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Calendaring extensions N. Jenkins
Internet-Draft R. Stepanek
Intended status: Standards Track FastMail
Expires: March 3, 2019 August 30, 2018
JSCalendar: A JSON representation of calendar data
draft-ietf-calext-jscalendar-06
Abstract
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.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 3, 2019.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Relation to the iCalendar format . . . . . . . . . . . . 4
1.2. Notational Conventions . . . . . . . . . . . . . . . . . 5
2. JSCalendar objects . . . . . . . . . . . . . . . . . . . . . 5
2.1. JSEvent . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. JSTask . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. JSGroup . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Structure of JSCalendar objects . . . . . . . . . . . . . . . 6
3.1. Type signatures . . . . . . . . . . . . . . . . . . . . . 6
3.2. Data Types . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.1. UTCDate . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.2. LocalDate . . . . . . . . . . . . . . . . . . . . . . 7
3.2.3. Duration . . . . . . . . . . . . . . . . . . . . . . 7
3.2.4. PatchObject . . . . . . . . . . . . . . . . . . . . . 8
3.2.5. Identifiers . . . . . . . . . . . . . . . . . . . . . 8
3.2.6. Normalization and equivalence . . . . . . . . . . . . 8
3.3. Custom property extensions and values . . . . . . . . . . 9
4. Common JSCalendar properties . . . . . . . . . . . . . . . . 9
4.1. Metadata properties . . . . . . . . . . . . . . . . . . . 9
4.1.1. @type . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1.2. uid . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1.3. relatedTo . . . . . . . . . . . . . . . . . . . . . . 10
4.1.4. prodId . . . . . . . . . . . . . . . . . . . . . . . 11
4.1.5. created . . . . . . . . . . . . . . . . . . . . . . . 11
4.1.6. updated . . . . . . . . . . . . . . . . . . . . . . . 11
4.1.7. sequence . . . . . . . . . . . . . . . . . . . . . . 12
4.1.8. method . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. What and where properties . . . . . . . . . . . . . . . . 12
4.2.1. title . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2.2. description . . . . . . . . . . . . . . . . . . . . . 12
4.2.3. descriptionContentType . . . . . . . . . . . . . . . 12
4.2.4. locations . . . . . . . . . . . . . . . . . . . . . . 12
4.2.5. virtualLocations . . . . . . . . . . . . . . . . . . 13
4.2.6. links . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2.7. locale . . . . . . . . . . . . . . . . . . . . . . . 15
4.2.8. keywords . . . . . . . . . . . . . . . . . . . . . . 15
4.2.9. categories . . . . . . . . . . . . . . . . . . . . . 15
4.2.10. color . . . . . . . . . . . . . . . . . . . . . . . . 16
4.3. Recurrence properties . . . . . . . . . . . . . . . . . . 16
4.3.1. recurrenceRule . . . . . . . . . . . . . . . . . . . 16
4.3.2. recurrenceOverrides . . . . . . . . . . . . . . . . . 21
4.3.3. excluded . . . . . . . . . . . . . . . . . . . . . . 22
4.4. Sharing and scheduling properties . . . . . . . . . . . . 22
4.4.1. priority . . . . . . . . . . . . . . . . . . . . . . 22
4.4.2. freeBusyStatus . . . . . . . . . . . . . . . . . . . 22
4.4.3. privacy . . . . . . . . . . . . . . . . . . . . . . . 23
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4.4.4. replyTo . . . . . . . . . . . . . . . . . . . . . . . 24
4.4.5. participants . . . . . . . . . . . . . . . . . . . . 25
4.5. Alerts properties . . . . . . . . . . . . . . . . . . . . 27
4.5.1. useDefaultAlerts . . . . . . . . . . . . . . . . . . 27
4.5.2. alerts . . . . . . . . . . . . . . . . . . . . . . . 27
4.6. Multilingual properties . . . . . . . . . . . . . . . . . 29
4.6.1. localizations . . . . . . . . . . . . . . . . . . . . 29
5. Type-specific JSCalendar properties . . . . . . . . . . . . . 30
5.1. JSEvent properties . . . . . . . . . . . . . . . . . . . 30
5.1.1. start . . . . . . . . . . . . . . . . . . . . . . . . 30
5.1.2. timeZone . . . . . . . . . . . . . . . . . . . . . . 30
5.1.3. duration . . . . . . . . . . . . . . . . . . . . . . 30
5.1.4. isAllDay . . . . . . . . . . . . . . . . . . . . . . 31
5.1.5. status . . . . . . . . . . . . . . . . . . . . . . . 31
5.2. JSTask properties . . . . . . . . . . . . . . . . . . . . 31
5.2.1. due . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.2.2. start . . . . . . . . . . . . . . . . . . . . . . . . 32
5.2.3. timeZone . . . . . . . . . . . . . . . . . . . . . . 32
5.2.4. estimatedDuration . . . . . . . . . . . . . . . . . . 32
5.2.5. statusUpdatedAt . . . . . . . . . . . . . . . . . . . 32
5.2.6. isAllDay . . . . . . . . . . . . . . . . . . . . . . 32
5.2.7. progress . . . . . . . . . . . . . . . . . . . . . . 33
5.2.8. status . . . . . . . . . . . . . . . . . . . . . . . 33
5.3. JSGroup properties . . . . . . . . . . . . . . . . . . . 34
