JSCalendar: A JSON representation of calendar dataFastMailPO Box 234Collins St WestMelbourneVIC 8007Australianeilj@fastmailteam.comhttps://www.fastmail.comFastMailPO Box 234Collins St WestMelbourneVIC 8007Australiarsto@fastmailteam.comhttps://www.fastmail.com
Applications
Calendaring extensionsJSONiCalendarcalendareventsdatetime
This specification defines a data model and JSON representation of calendar data that can be used
for storage and data exchange in a calendaring and scheduling environment. It aims to be an
alternative to the widely deployed iCalendar data format and to be unambiguous, extendable and
simple to process.
This document defines a data model for calendar event and task objects, or groups
of such objects, in electronic calendar applications and systems. It aims to be unambiguous,
extendable and simple to process.
The key design considerations for this data model are as follows:
The attributes of the calendar entry represented must be described as a simple key-value pair,
reducing complexity of its representation.
The data model should avoid all ambiguities and make it difficult
to make mistakes during implementation.
Most of the initial set of attributes should be taken from the iCalendar data format
(, also see ), but
the specification should add new attributes or value types, or not support existing
ones, where appropriate. Conversion between the data formats need not fully preserve
semantic meaning.
Extensions, such as new properties and components, MUST NOT lead to requiring an update to this
document.
The representation of this
data model is defined in the I-JSON format , which is a strict subset
of the JavaScript Object Notation (JSON) Data Interchange Format .
Using JSON mostly is a pragmatic choice: its widespread use should help to speed up JSCalendar
adoption and a wide range of production-ready JSON implementations allows to decrease
interoperability issues.
The iCalendar data format , a widely deployed interchange format for calendaring
and scheduling data, has served calendaring vendors for a long while, but contains some ambiguities and
pitfalls that can not be overcome without backward-incompatible changes.
For example, iCalendar defines various formats for local times, UTC time and dates, which
confuses new users. Other sources for errors are the requirement for custom time-zone definitions
within a single calendar component, as well as the iCalendar format itself; the latter causing
interoperability issues due to misuse of CR LF terminated strings, line continuations and subtle
differences between iCalendar parsers. Lastly, up until recently the iCalendar format did not allow to
express the difference between two calendar components, which results in verbose exchanges during
scheduling.
Some of these issues were addressed by the jCal format, which is a direct
mapping between iCalendar and JSON. However, it did not attempt to extend or update iCalendar semantics.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in
.
The underlying format used for this specification is JSON. Consequently, the terms "object" and
"array" as well as the four primitive types (strings, numbers, booleans, and null) are to be
interpreted as described in Section 1 of.
Some examples in this document contain "partial" JSON documents used for illustrative purposes. In
these examples, three periods "..." are used to indicate a portion of the document that has been
removed for compactness.
This section describes the calendar object types specified by JSCalendar.
MIME type: application/calendar+json;type=jsevent
A JSEvent represents a scheduled amount of time on a calendar, typically a meeting, appointment,
reminder or anniversary. Multiple participants may partake in the event at multiple locations.
The @type property value MUST be jsevent.
MIME type: application/calendar+json;type=jstask
A JSTask represents an action-item, assignment, to-do or work item .
The @type property value MUST be jstask.
A JSTask may start and be due at certain points in time, may take some estimated time to complete
and may recur; none of which is required. This notably differs from
JSEvent which is required to start at a certain point in time and typically takes some
non-zero duration to complete.
MIME type: application/calendar+json;type=jsgroup
A JSGroup is a collection of JSEvent and
JSTask objects. Typically, objects are grouped by topic
(e.g. by keywords) or calendar membership.
The @type property value MUST be jsgroup.
A JSCalendar object is a JSON object, which MUST be valid I-JSON (a stricter subset of JSON), as
specified in . Property names and values are case-sensitive.
The object has a collection of properties, as specified in the following sections. Unless otherwise
specified, all properties are mandatory. Optional properties may have a default value, if explicitly
specified in the property definition.
Types signatures are given for all JSON objects in this document. The following conventions are
used:
Boolean|String:
The value is either a JSON Boolean value, or a JSON
String value.
Foo:
Any name that is not a native JSON type means an object for which the properties (and
their types) are defined elsewhere within this document.
Foo[]:
An array of objects of type Foo.
String[Foo]:
A JSON Object being used as a map (associative array), where
all the values are of type Foo.
In addition to the standard JSON data types, the following data types are used in this
specification:
This is a string in
date-time
format, with the further restrictions that any letters
MUST be in upper-case, the time component MUST be included and the time MUST be in UTC.
Fractional second values MUST NOT be included unless non-zero and MUST NOT have
trailing zeros, to ensure there is only a single representation for each date-time.
For example
2010-10-10T10:10:10.003Z is OK, but
2010-10-10T10:10:10.000Z is invalid and MUST be
encoded as 2010-10-10T10:10:10Z.
In common notation, it should be of the form YYYY-MM-DDTHH:MM:SSZ.
This is a date-time string with no time-zone/offset information.
It is otherwise in the same format as UTCDate:
YYYY-MM-DDTHH:MM:SS. The time-zone to associate the LocalDate with comes from an
associated property, or if no time-zone is associated it defines
floating time. Floating date-times are not tied to any specific
time-zone. Instead, they occur in every timezone at the same wall-clock
time (as opposed to the same instant point in time).
A duration is represented by a subset of ISO8601 duration format, as specified by the following
ABNF:
In addition, the duration MUST NOT include fractional second values unless the fraction is
non-zero.
A PatchObject is of type
String[*|null], and represents an unordered set of patches on a JSON object.
The keys are a path in a subset of
JSON pointer format, with an implicit leading / (i.e. prefix each
key with / before applying the JSON pointer evaluation algorithm).
A patch within a PatchObject is only valid, if all of the following conditions apply:
The pointer MUST NOT reference inside an array (i.e. it MUST NOT insert/delete from an array;
the array MUST be replaced in its entirety instead).
When evaluating a path, all parts prior to the last (i.e. the value after the final slash) MUST
exist.
There MUST NOT be two patches in the PatchObject where the pointer of one is the prefix of the
pointer of the other, e.g. alerts/foo/offset and
alerts.
