| Internet-Draft | iCalendar tasks | November 2022 |
| Apthorp & Douglass | Expires 19 May 2023 | [Page] |
This document defines extensions to the Internet Calendaring and Scheduling Core Object Specification (iCalendar) (RFC5545) to provide improved status tracking, scheduling and specification of tasks.¶
It also defines how Calendaring Extensions to WebDAV (CalDAV) (RFC 4791) servers can be extended to support certain automated task management behaviours.¶
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 19 May 2023.¶
Copyright (c) 2022 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
The authors would like to thank the members of the Calendaring and Scheduling Consortium technical committees and the following individuals for contributing their ideas, support and comments:¶
John Chaffee, Marten Gajda, Ken Murchison¶
The authors would also like to thank CalConnect, the Calendaring and Scheduling Consortium, for advice with this specification.¶
This document specifies extensions to the existing Internet Calendaring and Scheduling Core Object Specification (iCalendar) [RFC5545], and associated protocols, in order to enhance the structured communication and execution of tasks. The enhancements allow for the communication, time planning and scheduling of tasks by and between automated systems (e.g. in smart power grids, business process management systems) as well as for human centered tasks.¶
A "task" is a representation of an item of work assigned to an individual or organization. In the iCalendar Object Model [RFC5545] the representation of tasks is by "VTODO" calendar components. Tasks can be identified in a number of situations, either informally as ad-hoc tasks in personal "to-do" lists or more formally in:¶
The extensions specified here are defined in the context of an overall architecture for task calendaring and scheduling.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
Calendaring and scheduling roles are referred to in quoted-strings of text with the first character of each word in upper case. For example, "Organizer" refers to a role of a "Calendar User" (CU) within the scheduling protocol.¶
Calendar components defined by [RFC5545] are referred to with capitalized, quoted-strings of text. All calendar components start with the letter "V". For example, "VEVENT" refers to the event calendar component, "VTODO" refers to the to-do calendar component, and "VJOURNAL" refers to the daily journal calendar component.¶
Scheduling methods are referred to with capitalized, quoted-strings of text. For example, "REQUEST" refers to the method for requesting a scheduling calendar component be created or modified; "REPLY" refers to the method a recipient of a request uses to update their status with the "Organizer" of the calendar component.¶
Properties defined by [RFC5545] are referred to with capitalized, quoted-strings of text, followed by the word "property". For example, "ATTENDEE" property refers to the iCalendar property used to convey the calendar address of a "Calendar User".¶
Property parameters defined by this specification are referred to with capitalized, quoted-strings of text, followed by the word "parameter". For example, "VALUE" parameter refers to the iCalendar property parameter used to override the default data type for a property value.¶
Enumerated values defined by this specification are referred to with capitalized text, either alone or followed by the word "value".¶
In tables, the quoted-string text is specified without quotes in order to minimize the table length.¶
Terms defined in this specification include:¶
A calendar user assigned to perform a given task. An assignee is equivalent to an attendee of an event.¶
A person or software system that accesses or modifies calendar information.¶
This may be¶
A calendar user who might be able to perform a given task, prior to actually being assigned the task, e.g., a dispatcher has a list of taxi drivers (candidates) from which one will be selected to pick-up a passenger.¶
A calendar user interested in a calendar component, e.g., a manager may have interest in all tasks that have not been completed.¶
A resource in the scheduling context is any shared entity that can be scheduled by a calendar user, but does not control its own attendance status. Resources can be of "Location", "Equipment", or "Role" type.¶
A reference architecture for task calendaring and scheduling is defined in order to identify the key logical elements involved in task management and the interfaces between them to enable interoperability. The logical elements identified here establish an appropriate separation of concerns and clarify the responsibilities of different elements. However, the architecture does not prescribe a binding or packaging of elements, i.e., software systems may be developed where some elements are tightly bound and the interfaces between bound elements are not exposed. The task architecture is also described in [TARCH].¶
Task +-------+
Trigger |