5.3.1. entries . . . . . . . . . . . . . . . . . . . . . . . 34
5.3.2. source . . . . . . . . . . . . . . . . . . . . . . . 35
6. Conversion from and to iCalendar . . . . . . . . . . . . . . 35
6.1. JSEvent . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.2. JSTask . . . . . . . . . . . . . . . . . . . . . . . . . 36
6.3. JSGroup . . . . . . . . . . . . . . . . . . . . . . . . . 38
6.4. Common properties . . . . . . . . . . . . . . . . . . . . 38
6.5. Locations and participants . . . . . . . . . . . . . . . 40
6.6. Unknown properties . . . . . . . . . . . . . . . . . . . 43
7. JSCalendar object examples . . . . . . . . . . . . . . . . . 43
7.1. Simple event . . . . . . . . . . . . . . . . . . . . . . 43
7.2. Simple task . . . . . . . . . . . . . . . . . . . . . . . 44
7.3. Simple group . . . . . . . . . . . . . . . . . . . . . . 44
7.4. All-day event . . . . . . . . . . . . . . . . . . . . . . 44
7.5. Task with a due date . . . . . . . . . . . . . . . . . . 45
7.6. Event with end time-zone . . . . . . . . . . . . . . . . 45
7.7. Floating-time event (with recurrence) . . . . . . . . . . 46
7.8. Event with multiple locations and localization . . . . . 46
7.9. Recurring event with overrides . . . . . . . . . . . . . 47
7.10. Recurring event with participants . . . . . . . . . . . . 48
8. Security Considerations . . . . . . . . . . . . . . . . . . . 50
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 50
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11.1. Normative References . . . . . . . . . . . . . . . . . . 50
11.2. Informative References . . . . . . . . . . . . . . . . . 52
11.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 53
1. Introduction
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:
o The attributes of the calendar entry represented must be described
as a simple key-value pair, reducing complexity of its
representation.
o The data model should avoid all ambiguities and make it difficult
to make mistakes during implementation.
o Most of the initial set of attributes should be taken from the
iCalendar data format ([RFC5545], also see Section 1.1), 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.
o 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
[RFC7493], which is a strict subset of the JavaScript Object Notation
(JSON) Data Interchange Format [RFC8259]. 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.
1.1. Relation to the iCalendar format
The iCalendar data format [RFC5545], 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
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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 [RFC7265] format,
which is a direct mapping between iCalendar and JSON. However, it
did not attempt to extend or update iCalendar semantics.
1.2. Notational Conventions
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 [RFC2119].
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[RFC8259].
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.
2. JSCalendar objects
This section describes the calendar object types specified by
JSCalendar.
2.1. JSEvent
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 (Section 4.1.1) property value MUST be "jsevent".
2.2. JSTask
MIME type: "application/calendar+json;type=jstask"
A JSTask represents an action-item, assignment, to-do or work item .
The @type (Section 4.1.1) property value MUST be "jstask".
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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 (Section 2.1) which is
required to start at a certain point in time and typically takes some
non-zero duration to complete.
2.3. JSGroup
MIME type: "application/calendar+json;type=jsgroup"
A JSGroup is a collection of JSEvent (Section 2.1) and JSTask
(Section 2.2) objects. Typically, objects are grouped by topic (e.g.
by keywords) or calendar membership.
The @type (Section 4.1.1) property value MUST be "jsgroup".
3. Structure of JSCalendar objects
A JSCalendar object is a JSON object, which MUST be valid I-JSON (a
stricter subset of JSON), as specified in [RFC8259]. 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.
3.1. Type signatures
Types signatures are given for all JSON objects in this document.
The following conventions are used:
o "Boolean|String": The value is either a JSON "Boolean" value, or a
JSON "String" value.
o "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.
o "Foo[]": An array of objects of type "Foo".
o "String[Foo]": A JSON "Object" being used as a map (associative
array), where all the values are of type "Foo".
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3.2. Data Types
In addition to the standard JSON data types, the following data types
are used in this specification:
3.2.1. UTCDate
This is a string in [RFC3339] "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".
3.2.2. LocalDate
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).