The value associated with each pointer is either:
null: Remove the property from the patched object. If not
present in the parent, this a no-op.
Anything else: The value to replace the inherited property on the patch object with (if
present) or add to the property (if not present).
Implementations MUST reject a PatchObject if any of its patches are invalid.
If not noted otherwise, properties and object keys that define identifiers MUST
be string values, MUST be at least 1 character in
length and maximum 256 octets in size, and MUST only contain characters from the
“URL and Filename safe” Base 64 Alphabet, as defined in section 5 of
. This is the ASCII alphanumeric
characters (A-Za-z0-9), hyphen (-), and underscore (_).
JSCalendar aims to provide unambiguous definitions for value types and
properties, but does not define a general normalization or equivalence method for
JSCalendar objects and types. This is because the notion of equivalence might range
from byte-level equivalence to semantic equivalence, depending on the
respective use case (for example, the CalDAV protocol
requires octet equivalence of the encoded calendar
object to determine ETag equivalence).
Normalization of JSCalendar objects is hindered because of the following reasons:
Custom JSCalendar properties may contain arbitrary JSON values,
including arrays. However, equivalence of arrays might or might not
depend on the order of elements, depending on the respective property
definition.
Several JSCalendar property values are defined as URIs
and MIME types, but normalization of these types is inherently
protocol and scheme-specific, depending on the use-case of the
equivalence definition (see section 6 of ).
Considering this, the definition of equivalence and
normalization is left to client and server implementations and to be negotiated
by a calendar exchange protocol or defined by another RFC.
Vendors MAY add additional properties to the calendar object to support their custom features. The
names of these properties MUST be prefixed with a domain name controlled by the vendor to avoid
conflict, e.g. example.com/customprop.
Some JSCalendar properties allow vendor-specific value extensions. If so, vendor specific values
MUST be prefixed with a domain name controlled by the vendor,
e.g. example.com/customrel, unless otherwise noted.
This section describes the properties that are common to the various JSCalendar object
types. Specific JSCalendar object types may only support a subset of these properties.
The object type definitions in describe the
set of supported properties per type.
Type:
String
Specifies the type which this object represents.
This MUST be one of the following values,
registered in a future RFC, or a vendor-specific value:
jsevent: a JSCalendar event ().
jstask: a JSCalendar task ().
jsgroup: a JSCalendar group ().
A valid JSCalendar object MUST include this property.
Type:
String
A globally unique identifier, used to associate the object as the same across different systems,
calendars and views. The value of this property MUST be unique across all
JSCalendar objects, even if they are of different type.
describes a range of established algorithms to generate universally unique
identifiers (UUID), and the random or pseudo-random version is recommended to use.
For compatibility with UIDs, implementations MUST be able to receive and
persist values of at least 255 octets for this property, but they MUST NOT truncate values in the
middle of a UTF-8 multi-octet sequence.
A valid JSCalendar object MUST include this property.
Type:
String[Relation] (optional)
Relates the object to other JSCalendar objects. This is represented as a map of the uids of
the related objects to information about the relation.
A Relation object has the following properties:
relation: String[] Describes
how the linked object is related to this object.
Strings in the array MUST be one of the following values, defined in a future specification or a vendor-specific value.
There MUST NOT be duplicate strings in the array.
first: The linked object is the first in the series
this object is part of.
next: The linked object is the next in the series
this object is part of.
child: The linked object is a subpart of this
object.
parent: This object is part of the overall linked
object.
If an object is split to make a "this and future" change to a recurrence, the original object
MUST be truncated to end at the previous occurrence before this split, and a new object
created to represent all the objects after the split.
A relation=["next"]
relatedTo property MUST be set on the original object with the
uid of the new object. A relation=["first"]
relatedTo property with the UID of the first object in the
series MUST be set on the new object. Clients can then follow these UIDs to get the complete
set of objects if the user wishes to modify them all at once.
Type:
String (optional)
The identifier for the product that created the JSCalendar object.
The vendor of the implementation SHOULD ensure that this is a globally unique identifier, using
some technique such as an FPI value, as defined in [ISO.9070.1991]. It MUST only use characters
of an iCalendar TEXT data value (see section 3.3.11 in ).
This property SHOULD NOT be used to alter the interpretation of an JSCalendar object beyond the
semantics specified in this document. For example, it is not to be used to further the
understanding of non-standard properties.
Type:
UTCDate (optional)
The date and time this object was initially created.
Type:
UTCDate
The date and time the data in this object was last modified.
Type: Number (optional, default:0)
Initially zero, this MUST be a non-negative integer that is monotonically
incremented each time a change is made to the object.
Type:
String (optional)
The iTIP () method, in lower-case. Used for scheduling.
Type: String (optional, default:)
A short summary of the object.
Type: String (optional, default:)
A longer-form text description of the object. The content is formatted according
to the descriptionContentType property.
Type: String (optional, default:text/plain)
Describes the media type () of the
contents of the description property.
Media types MUST be sub-types of type text,
and SHOULD be text/plain or
text/html ().
They MAY define parameters and the
charset parameter MUST be utf-8, if specified.
Descriptions of type text/html MAY contain
cid URLs
() to reference links in the calendar object by use of
the cid property of the Link
object.
Type:
String[Location] (optional)
A map of location ids to Location objects, representing locations associated with the object.
A location id MUST be unique
to this object; a UUID is a practical choice.
A Location object has the following properties. It must define
at least one other property than rel.
name:
String (optional, default:)
The human-readable name of the location.
description:
String (optional)
Human-readable, plain-text instructions for accessing this location. This may be an address, set of
directions, door access code, etc.
rel:
String (optional)
The relation type of this location to the JSCalendar object.
This MUST be either one of the following values, registered in a future RFC, or a
vendor-specific value. Any value the client or server doesn't understand should be
treated the same as if this property is omitted.
start: The JSCalendar object starts at this
location.
end: The JSCalendar object ends at this location.
timeZone:
String (optional)
A time-zone for this location.
If omitted, the
timeZone from the
JSCalendar object MUST be presumed when a time-zone is needed in
relation to this location.
coordinates:
String (optional)
An
geo:
URI for the location.
linkIds:
String[] (optional)
A list of ids for links to alternate representations of this location.
For example, an alternative representation could be in vCard format.