+---------------------V---------------------+ +-----------+
| Task Generating System | | |
| +-------------------------+ | | |
| | O | | | |
| | /|\ | | | |
| | / \ | | | |
| | Task Organizer | <----> |
| +-^--------^--------------+ | | |
| | | | | |
| +--------V-+ +----V-----+ +----------+ | | |
| | Task | | Process | | Task | | | |
| |Assignment| | Logic <----> Domain | | | |
| | Rules | | | | Data | | | |
| +----------+ +----------+ +----------+ | | |
| | | |
+------^----------+-----^-------------------+ | |
| | | | |
Availability Task Task | |
| | Status | |
| | | | |
+------v----------v-----+-------------------+ | |
| Calendar and Scheduling System | | Directory |
| +---------+ +---------+ | | Service |
| | | | Task | <----> |
| |Schedule | | Lists | | | |
| | | | | | | |
| +---------+ +---------+ Server | | |
+-------------------------------------------+ | |
| Client | | |
| +----------------------+ +-----------+ | | |
| | Calendar | | Task | | | |
| | User Agent +----> Specific | <----> |
| | | |Application| | | |
| +----------------------+ +-----------+ | | |
| | | |
+-----^---------^--------+---------+--------+ | |
| | | | | |
+-----V---------V--------V---------V--------+ | |
| Task Actors | | |
| O O O O | | |
| /|\ /|\ /|\ /|\ +----> |
| / \ / \ / \ / \ | | |
| Candidate(s) Observer(s) | | |
| Assignee(s) Resource(s) | | |
+-------------------------------------------+ +-----------+¶
The following logical elements form the task architecture that this specification is based on:¶
Various calendar users that may be involved in the monitoring or performing of a task. The set of actors includes: Organizers, Observers, Resources, Assignees, and Candidates.¶
The Organizer of a task.¶
This is any domain specific data that may be acted on or provides context to it in performing a task.¶
A task specific application renders the data concerning the task (including task domain data) for presentation and manipulation by a task actor.¶
Determines under what conditions a task (or tasks) is generated and the actions to take on completion, or some other status event occurring (or not) on the task.¶
This is some event that gives rise to the generation of a task according to Process Logic. Task triggers can come from many different sources including, for example; a task being requested through the calendaring system, a status change in the progression of a business process being managed by a business process management or ERP system.¶
Govern how actors are assigned to a task. A range of different assignment patterns [WfRP] may be considered, including the two general cases:¶
In either case the assignment may be made based on a variety of criteria including, name, availability, skills, capacity, etc.¶
A system that creates and assigns tasks in response to some initiating event (task trigger). Task creation is according to Process Logic with task assignment determined by Task Assignment Rules. This system also tracks the status of tasks and will initiate further actions based upon the status. A task generating system can take many forms, for example; Business Process Management System, Project Management System, Bug Tracking System, Building Control System. A Task Generating System may also be a human. In iCalendar terms the Task Generating System is the organizer.¶
Task creation, assignment and tracking coordinated by a human organizer is a special case of a task generating system. In this case Task Assignment Rules and Process Logic may be either explicit or tacit.¶
A software system that stores and provides access to information providing details of task actors that may participate or be interested in a task.¶
A software system that stores, publishes and synchronizes calendar data such as events, tasks and journal entries for actors. In the context of tasks this includes schedules (i.e. allocated time and availability to perform tasks) and task lists. A calendar and scheduling system typically consists of server and client software components.¶
The key standards that enable interoperability between the logical elements of the architecture are the Internet Calendaring and Scheduling Core Object Specification (iCalendar) [RFC5545] and associated protocols. Task and task status are represented by the iCalendar "VTODO" component. Protocols include, in particular, the iCalendar Transport-Independent Interoperability Protocol (iTIP) [RFC5546] for task assignment and scheduling, and Calendaring Extensions to WebDAV (CalDAV) [RFC4791] for client server communication.¶
In order to support the task architecture described in Section 3, this document defines a number of extensions to the current iCalendar standards in the areas of:¶
improved ability to specify domain specific tasks¶
clarification of deadlines and extension for task duration to support task time planning¶
ensure support for common pattens of scheduling and assigning tasks¶
improved granularity in status tracking information and alerting task actors to pending or actual task status changes¶
