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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Apthorp 3 Internet-Draft DHL Express 4 Updates: 5545 (if approved) M. Douglass 5 Intended status: Standards Track Bedework Commercial Services 6 Expires: 23 February 2022 22 August 2021 8 Task Extensions to iCalendar 9 draft-ietf-calext-ical-tasks-00 11 Abstract 13 This document defines extensions to the Internet Calendaring and 14 Scheduling Core Object Specification (iCalendar) (RFC5545) to provide 15 improved status tracking, scheduling and specification of tasks. 17 It also defines how Calendaring Extensions to WebDAV (CalDAV) (RFC 18 4791) servers can be extended to support certain automated task 19 management behaviours. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on 23 February 2022. 38 Copyright Notice 40 Copyright (c) 2021 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 45 license-info) in effect on the date of publication of this document. 46 Please review these documents carefully, as they describe your rights 47 and restrictions with respect to this document. Code Components 48 extracted from this document must include Simplified BSD License text 49 as described in Section 4.e of the Trust Legal Provisions and are 50 provided without warranty as described in the Simplified BSD License. 52 Table of Contents 54 1. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 55 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 56 2.1. Terms and Definitions . . . . . . . . . . . . . . . . . . 4 57 3. Task Architecture . . . . . . . . . . . . . . . . . . . . . . 5 58 4. Task Architecture Elements . . . . . . . . . . . . . . . . . 7 59 5. Architecture Foundations . . . . . . . . . . . . . . . . . . 8 60 6. Task Extensions . . . . . . . . . . . . . . . . . . . . . . . 9 61 7. Task Specification . . . . . . . . . . . . . . . . . . . . . 9 62 7.1. CONCEPT for task type identification . . . . . . . . . . 10 63 7.2. Task Context and Relationships . . . . . . . . . . . . . 10 64 7.3. Task Domain Data Handling . . . . . . . . . . . . . . . . 10 65 8. Task Deadlines, Milestones and Time Planning . . . . . . . . 11 66 9. Task Scheduling and Assignment . . . . . . . . . . . . . . . 11 67 10. Status Reporting . . . . . . . . . . . . . . . . . . . . . . 12 68 10.1. Improved granularity in status reporting information . . 12 69 10.2. Relating comments to status . . . . . . . . . . . . . . 12 70 10.3. Comments associated to reasons and status changes . . . 12 71 10.4. Task Alerts and Notifications . . . . . . . . . . . . . 12 72 10.5. Automated Status Changes . . . . . . . . . . . . . . . . 13 73 11. New Property Parameters . . . . . . . . . . . . . . . . . . . 13 74 11.1. Group . . . . . . . . . . . . . . . . . . . . . . . . . 13 75 11.2. Reason . . . . . . . . . . . . . . . . . . . . . . . . . 14 76 11.3. Modified . . . . . . . . . . . . . . . . . . . . . . . . 14 77 11.4. Sub-State . . . . . . . . . . . . . . . . . . . . . . . 15 78 12. New Parameter Values . . . . . . . . . . . . . . . . . . . . 16 79 12.1. Redefined VTODO Participant Status . . . . . . . . . . . 16 80 13. New Properties . . . . . . . . . . . . . . . . . . . . . . . 16 81 13.1. Estimated Duration . . . . . . . . . . . . . . . . . . . 16 82 13.2. Task Mode . . . . . . . . . . . . . . . . . . . . . . . 17 83 14. Property Extensions and Clarifications . . . . . . . . . . . 18 84 14.1. The ATTENDEE property . . . . . . . . . . . . . . . . . 19 85 14.2. Redefined COMMENT Property Parameter List . . . . . . . 19 86 14.3. Redefined STATUS Property . . . . . . . . . . . . . . . 20 87 15. CalDAV Support for Task Mode . . . . . . . . . . . . . . . . 21 88 15.1. CALDAV:supported-task-mode-set Property . . . . . . . . 21 89 16. Security Considerations . . . . . . . . . . . . . . . . . . . 22 90 17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 91 17.1. Initialization of the Status registry . . . . . . . . . 22 92 17.2. Update of the Status registry . . . . . . . . . . . . . 23 93 17.3. Sub-State value registry . . . . . . . . . . . . . . . . 23 94 17.4. Task Mode value registry . . . . . . . . . . . . . . . . 24 95 17.5. Participation Statuses registry . . . . . . . . . . . . 24 96 17.6. Properties registry . . . . . . . . . . . . . . . . . . 24 97 17.7. Parameters registry . . . . . . . . . . . . . . . . . . 25 98 18. Normative References . . . . . . . . . . . . . . . . . . . . 25 99 19. Informative References . . . . . . . . . . . . . . . . . . . 26 100 Appendix A. Examples of Task State Lifecycle . . . . . . . . . . 27 101 A.1. Simple Case Status Change . . . . . . . . . . . . . . . . 27 102 A.2. Example for multiple Attendees . . . . . . . . . . . . . 27 103 A.3. Example of Failure . . . . . . . . . . . . . . . . . . . 29 104 Appendix B. Change log . . . . . . . . . . . . . . . . . . . . . 29 105 Appendix C. Working Notes . . . . . . . . . . . . . . . . . . . 30 106 C.1. Advertising tasks . . . . . . . . . . . . . . . . . . . . 30 107 C.2. Subscribing to task updates . . . . . . . . . . . . . . . 30 108 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 110 1. Acknowledgements 112 The authors would like to thank the members of the Calendaring and 113 Scheduling Consortium technical committees and the following 114 individuals for contributing their ideas, support and comments: 116 John Chaffee, Marten Gajda, Ken Murchison 118 The authors would also like to thank CalConnect, the Calendaring and 119 Scheduling Consortium, for advice with this specification. 121 2. Introduction 123 This document specifies extensions to the existing Internet 124 Calendaring and Scheduling Core Object Specification (iCalendar) 125 [RFC5545], and associated protocols, in order to enhance the 126 structured communication and execution of tasks. The enhancements 127 allow for the communication, time planning and scheduling of tasks by 128 and between automated systems (e.g. in smart power grids, business 129 process management systems) as well as for human centered tasks. 131 A "task" is a representation of an item of work assigned to an 132 individual or organization. In the iCalendar Object Model [RFC5545] 133 the representation of tasks is by "VTODO" calendar components. Tasks 134 can be identified in a number of situations, either informally as ad- 135 hoc tasks in personal "to-do" lists or more formally in: 137 * Business processes - ranging from repetitive workflows to adaptive 138 cases and trouble ticketing 140 * Project Management - whether for large scale construction projects 141 or collaborative software development 143 The extensions specified here are defined in the context of an 144 overall architecture for task calendaring and scheduling. 