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. Silverberg/Mansour/Dawson/Hopson 1 Expires MAY 1998 Internet Draft iTIP October 24, 1997 Silverberg/Mansour/Dawson/Hopson 2 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 3 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 4 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 5 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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". Silverberg/Mansour/Dawson/Hopson 6 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 | Silverberg/Mansour/Dawson/Hopson 7 Expires MAY 1998 Internet Draft iTIP October 24, 1997 | | 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" | +================+==================================================+ Silverberg/Mansour/Dawson/Hopson 8 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 9 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 ")" Silverberg/Mansour/Dawson/Hopson 10 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 11 Expires MAY 1998 Internet Draft iTIP October 24, 1997 +================+==================================================+ | 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 Silverberg/Mansour/Dawson/Hopson 12 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 13 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 14 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 15 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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, Silverberg/Mansour/Dawson/Hopson 16 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 17 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 ( Silverberg/Mansour/Dawson/Hopson 18 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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, Silverberg/Mansour/Dawson/Hopson 19 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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, Silverberg/Mansour/Dawson/Hopson 20 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 21 Expires MAY 1998 Internet Draft iTIP October 24, 1997 |================|==================================================| | 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 Silverberg/Mansour/Dawson/Hopson 22 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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" Silverberg/Mansour/Dawson/Hopson 23 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 24 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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| Silverberg/Mansour/Dawson/Hopson 25 Expires MAY 1998 Internet Draft iTIP October 24, 1997 | | 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) Silverberg/Mansour/Dawson/Hopson 26 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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, Silverberg/Mansour/Dawson/Hopson 27 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 28 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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". Silverberg/Mansour/Dawson/Hopson 29 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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" Silverberg/Mansour/Dawson/Hopson 30 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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"}) Silverberg/Mansour/Dawson/Hopson 31 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 32 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 33 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 ) Silverberg/Mansour/Dawson/Hopson 34 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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) Silverberg/Mansour/Dawson/Hopson 35 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 ) Silverberg/Mansour/Dawson/Hopson 36 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 | Silverberg/Mansour/Dawson/Hopson 37 Expires MAY 1998 Internet Draft iTIP October 24, 1997 | | 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. | Silverberg/Mansour/Dawson/Hopson 38 Expires MAY 1998 Internet Draft iTIP October 24, 1997 |==============+============================+=========================| | 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 Silverberg/Mansour/Dawson/Hopson 39 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 40 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 41 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 42 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 43 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 44 Expires MAY 1998 Internet Draft iTIP October 24, 1997 RELATED-TO:0981234-1234234-14@host.com BEGIN:VALARM DTSTART:19970701T190000Z REPEAT:2 DURATION:PT2H CATEGORIES:DISPLAY,AUDIO DESCRIPTION:Its 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 users 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 Silverberg/Mansour/Dawson/Hopson 45 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 46 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 47 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 48 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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: Silverberg/Mansour/Dawson/Hopson 49 Expires MAY 1998 Internet Draft iTIP October 24, 1997 · 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". | Silverberg/Mansour/Dawson/Hopson 50 Expires MAY 1998 Internet Draft iTIP October 24, 1997 +---------------------------------------------------------------------+ | 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 Silverberg/Mansour/Dawson/Hopson 51 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 52 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 53 Expires MAY 1998 Internet Draft iTIP October 24, 1997 BEGIN:VCALENDAR PRODID:-//ACME/DesktopCalendar//EN METHOD:CANCEL VERSION:2.0 BEGIN:VEVENT COMMENT:Mr. B cannot attend. Ill 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 Silverberg/Mansour/Dawson/Hopson 54 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 55 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 56 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 57 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 58 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 59 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 60 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 61 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 | +--------------------------------------------------------------------+ Silverberg/Mansour/Dawson/Hopson 62 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 63 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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%. Silverberg/Mansour/Dawson/Hopson 64 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 65 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 66 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 Silverberg/Mansour/Dawson/Hopson 67 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 -------------- ----------------------------------------------------- Silverberg/Mansour/Dawson/Hopson 68 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 69 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 70 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 71 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 72 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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. Silverberg/Mansour/Dawson/Hopson 73 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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". Silverberg/Mansour/Dawson/Hopson 74 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 senders 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. Silverberg/Mansour/Dawson/Hopson 75 Expires MAY 1998 Internet Draft iTIP October 24, 1997 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 "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it MAY be copied and furnished to others, and derivative works that comment on or otherwise explain it 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 Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process MUST be followed, or as required to translate it into languages other than 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 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 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 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Silverberg/Mansour/Dawson/Hopson 78 Expires MAY 1998
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