]> Apple Inc.

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Oracle Corporation

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Applications availability calendaring free-busy iCalendar CalDAV This document specifies a new iCalendar calendar component that allows the publication of available and unavailable time periods associated with a calendar user. This component can be used in standard iCalendar free-busy lookups, including iTIP free-busy requests, to generate repeating blocks of available or busy time with exceptions as needed. This document also defines extensions to CalDAV calendar-access and calendar-auto-schedule which specify how this new calendar component should be used when doing free busy time evaluation in CalDAV. Discussion of this specification is taking place on the mailing list http://lists.osafoundation.org/mailman/listinfo/ietf-caldav.

Often calendar users have regular periods of time when they are either available to be scheduled or always unavailable. For example, an office worker will often wish to only appear free to their work colleagues during normal 'office hours' (e.g., Monday through Friday, 9 am through 5 pm). Or, a university professor may only be available to students during a set period of time (e.g., Thursday afternoons, 2 pm through 5 pm during term time only). Ideally users should be able to specify such periods directly via their calendar user agent, and have them automatically considered as part of the normal free-busy lookup for that user. In addition it should be possible for different periods of available time to appear for different users. However, iCalendar does not provide a way to specify a repeating period of available or unavailable time as "VFREEBUSY" components cannot include any form of recurrence information, as opposed to "VEVENT" components which can. Since repeating patterns are often the case, "VFREEBUSY" components are not sufficient to solve this problem. This specification defines a new type of iCalendar calendar component that can be used to publish user availability. CalDAV provides a way for calendar users to access and manage calendar data and exchange this data via scheduling operations. As part of this the CalDAV calendar-access feature provides a CALDAV:free-busy-query REPORT that returns free-busy information for a calendar collection or hierarchy of calendar collections. Also, the CalDAV calendar-auto-schedule feature allows free-busy information for a calendar user to be determined. Both of these operations involve examining user calendars for events that 'block time', with the blocked out periods being returned in a "VFREEBUSY" component. This specification extends the CalDAV calendar-access and CalDAV calendar-auto-schedule features to allow the new iCalendar availability components to be stored and manipulated, and to allow free-busy lookups to use the information from any such components, if present.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in . When XML element types in the namespaces "DAV:" and "urn:ietf:params:xml:ns:caldav" are referenced in this document outside of the context of an XML fragment, the string "DAV:" and "CALDAV:" will be prefixed to the element type names respectively.

This specification adds a new "VAVAILABILITY" calendar component to iCalendar. The "VAVAILABILITY" component is itself a container for new "AVAILABLE" sub-components. The purpose of the "VAVAILABILITY" calendar component is to provide a grouping of available time information over a specific range of time. Within that there are specific time ranges that are marked as available via a set of "AVAILABLE" calendar sub-components. Together these can be used to specify available time that can repeat over set periods of time, and which can vary over time.

VAVAILABILITY Provide a grouping of component properties that describe the availability associated with a calendar user. A "VAVAILABILITY" calendar component is defined by the following notation:

availabilityc = "BEGIN" ":" "VAVAILABILITY" CRLF availabilityprop *availablec "END" ":" "VAVAILABILITY" CRLF availabilityprop = *( ; the following are REQUIRED, ; but MUST NOT occur more than once dtstamp / uid ; the following are OPTIONAL, ; but MUST NOT occur more than once busytype / created / dtend /dtstart / last-mod / organizer / seq / summary / url / ; 'duration' is OPTIONAL in a ; 'availabilityprop' but MUST only be ; present if 'dtstart' is also present and ; 'dtend' is not present, and it MUST NOT ; occur more than once duration / ; the following are OPTIONAL, ; and MAY occur more than once categories / comment / contact / x-prop ) availablec = "BEGIN" ":" "AVAILABLE" CRLF availableprop "END" ":" "AVAILABLE" CRLF availableprop = *( ; the following are REQUIRED, ; but MUST NOT occur more than once dtstamp / dtstart / uid / ; either a 'dtend' or a 'duration' is REQUIRED ; in a 'availableprop', but 'dtend' and ; 'duration' MUST NOT occur in the same ; 'availableprop', and each MUST NOT occur more ; than once dtend / duration / ; the following are OPTIONAL, ; but MUST NOT occur more than once created / last-mod / recurid / rrule / summary / ; the following are OPTIONAL, ; and MAY occur more than once categories / comment / contact / exdate / rdate / x-prop )