Type:
String[VirtualLocation] (optional)
A map of ids to VirtualLocation objects, representing virtual locations, such as
video conferences or chat rooms, associated with the object.
A virtual location id MUST be unique
to this object; a UUID is a practical choice.
A VirtualLocation object has the following properties.
name:
String (optional, default:)
The human-readable name of the virtual location.
description:
String (optional)
Human-readable plain-text instructions for accessing this location. This may be an address, set of
directions, door access code, etc.
uri:
String
A URI that represents how to connect to this virtual location.
This may be a telephone number (represented as
tel:+1-555-555-555) for a teleconference, a web address for online chat, or any
custom URI.
Type:
String[Link] (optional)
A map of link ids to Link objects, representing external resources associated with the object.
A link id MUST be unique to this
calendar object; a UUID is a practical choice.
A Link object has the following properties:
href:
String
A URI from which the resource may be fetched.
This MAY be a data: URL, but it is recommended that the file
be hosted on a server to avoid embedding arbitrarily large data in JSCalendar
object instances.
cidString (optional)
This MUST be a valid content-id
value according to the definition of section 2 in .
The identifier MUST be unique within
this JSCalendar object but has no meaning beyond that. Specifically,
it MAY be different from the link
identifier in the enclosing links
property.
type: String (optional)
The content-type of the resource, if known.
size: Number (optional)
The size, in bytes, of the resource when fully decoded (i.e. the number of bytes in the
file the user would download), if known.
rel: String (optional)
Identifies the relation of the linked resource to the object. If set, the value MUST be a
registered relation type (see and IANA Link Relations).
Links with a rel of enclosure SHOULD be considered by the
client as attachments for download.
Links with a rel of describedby SHOULD be considered by the
client to be an alternate representation of the description.
Links with a rel of icon SHOULD be considered by the client
to be an image that it MAY use when presenting the calendar data to a user. The
display property MAY be set to indicate the purpose
of this image.
display: String (optional)
Describes the intended purpose of a link to an image. If set,
the rel property MUST be set to icon.
The value MUST be either
one of the following values, registered in a future RFC, or a vendor-specific value:
badge: an image inline with the title of the object
graphic: a full image replacement for the object
itself
fullsize: an image that is used to enhance the
object
thumbnail: a smaller variant of
fullsize
to be used when space for the image is constrained
title: String (optional)
A human-readable plain-text description of the resource.
Type:
String (optional)
The
language tag that best describes the locale used for the calendar object, if known.
Type:
String[Boolean] (optional)
A set of keywords or tags that relate to the object.
The set is represented as a map, with the keys being the keywords.
The value for each key in the map MUST be true.
Type:
String[Boolean] (optional)
A set of categories that relate to the calendar object.
The set is represented as a map, with the keys being the categories specified
as URIs. The value for each key in the map MUST be true.
In contrast to keywords, categories typically
are structured.
For example, a vendor owning the domain example.com
might define the categories
http://example.com/categories/sports/american-football"
and http://example.com/categories/music/r-b.
Type:
String (optional)
Specifies a color clients MAY use when displaying this calendar object. The value is a case-insensitive
color name taken from the CSS3 set of names, defined in Section 4.3 of
W3C.REC-css3-color-20110607 or a CSS3 RGB color hex value.
Type:
Recurrence
Defines a recurrence rule (repeating pattern) for recurring calendar objects.
A Recurrence object is a JSON object mapping of a RECUR value type
in iCalendar, see
and.
A JSEvent recurs by applying the recurrence rule (and
recurrenceOverrides) to the start date/time.
A JSTask recurs by applying the recurrence rule (and recurrenceOverrides) to its start date/time, if defined.
If the task does not define a start date-time, it recurs by its due date-time. If it neither defines a start
or due date-time, it MUST NOT define a recurrenceRule.
A Recurrence object has the following properties:
frequency:
String
This MUST be one of the following values:
yearlymonthlyweeklydailyhourlyminutelysecondly
To convert from iCalendar, simply lower-case the FREQ part.
interval: Number(optional, default:1)
The INTERVAL part from iCal. If included, it MUST be an integer x >=
1.
rscale: String(optional, default:"gregorian")
The RSCALE part from iCalendar RSCALE, converted to
lower-case.
skip: String(optional, default:"omit")
The SKIP part from iCalendar RSCALE, converted to
lower-case.
firstDayOfWeek: String(optional, default:"mo")
The WKST part from iCalendar, represented as a lower-case abbreviated two-letter English
day of the week.
If included, it MUST be one of the following values:
"mo"|"tu"|"we"|"th"|"fr"|"sa"|"su".
byDay: NDay[] (optional)
An NDay object has the following properties:
day: String The
day-of-the-week part of the BYDAY value in iCalendar, lower-cased. MUST be one
of the following values:
"mo"|"tu"|"we"|"th"|"fr"|"sa"|"su".
nthOfPeriod: Number (optional)
The ordinal part of the BYDAY value in iCalendar
(e.g. "+1" or "-3").
If present, rather than representing every occurrence of the weekday defined
in the day property of this NDay,
it represents only a specific instance within the recurrence period.
The value can be positive or negative, but MUST NOT be
zero. A negative integer means nth-last of period.
byMonthDay: Number[] (optional)
The BYMONTHDAY part from iCalendar. The array MUST have at least one entry if included.
byMonth: String[] (optional)
The BYMONTH part from iCalendar. Each entry is a string representation of a number,
starting from 1 for the first month in the calendar (e.g. "1"
means "January" with Gregorian calendar), with an
optional "L" suffix (see ) for
leap months (this MUST be upper-case, e.g. "3L").
The array MUST have at least one entry if included.
byYearDay: Number[](optional)
The BYYEARDAY part from iCalendar. The array MUST have at least one entry if included.
byWeekNo: Number[](optional)
The BYWEEKNO part from iCalendar. The array MUST have at least one entry if included.
byHour: Number[](optional)
The BYHOUR part from iCalendar. The array MUST have at least one entry if included.
byMinute: Number[](optional)
The BYMINUTE part from iCalendar. The array MUST have at least one entry if included.
bySecond: Number[](optional)
The BYSECOND part from iCalendar. The array MUST have at least one entry if included.
bySetPosition: Number[](optional)
The BYSETPOS part from iCalendar. The array MUST have at least one entry if included.
count: Number(optional)
The COUNT part from iCalendar. This MUST NOT be included if an
until property is specified.
until: LocalDate(optional)
The UNTIL part from iCalendar. This MUST NOT be included if a
count property is specified. Note, as in iCalendar, this
date is presumed to be in the time-zone specified in
timeZone. It is not a UTC time.
