prevent unauthorized reading of the message contents
in transit. iTIP transport binding documents describe this process in
detail.
6.2.2 Implementation Controls
The threat of flooding a calendar SHOULD be mitigated by a calendar
system that uses this protocol by providing controls that MAY be used
to limit the acceptable sources for iTIP transactions, and perhaps
the size of messages and volume of traffic, by source.
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The threat of malicious procedural alarms SHOULD be mitigated by a
calendar system that uses this protocol by providing controls that
MAY be used to disallow procedural alarms in iTIP transactions and/or
remove all alarms from the object before delivery to the recipient.
7 Acknowledgments
A hearty thanks to the following individuals who have participated in
the drafting, review and discussion of this memo:
Anik Ganguly, Bruce Kahn, John Noerenberg, Leo Parker, John Rose,
Vinod Seraphin, Richard Shusterman, Derik Stenerson, John Sun, Kevin
Tsurutome.
8 Bibliography
[ICAL] "Internet Calendaring and Scheduling Core Object Specification
- iCalendar", Internet-Draft, October 1997,
ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-ical-03.txt.
[ICMS] "Internet Calendaring Model Specification", Internet-Draft,
October 1997, ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-
mod-01.txt.
[ID-UTF8] "UTF-8, a transformation format of Unicode and ISO 10646",
Internet-Draft, July 1996, ftp://ftp.ietf.org/internet-drafts/draft-
yergeau-utf8-01.txt.
[IMIP] "iCalendar Message-Based Interoperability Protocol - iMIP",
Internet-Draft, October 1997, ftp://ftp.ietf.org/internet-
drafts/draft-ietf-calsch-imip-01.txt.
[ISO8601] "Data elements and interchange formats - information
interchange - Representation of dates and times", ISO 8601, 1996-06-
15, +1 (212) 642-4900 for ANSI Sales.
[VCAL] "vCalendar - The Electronic Calendaring and Scheduling Format
- Version 1.0", Versit Consortium, September 18, 1996,
http://www.imc.org/pdi/vcal-10.doc.
[VCARD] "vCard - The Electronic Business Card Exchange Format -
Version 2.1", Versit Consortium, September 18, 1996,
http://www.imc.org/pdi/vcard-21.doc.
[RFC821] Postel, "Simple Mail Transfer Protocol", RFC 821,
organization name, November 1996,
http://ds.internic.net/rfc/rfc821.txt.
[RFC1983] "Internet Users' Glossary", RFC 1983, August 1996,
http://ds.internic.net/rfc/rfc1983.txt.
[RFC2119] "Key words for use in RFCs to Indicate Requirement Levels",
RFC 2119, March 1997, http://ds.internic.net/rfc/rfc2119.txt.
[RFC2045] N. Freed and N. Borenstein, "Multipurpose Internet Mail
Extensions - Part One - Format of Internet Message Bodies", RFC 2045,
Innosoft, First Virtual, November 1996,
http://ds.internic.net/rfc/rfc2045.txt.
Silverberg/Mansour/Dawson/Hopson 76 Expires MAY 1998
Internet Draft iTIP October 24, 1997
[RFC2046] N. Freed and N. Borenstein, "Multipurpose Internet Mail
Extensions - Part Two - Media Types", RFC 2046, Innosoft, First
Virtual, November 1996, http://ds.internic.net/rfc/rfc2046.txt.
[UNICODE] The Unicode Consortium, "The Unicode Standard -Version
2.0", Addison-Wesley Developers Press, July 1996. UTF-8 is described
in section A-2.
[US-ASCII] Coded Character Set--7-bit AmeriMAYStandard Code for
Information Interchange, ANSI X3.4-1986.
9 Authors Addresses
The following address information is provided in a MIME-VCARD,
Electronic Business Card, format.
The authors of this draft are:
BEGIN:VCARD
FN:Frank Dawson
ORG:Lotus Development Corporation
ADR;WORK;POSTAL;PARCEL:;;6544 Battleford Drive;Raleigh;NC;27613-
3502;USA
TEL;WORK;MSG:+1-919-676-9515
TEL;WORK;FAX:+1-919-676-9564
EMAIL;INTERNET:Frank_Dawson@Lotus.com
URL:http://home.earthlink.net/~fdawson
END:VCARD
BEGIN:VCARD
FN:Ross Hopson
ORG:On Technology, Inc.
ADR;WORK;POSTAL;PARCEL:Suite 1600;;434 Fayetteville St.
Mall, Two Hannover Square;Raleigh;NC;27601
TEL;WORK;MSG:+1-919-890-4036
TEL;WORK;FAX:+1-919-890-4100
EMAIL;INTERNET:rhopson@on.com
END:VCARD
BEGIN:VCARD
FN:Steve Mansour
ORG:Netscape Communications Corporation
ADR;WORK;POSTAL;PARCEL:;;501 East Middlefield Road;Mountain
View;CA;94043;USA
TEL;WORK;MSG:+1-415-937-2378
TEL;WORK;FAX:+1-415-428-4059
EMAIL;INTERNET:sman@netscape.com
END:VCARD
BEGIN:VCARD
FN:Steve Silverberg
ORG:Microsoft Corporation
ADR;WORK;POSTAL;PARCEL:;;One Microsoft Way;
Redmond;WA;98052-6399;USA
TEL;WORK;MSG:+1-425-936-9277
Silverberg/Mansour/Dawson/Hopson 77 Expires MAY 1998
Internet Draft iTIP October 24, 1997
TEL;WORK;FAX:+1-425-936-8019
EMAIL;INTERNET:stevesil@Microsoft.com
END:VCARD
The iCalendar object is a result of the work of the Internet
Engineering Task Force Calendaring and scheduling Working Group. The
chairman of that working group is:
BEGIN:VCARD
FN:Anik Ganguly
ORG:Campbel Services, Inc.
ADR;WORK;POSTAL;PARCEL:10 Floor;;21700 Northwestern
Highway;Southfield;MI;48075;USA
TEL;WORK;MSG:+1-248-559-5955
TEL;WORK;FAX:+1-248-559-5034
EMAIL;INTERNET:anik@ontime.com
END:VCARD
10 Full Copyright Statement
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This document and translations of it MAY be copied and furnished to
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or assist in its implmentation MAY be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself MAY NOT be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
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English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Silverberg/Mansour/Dawson/Hopson 78 Expires MAY 1998