A "VAVAILABILITY" component indicates a period of time within which availability information is provided. A "VAVAILABILITY" component MUST specify a start time and optionally an end time or duration. Within that time period, availability defaults to a free-busy type of "BUSY-UNAVAILABLE", except for any time periods corresponding to "AVAILABLE" sub-components. "AVAILABLE" sub-components are used to indicate periods of free time within the time range of the enclosing "VAVAILABILITY" component. "AVAILABLE" sub-components MAY include recurrence properties to specify recurring periods of time, which may be overridden using normal recurrence behavior (i.e., use of the "RECURRENCE-ID" property). If specified, the "DTSTART" and "DTEND" properties in "VAVAILABILITY" components and "AVAILABLE" sub-components MUST be "DATE-TIME" values specified as either date with UTC time or date with local time and a time zone reference. If any property with a "DATE-TIME" value is present in a "VAVAILABILITY" component or any of its "AVAILABLE" sub-components, and that property includes a "TZID" parameter, then the iCalendar object containing the "VAVAILABILITY" component MUST contain "VTIMEZONE" components corresponding to each unique "TZID" parameter value. When used to publish available time, the "ORGANIZER" property specifies the calendar user associated with the published available time. The following is an example of a "VAVAILABILITY" calendar component used to represent the availability of a user available Monday through Friday, 9:00 AM to 5:00 PM in the America/Montreal time zone:

BEGIN:VAVAILABILITY ORGANIZER:mailto:bernard@example.com UID:20061005T133225Z-00001@example.com DTSTAMP:20061005T133225Z DTSTART;TZID=America/Montreal:20061002T000000 BEGIN:AVAILABLE UID:20061005T133225Z-00001-A@example.com SUMMARY:Monday to Friday from 9:00 to 17:00 DTSTART;TZID=America/Montreal:20061002T090000 DTEND;TZID=America/Montreal:20061002T170000 RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR END:AVAILABLE END:VAVAILABILITY

The following is an example of a "VAVAILABILITY" calendar component used to represent the availability of a user available Monday through Thursday, 9:00 AM to 5:00 PM, and Friday 9:00 AM to 12:00 PM in the America/Montreal time zone:

BEGIN:VAVAILABILITY ORGANIZER:mailto:bernard@example.com UID:20061005T133225Z-00001@example.com DTSTAMP:20061005T133225Z DTSTART;TZID=America/Montreal:20061002T000000 DTEND;TZID=America/Montreal:20061202T000000 BEGIN:AVAILABLE UID:20061005T133225Z-00001-A@example.com SUMMARY:Monday to Thursday from 9:00 to 17:00 DTSTART;TZID=America/Montreal:20061002T090000 DTEND;TZID=America/Montreal:20061002T170000 RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH END:AVAILABLE BEGIN:AVAILABLE UID:20061005T133225Z-00001-B@example.com SUMMARY:Friday from 9:00 to 12:00 DTSTART;TZID=America/Montreal:20061006T090000 DTEND;TZID=America/Montreal:20061006T120000 RRULE:FREQ=WEEKLY;BYDAY=FR END:AVAILABLE END:VAVAILABILITY

The following is an example of three "VAVAILABILITY" calendar components used to represent the availability of an itinerant worker: Monday through Friday, 9:00 AM to 5:00 PM each day. However, for three weeks the calendar user is working in Montreal, then one week in Los Angeles, then back to Montreal. Note that each overall period is covered by separate "VAVAILABILITY" components. The last of these has no DTEND so continues on "for ever". This example shows how "exceptions" to available time can be handled.

BEGIN:VAVAILABILITY ORGANIZER:mailto:bernard@example.com UID:20061005T133225Z-00001@example.com DTSTAMP:20061005T133225Z DTSTART;TZID=America/Montreal:20061002T000000 DTEND;TZID=America/Montreal:20061023T030000 BEGIN:AVAILABLE UID:20061005T133225Z-00001-A@example.com SUMMARY:Monday to Friday from 9:00 to 17:00 DTSTART;TZID=America/Montreal:20061002T090000 DTEND;TZID=America/Montreal:20061002T170000 RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR END:AVAILABLE END:VAVAILABILITY BEGIN:VAVAILABILITY ORGANIZER:mailto:bernard@example.com UID:20061005T133225Z-00001@example.com DTSTAMP:20061005T133225Z DTSTART;TZID=America/Los_Angeles:20061023T000000 DTEND;TZID=America/Los_Angeles:20061030T000000 BEGIN:AVAILABLE UID:20061005T133225Z-00001-A@example.com SUMMARY:Monday to Friday from 9:00 to 17:00 DTSTART;TZID=America/Los_Angeles:20061023T090000 DTEND;TZID=America/Los_Angeles:20061023T170000 RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR END:AVAILABLE END:VAVAILABILITY BEGIN:VAVAILABILITY ORGANIZER:mailto:bernard@example.com UID:20061005T133225Z-00001@example.com DTSTAMP:20061005T133225Z DTSTART;TZID=America/Montreal:20061030T030000 BEGIN:AVAILABLE UID:20061005T133225Z-00001-A@example.com SUMMARY:Monday to Friday from 9:00 to 17:00 DTSTART;TZID=America/Montreal:20061030T090000 DTEND;TZID=America/Montreal:20061030T170000 RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR END:AVAILABLE END:VAVAILABILITY