These extensions are supported mainly by additions to the properties and parameters used within the "VTODO" component.¶
The specification of tasks must be semantically explicit in order for them to be managed within the context of a business process or project, and be understood by both humans and IT systems. The current VTODO component only provides for simple ad-hoc tasks or 'to do' lists, and is therefore extended by this specification as follows:¶
explicitly what type of task is to be performed is identified.¶
how a specific task relates to other tasks and other objects that need to be understood for the effective execution of a task.¶
the form and content of domain data provided as input to a task and/or that may be output from a task.¶
recognizes that a task organizer or attendee can be an automated system.¶
The CONCEPT property is used to identify the type of task, for example;¶
CONCEPT:http://example.com/task/delivery¶
The LINK property specifies a link to external information, which may be context to the task. For example:¶
LINK;REL=SOURCE:http://example.com/package/1234567890 LINK;REL=describedby:mid:752142.1414823874.307E5@mx123.example.com¶
The external information may be data to be manipulated in performing the task. See section 3.1.3 Task Domain Data Handling.¶
REFID is used to identify a key allowing the association of tasks that are related to the same object and retrieval of a task based on this key. This may be, for example, to identify the tasks associated with a given project without having to communicate the task structure of the project, or all tasks associated to a specific package.¶
REFID:Manhattan REFID:1234567890¶
Extensions [Doug114] to the RELATED-TO property allow temporal relationships between tasks as found in project management to be specified as well as parent/child relationships and dependencies (DEPENDS-ON). Tasks (VTODOs) may also be related to other calendar components; for example to a VEVENT to block time to perform a task.¶
Provide support for task specific input and output data (including updates) beyond the standard iCalendar properties. It is envisaged that standard calendar user agents will be able to launch task specific applications by passing task specific data.¶
The LINK property can be used to 'attach' the domain specific data to the task. For example, it might be a URI pointing to a web page where the status of the task can be directly manipulated.¶
LINK;REL="vacation-system";VALUE=URI:http://example.com/ vacation-approval?id=1234¶
Or it might be used for attachments specific to the task, for example an electronic copy of a signature taken to confirm delivery of a package.¶
LINK;REL="electronic-signature";VALUE=URI:http://example.com/ delivery/sig1234.jpg¶
Deadlines for starting and finishing a task are defined by the DTSTART, DUE and DURATION properties. DTSTART represents the earliest start time for beginning work on a task. DUE, or DTSTART + DURATION represent the latest finish time for a task. Thus, these properties define a "window" within which a task has to be performed. However, there is currently no way to indicate how long the task is expected to take. This document defines a new property, ESTIMATED-DURATION, to allow the estimated time that a task should take to be specified separately from the deadlines for starting and finishing a task. This supports time planning by enabling calendar user agents to display when tasks should occur and therefore allow calendar users to visualize when tasks should be performed and allocate time to them.¶
A task that has intermediary deadlines (i.e., milestones) SHOULD be expressed by child VTODO components (i.e., sub-tasks associated with each of the milestones) in conjunction with the RELATED-TO property to relate the parent and child tasks.¶
This specification supports the two distinct models of assigning actors to tasks, i.e., 1) strictly one assignee per task or 2) task assignment to multiple assignees. In this regard one or many ATTENDEES may be specified against a task depending upon the model applied by the task organizer.¶
In addition, a number of different patterns of resource or assignee identification are anticipated. The specific Task Assignment Rules are the responsibility of the Task Organizer.¶
Communication of task assignment or delegation to one or more actors who are allocated to a task by the organizer is directly supported by iTIP, i.e., all included ATTENDEES in an iTIP REQUEST are expected to perform the task.¶
The offering or advertising of a task to one or more (potential) actors where only one or a subset of the candidates may accept the task will be addressed by a later specification.¶
This document defines a new status component that can be used to group related information about the status. This might include information on why (REASON) and when (DTSTAMP) a status has changed. In addition, new status values are specified to provide for task suspension, failure and preparation.¶