146 2.1. Terms and Definitions 148 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 149 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 150 "OPTIONAL" in this document are to be interpreted as described in BCP 151 14 [RFC2119] [RFC8174] when, and only when, they appear in all 152 capitals, as shown here. 154 Terms defined in this specification include: 156 Assignee A calendar user assigned to perform a given task. An 157 assignee is equivalent to an attendee of an event. 159 Calendar User (CU) A person or software system that accesses or 160 modifies calendar information. 162 Calendar User Agent (CUA) This may be 164 1. Software with which the calendar user communicates with a 165 calendar service or local calendar store to access calendar 166 information. 168 2. Software that gathers calendar data on the Calendar User's 169 behalf. 171 Candidate A calendar user who might be able to perform a given task, 172 prior to actually being assigned the task, e.g., a dispatcher has 173 a list of taxi drivers (candidates) from which one will be 174 selected to pick-up a passenger. 176 Organizer A calendar user who creates a calendar item, requests 177 free/busy information, or published free/busy information. It is 178 an Organizer who invites Attendees [RFC5545]. 180 Observer A calendar user interested in a calendar component, e.g., a 181 manager may have interest in all tasks that have not been 182 completed. 184 Resource A resource in the scheduling context is any shared entity 185 that can be scheduled by a calendar user, but does not control its 186 own attendance status. Resources can be of "Location", 187 "Equipment", or "Role" type. 189 Task A representation of an item of work that can be assigned to one 190 or more task actor assignees. In [RFC5545], these are "VTODO" 191 calendar components, which are groupings of component properties 192 and possibly "VALARM" calendar components that represent an 193 action-item or assignment. 195 3. Task Architecture 197 A reference architecture for task calendaring and scheduling is 198 defined in order to identify the key logical elements involved in 199 task management and the interfaces between them to enable 200 interoperability. The logical elements identified here establish an 201 appropriate separation of concerns and clarify the responsibilities 202 of different elements. However, the architecture does not prescribe 203 a binding or packaging of elements, i.e., software systems may be 204 developed where some elements are tightly bound and the interfaces 205 between bound elements are not exposed. The task architecture is 206 also described in [TARCH]. 208 Task +-------+ 209 Trigger | 210 +---------------------V---------------------+ +-----------+ 211 | Task Generating System | | | 212 | +-------------------------+ | | | 213 | | O | | | | 214 | | /|\ | | | | 215 | | / \ | | | | 216 | | Task Organizer | <----> | 217 | +-^--------^--------------+ | | | 218 | | | | | | 219 | +--------V-+ +----V-----+ +----------+ | | | 220 | | Task | | Process | | Task | | | | 221 | |Assignment| | Logic <----> Domain | | | | 222 | | Rules | | | | Data | | | | 223 | +----------+ +----------+ +----------+ | | | 224 | | | | 225 +------^----------+-----^-------------------+ | | 226 | | | | | 227 Availability Task Task | | 228 | | Status | | 229 | | | | | 230 +------v----------v-----+-------------------+ | | 231 | Calendar and Scheduling System | | Directory | 232 | +---------+ +---------+ | | Service | 233 | | | | Task | <----> | 234 | |Schedule | | Lists | | | | 235 | | | | | | | | 236 | +---------+ +---------+ Server | | | 237 +-------------------------------------------+ | | 238 | Client | | | 239 | +----------------------+ +-----------+ | | | 240 | | Calendar | | Task | | | | 241 | | User Agent +----> Specific | <----> | 242 | | | |Application| | | | 243 | +----------------------+ +-----------+ | | | 244 | | | | 245 +-----^---------^--------+---------+--------+ | | 246 | | | | | | 247 +-----V---------V--------V---------V--------+ | | 248 | Task Actors | | | 249 | O O O O | | | 250 | /|\ /|\ /|\ /|\ +----> | 251 | / \ / \ / \ / \ | | | 252 | Candidate(s) Observer(s) | | | 253 | Assignee(s) Resource(s) | | | 254 +-------------------------------------------+ +-----------+ 256 4. Task Architecture Elements 258 The following logical elements form the task architecture that this 259 specification is based on: 261 Task Actors Various calendar users that may be involved in the 262 monitoring or performing of a task. The set of actors includes: 263 Organizers, Observers, Resources, Assignees, and Candidates. 265 Task Organizer The Organizer of a task. 267 Task Domain Data This is any domain specific data that may be acted 268 on or provides context to it in performing a task. 270 Task Specific Application A task specific application renders the 271 data concerning the task (including task domain data) for 272 presentation and manipulation by a task actor. 274 Process Logic Determines under what conditions a task (or tasks) is 275 generated and the actions to take on completion, or some other 276 status event occurring (or not) on the task. 278 Task Trigger This is some event that gives rise to the generation of 279 a task according to Process Logic. Task triggers can come from 280 many different sources including, for example; a task being 281 requested through the calendaring system, a status change in the 282 progression of a business process being managed by a business 283 process management or ERP system. 285 Task Assignment Rules Govern how actors are assigned to a task. A 286 range of different assignment patterns [WfRP] may be considered, 287 including the two general cases: 289 1. Delegation to a named actor or group of actors 291 2. Advertising to a pool of actors for self-selection 293 In either case the assignment may be made based on a variety of 294 criteria including, name, availability, skills, capacity, etc. 296 Task Generating System A system that creates and assigns tasks in 297 response to some initiating event (task trigger). Task creation 298 is according to Process Logic with task assignment determined by 299 Task Assignment Rules. This system also tracks the status of 300 tasks and will initiate further actions based upon the status. A 301 task generating system can take many forms, for example; Business 302 Process Management System, Project Management System, Bug Tracking 303 System, Building Control System. A Task Generating System may 304 also be a human. In iCalendar terms the Task Generating System is 305 the organizer. 