A recurrence rule specifies a set of set of date-times for recurring
calendar objects. A recurrence rule has the following semantics:
A set of candidates is generated. This is every second within a
period defined by the frequency property:
yearly:
every second from midnight on the 1st January
(inclusive) to midnight the following 1st January
(exclusive)
monthly: every second from
midnight on the 1st of a month (inclusive) to midnight
on the 1st of the following month (exclusive)
weekly: every second from
midnight (inclusive) on the first day of the week (as
defined by the firstDayOfWeek property, or Monday if
omitted), to midnight 7 days later (exclusive).
daily: every second from
midnight at the start of the day (inclusive) to midnight
at the end of the day (exclusive).
hourly: every second from
the beginning of the hour (inclusive) to the beginning
of the next hour (exclusive).
minutely: every second
from the beginning of the minute (inclusive) to the
beginning of the next minute (exclusive).
secondly: the second
itself, only.
Each date-time candidate is compared against all of the byX
properties of the rule except bySetPosition. If any property in
the rule does not match the date-time, it is eliminated. Each
byX property is an array; the date-time matches the property if
it matches any of the values in the array. The properties have
the following semantics:
byMonth: the date-time is
in the given month.
byMonthDay: the date-time
is on the given day of the month. Negative numbers mean
the nth last day of the month.
byDay: the date-time is on
the given day of the week. If the day is prefixed by a
number, it is the nth occurrence of that day of the week
within the month (if frequency is monthly) or year (if
frequency is yearly). Negative numbers means nth last
occurrence within that period.
byYearDay: the date-time is
on the nth day of year. Negative numbers mean the nth
last day of the year.
byWeekNo: the date-time is
in the nth week of the year. Negative numbers mean the
nth last week of the year. This corresponds to weeks
according to week numbering as defined in ISO.8601.2004,
with a week defined as a seven day period, starting on
the firstDayOfWeek property value or Monday if omitted.
Week number one
of the calendar year is the first week that contains at
least four days in that calendar year.
byHour: the date-time has
the given hour value.
byMinute: the date-time has
the given minute value.
bySecond: the date-time has
the given second value.
If a bySetPosition property is included, this is now applied to
the ordered list of remaining dates (this property specifies the
indexes of date-times to keep; all others should be eliminated.
Negative numbers are indexes from the end of the list, with -1
being the list item).
Any date-times before the start date of the event are eliminated
(see below for why this might be needed).
If further dates are required (we have not reached the until
date, or count limit) skip the next (interval - 1) sets of
candidates, then continue from step 1.
When determining the set of occurrence dates for an event or task, the
following extra rules must be applied:
The start date-time is always the first occurrence in the expansion (and
is counted if the recurrence is limited by a "count" property), even if it
would normally not match the rule.
The first set of candidates to consider is that which would contain the
start date-time. This means the first set may include candidates before
the start; such candidates are eliminated from the results in step (4) as
outlined before.
The following properties MUST be implicitly added to the rule under the
given conditions:
If frequency > secondly and no bySecond property:
Add a bySecond property with the sole value being the seconds value of
the start date-time.
If frequency > minutely and no byMinute property:
Add a byMinute property with the sole value being the minutes value of
the start date-time.
If frequency > hourly and no byHour property:
Add a byHour property with the sole value being the hours value of the
start date-time.
If frequency is weekly and no byDay property:
Add a byDay property with the sole value being the day-of-the-week of
the start date-time.
If frequency is monthly and no byDay property and no byMonthDay
property:
Add a byMonthDay property with the sole value being the
day-of-the-month of the start date-time.
If frequency is yearly and no byYearDay property:
if there are no byMonth or byWeekNo properties, and either there is a
byMonthDay property or there is no byDay property: Add a byMonth property
with the sole value being the month of the start date-time.
if there is no byMonthDay, byWeekNo or byDay properties: Add a byMonthDay
property with the sole value being the day-of-the-month of the start date-time.
if there is a byWeekNo property and no byMonthDay or byDay properties:
Add a byDay property with the sole value being the day-of-the-week of the
start date-time.
Type:
LocalDate[PatchObject] (optional)
A map of the recurrence-ids (the date-time of the start of the occurrence) to
an object of patches to apply to the generated occurrence object.
If the recurrence-id does not match an expanded start date from a recurrence rule, it is to be
treated as an additional occurrence (like an RDATE from iCalendar). The patch object may often
be empty in this case.
If the patch object defines the excluded property to be
true, then the recurring calendar object does not occur
at the recurrence-id date-time (like an EXDATE from iCalendar). Such a patch object
MUST NOT patch any other property.
By default, an occurrence inherits all properties from the main object except the start (or due)
date-time, which is shifted to the new start time of the LocalDate key. However, individual
properties of the occurrence can be modified by a patch, or multiple patches. It is valid to patch
the start property value, and this patch takes precedence over the LocalDate key. Both the LocalDate
key as well as the patched start date-time may occur before the original JSCalendar object's start or
due date.
A pointer in the PatchObject MUST NOT start with one of the following prefixes; any patch with
such a key MUST be ignored:
@type
uid
relatedTo
prodId
method
isAllDay
recurrenceRule
recurrenceOverrides
replyTo
Type:
Boolean (optional, default:false)
Defines if this object is an overridden, excluded instance of a recurring
JSCalendar object (also see ). If this property
value is true, this calendar object instance MUST be
treated as if not existent.
Type: Number (optional, default:0)
Specifies a priority for the calendar object. This may be used as part of scheduling systems to help
resolve conflicts for a time period.
The priority is specified as an integer in the range 0 to 9. A value of 0 specifies an undefined
priority. A value of 1 is the highest priority. A value of 2 is the second highest priority.
Subsequent numbers specify a decreasing ordinal priority. A value of 9 is the lowest priority.
Other integer values are reserved for future use.
