4.6.4 Free/Busy Component

    Component Name: VFREEBUSY

    Purpose: Provide a grouping of component properties that describe
    either a request for free/busy time, describe a response to a request
    for free/busy time or describe a published set of busy time.

    Formal Definition: A "VFREEBUSY" calendar component is defined by the
    following notation:

      freebusyc  = "BEGIN" ":" "VFREEBUSY" CRLF
                   fbprop
                   "END" ":" "VFREEBUSY" CRLF

      fbprop     = *(

                 ; the following are optional,
                 ; but MUST NOT occur more than once

                 contact / dtstart / dtend / duration / dtstamp /
                 organizer / uid / url /

                 ; the following are optional,
                 ; and MAY occur more than once

                 attendee / comment / freebusy / rstatus / x-prop

                 )

    Description: A "VFREEBUSY" calendar component is a grouping of
    component properties that represents either a request for, a reply to
    a request for free or busy time information or a published set of
    busy time information.

    When used to request free/busy time information, the "ATTENDEE"
    property specifies the calendar users whose free/busy time is being
    requested; the "ORGANIZER" property specifies the calendar user who
    is requesting the free/busy time; the "DTSTART" and "DTEND"
    properties specify the window of time for which the free/busy time is
    being requested; the "UID" and "DTSTAMP" properties are specified to
    assist in proper sequencing of multiple free/busy time requests.

    When used to reply to a request for free/busy time, the "ATTENDEE"
    property specifies the calendar user responding to the free/busy time
    request; the "ORGANIZER" property specifies the calendar user that
    originally requested the free/busy time; the "FREEBUSY" property
    specifies the free/busy time information (if it exists); and the
    "UID" and "DTSTAMP" properties are specified to assist in proper
    sequencing of multiple free/busy time replies.

    When used to publish busy time, the "ORGANIZER" property specifies
    the calendar user associated with the published busy time; the
    "DTSTART" and "DTEND" properties specify an inclusive time window
    that surrounds the busy time information; the "FREEBUSY" property
    specifies the published busy time information; and the "DTSTAMP"
    property specifies the date/time that iCalendar object was created.

    The "VFREEBUSY" calendar component cannot be nested within another
    calendar component. Multiple "VFREEBUSY" calendar components can be
    specified within an iCalendar object. This permits the grouping of
    Free/Busy information into logical collections, such as monthly
    groups of busy time information.

    The "VFREEBUSY" calendar component is intended for use in iCalendar
    object methods involving requests for free time, requests for busy
    time, requests for both free and busy, and the associated replies.

    Free/Busy information is represented with the "FREEBUSY" property.
    This property provides a terse representation of time periods. One or
    more "FREEBUSY" properties can be specified in the "VFREEBUSY"
    calendar component.

    When present in a "VFREEBUSY" calendar component, the "DTSTART" and
    "DTEND" properties SHOULD be specified prior to any "FREEBUSY"
    properties. In a free time request, these properties can be used in
    combination with the "DURATION" property to represent a request for a
    duration of free time within a specified window of time.

    The recurrence properties ("RRULE", "EXRULE", "RDATE", "EXDATE") are
    not permitted within a "VFREEBUSY" calendar component. Any recurring
    events are resolved into their individual busy time periods using the
    "FREEBUSY" property.

    Example: The following is an example of a "VFREEBUSY" calendar
    component used to request free or busy time information:

      BEGIN:VFREEBUSY
      ORGANIZER:MAILTO:[email protected]
      ATTENDEE:MAILTO:[email protected]
      DTSTART:19971015T050000Z
      DTEND:19971016T050000Z
      DTSTAMP:19970901T083000Z
      END:VFREEBUSY

    The following is an example of a "VFREEBUSY" calendar component used
    to reply to the request with busy time information:

      BEGIN:VFREEBUSY
      ORGANIZER:MAILTO:[email protected]
      ATTENDEE:MAILTO:[email protected]
      DTSTAMP:19970901T100000Z
      FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M,
       19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M
      URL:http://host2.com/pub/busy/jpublic-01.ifb
      COMMENT:This iCalendar file contains busy time information for
        the next three months.
      END:VFREEBUSY

    The following is an example of a "VFREEBUSY" calendar component used
    to publish busy time information.

      BEGIN:VFREEBUSY
      ORGANIZER:[email protected]
      DTSTART:19980313T141711Z
      DTEND:19980410T141711Z
      FREEBUSY:19980314T233000Z/19980315T003000Z
      FREEBUSY:19980316T153000Z/19980316T163000Z
      FREEBUSY:19980318T030000Z/19980318T040000Z
      URL:http://www.host.com/calendar/busytime/jsmith.ifb
      END:VFREEBUSY

// request all busy times between today and 1 week from now..
DateTime start = new DateTime();
DateTime end = new DateTime(start.getTime() + 1000 * 60 * 60 * 24 * 7);

VFreeBusy request = new VFreeBusy(start, end);

VFreeBusy reply = new VFreeBusy(request, calendar.getComponents());

// request all free time between today and 1 week from now of
// duration 2 hours or more..
DateTime start = new DateTime();
DateTime end = new DateTime(start.getTime() + 1000 * 60 * 60 * 24 * 7);

VFreeBusy request = new VFreeBusy(start, end, new Dur(0, 2, 0, 0));

VFreeBusy response = new VFreeBusy(request, myCalendar.getComponents());