3.2.3. Duration
A duration is represented by a subset of ISO8601 duration format, as
specified by the following ABNF:
dur-secfrac = "." 1*DIGIT
dur-second = 1*DIGIT [dur-secfrac] "S"
dur-minute = 1*DIGIT "M" [dur-second]
dur-hour = 1*DIGIT "H" [dur-minute]
dur-time = "T" (dur-hour / dur-minute / dur-second)
dur-day = 1*DIGIT "D"
dur-week = 1*DIGIT "W"
duration = "P" (dur-day [dur-time] / dur-time / dur-week)
In addition, the duration MUST NOT include fractional second values
unless the fraction is non-zero.
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3.2.4. PatchObject
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 [RFC6901] 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:
1. 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).
2. When evaluating a path, all parts prior to the last (i.e. the
value after the final slash) MUST exist.
3. 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:
o "null": Remove the property from the patched object. If not
present in the parent, this a no-op.
o 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.
3.2.5. Identifiers
If not noted otherwise, properties 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
[RFC4648]. This is the ASCII alphanumeric characters (A-Za-z0-9),
hyphen (-), and underscore (_).
3.2.6. Normalization and equivalence
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
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the notion of equivalence might range from byte-level equivalence to
semantic equivalence, depending on the respective use case (for
example, the CalDAV protocol [RFC4791] requires octet equivalence of
the encoded calendar object to determine ETag equivalence).
Normalization of JSCalendar objects is hindered because of the
following reasons:
o 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.
o 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 [RFC3986]).
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.
3.3. Custom property extensions and values
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.
4. Common JSCalendar properties
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
Section 5 describe the set of supported properties per type.
4.1. Metadata properties
4.1.1. @type
Type: "String"
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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:
o "jsevent": a JSCalendar event (Section 2.1).
o "jstask": a JSCalendar task (Section 2.2).
o "jsgroup": a JSCalendar group (Section 2.3).
A valid JSCalendar object MUST include this property.
4.1.2. uid
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. [RFC4122] 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 [RFC5545] 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.
4.1.3. relatedTo
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:
o *relation*: "String[]" Describes how the linked object is related
to this object.
The strings in the array MUST each be at most one of the following
values, registered in a future RFC, or a vendor-specific value:
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* "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.
4.1.4. prodId
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 [RFC5545]).
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.
4.1.5. created
Type: "UTCDate" (optional)
The date and time this object was initially created.
4.1.6. updated
Type: "UTCDate"
The date and time the data in this object was last modified.
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4.1.7. sequence
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.
4.1.8. method
Type: "String" (optional)
The iTIP ([RFC5546]) method, in lower-case. Used for scheduling.
4.2. What and where properties
4.2.1. title
Type: "String" (optional, default:"")
A short summary of the object.
4.2.2. description
Type: "String" (optional, default:"")
A longer-form text description of the object. The content is
formatted according to the *descriptionContentType* property.
4.2.3. descriptionContentType
Type: "String" (optional, default:"text/plain")
Describes the media type ([RFC6838]) of the contents of the
"description" property. Media types MUST be sub-types of type
"text", and SHOULD be "text/plain" or "text/html" ([MIME]). They MAY
define parameters and the "charset" parameter MUST be "utf-8", if
specified. Descriptions of type "text/html" MAY contain "cid" URLs
([RFC2392]) to reference links in the calendar object by use of the
*cid* property of the *Link* object.
4.2.4. locations
Type: "String[Location]" (optional)
A map of location ids to Location objects, representing locations
associated with the object. A location id may be any valid [RFC6901]
JSON pointer and need only be unique to this object; a UUID is a
practical choice.
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A *Location* object has the following properties. It must define at
least one other property than *rel*.
o *name*: "String" (optional, default:"") The human-readable name of
the location.
o *description*: "String" (optional) Human-readable, plain-text
instructions for accessing this location. This may be an address,
set of directions, door access code, etc.
o *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.
o *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.
o *coordinates*: "String" (optional) An [RFC5870] "geo:" URI for the
location.
o *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.
4.2.5. virtualLocations
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 may be any valid [RFC6901] JSON
pointer and need only be unique to this object; a UUID is a practical
choice.
A *VirtualLocation* object has the following properties.
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o *name*: "String" (optional, default:"") The human-readable name of
the virtual location.
o *description*: "String" (optional) Human-readable plain-text
instructions for accessing this location. This may be an address,
set of directions, door access code, etc.
o *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.
4.2.6. links
Type: "String[Link]" (optional)
A map of link ids to Link objects, representing external resources
associated with the object. A link id may be any valid [RFC6901]
JSON pointer and need only be unique to this object; the href or a
UUID are practical choices.
A *Link* object has the following properties:
o *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.
o *cid* "String" (optional) This MUST be a valid "content-id" value
according to the definition of section 2 in [RFC2392]. 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.
o *type*: "String" (optional) The content-type [RFC6838] of the
resource, if known.
o *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.
o *rel*: "String" (optional) Identifies the relation of the linked
resource to the object. If set, the value MUST be a registered
relation type (see [RFC8288] and IANA Link Relations [1]).