Type: String(optional, default:busy)
Specifies how this property should be treated when calculating free-busy state. The value MUST be
one of:
"free": The object should be ignored when calculating
whether the user is busy.
"busy": The object should be included when calculating
whether the user is busy.
Type: String(optional, default:public)
Calendar objects are normally collected together and may be shared with other users. The privacy
property allows the object owner to indicate that it should not be shared, or should only have
the time information shared but the details withheld.
Enforcement of the restrictions indicated by this property are up to the implementations.
This property MUST NOT affect the information sent to scheduled participants; it is only
interpreted when the object is shared as part of a shared calendar.
The value MUST be either one of the following values, registered in a future RFC, or a
vendor-specific value. Vendor specific values MUST be prefixed with a domain name controlled by
the vendor, e.g. example.com/topsecret. Any value the client or
server doesn't understand should be preserved but treated as equivalent to
private.
public: The full details of the object are visible to those
whom the object's calendar is shared with.
private: The details of the object are hidden; only the
basic time and metadata is shared. Implementations MUST ensure the following
properties are stripped when the object is accessed by a sharee:
title
description
locations
links
locale
localizations
participants
replyTo
In addition, any patches in recurrenceOverrides whose key is
prefixed with one of the above properties MUST be stripped.
secret: The object is hidden completely (as though it did
not exist) when the calendar is shared.
Type:
String[String] (optional)
Represents methods by which participants may submit their RSVP response to the organizer of the calendar object. The
keys in the property value are the available methods. The value is a URI to use that method.
Future methods may be defined in future specifications; a calendar client MUST ignore any
method it does not understand.
The following methods are defined:
imip: The organizer accepts an iMIP
response at this email address.
The value MUST be a mailto: URI.
other:
The user may submit the RSVP using this URI. The URI MUST be a
valid URI Template () in level 2
format. The template MAY contain variables that MUST be expanded from the
JSCalendar object as defined in table .
Calendar clients SHOULD be prepared to handle authentication requests
from the respective URI and for the participant email, but this
specification does not mandate any specific mechanism.
VariableExpand to
participantId
The participant id of the replying Participant object.
uid
The uid property value of the
JSCalendar object.
sequence
The sequence property value
of the JSCalendar object.
recurrenceId
The recurrence-id when replying for a single occurrence
of a recurring JSCalendar object. The LocalDate-typed value is
the recurrence-id of a non-overridden recurrence,
or the key of a recurrenceOverride of this JSCalendar object.
Type:
String[Participant] (optional)
A map of participant ids to participants, describing their participation in the calendar object.
A participant id MUST be a valid URI and MUST be unique
to this calendar object; a mailto: URI with the email
address of the participant is a good choice.
A Participant object has the following properties:
name: String The display name
of the participant (e.g. "Joe Bloggs").
email: String (optional)
The email address for the participant.
kind: String (optional)
What kind of entity this participant is, if known.
This MUST be either one of the following values, registered in a future RFC, or a
vendor-specific value. Any value the client or server doesn't understand should be
treated the same as if this property is omitted.
individual: a single person
group: a collection of people invited as a whole
resource: a non-human resource, e.g. a projector
location: a physical location involved in the calendar object
that needs to be scheduled, e.g. a conference room.
roles:
String[]
A list of roles that this participant fulfills.
At least one value MUST be specified for the participant. This MUST be either one of the
following values, registered in a future RFC, or a vendor-specific value.
Any value the client or server doesn't understand should be preserved but ignored.
owner: The participant is an owner of the object.
attendee: The participant is an attendee of the
calendar object.
chair: The participant is in charge of the calendar
object when it occurs.
locationId: String (optional)
The location at which this participant is expected to be attending.
If the value does not correspond to any location id in the locations
property of the instance, this MUST be treated the same as if the participant's locationId were omitted.
rsvpResponse: String(optional, default:needs-action)
The RSVP response, if any, of this participant.
The value MUST be either one of the following values, registered in a future RFC, or a
vendor-specific value:
needs-action: No status yet set by the participant.
accepted: The invited participant will participate.
declined: The invited participant will not participate.
tentative: The invited participant may participate.
participation: String(optional, default:required)
The required participation of this participant.
The value MUST be either one of the following values, registered in a future RFC, or a
vendor-specific value. Any value the client or server doesn't understand should be
treated the same as required.
non-participant: Indicates a participant who is
copied for information purposes only.
optional: Indicates a participant whose
participation is optional.
required: Indicates a participant whose
participation is required.
rsvpWanted: Boolean(optional, default:false)
If true, the organizer is expecting the participant to notify them of their status.
scheduleSequence: Number(optional, default:0)
The sequence number of the last response from the participant. If defined, this MUST be a non-negative integer.
This can be used to determine whether the participant has sent a new RSVP following
significant changes to the calendar object, and to determine if future responses are responding to
a current or older view of the data.
scheduleUpdated: UTCDate (optional)
The updated property of the last iMIP response from the
participant.
This can be compared to the updated timestamp in future iMIP
responses to determine if the response is older or newer than the current data.
invitedBy: String (optional)
The participant id of the participant who invited this one, if known.
delegatedTo: String[] (optional)
A list of participant ids of participants that this participant has delegated their
participation to.
This MUST be omitted if none (rather than an empty array).
delegatedFrom: String[] (optional)
A list of participant ids that this participant is acting as a delegate for. This MUST
be omitted if none (rather than an empty array).
memberOf: String[] (optional)
A list of group participants that were invited to this calendar object, which caused this
participant to be invited due to their membership of the group(s). This MUST be omitted
if none (rather than an empty array).
linkIds: String[] (optional)
Links to more information about this participant, for example in vCard format.
Type: Boolean (optional, default:false)
If true, use the user's default alerts and ignore the
value of the alerts
property. Fetching user defaults is dependent on the API from which this JSCalendar object is
being fetched, and is not defined in this specification.
If an implementation cannot determine the user's default alerts, or none
are set, it MUST process the alerts property as if
useDefaultAlerts is set to false.
Type:
String[Alert] (optional)
A map of alert ids to Alert objects, representing alerts/reminders to display or send the user
for this calendar object. The id MUST be unique to this calendar object;
a UUID is a practical choice.