The [RFC9073] PARTICIPANT component can be used to provide additional information about why an ATTENDEE participation status has changed. The COMMENT property can also be used to include additional human-readable information about why the associated STATUS or ATTENDEE property changed.¶
BEGIN:VSTATUS STATUS:FAILED REASON:https://example.com/reason/delivery-failed SUBSTATE:ERROR DTSTAMP:20130212T120000Z COMMENT:Breakdown END:VSTATUS ATTENDEE;PARTSTAT=FAILED:mailto:xxx@example.com ... BEGIN:PARTICIPANT CALENDAR-ADDRESS:mailto:xxx@example.com DTSTAMP:20130226T1104510Z REASON:https://example.com/reason/van-break-down COMMENT:Puncture END:PARTICIPANT¶
Multiple comments and reasons may have the same status. As situations change further VSTATUS components can be added to provide additional information..¶
CONCEPT:https://example.com/task/delivery BEGIN:VSTATUS STATUS:FAILED SUBSTATE:ERROR DTSTAMP:20220212T104900Z COMMENT:Out of time END:VSTATUS BEGIN:VSTATUS STATUS:FAILED COMMENT:Traffic Accident on E44 REASON:https://example.com/reason/traffic DTSTAMP:20220212T110451Z END:VSTATUS BEGIN:VSTATUS STATUS:FAILED COMMENT:Arrived after office hours REASON:https://example.com/reason/closed DTSTAMP:20220212T180451Z END:VSTATUS¶
Different needs to alert or notify task actors of pending or actual task status changes are recognized:¶
Alarms (VLARM components) operate in the calendar user agent space to notify the task actor of a pending task state for a task they are assigned to or are interested in. Note: there is no constraint in the current standards on the propagation of alarms specified on calendar objects by organizers to individual attendees.¶
An escalation or notification to the ATTENDEE, ORGANIZER, or other task actor may be required if a deadline associated with a task is exceeded or for some other reason. Process Logic identifying when and who to propagate escalations to is the responsibility of the Task Generating System, e.g., a BPMS.¶
Task actors (observers) not directly involved in performing a task but with a known interest in a given task's status can be identified by the ASSOCIATE property [Doug214] against certain components e.g. ALARM, to identify which task events the stakeholder/party is interested in. Notifications on shared calendars will allow task actors to register an interest in changes to tasks within a calendar (see Appendix A).¶
A new property, TASK-MODE, is introduced to instruct servers to apply automated operations for changing the status of a task.¶
Participant status parameter type values are defined in Section 3.2.12 of [RFC5545]. This specification redefines that type to include the new value FAILED for VTODO iCalendar components.¶
This property parameter is extended by the following notation:¶
partstat-todo /= *("FAILED") ; To-do cannot be completed¶
ATTENDEE;REASON="https://example.com/reason/not-enough-time"; PARTSTAT=FAILED:mailto:jsmith@example.com¶
ESTIMATED-DURATION¶
This property specifies the estimated positive duration of time the corresponding task will take to complete.¶
DURATION¶
IANA and non-standard property parameters can be specified on this property.¶
This property can be specified in "VTODO" calendar components.¶
This property is defined by the following notation:¶
est-duration = "ESTIMATED-DURATION" durparam ":" dur-value CRLF
;consisting of a positive duration of time.
durparam = *(";" other-param)¶
In a "VTODO" calendar component the property MAY be used to specify the estimated duration for the to-do, with or without an explicit time window in which the event should be started and completed. When present, DTSTART and DUE/DURATION represent the window in which the task can be performed. ESTIMATED-DURATION SHOULD be passed from ORGANIZER to ATTENDEE in iTIP [RFC5546] messages.¶
The following is an example of this property that specifies an interval of time of exactly one hour:¶
ESTIMATED-DURATION:PT1H¶
REASON¶
To indicate the reason for a change in status of a task or attendee participation status.¶
URI¶
IANA and non-standard property parameters can be specified on this property.¶
This property can be specified in "VSTATUS" and PARTICIPANT calendar components.¶
This property is defined by the following notation:¶
reason = "REASON" reasonparam ":" uri CRLF
reasonparam = *(";" other-param)¶
This property allows the change in status of a task or participant status to be qualified by the reason for the change with a codified reason. Typically, reasons are defined within the context of the task type and therefore SHOULD include the name-space of the authority defining the task. Common reason codes are IANA registered and do not have a name-space prefix.¶
REASON:https://example.com/reason/delivered-on-time REASON:out-of-office¶
SUBSTATE¶
To provide additional granularity of task status for e.g. IN-PROCESS.¶
TEXT¶
IANA and non-standard property parameters can be specified on this property.¶
This property can be specified in a "VSTATUS" calendar component.¶
This property is defined by the following notation:¶