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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.
o *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
o *title*: "String" (optional) A human-readable plain-text
description of the resource.
4.2.7. locale
Type: "String" (optional)
The [RFC5646] language tag that best describes the locale used for
the calendar object, if known.
4.2.8. keywords
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".
4.2.9. categories
Type: "String[Boolean]" (optional)
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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".
4.2.10. color
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 [2] or a CSS3 RGB color hex value.
4.3. Recurrence properties
4.3.1. recurrenceRule
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 [RFC5545] and[RFC7529]. 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:
o *frequency*: "String" This MUST be one of the following values:
* "yearly"
* "monthly"
* "weekly"
* "daily"
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* "hourly"
* "minutely"
* "secondly"
To convert from iCalendar, simply lower-case the FREQ part.
o *interval*: "Number"(optional, default:"1") The INTERVAL part from
iCal. If included, it MUST be an integer "x >= 1".
o *rscale*: "String"(optional, default:""gregorian"") The RSCALE
part from iCalendar RSCALE [RFC7529], converted to lower-case.
o *skip*: "String"(optional, default:""omit"") The SKIP part from
iCalendar RSCALE [RFC7529], converted to lower-case.
o *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"".
o *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.
o *byMonthDay*: "Number[]" (optional) The BYMONTHDAY part from
iCalendar. The array MUST have at least one entry if included.
o *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 [RFC7529]) for leap months (this MUST be upper-case,
e.g. ""3L""). The array MUST have at least one entry if included.
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o *byYearDay*: "Number[]"(optional) The BYYEARDAY part from
iCalendar. The array MUST have at least one entry if included.
o *byWeekNo*: "Number[]"(optional) The BYWEEKNO part from iCalendar.
The array MUST have at least one entry if included.
o *byHour*: "Number[]"(optional) The BYHOUR part from iCalendar.
The array MUST have at least one entry if included.
o *byMinute*: "Number[]"(optional) The BYMINUTE part from iCalendar.
The array MUST have at least one entry if included.
o *bySecond*: "Number[]"(optional) The BYSECOND part from iCalendar.
The array MUST have at least one entry if included.
o *bySetPosition*: "Number[]"(optional) The BYSETPOS part from
iCalendar. The array MUST have at least one entry if included.
o *count*: "Number"(optional) The COUNT part from iCalendar. This
MUST NOT be included if an *until* property is specified.
o *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:
1. 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).
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* *minutely*: every second from the beginning of the minute
(inclusive) to the beginning of the next minute (exclusive).
* *secondly*: the second itself, only.
2. 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.
3. 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).
4. Any date-times before the start date of the event are eliminated
(see below for why this might be needed).
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5. 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:
1. 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.
2. 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.
3. 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.
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+ 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.
4.3.2. recurrenceOverrides
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:
o @type
o uid
o relatedTo
o prodId
o method
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o isAllDay
o recurrenceRule
o recurrenceOverrides
o replyTo
4.3.3. excluded
Type: "Boolean" (optional, default:"false")
Defines if this object is an overridden, excluded instance of a
recurring JSCalendar object (also see Section 4.3.2). If this
property value is "true", this calendar object instance MUST be
treated as if not existent.
4.4. Sharing and scheduling properties
4.4.1. priority
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.
4.4.2. freeBusyStatus
Type: "String"(optional, default:"busy")
Specifies how this property should be treated when calculating free-
busy state. The value MUST be one of:
o ""free"": The object should be ignored when calculating whether
the user is busy.
o ""busy"": The object should be included when calculating whether
the user is busy.
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4.4.3. privacy
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".
o "public": The full details of the object are visible to those whom
the object's calendar is shared with.
o "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.
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o "secret": The object is hidden completely (as though it did not
exist) when the calendar is shared.
4.4.4. replyTo
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:
o "imip": The organizer accepts an iMIP [RFC6047] response. The
value MUST be a "mailto:" URI.
o "web": There is a web page where the user may submit the RSVP
response using a browser. The value MUST be a "https:" URI
Template ([RFC6570]) in level 1 format. The template MAY contain
variables that MUST be expanded from the JSCalendar object as
defined in table Table 1. Calendar clients SHOULD be prepared to
handle authentication requests from the respective web page and
for the participant email, but this specification does not mandate
any specific mechanism.
+--------------+----------------------------------------------------+
| Variable | Expand to |
+--------------+----------------------------------------------------+
| email | The *email* property value 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. |
+--------------+----------------------------------------------------+
Table 1: replyTo URI Template variables
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4.4.5. participants
Type: "String[Participant]" (optional)
A map of participant ids to participants, describing their
participation in the calendar object. A participant id may be any
valid [RFC6901] JSON pointer and need only be unique to this calendar
object; the email address of the participant is a good choice.
A *Participant* object has the following properties:
o *name*: "String" The display name of the participant (e.g. "Joe
Bloggs").
o *email*: "String" The email address for the participant.
o *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.
o *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.