An Alert Object has the following properties:
relativeTo: String (optional, default:before-start)
Specifies where the offset is relative to for the alarm to trigger. The value MUST be
one of:
before-startafter-startbefore-endafter-endoffset:
Duration
The offset from the start and end/due of the calendar object to fire the alert.
If the calendar object does not define a time-zone,
the user's default time-zone SHOULD be used when determining the offset,
if known. Otherwise, the time-zone to use is implementation specific.
acknowledged: UTCDate (optional)
When the user has permanently dismissed the alert the client MUST set this to
the current time in UTC. Other clients which sync this property can then
automatically dismiss or suppress duplicate alerts (alerts with the same alert
id that triggered on or before this date-time).
For a recurring calendar object, the acknowledged property of
the parent object MUST be updated, unless the alert is already overridden
in recurrenceOverrides.
snoozed: UTCDate (optional)
If the user temporarily dismisses the alert, this is the UTC date-time after
which it should trigger again.
Setting this property on an instance of a recurring calendar object MUST update the alarm
on the master object, unless the respective instance already is defined in
recurrenceOverrides. It MUST NOT generate an override
for the sole use of snoozing an alarm.
action: String (optional, default:display)
Describes how to alert the user.
The value MUST be at most one of the following values,
registered in a future RFC, or a vendor-specific value:
display: The alert should be displayed as appropriate for the current device and user context.
email: The alert should trigger an email sent out to the user, notifying about the alert.
This action is typically only appropriate for server implementations.
Type:
String[PatchObject] (optional)
A map of
language tags to patch objects, which localize the calendar object into the locale of the respective language tag.
See the description of PatchObject for the
structure of the PatchObject. The patches are applied to the top-level object.
In addition to all the restrictions on patches specified there, the pointer also
MUST NOT start with one of the following prefixes; any
patch with a such a key MUST be ignored:
@typeduedurationfreeBusyStatuslocalizationmethodparticipantsprodIdprogressrelatedTosequencestartstatustimeZoneuiduseDefaultAlerts
Note that this specification does not define how to maintain validity of
localized content. For example, a client application changing a JSCalendar
object's title property might also need to update any localizations
of this property. Client implementations SHOULD provide the means to
manage localizations, but how to achieve this is specific to the
application's workflow and requirements.
In addition to the common JSCalendar object properties a
JSEvent
has the following properties:
Type: LocalDate e.g.
2015-09-02T00:00:00
The date/time the event would start in the event's time-zone.
A valid JSEvent MUST include this property.
Type:
String|null (optional, default:null)
The IANA Time Zone Database name for the
time-zone the event is scheduled in, or null for floating time. If
omitted, this MUST be presumed to be null (i.e. floating time).
Type: Duration, e.g. P2DT3H
(optional, default: P0D)
The zero or positive duration of the event in absolute time (i.e. in UTC time; ignoring DST shifts).
To get the end date in the event time-zone, convert start into UTC, then add the duration,
then convert the result into the appropriate time-zone.
A JSEvent MAY be end in a different time-zone (e.g. a plane flight crossing
time-zones). In this case, the JSEvent MUST specify the end time-zone in a
location property value that defines its
rel to be end and
the end time-zone in its timeZone property.
Type: Boolean (optional, default:false)
Specifies if the event an all day event, such as a birthday or public holiday.
If isAllDay is true, then the following restrictions apply:
the start property
MUST have a time component of T00:00:00.
the duration property MUST only include a day
component.
Note that all-day events MAY be bound to a specific time-zone, as defined by
the timeZone property.
Type: String (optional, default:confirmed)
The scheduling status () of a JSEvent.
If set, it MUST be one of:
confirmed: Indicates the event is definite.
cancelled: Indicates the event is cancelled.
tentative: Indicates the event is tentative.
In addition to the common JSCalendar object properties a
JSTask has the following properties:
Type: LocalDate (optional) e.g.
2015-09-02T00:00:00
The date/time the task is due in the task's time-zone.
Type: LocalDate (optional) e.g.
2015-09-02T00:00:00
The date/time the task should start in the task's time-zone.
Type:
String|null (optional, default:null)
The IANA Time Zone Database name for the
time-zone the task is scheduled in, or null for floating time. If
omitted, this MUST be presumed to be null (i.e. floating time).
Type: Duration (optional), e.g.
P2DT3HSpecifies the estimated positive duration of time the task takes to complete.
Type: UTCDate (optional), e.g.
2016-06-13T12:00:00ZSpecifies the date/time the task status properties was last updated.
If the task is recurring and has future instances, a client may want to keep track of the
last status update timestamp of a specific task recurrence, but leave other instances
unchanged. One way to achieve
this is by overriding the statusUpdatedAt property in the task
recurrenceOverrides.
However, this could produce a long list of timestamps for regularly recurring tasks. An
alternative approach is to split the JSTask into a current, single instance of JSTask with this
instance status update time and a future recurring instance. Also see the definition of the
relatedTo on splitting.
Type: Boolean (optional, default:false)
Specifies if the task is an all day task.
If isAllDay is true, then
the start and due properties
MUST have a time component of T00:00:00.
Note that the estimatedDuration property MAY
contain a non-zero time duration. All-day tasks MAY be bound to a
specific time-zone, as defined by the timeZone property.
In addition to the common properties of a Participant
object (), a Participant within a JSTask supports the following property:
progress:
ParticipantProgress (optional) The progress of the participant for this task, if known.
This property MUST NOT be set if the rsvpResponse
of this participant is any other value but accepted.
A ParticipantProgress object has the following properties:
status: String Describes
the completion status of the participant's progress.
The value MUST be at most one of the following values,
registered in a future RFC, or a vendor-specific value:
completed: The participant completed their task.
in-process: The participant has started this task.
failed: The participant failed to complete their task.
timestamp: UTCDate Describes
the last time when the participant progress got updated.
Type: String
Defines the overall status of this task. If omitted, the default status
() of a JSTask is defined as follows
(in order of evaluation):
completed: if all the ParticipantProgress
status of the task participants is completed.
failed: if at least one ParticipantProgress
status of the task participants is failed.
in-process: if at least one ParticipantProgress
status of the task participants is in-process.
needs-action: If none of the other criteria match.