substate = "SUBSTATE" substateparam ":" substatevalue CRLF
substateparam = *(";" other-param)
substatevalue = ("OK" ; everything is fine(the default)
/ "ERROR" ; something is wrong (the REASON
; code explains why)
/ "SUSPENDED" ; waiting on some other task to
; complete or availability of a
; resource (REASON code explains
; why)
/ iana-token) ; Other IANA-registered type¶
The sub-state property allows additional qualification and granularity of states to be recorded, in particular for the IN-PROCESS state. It allows individual sub-states to be recorded without the need to define and publish a sub-task associated with a parent task purely to track that a particular state has been reached. This property also allows parallel states to be expressed e.g. that a task has been suspended at whatever state it has reached.¶
BEGIN:VSTATUS STATUS:FAILED REASON:https://example.com/reason/no-one-home SUBSTATE:ERROR END:VSTATUS BEGIN:VSTATUS STATUS:IN-PROCESS REASON:https://example.com/reason/paint-drying SUBSTATE:SUSPENDED END:VSTATUS¶
TASK-MODE¶
This property specifies automatic operations that servers apply to tasks based on changes in attendee status (PARTSTAT).¶
TEXT¶
IANA and non-standard property parameters can be specified on this property.¶
This property can be specified zero or more times in a "VTODO" calendar component.¶
This property is defined by the following notation:¶
task-mode = "TASK-MODE taskmodeparam ":" taskvalue
*("," taskvalue) CRLF
taskvalue = "AUTOMATIC-COMPLETION" ; set STATUS completed
;if all attendees have completed
/ "AUTOMATIC-FAILURE"
/ "SERVER"
/ "CLIENT"
/ iana-token
/ x-name
taskmodeparam = *(";" other-param)¶
In a "VTODO" calendar component this property MAY be used to indicate to servers how they can automatically change the state of the task based on iTIP replies from Attendees. For example, the server can automatically set the overall task status (STATUS) to COMPLETED when every attendee has marked their own status (PARTSTAT) as COMPLETED, or the server could mark the task as FAILED if its DUE date passes without it being completed. TASK-MODE processing is performed on the organizer's copy of the task.¶
The property value is a list of one or more IANA registered tokens that defines modes to be used for the task. This specification defines three modes which are described in the following subsections.¶
TASK-MODE:AUTOMATIC-COMPLETION,AUTOMATIC-FAILURE TASK-MODE:SERVER TASK-MODE:AUTOMATIC-FAILURE¶
The task mode value "AUTOMATIC-COMPLETION" indicates to the server that it can change the "VTODO" component's STATUS property value to "COMPLETED" as soon as all ATTENDEEs in the task have replied with a "PARTSTAT" parameter set to "COMPLETED".¶
The task mode value "AUTOMATIC-FAILURE" indicates to the server that it SHOULD change the "VTODO" component's STATUS property value to "FAILED" if either:¶
Note: The effective due date is either the "DUE" property value or the combination of the "DTSTART" and "DURATION" property values.¶
The task mode value "CLIENT" is an instruction to the server to honour the status set by the client.¶
The task mode value "SERVER" indicates to the server that it can change the "VTODO" component's STATUS property value to an appropriate value, based on implementation defined "business rules", as ATTENDEE responses are processed or as deadlines related to the task pass.¶
The server can add this property to a "VTODO" component to indicate to the client that it will be managing the status.¶
[RFC5545] section 3.6.2 introduced a constraint on the duration property requiring that a DURATION MUSt be accompanied by a DTSTART. This constraint is dropped reverting to the situation as specified previously.¶
Thus the text:¶
; Either 'due' or 'duration' MAY appear in
; a 'todoprop', but 'due' and 'duration'
; MUST NOT occur in the same 'todoprop'.
; If 'duration' appear in a 'todoprop',
; then 'dtstart' MUST also appear in
; the same 'todoprop'.¶
is replaced by
; Either 'due' or 'duration' MAY appear in
; a 'todoprop', but 'due' and 'duration'
; MUST NOT occur in the same 'todoprop'.¶
This allows a VTODO to only have a DURATION property.¶
Furthermore, the following text:¶
A "VTODO" calendar component without the "DTSTART" and "DUE" (or
"DURATION") properties specifies a to-do that will be associated
with each successive calendar date, until it is completed.¶
is replaced by¶
A "VTODO" calendar component without the "DTSTART" and "DUE"
properties specifies a to-do that will be associated
with each successive calendar date, until it is completed.¶
The Status property is defined in Section 3.8.1.11 of [RFC5545]. This specification extends that property to include new values associated with VTODO iCalendar components (See Appendix A for examples of the task state lifecycle).¶
The "STATUS" property parameter list is augmented as follows:¶
statvalue-todo = / "PENDING" ;Indicates a to-do has been
;created and accepted, but has not
;yet started.
/ "FAILED" ;Indicates to-do has failed.