307 Human Task Generation Task creation, assignment and tracking 308 coordinated by a human organizer is a special case of a task 309 generating system. In this case Task Assignment Rules and Process 310 Logic may be either explicit or tacit. 312 Directory Service A software system that stores and provides access 313 to information providing details of task actors that may 314 participate or be interested in a task. 316 Calendar and Scheduling System A software system that stores, 317 publishes and synchronizes calendar data such as events, tasks and 318 journal entries for actors. In the context of tasks this includes 319 schedules (i.e. allocated time and availability to perform tasks) 320 and task lists. A calendar and scheduling system typically 321 consists of server and client software components. 323 It is not within the scope of this document to specify how Process 324 Logic or Task Assignment Rules are codified. Such logic and rules 325 may be codified in a variety of ways, including traditional 326 programming languages (e.g. C++, Java) or process modelling 327 languages (e.g. BPMN [BPMN]). 329 5. Architecture Foundations 331 The key standards that enable interoperability between the logical 332 elements of the architecture are the Internet Calendaring and 333 Scheduling Core Object Specification (iCalendar) [RFC5545] and 334 associated protocols. Task and task status are represented by the 335 iCalendar "VTODO" component. Protocols include, in particular, the 336 iCalendar Transport-Independent Interoperability Protocol (iTIP) 337 [RFC5546] for task assignment and scheduling, and Calendaring 338 Extensions to WebDAV (CalDAV) [RFC4791] for client server 339 communication. 341 Additionally, this specification uses definitions from Support for 342 iCalendar Relationships [I-D.ietf-calext-ical-relations]. The LINK, 343 REFID, RELATED-TO and CONCEPT properties enable context and a rich 344 set of relationships between tasks and other iCalendar components to 345 be specified. 347 6. Task Extensions 349 In order to support the task architecture described in Section 3, 350 this document defines a number of extensions to the current iCalendar 351 standards in the areas of: 353 Task Specification improved ability to specify domain specific tasks 355 Task Deadlines, Milestones and Time Planning clarification of 356 deadlines and extension for task duration to support task time 357 planning 359 Task Scheduling and Assignment ensure support for common pattens of 360 scheduling and assigning tasks 362 Task Status Tracking improved granularity in status tracking 363 information and alerting task actors to pending or actual task 364 status changes 366 These extensions are supported mainly by additions to the properties 367 and parameters used within the "VTODO" component. 369 7. Task Specification 371 The specification of tasks must be semantically explicit in order for 372 them to be managed within the context of a business process or 373 project, and be understood by both humans and IT systems. The 374 current VTODO component only provides for simple ad-hoc tasks or 'to 375 do' lists, and is therefore extended by this specification as 376 follows: 378 Task type explicitly what type of task is to be performed is 379 identified. 381 Task context and relationships how a specific task relates to other 382 tasks and other objects that need to be understood for the 383 effective execution of a task. 385 Task specific data the form and content of domain data provided as 386 input to a task and/or that may be output from a task. 388 Organizer and attendee recognizes that a task organizer or attendee 389 can be an automated system. 391 7.1. CONCEPT for task type identification 393 The CONCEPT property is used to identify the type of task, for 394 example; 396 CONCEPT:http://example.com/task/delivery 398 7.2. Task Context and Relationships 400 The LINK property specifies a link to external information, which may 401 be context to the task. For example: 403 LINK;REL=SOURCE:http://example.com/package/1234567890 405 LINK;REL=describedby:mid:752142.1414823874.307E5@mx123.example.com 407 The external information may be data to be manipulated in performing 408 the task. See section 3.1.3 Task Domain Data Handling. 410 REFID is used to identify a key allowing the association of tasks 411 that are related to the same object and retrieval of a task based on 412 this key. This may be, for example, to identify the tasks associated 413 with a given project without having to communicate the task structure 414 of the project, or all tasks associated to a specific package. 416 REFID:Manhattan 418 REFID:1234567890 420 Extensions [Doug114] to the RELATED-TO property allow temporal 421 relationships between tasks as found in project management to be 422 specified as well as parent / child relationships and dependencies 423 (DEPENDS-ON). Tasks (VTODOs) may also be related to other calendar 424 components; for example to a VEVENT to block time to perform a task. 426 7.3. Task Domain Data Handling 428 Provide support for task specific input and output data (including 429 updates) beyond the standard iCalendar properties. It is envisaged 430 that standard calendar user agents will be able to launch task 431 specific applications by passing task specific data. 433 The LINK property can be used to 'attach' the domain specific data to 434 the task. For example, it might be a URI pointing to a web page 435 where the status of the task can be directly manipulated. 437 LINK;REL="vacation-system";VALUE=URI:http://example.com/ 438 vacation-approval?id=1234 440 Or it might be used for attachments specific to the task, for example 441 an electronic copy of a signature taken to confirm delivery of a 442 package. 444 LINK;REL="electronic-signature";VALUE=URI:http://example.com/ 445 delivery/sig1234.jpg 447 8. Task Deadlines, Milestones and Time Planning 449 Deadlines for starting and finishing a task are defined by the 450 DTSTART, DUE and DURATION properties. DTSTART represents the 451 earliest start time for beginning work on a task. DUE, or DTSTART + 452 DURATION represent the latest finish time for a task. Thus these 453 properties define a "window" within which a task has to be performed. 