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o *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.
o *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.
o *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.
o *rsvpWanted*: "Boolean"(optional, default:"false") If true, the
organizer is expecting the participant to notify them of their
status.
o *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
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to determine if future responses are responding to a current or
older view of the data.
o *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.
o *invitedBy*: "String" (optional) The participant id of the
participant who invited this one, if known.
o *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).
o *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).
o *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).
o *linkIds*: "String[]" (optional) Links to more information about
this participant, for example in vCard format.
4.5. Alerts properties
4.5.1. useDefaultAlerts
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".
4.5.2. alerts
Type: "String[Alert]" (optional)
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A map of alert ids to Alert objects, representing alerts/reminders to
display or send the user for this calendar object. An alert id may
be any valid [RFC6901] JSON pointer and need only be unique to this
calendar object; a globally unique id is a practical choice (also see
Section 4.1.2)).
An *Alert* Object has the following properties:
o *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-start"
* "after-start"
* "before-end"
* "after-end"
o *offset*: "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.
o *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*.
o *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.
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o *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.
4.6. Multilingual properties
4.6.1. localizations
Type: "String[PatchObject]" (optional)
A map of [RFC5646] language tags to patch objects, which localize the
calendar object into the locale of the respective language tag.
See the description of PatchObject (Section 3.2.4) 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:
o @type
o due
o duration
o freeBusyStatus
o localization
o method
o participants
o prodId
o progress
o relatedTo
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o sequence
o start
o status
o timeZone
o uid
o useDefaultAlerts
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.
5. Type-specific JSCalendar properties
5.1. JSEvent properties
In addition to the common JSCalendar object properties (Section 4) a
JSEvent has the following properties:
5.1.1. start
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.
5.1.2. timeZone
Type: "String|null" (optional, default:"null")
The IANA Time Zone Database [3] 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).
5.1.3. duration
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
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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.
5.1.4. isAllDay
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:
o the *start* property MUST have a time component of "T00:00:00".
o 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.
5.1.5. status
Type: "String" (optional, default:"confirmed")
The scheduling status (Section 4.4) of a JSEvent. If set, it MUST be
one of:
o "confirmed": Indicates the event is definite.
o "cancelled": Indicates the event is cancelled.
o "tentative": Indicates the event is tentative.
5.2. JSTask properties
In addition to the common JSCalendar object properties (Section 4) a
JSTask has the following properties:
5.2.1. due
Type: "LocalDate" (optional) e.g. "2015-09-02T00:00:00"
The date/time the task is due in the task's time-zone.
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5.2.2. start
Type: "LocalDate" (optional) e.g. "2015-09-02T00:00:00"
The date/time the task should start in the task's time-zone.
5.2.3. timeZone
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).
5.2.4. estimatedDuration
Type: "Duration" (optional), e.g. "P2DT3H"
Specifies the estimated positive duration of time the task takes to
complete.
5.2.5. statusUpdatedAt
Type: "UTCDate" (optional), e.g. "2016-06-13T12:00:00Z"
Specifies 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.
5.2.6. isAllDay
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.
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5.2.7. progress
In addition to the common properties of a *Participant* object
(Section 4.4.5), a Participant within a JSTask supports the following
property:
o *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:
o *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 progress.
* "in-process": The participant processes this task.
* "failed": The participant failed to complete their progress.
o *timestamp*: "UTCDate" Describes the last time when the
participant progress got updated.
5.2.8. status
Type: "String"
Defines the overall status of this task. If omitted, the default
status (Section 4.4) of a JSTask is defined as follows (in order of
evaluation):
o "completed": if all the *ParticipantProgress* status of the task
participants is "completed".
o "failed": if at least one *ParticipantProgress* status of the task
participants is "failed".
o "in-process": if at least one *ParticipantProgress* status of the
task participants is "in-process".
o "needs-action": If none of the other criteria match.
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If set, it MUST be one of:
o "needs-action": Indicates the task needs action.
o "completed": Indicates the task is completed.
o "in-process": Indicates the task is in process.
o "cancelled": Indicates the task is cancelled.
o "pending": Indicates the task has been created and accepted for
processing, but not yet started.
o "failed": Indicates the task failed.
5.3. JSGroup properties
JSGroup supports the following JSCalendar properties (Section 4):
o @type
o uid
o created
o updated
o categories
o keywords
o name
o description
o color
o links
as well as the following JSGroup-specific properties:
5.3.1. entries
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.
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5.3.2. source
Type: "String" (optional)
The source from which updated versions of this group may be retrieved
from. The value MUST be a URI.
6. Conversion from and to iCalendar
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.
6.1. JSEvent
The iCalendar counterpart to *JSEvent* is the VEVENT component type
[RFC5545]. 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.