BUSYTYPE This property specifies the default busy time type. TEXT Non-standard property parameters can be specified on this property. This property can be specified within "VAVAILABILITY" calendar components. This property is defined by the following notation:

busytype = "BUSYTYPE" busytypeparam ":" busytypevalue CRLF busytypeparam = *(";" xparam) busytypevalue = "BUSY" / "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE" / iana-token / x-name ; Default is "BUSY-UNAVAILABLE"

This property is used to specify the default busy time type. The values correspond to those used by the "FBTYPE" parameter used on a "FREEBUSY" property, with the exception that the "FREE" value is not used. If not specified on a component that allows this property, the default is "BUSY-UNAVAILABLE". The following is an example of this property:

BUSYTYPE:BUSY

This section describes how free-busy time information for a calendar user is calculated in the presence of "VAVAILABILITY" calendar components. An iCalendar "VFREEBUSY" component is used to convey "rolled-up" free-busy time information for a calendar user. This can be generated as the result of an iTIP "VFREEBUSY" request or through some other mechanism (e.g., a CalDAV calendar-access CALDAV:free-busy-query REPORT). When a "VAVAILABILITY" component is present and intersects the time-range for the free-busy request, the time covered by the "VAVAILABILITY" component is set to busy and then portions of it "carved out" to be free based on the "AVAILABLE" components in the "VAVAILABILITY" component. Once that is done, regular "VEVENT" and "VFREEBUSY" components can be "overlaid" in the usual way to block out additional time. An example procedure for this is as follows: Initially mark the entire period of the free-busy request as free. For each "VAVAILABILITY" component: Determine if the "VAVAILABILITY" intersects the time-range of the free-busy request. If not ignore it. For the time period covered by the "VAVAILABILITY" component, mark time in the free-busy request result set as busy, using the busy time type derived from the "BUSYTYPE" property in the "VAVAILABILITY" component. For each remaining "VAVAILABILITY" component: For each "AVAILABLE" component in the "VAVAILABILITY" component: Expand all recurring instances, taking into account overridden instances, ignoring those not within the free-busy request time-range. For each instance, mark the corresponding time in the free-busy request result set as free. For each "VEVENT" or "VFREEBUSY" component apply normal free-busy processing within the free-busy request time-range.

In the examples below a table is used to represent time slots for the period of a free-busy request. Each time slot is two hours long. The column header represents the hours from midnight local time. Each row below the column headers represents a step in the free-busy result set determination, following the procedure outlined above. Each cell in the rows below the column header contains a single character that represents the free-busy type for the corresponding time period at the end of the process step represented by the row. The characters in the row are: Character Meaning F Represents "FREE" time in that slot. B Represents "BUSY" time in that slot. U Represents "BUSY-UNAVAILABLE" time in that slot. T Represents "BUSY-TENTATIVE" time in that slot.

A free-busy request for Monday, 6th November 2006, midnight to midnight in the America/Montreal timezone. The user's calendar is as shown in . This includes one "VAVAILABILITY" component giving available time within the requested time-range of 8:00 AM to 6:00 PM, together with one "VEVENT" component representing a two hour meeting starting at 12:00 PM. Step  0  2  4  6  8 10 12 14 16 18 20 22 1. F F F F F F F F F F F F 2. U U U U U U U U U U U U 3. U U U U F F F F F U U U 4. U U U U F F B F F U U U

More examples here../not sure what though.

This section lists what functionality is required of a CalDAV server which supports this extension. A server: MUST support "VAVAILABILITY" components in a calendar collection resource if the CALDAV calendar-access feature is supported; MUST support CALDAV:free-busy-query REPORTs that aggregate the information in any "VAVAILABILITY" components; MUST support "VAVAILABILITY" components stored in a CALDAV:inbox-availability WebDAV property on a CALDAV scheduling inbox collection if the CALDAV calendar-auto-schedule feature is supported; MUST support iTIP free busy requests that aggregate the information in any "VAVAILABILITY" components in calendar collections that contribute to free-busy, or in any "VAVAILABILITY" components stored in the CALDAV:calendar-availability in the CALDAV scheduling inbox collection of the calendar user targeted by the iTIP free-busy request, if the CalDAV calendar-auto-schedule feature is available.