454 However, there is currently no way to indicate how long the task is 455 expected to take. This document defines a new property, ESTIMATED- 456 DURATION, to allow the estimated time that a task should take to be 457 specified separately from the deadlines for starting and finishing a 458 task. This supports time planning by enabling calendar user agents 459 to display when tasks should occur and therefore allow calendar users 460 to visualize when tasks should be performed and allocate time to 461 them. 463 A task that has intermediary deadlines (i.e., milestones) SHOULD be 464 expressed by child VTODO components (i.e., sub-tasks associated with 465 each of the milestones) in conjunction with the RELATED-TO property 466 to relate the parent and child tasks. 468 9. Task Scheduling and Assignment 470 This specification supports the two distinct models of assigning 471 actors to tasks, i.e., 1) strictly one assignee per task or 2) task 472 assignment to multiple assignees. In this regard one or many 473 ATTENDEES may be specified against a task depending upon the model 474 applied by the task organizer. 476 In addition a number of different patterns of resource or assignee 477 identification are anticipated. The specific Task Assignment Rules 478 are the responsibility of the Task Organizer. 480 Communication of task assignment or delegation to one or more actors 481 who are allocated to a task by the organizer is directly supported by 482 iTIP, i.e., all included ATTENDEES in an iTIP REQUEST are expected to 483 perform the task. 485 The offering or advertising of a task to one or more (potential) 486 actors where only one or a subset of the candidates may accept the 487 task will be addressed by a new VPOLL mode (See Appendix B) [VPOLL]. 489 10. Status Reporting 491 10.1. Improved granularity in status reporting information 493 This document defines new status parameters that can be applied to 494 the VTODO status (STATUS) property, as well as the participant status 495 (PARTSTAT) parameter. These new parameters provide additional 496 information on why (REASON) and when (MODIFIED) a status has changed. 497 In addition to these parameters new status values are specified to 498 provide for task suspension, failure and preparation. 500 10.2. Relating comments to status 502 The GROUP parameter is used with the STATUS or ATTENDEE properties to 503 relate an associated COMMENT property. The COMMENT property can then 504 be used to include additional human readable information about why 505 the associated STATUS or ATTENDEE property changed. 507 STATUS;REASON="http://example.com/reason/delivery-failed"; 508 SUBSTATE=ERROR;MODIFIED=20130212T120000Z;GROUP=G1:FAILED 509 COMMENT;MODIFIED=20130226T110451Z;GROUP=G1:Breakdown 510 ATTENDEE;PARTSTAT=FAILED;MODIFIED=20130226T1104510Z;GROUP=G2: 511 REASON="http://example.com/reason/van-break-down": 512 mailto:xxx@example.com 513 COMMENT;MODIFIED=20130226T110451Z;GROUP=G2:Puncture 515 10.3. Comments associated to reasons and status changes 517 Reasons may be associated directly with a comment, allowing for 518 multiple reasons associated with a status to each have a comment 519 associated with them [EDISTS]. 521 CONCEPT:http://example.com/task/delivery 522 STATUS;SUBSTATE=ERROR;MODIFIED=20130212T120000Z;GROUP=G1:FAILED 523 COMMENT;MODIFIED=20130226T110451Z;GROUP=G1:Out of time 524 COMMENT;REASON="http://example.com/reason/traffic"; 525 MODIFIED=20130226T110451Z;GROUP=G1:Traffic Accident on E44 526 COMMENT;REASON="http://example.com/reason/closed"; 527 MODIFIED=20130226T110451Z;GROUP=G1:Arrived after office hours 529 10.4. Task Alerts and Notifications 531 Different needs to alert or notify task actors of pending or actual 532 task status changes are recognized: 534 Alarms Alarms (VLARM components) operate in the calendar user agent 535 space to notify the task actor of a pending task state for a task 536 they are assigned to or are interested in. Note: there is no 537 constraint in the current standards on the propagation of alarms 538 specified on calendar objects by organizers to individual 539 attendees. 541 Escalations An escalation or notification to the ATTENDEE, 542 ORGANIZER, or other task actor may be required if a deadline 543 associated with a task is exceeded or for some other reason. 544 Process Logic identifying when and who to propagate escalations to 545 is the responsibility of the Task Generating System, e.g., a BPMS. 547 Notifications Task actors (observers) not directly involved in 548 performing a task but with a known interest in a given task's 549 status can be identified by the ASSOCIATE property [Doug214] 550 against certain components e.g. ALARM, to identify which task 551 events the stakeholder/party is interested in. Notifications on 552 shared calendars will allow task actors to register an interest in 553 changes to tasks within a calendar (see Appendix A). 555 10.5. Automated Status Changes 557 A new property, TASK-MODE, is introduced to instruct servers to apply 558 automated operations for changing the status of a task. 560 11. New Property Parameters 562 11.1. Group 564 Parameter name GROUP 566 Purpose This parameter allows the association of different (usually) 567 multiply occurring properties. 569 Format Definition This parameter is defined by the following 570 notation: 572 groupparam = "GROUP" "=" text 573 *("," text) 575 Description The value of this parameter is free-form text that 576 creates an identifier for associated properties. All properties 577 that use the same GROUP value are associated through that value. 578 For example, multiple comments and an attendee may be associated 579 with a status value. 581 Example The following is an example of this property. 583 GROUP=G1 585 11.2. Reason 587 Parameter name REASON 589 Purpose To indicate the reason for a change in status of a task or 590 attendee participation status. 592 Format Definition This parameter is defined by the following 593 notation: 595 reasonparam = "REASON" "=" DQUOTE uri DQUOTE 596 *("," DQUOTE uri DQUOTE) 598 Description This property parameter allows the change in status of a 599 task or participant status to be qualified by the reason for the 600 change with a codified reason. Typically reasons are defined 601 within the context of the task type and therefore SHOULD include 602 the name-space of the authority defining the task. Common reason 603 codes are IANA registered and do not have a name-space prefix. 605 Example 607 STATUS;REASON="http://example.com/reason/delivered-on-time"; 608 MODIFIED=20130212T120000Z;GROUP=G1:COMPLETED 609 ATTENDEE;REASON="x-example-reason:out-of-office"; 610 PARTSTAT=DECLINED;MODIFIED=20130212T120000Z; 611 GROUP=123:mailto:cyrus@example.com 613 11.3. Modified 615 Parameter name MODIFIED 617 Purpose To specify the time and date of when the status of a task or 618 attendee participant status changed. 