+----------+--------------------------------------------------------+
| Property | iCalendar counterpart |
+----------+--------------------------------------------------------+
| isAllDay | 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. |
+----------+--------------------------------------------------------+
Table 2: Translation between JSEvent and iCalendar
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6.2. JSTask
The iCalendar counterpart to *JSTask* is the VTODO component type
[RFC5545]. 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.
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+-------------------+-----------------------------------------------+
| Property | iCalendar counterpart |
+-------------------+-----------------------------------------------+
| isAllDay | 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 |
| | [draft-apthorp-ical-tasks]. |
| | |
| 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 |
| | [draft-apthorp-ical-tasks]. |
| | |
| status | Corresponds to the STATUS property in |
| | iCalendar, including the definitions in the |
| | RFC draft [draft-apthorp-ical-tasks]. |
+-------------------+-----------------------------------------------+
Table 3: Translation between JSTask and iCalendar
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6.3. JSGroup
A JSGroup converts to a iCalendar VCALENDAR containing VEVENT or
VTODO components.
+----------+--------------------------------------------------------+
| Property | iCalendar counterpart |
+----------+--------------------------------------------------------+
| entries | The VEVENT and VTODO components within a top-level |
| | VCALENDAR component. |
| | |
| source | Corresponds to the SOURCE property in iCalendar. |
+----------+--------------------------------------------------------+
Table 4: Translation between JSGroup and iCalendar
6.4. Common properties
+------------------------+------------------------------------------+
| Property | iCalendar counterpart |
+------------------------+------------------------------------------+
| alerts | 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 |
| | [draft-ietf-calext-ical-relations]. |
| | |
| color | Corresponds to the COLOR property in |
| | iCalendar, as specified in [RFC7986]. |
| | |
| 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 |
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| | iCalendar. |
| | |
| keywords | Corresponds to the CATEGORIES property |
| | in iCalendar, as specified in [RFC7986]. |
| | |
| links | Corresponds to the ATTACH ([RFC5545]) or |
| | IMAGE ([RFC7986]) properties with a URI |
| | value type set to the link "href". |
| | ([RFC7986]). 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 Section 6.5. |
| | |
| method | Corresponds to the METHOD property of |
| | the embedding VCALENDAR in iCalendar. |
| | |
| participants | See Section 6.5. |
| | |
| 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 Section 4.3.1 how to map a |
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| | 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 "web" |
| | 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.) |
+------------------------+------------------------------------------+
Table 5: Translation between JSCalendar and iCalendar
6.5. Locations and participants
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.
+--------------------------------------------------+----------------+
| Property | iCalendar |
| | counterpart |
+--------------------------------------------------+----------------+
| delegatedFrom | the DELEGATED- |
| | FROM parameter |
| | |
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| delegatedTo | email |
| | |
| the value of the ORGANIZER or ATTENDEE property | kind |
| | |
| the CUTYPE parameter | linkIds |
| | |
| Implementation-specific. | locationId |
| | |
| Implementation-specific. When mapping from | memberOf |
| 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. | |
| | |
| the MEMBER parameter | name |
| | |
| the CN parameter | participation |
| | |
| Maps to the standard iCalendar ROLE parameter | roles |
| values REQ-PARTICIPANT, OPT-PARTICIPANT and NON- | |
| PARTICIPANT. | |
| | |
| The "chair" role maps to the standard iCalendar | rsvpResponse |
| 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. | |
| | |
| 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 |
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+--------------------------------------------------+----------------+
Table 6: Translation of Participant between JSCalendar and iCalendar
The iCalendar counterpart for JSCalendar Location objects is the
iCalendar [RFC5545] LOCATION property, or implementation-specific.
+-------------+-----------------------------------------------------+
| Property | iCalendar 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. |
+-------------+-----------------------------------------------------+
Table 7: Translation of Location between JSCalendar and iCalendar
The iCalendar counterpart for JSCalendar VirtualLocation objects is
the iCalendar [RFC7986] CONFERENCE property, or implementation-
specific.
+--------------+--------------------------------------------------+
| Property | iCalendar counterpart |
+--------------+--------------------------------------------------+
| name | Corresponds to the CONFERENCE LABEL parameter. |
| | |
| description | Implementation-specific. |
| | |
| uri | Corresponds to the CONFERENCE property value. |
+--------------+--------------------------------------------------+
Table 8: Translation of VirtualLocation between JSCalendar and
iCalendar
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6.6. Unknown properties
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:
o *JCal*: Define iCalendar properties in JCal format ([RFC7265]) 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.
o *Alternate link*: Define an alternate link (Section 4.2.6) 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".
7. JSCalendar object examples
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.
7.1. Simple event
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.
{
"@type": "jsevent",
"uid": "2a358cee-6489-4f14-a57f-c104db4dc2f1",
"updated": "2018-01-15T18:00:00Z",
"title": "Some event",
"start": "2018-01-15T13:00:00",
"timeZone": "America/New_York",
"duration": "PT1H"
}
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7.2. Simple task
This example illustrates a simple task for a plain to-do item.