;Extended status values for
;"VTODO".¶
Description:¶
PENDING - A task has been created but has not yet started and is ready to start subject to other dependencies (e.g. preceding task or DTSTART). This is the default state.¶
FAILED - task has failed and may need some follow-up from the organizer to re-schedule or cancel¶
Example: The following is an example of this property for a "VTODO" calendar component:¶
STATUS:FAILED¶
VSTATUS¶
This component allows information to be associated with a status, for example comments and date stamps.¶
This component can be specified multiple times in any appropriate calendar component.¶
This component provides a way for multiple date-stamped statuses to be associated with a component such as a task or an event.¶
This component may also be added to the [RFC9073] PARTICIPANT component to allow participants in a task to specify their own status.¶
This component is defined by the following notation:¶
statusc = "BEGIN" ":" "VSTATUS" CRLF
statusprop
"END" ":" "VSTATUS" CRLF
statusprop = *(
;
; The following is REQUIRED,
; but MUST NOT occur more than once.
;
status /
;
; The following are OPTIONAL,
; but MUST NOT occur more than once.
;
description / dtstamp / reason / substate / summary
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
comment / styleddescription / iana-prop
;
)¶
BEGIN:VSTATUS STATUS:COMPLETED REASON: https://example.com/reason/delivered-on-time DTSTAMP:20220212T120000Z END:VSTATUS¶
The CalDAV [RFC4791] calendar access protocol allows clients and servers to exchange iCalendar data. With the introduction of the "TASK-MODE" property in this specification, different automated task management behaviours may be delegated to the server by the Task Organizer depending upon the value of "TASK-MODE".¶
In order for a CalDAV client to know what task modes are available, a CalDAV server advertises a CALDAV:supported-task-mode-set WebDAV property on calendar home or calendar collections if it supports the use of the "TASK-MODE" property as described in this specification. The server can advertise a specific set of supported task modes by including one or more CALDAV:supported-task-mode XML elements within the CALDAV:supported-task-mode-set XML element. If no CALDAV:supported-task-mode XML elements are included in the WebDAV property, then clients can try any task mode, but need to be prepared for a failure when attempting to store the calendar data.¶
Clients MUST NOT attempt to store iCalendar data containing "TASK-MODE" elements if the CALDAV:supported-task-mode-set WebDAV property is not advertised by the server.¶
The server SHOULD return an HTTP 403 response with a DAV:error element containing a CALDAV:supported-task-mode XML element, if a client attempts to store iCalendar data with an "TASK-MODE" element value not supported by the server.¶
It is possible for a "TASK-MODE" value to be present in calendar data on the server being accessed by a client that does not support the "TASK-MODE" property. It is expected that existing clients, unaware of "TASK-MODE", will fail gracefully by ignoring the calendar property.¶
<!ELEMENT supported-task-mode-set(supported-task-mode*)> <!ELEMENT supported-task-mode (#PCDATA)> <!-- PCDATA value: string - case insensitive but uppercase preferred -->¶
<C:supported-task-mode-set xmlns:C="urn:ietf:params:xml:ns:caldav"> <C:supported-task-mode>AUTOMATIC-COMPLETION</C:supported-task-mode> <C:supported-task-mode>AUTOMATIC-FAILURE</C:supported-task-mode> <C:supported-task-mode>SERVER</C:supported-task-mode> <C:supported-task-mode>CLIENT</C:supported-task-mode> </C:supported-task-mode-set>¶
This specification updates [RFC5545] by adding a Status value registry to the iCalendar Elements registry and initializing it as per [RFC5545].¶
| Name | Status | Reference |
|---|---|---|
|
CANCELLED¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
|
COMPLETED¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
|
CONFIRMED¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
|