620 Format Definition This parameter is defined by the following 621 notation: 623 modifiedparam = "MODIFIED" "=" date-time 625 Description The modified parameter allows the specification of the 626 date time of when a status (STATUS) or participant status 627 (PARTSTAT) changed. It MUST be specified in the UTC time format. 628 The value of MODIFIED SHOULD be set at the time when the 629 associated status (either STATUS or PARTSTAT)is changed. 630 Therefore either a client or server may set the value of MODIFIED 631 depending on which is updating the value of STATUS or PARTSTAT. 632 For backwards compatibility if the server detects that MODIFIED 633 should have changed but wasn't (for example the client doesn't 634 support MODIFIED) then the server MAY set MODIFIED 635 retrospectively. 637 Example 639 STATUS;REASON=""http://example.com/reason/delivered-on-time"; 640 MODIFIED=20130212T120000Z;GROUP=G1:COMPLETED 642 11.4. Sub-State 644 Parameter name SUBSTATE 646 Purpose To provide additional granularity of task status for e.g. 647 IN-PROCESS. 649 Format Definition This parameter is defined by the following 650 notation: 652 substateparam = "SUBSTATE" "=" 653 ( "OK" ; everything is fine(the default) 654 / "ERROR" ; something is wrong (the REASON 655 ; code explains why) 656 / "SUSPENDED" ; waiting on some other task to 657 ; complete or availability of a 658 ; resource (REASON code explains 659 ; why) 660 / x-name ; Experimental type 661 / iana-token) ; Other IANA-registered type 663 Description The sub-state parameter allows additional qualification 664 and granularity of states to be recorded, in particular for the 665 IN-PROCESS state. It allows individual sub-states to be recorded 666 without the need to define and publish a sub-task associated with 667 a parent task purely to track that a particular state has been 668 reached. This property also allows parallel states to be 669 expressed e.g. that a task has been suspended at whatever state it 670 has reached. 672 Example 674 STATUS;REASON="http://example.com/reason/no-one-home"; 675 SUBSTATE=ERROR:FAILED 676 STATUS;REASON="http://example.com/reason/paint-drying"; 677 SUBSTATE=SUSPENDED:IN-PROCESS 679 12. New Parameter Values 681 12.1. Redefined VTODO Participant Status 683 Participant status parameter type values are defined in [RFC5545]. 684 This specification redefines that type to include the new value 685 FAILED for VTODO iCalendar components. 687 Format Definition This property parameter is extended by the 688 following notation: 690 partstat-todo /= *("FAILED") ; To-do cannot be completed 692 Example 694 ATTENDEE;REASON="http://example.com/reason/not-enough-time"; 695 PARTSTAT=FAILED:mailto:jsmith@example.com 697 13. New Properties 699 13.1. Estimated Duration 701 Property Name ESTIMATED-DURATION 703 Purpose This property specifies the estimated positive duration of 704 time the corresponding task will take to complete. 706 Value Type DURATION 708 Property Parameters IANA and non-standard property parameters can be 709 specified on this property. 711 Conformance This property can be specified in "VTODO" calendar 712 components. 714 Format Definition This property is defined by the following 715 notation: 717 est-duration = "ESTIMATED-DURATION" durparam ":" dur-value CRLF 718 ;consisting of a positive duration of time. 720 durparam = *(";" other-param) 722 Description In a "VTODO" calendar component the property MAY be used 723 to specify the estimated duration for the to-do, with or without 724 an explicit time window in which the event should be started and 725 completed. When present, DTSTART and DUE/DURATION represent the 726 window in which the task can be performed. ESTIMATED-DURATION 727 SHOULD be passed from ORGANIZER to ATTENDEE in iTIP [RFC5546] 728 messages. 730 Example The following is an example of this property that specifies 731 an interval of time of exactly one hour: 733 ESTIMATED-DURATION:PT1H 735 13.2. Task Mode 737 Property Name TASK-MODE 739 Purpose This property specifies automatic operations that servers 740 apply to tasks based on changes in attendee status (PARTSTAT). 742 Value Type TEXT 744 Property Parameters IANA and non-standard property parameters can be 745 specified on this property. 747 Conformance This property can be specified zero or more times in a 748 "VTODO" calendar component. 750 Format Definition This property is defined by the following 751 notation: 753 task-mode = "TASK-MODE taskmodeparam ":" taskvalue 754 *("," taskvalue) CRLF 756 taskvalue = "AUTOMATIC-COMPLETION" ; set STATUS completed 757 ;if all attendees have completed 758 / "AUTOMATIC-FAILURE" 759 / "SERVER" 760 / "CLIENT" 761 / iana-token 762 / x-name 764 taskmodeparam = *(";" other-param) 766 Description In a "VTODO" calendar component this property MAY be 767 used to indicate to servers how they can automatically change the 768 state of the task based on iTIP replies from Attendees. For 769 example, the server can automatically set the overall task status 770 (STATUS) to COMPLETED when every attendee has marked their own 771 status (PARTSTAT) as COMPLETED, or the server could mark the task 772 as FAILED if its DUE date passes without it being completed. 773 TASK-MODE processing is performed on the organizer's copy of the 774 task. 776 The property value is a list of one or more IANA registered tokens 777 that defines modes to be used for the task. This specification 778 defines three modes which are described in the following sub- 779 sections. 781 Examples 783 TASK-MODE:AUTOMATIC-COMPLETION,AUTOMATIC-FAILURE 784 TASK-MODE:SERVER 785 TASK-MODE:AUTOMATIC-FAILURE 787 AUTOMATIC-COMPLETION Task Mode The task mode value "AUTOMATIC- 788 COMPLETION" indicates to the server that it can change the "VTODO" 789 component's STATUS property value to "COMPLETED" as soon as all 790 ATTENDEEs in the task have replied with a "PARTSTAT" parameter set 791 to "COMPLETED". 793 AUTOMATIC-FAILURE Task Mode The task mode value "AUTOMATIC-FAILURE" 794 indicates to the server that it SHOULD change the "VTODO" 795 component's STATUS property value to "FAILED" if either: 797 * the PARTSTAT of one ATTENDEE is set to FAILED; or 799 * the current time is past the effective due date of the 800 component and the task has not yet been completed. 802 Note: The effective due date is either the "DUE" property value or 803 the combination of the "DTSTART" and "DURATION" property values. 805 CLIENT Task Mode The task mode value "CLIENT" is an instruction to 806 the server to honour the status set by the client. 