{
"@type": "jstask",
"uid": "2a358cee-6489-4f14-a57f-c104db4dc2f2",
"updated": "2018-01-15T18:00:00Z",
"title": "Do something"
}
7.3. Simple group
This example illustrates a simple calendar object group that contains
an event and a task.
{
"@type": "jsgroup",
"uid": "2a358cee-6489-4f14-a57f-c104db4dc343",
"updated": "2018-01-15T18:00:00Z",
"name": "A simple group",
"entries": [
{
"@type": "jsevent",
"uid": "2a358cee-6489-4f14-a57f-c104db4dc2f1",
"updated": "2018-01-15T18:00:00Z",
"title": "Some event",
"start": "2018-01-15T13:00:00",
"timeZone": "America/New_York",
"duration": "PT1H"
},
{
"@type": "jstask",
"uid": "2a358cee-6489-4f14-a57f-c104db4dc2f2",
"updated": "2018-01-15T18:00:00Z",
"title": "Do something"
}
]
}
7.4. All-day event
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.
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{
"...": "",
"title": "April Fool's Day",
"isAllDay": true,
"start": "1900-04-01T00:00:00",
"duration": "P1D",
"recurrenceRule": {
"frequency": "yearly"
}
}
7.5. Task with a due date
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.
{
"...": "",
"title": "Buy groceries",
"due": "2018-01-19T18:00:00",
"timeZone": "Europe/Vienna",
"estimatedDuration": "PT1H"
}
7.6. Event with end time-zone
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.
{
"...": "",
"title": "Flight XY51 from FRA to NRT",
"start": "2018-04-01T09:00:00",
"timeZone": "Europe/Berlin",
"duration": "PT10H30M",
"locations": {
"2a358cee-6489-4f14-a57f-c104db4dc2f1": {
"rel": "end",
"timeZone": "Asia/Tokyo"
}
}
}
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7.7. Floating-time event (with recurrence)
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.
{
"...": "",
"title": "Yoga",
"start": "2018-01-01T07:00:00",
"duration": "PT30M",
"recurrenceRule": {
"frequency": "daily"
}
}
7.8. Event with multiple locations and localization
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)
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{
"...": "",
"title": "Live from Music Bowl: The Band",
"description": "Go see the biggest music event ever!",
"locale": "en",
"start": "2018-07-04T17:00:00",
"timeZone": "America/New_York",
"duration": "PT3H",
"locations": {
"c0503d30-8c50-4372-87b5-7657e8e0fedd": {
"name": "The Music Bowl",
"description": "Music Bowl, Central Park, New York",
"coordinates": "geo:40.7829,73.9654"
}
},
"virtualLocations": {
"6f3696c6-1e07-47d0-9ce1-f50014b0041a": {
"name": "Free live Stream from Music Bowl",
"uri": "https://stream.example.com/the_band_2018"
}
},
"localizations": {
"de": {
"title": "Live von der Music Bowl: The Band!",
"description": "Schau dir das groesste Musikereignis an!",
"virtualLocations/6f3696c6-1e07-47d0-9ce1-f50014b0041a/name":
"Gratis Live-Stream aus der Music Bowl"
}
}
}
7.9. Recurring event with overrides
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.
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{
"...": "",
"title": "Calculus I",
"start": "2018-01-08T09:00:00",
"timeZone": "Europe/London",
"duration": "PT1H30M",
"locations": {
"2a358cee-6489-4f14-a57f-c104db4dc2f1": {
"title": "Math lab room 1",
"description": "Math Lab I, Department of Mathematics"
}
},
"recurrenceRule": {
"frequency": "weekly",
"until": "2018-06-25T09:00:00"
},
"recurrenceOverrides": {
"2018-01-05T14:00:00": {
"title": "Introduction to Calculus I (optional)"
},
"2018-04-02T09:00:00": {
"excluded": "true"
},
"2018-06-25T09:00:00": {
"title": "Calculus I Exam",
"start": "2018-06-25T10:00:00",
"duration": "PT2H",
"locations": {
"2a358cee-6489-4f14-a57f-c104db4dc2f1": {
"title": "Big Auditorium",
"description": "Big Auditorium, Other Road"
}
}
}
}
}
7.10. Recurring event with participants
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.