DRAFT¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
|
FINAL¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
|
IN-PROCESS¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
|
NEEDS-ACTION¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
|
TENTATIVE¶ |
Current¶ |
Section 3.8.1.11 of [RFC5545]¶ |
This specification further updates the Status registry with additional values defined in this document.¶
| Value | Status | Reference |
|---|---|---|
|
PENDING¶ |
Current¶ |
This Spec, Section 13.2¶ |
|
FAILED¶ |
Current¶ |
This Spec, Section 13.2¶ |
The following table has been used to initialize the Sub-State registry.¶
| Substate | Status | Reference |
|---|---|---|
|
OK¶ |
Current¶ |
This Spec, Section 12.3¶ |
|
ERROR¶ |
Current¶ |
This Spec, Section 12.3¶ |
|
SUSPENDED¶ |
Current¶ |
This Spec, Section 12.3¶ |
The following table has been used to initialize the Task Mode registry.¶
| Task Mode | Status | Reference |
|---|---|---|
|
AUTOMATIC-COMPLETION¶ |
Current¶ |
This Spec, Section 12.4¶ |
|
AUTOMATIC-FAILURE¶ |
Current¶ |
This Spec, Section 12.4¶ |
|
CLIENT¶ |
Current¶ |
This Spec, Section 12.4¶ |
|
SERVER¶ |
Current¶ |
This Spec, Section 12.4¶ |
The following table has been used to update the Participation Statuses registry.¶
| Value | Status | Reference |
|---|---|---|
|
FAILED¶ |
Current¶ |
This Spec, Section 11.1¶ |
The following table has been used to update the Properties registry.¶
| Property | Status | Reference |
|---|---|---|
|
ESTIMATED_DURATION¶ |
Current¶ |
This Spec, Section 12.1¶ |
|
REASON¶ |
Current¶ |
This Spec, Section 12.2¶ |
|
SUBSTATE¶ |
Current¶ |
This Spec, Section 12.3¶ |
|
STATUS¶ |
Current¶ |
This Spec, Section 13.2¶ |
|
TASK-MODE¶ |
Current¶ |
This Spec, Section 12.4¶ |
| STATUS | PARTSTAT | Action | |
|---|---|---|---|
| 1 | - | - | Organizer draft |
| 2 | NEEDS-ACTION | NEEDS-ACTION | Organizer sends iTIP request |
| 3 | NEEDS-ACTION | ACCEPTED | Attendee reply |
| 4 | PENDING | ACCEPTED | Task accepted but waiting on some "trigger" to start (e.g. another task has to finish first) |
| 5 | IN-PROCESS | IN-PROCESS | Attendee reply now working on the task |
| 6 | IN-PROCESS | COMPLETED | Attendee reply completed |
| 7 | COMPLETED | COMPLETED | Organizer changes overall state |
Example of status changes in assigning and performing a task with two attendees (A1 and A2).¶
| STATUS | PARTSTAT (A1) | PARTSTAT (A2) | Action | |
|---|---|---|---|---|
| 1 | - | - | - | Organizer draft. |
| 2 | NEEDS-ACTION | NEEDS-ACTION | NEEDS-ACTION | Organizer sends iTIP request. |
| 4 | NEEDS-ACTION | ACCEPTED | NEEDS-ACTION | Attendee 1 reply. |
| 5 | NEEDS-ACTION | ACCEPTED | ACCEPTED | Attendee 2 reply. |
| 6 | PENDING | ACCEPTED | ACCEPTED | Task accepted but waiting on some"trigger" to start (e.g. another task has to finish first) |
| 7 | IN-PROCESS | ACCEPTED | IN-PROCESS | Attendee 2 reply now working on the task. |
| 8 | IN-PROCESS | IN-PROCESS | IN-PROCESS | Attendee 1 reply now working on the task. |
| 9 | IN-PROCESS | COMPLETED | IN-PROCESS | Attendee 1 reply Completed (overall status still IN-PROCESS). |
| 10 | IN-PROCESS | COMPLETED | COMPLETED | Attendee 2 reply Completed |
| 11 | COMPLETED | COMPLETED | COMPLETED | Organizer changes overall state once both attendees are finished. |
Note: The logic for determining the status change to the VTODO is determined by the task organizer based on the ATTENDEE status and other business logic.¶
Example of status changes for a task that fails.¶
| STATUS | PARTSTAT | Action | |
|---|---|---|---|
| 1 | - | - | Organizer draft |
| 2 | NEEDS-ACTION | NEEDS-ACTION | Organizer sends iTIP request |
| 3 | NEEDS-ACTION | ACCEPTED | Attendee reply |
| 4 | IN-PROCESS | IN-PROCESS | Attendee reply now working on the task |
| 5 | IN-PROCESS | FAILED | Attendee reply task failed |
| 6 | FAILED | FAILED | Organizer changes overall state |
V02. 2021-05-05 MD¶
V01. 2015-08-23 AA¶
Stakeholders should have the ability to subscribe to categories / types of tasks on an ongoing basis. Reference calendarserver.org notifications draft¶