If set, it MUST be one of:
needs-action: Indicates the task needs action.
completed: Indicates the task is completed.
in-process: Indicates the task is in process.
cancelled: Indicates the task is cancelled.
pending: Indicates the task has been created and accepted for processing, but not yet started.
failed: Indicates the task failed.
JSGroup supports the following JSCalendar properties:
@type
uid
created
updated
categories
keywords
name
description
color
links
as well as the following JSGroup-specific properties:
Type: String[JSTask|JSEvent]
A collection of group members. This is represented as a map of
the uid property value to the
JSCalendar object member having that uid. Implementations MUST ignore
entries of unknown type.
Type: String (optional)
The source from which updated versions of this group may be retrieved from.
The value MUST be a URI.
This section specifies which JSCalendar properties can be mapped from and to iCalendar
format. Implementations SHOULD follow these conversion guidelines. Still, JSCalendar does not restrict
itself to iCalendar and conversion between these two formats MAY be lossy.
The iCalendar counterpart to JSEvent is the VEVENT component type
. A VEVENT component that is a direct child of a VCALENDAR component is
equivalent to a standalone JSEvent. A VEVENT component within a VEVENT
maps to the entries of
the JSEvent recurrenceOverrides property.
PropertyiCalendar counterpartisAllDay
True, if the type of the DTSTART property in iCalendar is DATE. When translating from JSCalendar
the iCalendar DTSTART property is of DATE value type, if the isAllDay
property is set to true and the timeZone property is null.
start
Corresponds to the DTSTART property in iCalendar. Note that time-zone information is stored separately in JSEvent.
timeZone
Corresponds to the TZID part of the DTSTART property in iCalendar.
If the event has a different end time-zone to start time-zone, this should be
added as a JSCalendar location with just a
timeZone property and rel="end".
duration
Corresponds to the DURATION or DSTART+DTEND properties in iCalendar.
The iCalendar counterpart to JSTask is the VTODO component type
. A VTODO component that is a direct child of a VCALENDAR component is
equivalent to a standalone JSTask. A VTODO component within a master
VTODO maps to the entries of
the JSTask recurrenceOverrides property.
PropertyiCalendar counterpartisAllDay
True, if the type of the DTSTART property in iCalendar is DATE. When translating from JSCalendar
the iCalendar DTSTART property is of DATE value type, if the isAllDay
property is set to true and the timeZone property is null.
due
Corresponds to the DUE and DTSTART+DURATION properties in iCalendar. When mapping iCalendar
VTODOs with DTSTART+DURATION, the due date is the result of adding DURATION to DTSTART in the
DTSTART time-zone.
start
Corresponds to the DTSTART property in iCalendar.
timeZone
Corresponds to the TZID part of the DTSTART/DUE properties in iCalendar.
If the task has a different end time-zone to start or due time-zone, this should be
added as a JSCalendar location with just a
timeZone property and rel="end".
estimatedDuration
Corresponds to the ESTIMATED-DURATION iCalendar
property in the RFC draft .
statusUpdatedAt
Maps to the COMPLETED iCalendar property. The JSTask status property
MUST have value completed.
progress
Corresponds to the PARTSTAT and COMPLETED properties in iCalendar, including the
definitions in the RFC draft .
status
Corresponds to the STATUS property in iCalendar, including the
definitions in the RFC draft .
A JSGroup converts to a iCalendar VCALENDAR containing VEVENT or VTODO components.
PropertyiCalendar counterpartentries
The VEVENT and VTODO components within a top-level VCALENDAR component.
source
Corresponds to the SOURCE property in iCalendar.
PropertyiCalendar counterpartalerts
An Alert corresponds to the VALARM component in iCalendar, where
the action is determined by the iCalendar ACTION property value
(e.g., both DISPLAY and AUDIO actions
map to a JSCalendar display action, and similarly for
EMAIL).
The relativeTo and offset properties
corresponds to the iCalendar TRIGGER property.
categories
Corresponds to the CONCEPT property in iCalendar,
see in the RFC draft .
color
Corresponds to the COLOR property in iCalendar, as specified in .
created
Corresponds to the CREATED property in iCalendar.
description
Corresponds to the DESCRIPTION property and its ALTREP parameters in iCalendar.
descriptionContentType
Implementation-specific.
freeBusyStatus
Corresponds to the TRANSP property in iCalendar.
keywords
Corresponds to the CATEGORIES property in iCalendar, as specified in .
links
Corresponds to the ATTACH () or IMAGE ()
properties with a URI value type set to the link href.
(). The type property
corresponds to the FMTTYPE parameter, the size
property to the SIZE parameter.
Mapping all other properties is implementation-specific.
locale
Corresponds to the LANGUAGE parameter in iCalendar, which is added to individual properties.
When converting from iCalendar, one language must be picked as the main locale for the
object, and all properties in other languages moved to the localizations JSEvent property.
localizations
Implementation-specific.
locations
See .
method
Corresponds to the METHOD property of the embedding VCALENDAR in iCalendar.
participants
See .
priority
Corresponds to the PRIORITY property in iCalendar.
privacy
Corresponds to the CLASS property in iCalendar.
prodId
Corresponds to the PRODID property in iCalendar.
recurrenceOverrides
Corresponds to the RDATE and EXDATE properties in iCalendar, plus VEVENT (for JSEvent) or
VTODO (for JSTask) instances with a recurrence-id.
recurrenceRule
Corresponds to the RRULE property in iCalendar. See the property definition at section
how to map a RRULE value.
relatedTo
Corresponds to the RELATED-TO property in iCalendar.
replyTo
An iCalendar ORGANIZER with one of the mapped URIs as value. If URIs are defined
for both the imip and other
type, it is recommended to map the imip value to the
calendar address value of the ORGANIZER.
sequence
Corresponds to the SEQUENCE property in iCalendar.
status
Corresponds to the STATUS property in iCalendar (converted to lower-case).
title
Corresponds to the SUMMARY property in iCalendar.
uid
Corresponds to the UID property in iCalendar.
updated
Corresponds to the DTSTAMP and LAST-MODIFIED properties in iCalendar. (These are only
different in the iTIP case, and the difference is not actually useful.)
Both JSCalendar participants and locations have counterparts in iCalendar
but provide richer representation.