{
"...": "",
"title": "FooBar team meeting",
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"start": "2018-01-08T09:00:00",
"timeZone": "Africa/Johannesburg",
"duration": "PT1H",
"locations": {
"2a358cee-6489-4f14-a57f-c104db4dc2f1": {
"title": "ChatMe meeting room",
"rel": "virtual",
"features": [
"audio",
"chat",
"video"
],
"uri": "https://chatme.example.com?id=1234567"
}
},
"recurrenceRule": {
"frequency": "weekly"
},
"replyTo": {
"imip": "zoe@foobar.example.com"
},
"participants": {
"tom@foobar.example.com": {
"name": "Tom Tool",
"email": "tom@foobar.example.com",
"rsvpResponse": "accepted",
"roles": [
"attendee"
]
},
"zoe@foobar.example.com": {
"name": "Zoe Zelda",
"email": "zoe@foobar.example.com",
"rsvpResponse": "accepted",
"roles": [
"owner",
"chair"
]
},
"...": ""
},
"recurrenceOverrides": {
"2018-03-08T09:00:00": {
"participants/tom@foobar.example.com/rsvpResponse": "declined"
}
}
}
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8. Security Considerations
The use of JSON as a format does have its own inherent security risks
as discussed in Section 12 of [RFC8259]. 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[RFC8259]. A native parser with full awareness of the JSON format
should be preferred.
9. IANA Considerations
This document amends the "application/calendar" MIME media type
defined in [RFC7265].
New optional parameter: "type" with value being one of "jsevent",
"jstask", "jsgroup". The parameter MUST NOT occur more than once.
10. Acknowledgments
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.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2392] Levinson, E., "Content-ID and Message-ID Uniform Resource
Locators", RFC 2392, DOI 10.17487/RFC2392, August 1998,
<https://www.rfc-editor.org/info/rfc2392>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
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[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/info/rfc4122>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault,
"Calendaring Extensions to WebDAV (CalDAV)", RFC 4791,
DOI 10.17487/RFC4791, March 2007,
<https://www.rfc-editor.org/info/rfc4791>.
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 5545, DOI 10.17487/RFC5545, September 2009,
<https://www.rfc-editor.org/info/rfc5545>.
[RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent
Interoperability Protocol (iTIP)", RFC 5546,
DOI 10.17487/RFC5546, December 2009,
<https://www.rfc-editor.org/info/rfc5546>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, <https://www.rfc-editor.org/info/rfc5646>.
[RFC5870] Mayrhofer, A. and C. Spanring, "A Uniform Resource
Identifier for Geographic Locations ('geo' URI)",
RFC 5870, DOI 10.17487/RFC5870, June 2010,
<https://www.rfc-editor.org/info/rfc5870>.
[RFC6047] Melnikov, A., Ed., "iCalendar Message-Based
Interoperability Protocol (iMIP)", RFC 6047,
DOI 10.17487/RFC6047, December 2010,
<https://www.rfc-editor.org/info/rfc6047>.
[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
and D. Orchard, "URI Template", RFC 6570,
DOI 10.17487/RFC6570, March 2012,
<https://www.rfc-editor.org/info/rfc6570>.
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[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC6901] Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed.,
"JavaScript Object Notation (JSON) Pointer", RFC 6901,
DOI 10.17487/RFC6901, April 2013,
<https://www.rfc-editor.org/info/rfc6901>.
[RFC7265] Kewisch, P., Daboo, C., and M. Douglass, "jCal: The JSON
Format for iCalendar", RFC 7265, DOI 10.17487/RFC7265, May
2014, <https://www.rfc-editor.org/info/rfc7265>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
DOI 10.17487/RFC7493, March 2015,
<https://www.rfc-editor.org/info/rfc7493>.
[RFC7529] Daboo, C. and G. Yakushev, "Non-Gregorian Recurrence Rules
in the Internet Calendaring and Scheduling Core Object
Specification (iCalendar)", RFC 7529,
DOI 10.17487/RFC7529, May 2015,
<https://www.rfc-editor.org/info/rfc7529>.
[RFC7986] Daboo, C., "New Properties for iCalendar", RFC 7986,
DOI 10.17487/RFC7986, October 2016,
<https://www.rfc-editor.org/info/rfc7986>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/info/rfc8288>.
11.2. Informative References
[draft-apthorp-ical-tasks]
"Task Extensions to iCalendar",
<https://tools.ietf.org/html/draft-apthorp-ical-tasks>.
[draft-ietf-calext-ical-relations]
"Support for iCalendar Relationships",
<https://tools.ietf.org/html/
draft-ietf-calext-ical-relations>.
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[MIME] "IANA Media Types", <https://www.iana.org/assignments/
media-types/media-types.xhtml>.
11.3. URIs
[1] https://www.iana.org/assignments/link-relations/link-
relations.xhtml
[2] https://www.w3.org/TR/2011/REC-css3-color-20110607/#svg-color
[3] http://www.iana.org/time-zones
Authors' Addresses
Neil Jenkins
FastMail
PO Box 234
Collins St West
Melbourne VIC 8007
Australia
Email: neilj@fastmailteam.com
URI: https://www.fastmail.com
Robert Stepanek
FastMail
PO Box 234
Collins St West
Melbourne VIC 8007
Australia
Email: rsto@fastmailteam.com
URI: https://www.fastmail.com
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