A server supporting the features described in this document MUST include "calendar-availability" as a field in the DAV response header from an OPTIONS request on any resource that supports any calendar properties, reports, method, or privilege. A value of "calendar-availability" in the DAV response header MUST indicate that the server supports all MUST level requirements specified in this document.

>> Request <<

>> Response <<

In this example, the OPTIONS method returns the value "calendar-availability" in the DAV response header to indicate that the collection "/home/bernard/calendars/" supports the new features defined in this specification.

A CALDAV:free-busy-query REPORT can be executed on a calendar collection that contains iCalendar "VAVAILABILITY" components. When that is done, the server MUST aggregate the information in any "VAVAILABILITY" components when generating the free-busy response, as described in .

calendar-availability urn:ietf:params:xml:ns:caldav Defines a "VAVAILABILITY" component that will be used in calculating free-busy time when an iTIP VFREEBUSY request is targetted at the calendar user who owns the Inbox. This property MAY be protected and SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 12.14.1 of ). Support for this property is REQUIRED. The value of this property MUST be a valid iCalendar object containing a single "VAVAILABILITY" component. This property allows a user to specify their availability by including a VAVAILABILITY component in the value of this property. If present, the server MUST use the "VAVAILABILITY" component in the value of this property when determining free-busy information as part of an iTIP VFREEBUSY requested being handled by the server.

; Data value MUST be iCalendar object containing a ; "VAVAILABILITY" component. ]]>

BEGIN:VCALENDAR CALSCALE:GREGORIAN PRODID:-//example.com//iCalendar 2.0//EN VERSION:2.0 BEGIN:VTIMEZONE LAST-MODIFIED:20040110T032845Z TZID:America/Montreal BEGIN:DAYLIGHT DTSTART:20000404T020000 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4 TZNAME:EDT TZOFFSETFROM:-0500 TZOFFSETTO:-0400 END:DAYLIGHT BEGIN:STANDARD DTSTART:20001026T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZNAME:EST TZOFFSETFROM:-0400 TZOFFSETTO:-0500 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20061113T044111Z DTSTART;TZID=America/Montreal:20061106T120000 DURATION:PT1H SUMMARY:Meeting UID:60A48841ECB90F3F215FE3D2@example.com END:VEVENT BEGIN:VAVAILABILITY UID:20061005T133225Z-00001@example.com DTSTAMP:20061005T133225Z DTSTART;TZID=America/Montreal:20061002T000000 BEGIN:AVAILABLE UID:20061005T133225Z-00001-A@example.com SUMMARY:Monday to Friday from 9:00 to 18:00 DTSTART;TZID=America/Montreal:20061002T090000 DTEND;TZID=America/Montreal:20061002T180000 RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR END:AVAILABLE END:VAVAILABILITY END:VCALENDAR ]]>

The processing of a "VFREEBUSY" request targeted at the owner of the CALDAV:schedule-inbox will include free-busy information derived from "VAVAILABILITY" components in any calendar collection targeted during the request, as described in . In addition, any "VAVAILABILITY" component specified in the CALDAV:calendar-availability property on the owner's Inbox, MUST be included in the free-busy calculation.

Free-busy information generated from "VAVAILABILITY" components MUST NOT include information other than busy or free time periods. In particular, user specified property values such as "SUMMARY" and "DESCRIPTION" MUST NOT be copied into the free-busy result data. Beyond this, this specification does not add any additional security issues that are not already present in and .

This documents defines the following new iCalendar components to be added to the registry defined in Section 8.2.2 of : Component Status Reference VAVAILABILITY Current RFCXXXX, AVAILABLE Current RFCXXXX,

This documents defines the following new iCalendar properties to be added to the registry defined in Section 8.2.3 of : Property Status Reference BUSYTYPE Current RFCXXXX,

This specification came about via discussions at the Calendaring and Scheduling Consortium.

&rfc2119; &rfc2518; &rfc4791; &id2445bis; &id2446bis; &idCaldavSched;

iCalendar object

Changes from -00: Allow property on Inbox for caldav-schedule. Clarify that DURATION can only be present in VAVAILABILITY if DTSTART is also present, and DTEND is not. Updated references. Added templates.