The following table outlines translation of JSCalendar participants. Where
iCalendar has distinct properties for ORGANIZER and ATTENDEE, these are merged
in JSCalendar into the Participant object type.
PropertyiCalendar counterpartdelegatedFrom
the DELEGATED-FROM parameter
delegatedTo
the DELEGATED-TO parameter
email
the value of the ORGANIZER or ATTENDEE property
kind
the CUTYPE parameter
linkIds
Implementation-specific.
locationId
Implementation-specific. When mapping from iCalendar to JSCalendar this
may be the JSCalendar identifier of a CONFERENCE property that has the
MODERATOR feature defined in its FEATURE parameter values. If multiple
such CONFERENCE properties are defined in iCalendar, then the one with the
most interactive features is chosen.
memberOf
the MEMBER parameter
name
the CN parameter
participation
Maps to the standard iCalendar ROLE parameter values REQ-PARTICIPANT, OPT-PARTICIPANT and
NON-PARTICIPANT.
roles
The chair role maps to the standard iCalendar ROLE
parameter value chair, with an implicit participant
of value required. The mapping of non-required chairs
and other roles is implementation-specific, but using x-name
parameter values is recommended.
rsvpResponse
the PARTSTAT parameter
the DELEGATED-TO parameter
scheduleSequence
the SEQUENCE property of the participant's latest iMIP message
scheduleUpdated
the DTSTAMP property of the participant's latest iMIP message
The iCalendar counterpart for JSCalendar Location objects is the iCalendar
LOCATION property, or implementation-specific.
PropertyiCalendar counterpart
name
Corresponds to the LOCATION property value.
description
Implementation-specific.
rel
Implementation-specific.
timeZone
Implementation-specific.
coordinates
Implementation-specific. Consider using a GEO iCalendar property, along with one LOCATION.
uri
Corresponds to the LOCATION ALTREP parameter.
linkIds
Implementation-specific.
The iCalendar counterpart for JSCalendar VirtualLocation objects is the iCalendar
CONFERENCE property, or implementation-specific.
PropertyiCalendar counterpart
name
Corresponds to the CONFERENCE LABEL parameter.
description
Implementation-specific.
uri
Corresponds to the CONFERENCE property value.
Both JSCalendar and iCalendar calendar objects may contain properties that are
not expressible in the other format. This specification does not mandate how to
preserve these properties. Instead, it leaves negotiation on how to treat unknown
properties to client and server implementations and their protocol used to exchange
calendar objects.
Two notable options to represent and preserve arbitrary iCalendar object
properties in JSCalendar are:
JCal: Define iCalendar properties in JCal
format
() in a vendor-specific property of the
JCalendar
object. The JCal-formatted value may either only contain iCalendar
properties that were not mapped to JSCalendar properties, or contain the
complete iCalendar object representation.
Alternate link: Define an alternate link
()
value pointing to the iCalendar representation of the JSCalendar object.
E.g. the alternative representation of a VEVENT would be represented as
a link with rel alternate and type
text/calendar;component=VEVENT.
The following examples illustrate several aspects of the JSCalendar data model and format.
The examples may omit mandatory or additional properties, which is indicated by a
placeholder property with key .... While most of the
examples use calendar event objects, they are also illustrative for tasks.
This example illustrates a simple one-time event. It specifies a one-time event that begins on January 15, 2018 at 1pm New York local time and ends after 1 hour.
This example illustrates a simple task for a plain to-do item.
This example illustrates a simple calendar object group that contains an event and a task.
This example illustrates an event for an international holiday. It specifies an all-day event on April 1 that occurs every year since the year 1900.
This example illustrates a task with a due date. It is a reminder to buy groceries before 6pm Vienna local time on January 19, 2018. The calendar user expects to need 1 hour for shopping.
This example illustrates the use of end time-zones by use of an international flight. The flight starts on April 1, 2018 at 9am in Berlin local time. The duration of the flight is scheduled at 10 hours 30 minutes. The time at the flights destination is in the same time-zone as Tokyo. Calendar clients could use the end time-zone to display the arrival time in Tokyo local time and highlight the time-zone difference of the flight. The location names can serve as input for navigation systems.
This example illustrates the use of floating-time. Since January 1, 2018, a calendar user blocks 30 minutes every day to practice Yoga at 7am local time, in whatever time-zone the user is located on that date.
This example illustrates an event that happens at both a physical and a virtual location. Fans can see a live convert on premises or online. The event title and descriptions are localized. (Note: the localization of the event description contains an UTF-8 encoded German Umlaut. This character may have been replaced with ASCII characters in the plain-text rendering of this RFC document)
This example illustrates the use of recurrence overrides. A math course at a University is held for the first time on January 8, 2018 at 9am London time and occurs every week until June 25, 2018. Each lecture lasts for one hour and 30 minutes and is located at the Mathematics department. This event has exceptional occurrences: at the last occurrence of the course is an exam, which lasts for 2 hours and starts at 10am. Also, the location of the exam differs from the usual location. On April 2 no course is held. On January 5 at 2pm is an optional introduction course, that occurs before the first regular lecture.
This example illustrates scheduled events. A team meeting occurs every week since January 8, 2018 at 9am Johannesburg time. The event owner also chairs the event. Participants meet in a virtual meeting room. An attendee has accepted the invitation, but on March 8, 2018 he is unavailable and declined participation for this occurrence.
The use of JSON as a format does have its own inherent security risks as discussed in Section 12 of
. Even though JSON is considered a safe subset of JavaScript, it should be kept in
mind that a flaw in the parser processing JSON could still impose a threat, which doesn't arise with
conventional iCalendar data.
With this in mind, a parser for JSON data aware of the security implications should be used for the
format described in this document. For example, the use of JavaScript's
eval() function is considered an unacceptable security risk, as described
in Section 12 of. A native parser with full awareness of the JSON format should
be preferred.
This document amends the application/calendar MIME media
type defined in .
New optional parameter: type with value being one of
jsevent, jstask,
jsgroup.
The parameter MUST NOT occur more than once.
The authors would like to thank the members of CalConnect for their valuable contributions. This
specification originated from the work of the API technical committee of CalConnect, the Calendaring and
Scheduling Consortium.
Task Extensions to iCalendarSupport for iCalendar RelationshipsIANA Media Types