808 SERVER Task Mode The task mode value "SERVER" indicates to the 809 server that it can change the "VTODO" component's STATUS property 810 value to an appropriate value, based on implementation defined 811 "business rules", as ATTENDEE responses are processed or as 812 deadlines related to the task pass. 814 The server can add this property to a "VTODO" component to 815 indicate to the client that it will be managing the status. 817 14. Property Extensions and Clarifications 818 14.1. The ATTENDEE property 820 The Attendee property is defined in [RFC5545]. This specification 821 extends that property to include new parameters to indicate the 822 reason for a participant status change (See Appendix A) and sub- 823 states. 825 Format Definition This property is defined by the following 826 notation: 828 attendee = "ATTENDEE" attparam ":" cal-address CRLF 830 attparam /= *( 831 ; 832 ; The following are OPTIONAL, 833 ; but MUST NOT occur more than once. 834 ; 835 (";" reasonparam) 836 (";" modifiedparam) 837 (";" substateparam) 838 ) 840 Example: The following are examples of this property's use for tasks: 842 ATTENDEE;PARTSTAT=DECLINED;MODIFIED=20130212T120000Z;GROUP=G1; 843 REASON="http://example.com/reason/too-busy":mailto:xxx@example.com 845 ATTENDEE;PARTSTAT=IN-PROCESS;MODIFIED=20130212T120000Z; 846 SUBSTATE=X-EXAMPLE-STEP-1:mailto:xxx@example.com 848 14.2. Redefined COMMENT Property Parameter List 850 The Comment property is defined in [RFC5545]. 852 Format Definition The "COMMENT" property parameter list is augmented 853 as follows: 855 commparam /= *( 856 ; The following are OPTIONAL, 857 ; but MUST NOT occur more than once. 858 (";" reasonparam) / 859 (";" modifiedparam) 860 ) 862 14.3. Redefined STATUS Property 864 The Status property is defined in [RFC5545]. This specification 865 extends that property to include new parameters to indicate the 866 reason for a status change as well as new values associated with 867 VTODO iCalendar components (See Appendix A for examples of the task 868 state lifecycle). 870 Format Definition The "STATUS" property parameter list is augmented 871 as follows: 873 statparam /= *( 874 ; The following are OPTIONAL, 875 ; but MUST NOT occur more than once. 876 ; 877 (";" reasonparam) 878 (";" modifiedparam) 879 (";" substateparam) / 880 ) 882 statvalue-todo = / "PENDING" ;Indicates a to-do has been 883 ;created and accepted, but has not 884 ;yet started. 885 / "FAILED" ;Indicates to-do has failed. 886 ;Extended status values for 887 ;"VTODO". 889 Description: 891 PENDING - A task has been created but has not yet started and is 892 ready to start subject to other dependencies (e.g. preceding task or 893 DTSTART). This is the default state. 895 FAILED - task has failed and may need some follow-up from the 896 organizer to re-schedule or cancel 898 Example: The following is an example of this property for a "VTODO" 899 calendar component: 901 STATUS;REASON="http://example.com/reason/delivery-failed"; 902 SUBSTATE=ERROR;MODIFIED=20130212T120000Z;GROUP=G1:FAILED 904 15. CalDAV Support for Task Mode 906 The CalDAV [RFC4791] calendar access protocol allows clients and 907 servers to exchange iCalendar data. With the introduction of the 908 "TASK-MODE" property in this specification, different automated task 909 management behaviours may be delegated to the server by the Task 910 Organizer depending upon the value of "TASK-MODE". 912 In order for a CalDAV client to know what task modes are available, a 913 CalDAV server advertises a CALDAV:supported-task-mode-set WebDAV 914 property on calendar home or calendar collections if it supports the 915 use of the "TASK-MODE" property as described in this specification. 916 The server can advertise a specific set of supported task modes by 917 including one or more CALDAV:supported-task-mode XML elements within 918 the CALDAV:supported-task-mode-set XML element. If no 919 CALDAV:supported-task-mode XML elements are included in the WebDAV 920 property, then clients can try any task mode, but need to be prepared 921 for a failure when attempting to store the calendar data. 923 Clients MUST NOT attempt to store iCalendar data containing "TASK- 924 MODE" elements if the CALDAV:supported-task-mode-set WebDAV property 925 is not advertised by the server. 927 The server SHOULD return an HTTP 403 response with a DAV:error 928 element containing a CALDAV:supported-task-mode XML element, if a 929 client attempts to store iCalendar data with an "TASK-MODE" element 930 value not supported by the server. 932 It is possible for a "TASK-MODE" value to be present in calendar data 933 on the server being accessed by a client that does not support the 934 "TASK-MODE" property. It is expected that existing clients, unaware 935 of "TASK-MODE", will fail gracefully by ignoring the calendar 936 property. 938 15.1. CALDAV:supported-task-mode-set Property 940 Name supported-task-mode-set 942 Namespace urn:ietf:params:xml:ns:caldav 944 Purpose Enumerates the set of supported iCalendar "TASK-MODE" 945 element values supported by the server. 947 Protected This property MUST be protected and SHOULD NOT be returned 948 by a PROPFIND allprop request (as defined in Section 14.2 of 949 [RFC4918]). 951 Description See above. 953 Definition 955 956 957 960 Example 962 963 AUTOMATIC-COMPLETION 964 AUTOMATIC-FAILURE 965 SERVER 966 CLIENT 967 969 16. Security Considerations 971 This specification introduces no new security considerations beyond 972 those identified in [RFC5545]. 974 17. IANA Considerations 976 17.1. Initialization of the Status registry 978 This specification updates [RFC5545] by adding a Status value 979 registry to the iCalendar Elements registry and initializing it as 980 per [RFC5545]. 982 +==============+=========+===========+ 983 | Name | Status | Reference | 984 +==============+=========+===========+ 985 | CANCELLED | Current | [RFC5545] | 986 +--------------+---------+-----------+ 987 | COMPLETED | Current | [RFC5545] | 988 +--------------+---------+-----------+ 989 | CONFIRMED | Current | [RFC5545] | 990 +--------------+---------+-----------+ 991 | DRAFT | Current | [RFC5545] | 992 +--------------+---------+-----------+ 993 | FINAL | Current | [RFC5545] | 994 +--------------+---------+-----------+ 995 | IN-PROCESS | Current | [RFC5545] | 996 +--------------+---------+-----------+ 997 | NEEDS-ACTION | Current | [RFC5545] | 998 +--------------+---------+-----------+ 999 | TENTATIVE | Current | [RFC5545] | 1000 +--------------+---------+-----------+ 1002 Table 1: Initial Status Value Registry 1004 17.2. Update of the Status registry 1006 This specification further updates the Status registry with 1007 additional values defined in this document. 1009 +=========+=========+=========================+ 1010 | Value | Status | Reference | 1011 +=========+=========+=========================+ 1012 | PENDING | Current | This Spec, Section 14.3 | 1013 +---------+---------+-------------------------+ 1014 | FAILED | Current | This Spec, Section 14.3 | 1015 +---------+---------+-------------------------+ 1017 Table 2: Updated Status Value Registry 1019 17.3. Sub-State value registry 1021 The following table has been used to initialize the Sub-State 1022 registry. 1024 +===========+=========+=========================+ 1025 | Substate | Status | Reference | 1026 +===========+=========+=========================+ 1027 | OK | Current | This Spec, Section 11.4 | 1028 +-----------+---------+-------------------------+ 1029 | ERROR | Current | This Spec, Section 11.4 | 1030 +-----------+---------+-------------------------+ 1031 | SUSPENDED | Current | This Spec, Section 11.4 | 1032 +-----------+---------+-------------------------+ 1034 Table 3: Sub-State registry 1036 17.4. Task Mode value registry 1038 The following table has been used to initialize the Task Mode 1039 registry. 1041 +======================+=========+=========================+ 1042 | Task Mode | Status | Reference | 1043 +======================+=========+=========================+ 1044 | AUTOMATIC-COMPLETION | Current | This Spec, Section 13.2 | 1045 +----------------------+---------+-------------------------+ 1046 | AUTOMATIC-FAILURE | Current | This Spec, Section 13.2 | 1047 +----------------------+---------+-------------------------+ 1048 | CLIENT | Current | This Spec, Section 13.2 | 1049 +----------------------+---------+-------------------------+ 1050 | SERVER | Current | This Spec, Section 13.2 | 1051 +----------------------+---------+-------------------------+ 1053 Table 4: Task Mode Value Registry 1055 17.5. Participation Statuses registry 1057 The following table has been used to update the Participation 1058 Statuses registry. 1060 +========+=========+=========================+ 1061 | Value | Status | Reference | 1062 +========+=========+=========================+ 1063 | FAILED | Current | This Spec, Section 12.1 | 1064 +--------+---------+-------------------------+ 1066 Table 5: Participation Statuses Registry 1068 17.6. Properties registry 1070 The following table has been used to update the Properties registry. 1072 +====================+=========+=========================+ 1073 | Property | Status | Reference | 1074 +====================+=========+=========================+ 1075 | ATTENDEE | Current | This Spec, Section 14.1 | 1076 +--------------------+---------+-------------------------+ 1077 | COMMENT | Current | This Spec, Section 14.2 | 1078 +--------------------+---------+-------------------------+ 1079 | ESTIMATED_DURATION | Current | This Spec, Section 13.1 | 1080 +--------------------+---------+-------------------------+ 1081 | STATUS | Current | This Spec, Section 14.3 | 1082 +--------------------+---------+-------------------------+ 1083 | TASK-MODE | Current | This Spec, Section 13.2 | 1084 +--------------------+---------+-------------------------+ 1086 Table 6: Updated Properties Registry 1088 17.7. Parameters registry 1090 The following table has been used to update the Parameters registry. 1092 +===========+=========+=========================+ 1093 | Parameter | Status | Reference | 1094 +===========+=========+=========================+ 1095 | REASON | Current | This Spec, Section 11.2 | 1096 +-----------+---------+-------------------------+ 1097 | MODIFIED | Current | This Spec, Section 11.3 | 1098 +-----------+---------+-------------------------+ 1099 | SUBSTATE | Current | This Spec, Section 11.4 | 1100 +-----------+---------+-------------------------+ 1102 Table 7: Ipdated Parameters Registry 1104 18. Normative References 1106 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1107 Requirement Levels", RFC 2119, IETF RFC 2119, 1108 DOI 10.17487/RFC2119, March 1997, 1109 . 1111 [RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault, 1112 "Calendaring Extensions to WebDAV (CalDAV)", RFC 4791, 1113 IETF RFC 4791, DOI 10.17487/RFC4791, March 2007, 1114 . 1116 [RFC4918] Dusseault, L., Ed., "HTTP Extensions for Web Distributed 1117 Authoring and Versioning (WebDAV)", RFC 4918, IETF RFC 1118 4918, DOI 10.17487/RFC4918, June 2007, 1119 . 1121 [RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and 1122 Scheduling Core Object Specification (iCalendar)", RFC 1123 5545, IETF RFC 5545, DOI 10.17487/RFC5545, September 2009, 1124 . 1126 [RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent 1127 Interoperability Protocol (iTIP)", RFC 5546, IETF RFC 1128 5546, DOI 10.17487/RFC5546, December 2009, 1129 . 1131 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1132 2119 Key Words", RFC 8174, IETF RFC 8174, 1133 DOI 10.17487/RFC8174, May 2017, 1134 . 1136 [I-D.ietf-calext-eventpub-extensions] 1137 Douglass, M., "Event Publishing Extensions to iCalendar", 1138 I-D.ietf-calext-eventpub-extensions, IETF I-D.ietf-calext- 1139 eventpub-extensions, March 2021. 1141 [I-D.ietf-calext-ical-relations] 1142 Douglass, M., "Support for iCalendar Relationships", I- 1143 D.ietf-calext-ical-relations, IETF I-D.ietf-calext-ical- 1144 relations, December 2020. 1146 19. Informative References 1148 [BPMN] "Business Process Model and Notation", OMG BPMN 2.0.2, 1149 January 2014, 1150 . 1152 [I-D.york-vpoll] 1153 York, E., Daboo, C., and M. Douglass, "VPOLL: Consensus 1154 Scheduling Component for iCalendar", I-D.york-vpoll, 1155 IETF I-D.york-vpoll, February 2017. 1157 [TARCH] "Apthorp, A., Daboo, C., Douglass, M., CalConnect, Task 1158 Architecture V1.0,", CalConnect Task Architecture V1.0. 1160 [EDISTS] "UN Economic Commission for Europe, UN/EDIFACT, D14.A, STS 1161 STATUS, April 30, 1162 2014,http://www.unece.org/fileadmin/DAM/trade/untdid/d14a/ 1163 trsd/trsdsts.htm", UN/EDIFACT, D14.A. 1165 [WfRP] "Russell, N., ter Hofstede, A.H.M., Edmond, T., van der 1166 Aalst,W.M.P., Workflow Resource Patterns, Eindhoven 1167 University of Technology, 2004,", WfRP. 1169 [WSCal] "Considine, T., Douglass, M., WS-Calendar Version 1.0, 1170 OASIS, 30 July 2011,", OASIS WS-Calendar V1.0. 1172 [WSHT] "Ings, D., Clement, L., Koenig, D., Mehta, V., Mueller, 1173 R., Rangaswamy, R., Rowley, M., Trickovic, I., Web 1174 Services - Human Task Version 1.1 (WS-HumanTask), OASIS, 1175 17 August 2010,", OASIS WS-HT V1.1. 1177 Appendix A. Examples of Task State Lifecycle 1179 A.1. Simple Case Status Change 1181 +===+==============+==============+===========================+ 1182 | | STATUS | PARTSTAT | Action | 1183 +===+==============+==============+===========================+ 1184 | 1 | - | - | Organizer draft | 1185 +---+--------------+--------------+---------------------------+ 1186 | 2 | NEEDS-ACTION | NEEDS-ACTION | Organizer sends iTIP | 1187 | | | | request | 1188 +---+--------------+--------------+---------------------------+ 1189 | 3 | NEEDS-ACTION | ACCEPTED | Attendee reply | 1190 +---+--------------+--------------+---------------------------+ 1191 | 4 | PENDING | ACCEPTED | Task accepted but waiting | 1192 | | | | on some "trigger" to | 1193 | | | | start (e.g. another task | 1194 | | | | has to finish first) | 1195 +---+--------------+--------------+---------------------------+ 1196 | 5 | IN-PROCESS | IN-PROCESS | Attendee reply now | 1197 | | | | working on the task | 1198 +---+--------------+--------------+---------------------------+ 1199 | 6 | IN-PROCESS | COMPLETED | Attendee reply completed | 1200 +---+--------------+--------------+---------------------------+ 1201 | 7 | COMPLETED | COMPLETED | Organizer changes overall | 1202 | | | | state | 1203 +---+--------------+--------------+---------------------------+ 1205 Table 8: Example of status changes in assigning and 1206 performing a task with one attendee. 1208 A.2. Example for multiple Attendees 1210 Example of status changes in assigning and performing a task with two 1211 attendees (A1 and A2). 1213 +====+==============+==============+==============+================+ 1214 | | STATUS | PARTSTAT | PARTSTAT | Action | 1215 | | | (A1) | (A2) | | 1216 +====+==============+==============+==============+================+ 1217 | 1 | - | - | - | Organizer | 1218 | | | | | draft. | 1219 +----+--------------+--------------+--------------+----------------+ 1220 | 2 | NEEDS-ACTION | NEEDS-ACTION | NEEDS-ACTION | Organizer | 1221 | | | | | sends iTIP | 1222 | | | | | request. | 1223 +----+--------------+--------------+--------------+----------------+ 1224 | 4 | NEEDS-ACTION | ACCEPTED | NEEDS-ACTION | Attendee 1 | 1225 | | | | | reply. | 1226 +----+--------------+--------------+--------------+----------------+ 1227 | 5 | NEEDS-ACTION | ACCEPTED | ACCEPTED | Attendee 2 | 1228 | | | | | reply. | 1229 +----+--------------+--------------+--------------+----------------+ 1230 | 6 | PENDING | ACCEPTED | ACCEPTED | Task accepted | 1231 | | | | | but waiting on | 1232 | | | | | some"trigger" | 1233 | | | | | to start (e.g. | 1234 | | | | | another task | 1235 | | | | | has to finish | 1236 | | | | | first) | 1237 +----+--------------+--------------+--------------+----------------+ 1238 | 7 | IN-PROCESS | ACCEPTED | IN-PROCESS | Attendee 2 | 1239 | | | | | reply now | 1240 | | | | | working on the | 1241 | | | | | task. | 1242 +----+--------------+--------------+--------------+----------------+ 1243 | 8 | IN-PROCESS | IN-PROCESS | IN-PROCESS | Attendee 1 | 1244 | | | | | reply now | 1245 | | | | | working on the | 1246 | | | | | task. | 1247 +----+--------------+--------------+--------------+----------------+ 1248 | 9 | IN-PROCESS | COMPLETED | IN-PROCESS | Attendee 1 | 1249 | | | | | reply | 1250 | | | | | Completed | 1251 | | | | | (overall | 1252 | | | | | status still | 1253 | | | | | IN-PROCESS). | 1254 +----+--------------+--------------+--------------+----------------+ 1255 | 10 | IN-PROCESS | COMPLETED | COMPLETED | Attendee 2 | 1256 | | | | | reply | 1257 | | | | | Completed | 1258 +----+--------------+--------------+--------------+----------------+ 1259 | 11 | COMPLETED | COMPLETED | COMPLETED | Organizer | 1260 | | | | | changes | 1261 | | | | | overall state | 1262 | | | | | once both | 1263 | | | | | attendees are | 1264 | | | | | finished. | 1265 +----+--------------+--------------+--------------+----------------+ 1267 Table 9: Example for multiple Attendees 1269 Note: The logic for determining the status change to the VTODO is 1270 determined by the task organizer based on the ATTENDEE status and 1271 other business logic. 1273 A.3. Example of Failure 1275 Example of status changes for a task that fails. 1277 +===+==============+==============+==============================+ 1278 | | STATUS | PARTSTAT | Action | 1279 +===+==============+==============+==============================+ 1280 | 1 | - | - | Organizer draft | 1281 +---+--------------+--------------+------------------------------+ 1282 | 2 | NEEDS-ACTION | NEEDS-ACTION | Organizer sends iTIP request | 1283 +---+--------------+--------------+------------------------------+ 1284 | 3 | NEEDS-ACTION | ACCEPTED | Attendee reply | 1285 +---+--------------+--------------+------------------------------+ 1286 | 4 | IN-PROCESS | IN-PROCESS | Attendee reply now working | 1287 | | | | on the task | 1288 +---+--------------+--------------+------------------------------+ 1289 | 5 | IN-PROCESS | FAILED | Attendee reply task failed | 1290 +---+--------------+--------------+------------------------------+ 1291 | 6 | FAILED | FAILED | Organizer changes overall | 1292 | | | | state | 1293 +---+--------------+--------------+------------------------------+ 1295 Table 10: Example of Failure 1297 Appendix B. Change log 1299 V02. 2021-05-05 MD 1301 * Redo in asciidoc 1303 * Change STRUCTURED-CATEGORY to CONCEPT 1305 * Add GROUP parameter definition 1307 V01. 2015-08-23 AA 1308 * Highlighted use of ESTIMATED-DURATION for time planning. 1310 * Corrected PARTSTAT example section 5.1. Changed DECLINED to 1311 FAILED. 1313 * Replaced Task Mode AUTOMATIC-STATUS with CLIENT and SERVER modes. 1314 Also, clarified that task mode processing is only done on the 1315 organizer's copy. 1317 * Clarified responsibility for setting MODIFIED. 1319 * CalDAV support added. 1321 * Updated normative references. 1323 Appendix C. Working Notes 1325 C.1. Advertising tasks 1327 Use VPOLL for advertising a task to a pool of possible ATTENDEEs and 1328 then select the respondent to assign one or more assignees. 1330 Introduce POLL-MODE:ASSIGNMENT 1332 Need to indicate number of assignees required. 1334 Potentially different types of response e.g. ACCEPT or DECLINE, or a 1335 weighting e.g. 0 - 100 1337 Take into FREEBUSY discussion. 1339 C.2. Subscribing to task updates 1341 Stakeholders should have the ability to subscribe to categories / 1342 types of tasks on an ongoing basis. Reference calendarserver.org 1343 notifications draft 1345 Authors' Addresses 1347 Adrian Apthorp 1348 DHL Express 1350 Email: aapthorp@theiet.org 1352 Michael Douglass 1353 Bedework Commercial Services 1354 Email: mdouglass@bedework.com