Network Working Group M. Douglass
Internet-Draft RPI
Intended status: Standards Track February 14, 2011
Expires: August 18, 2011

Event Publishing Extensions to Icalendar
draft-douglass-calendar-extension-00

Abstract

This specification introduces a number of new iCalendar properties which are of particular use for event publishers and in social networking.

Status of this Memo

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Table of Contents

1. Introduction

The currently existing iCalendar standard [RFC5545] lacks useful methods for referencing additional, external information relating to calendar components.

This document defines a number of properties referencing external information that can provide additional information about an iCalendar component. The intent is that such information can be automatically discovered and used by clients. Formats such as VCARD are likely to be most useful.

1.1. Conventions Used in This Document

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 [RFC2119].

2. Typed References

The properties defined here can all reference external meta-data which may be used by applications to provide enhanced value to users. By providing type information as parameters, clients and servers are able to discover interesting references and make use of them, perhaps for indexing or the presentation of additional related information for the user.

These properties are designed to handle common use cases in event publication. It is generally important to provide information about the organizers of such events. Sponsors wish to be referenced in a prominent manner. In social calendaring it is often important to identify the active participants in the event, for example a school sports team, and the inactive participants, for example the parents.

The [RFC5545] LOCATION property provides only an unstructured single text value for specifying the location where an event (or "TODO" item) will occur. This is inadequate for use cases where structured location information (e.g. address, region, country, postal code) is required or preferred, and limits widespread adoption of iCalendar in those settings.

In addition, using STRUCTURED-LOCATION, information about a number of interesting locations can be communicated, for example, parking, restaurants and the venue. Servers and clients can retrieve the objects when storing the event and use them to index by geographic location.

The properties defined here are all URI references to some related data. When a calendar client receives a calendar component it can search the set of supplied properties looking for those of particular interest. The TYPE and FMTTYPE parameters, if supplied, can be used to help the selection.

Having located such a property, e.g. STRUCTURED-LOCATION with TYPE=PARKING, the client can use http GET on the supplied URL perhaps with an ACCEPT header set to specify the desired format. The targeted server SHOULD respond with a 406 if the resource is not available in the desired format(s).

3. Use Cases

The main motivation for these properties has been event publication but there are opportunities for use elsewhere. The following use cases will describe some possible scenarios.

3.1. Piano Concert Performance

In putting together a concert there are many participants: piano tuner, performer, stage hands etc. In addition there are sponsors and various contacts to be provided. There will also be a number of related locations. A number of events can be created, all of which relate to the performance in different ways.

There may be an iTip meeting request for the piano tuner who will arrive before the performance. Other members of staff may also receive meeting requests.

An event can also be created for publication which will have a PARTICIPANT reference to the pianist providing vcard information about the performer. This event would also hold information about parking, local subway stations and the venue itself. In addition, there will be sponsorship information for sponsors of the event and perhaps paid sponsorship properties essentially advertising local establishments.

3.2. Itineraries

These properties also provide opportunities for the travel industry. When booking a flight the SPONSOR property can be used to provide references to businesses at the airports and to car hire businesses at the destination.

The embedded location information can guide the traveller at the airport or to their final destination. The contact information can provide detailed information about the booking agent, the airlines and car hire companies and the hotel.

4. New Property Parameters

4.1. Type

This parameter is defined by the following notation: 

  typeparam      = "TYPE" "=" text
Parameter name:
TYPE
Purpose:
To subtype the associated property.
Format Definition:
Description:
This parameter MAY be specified on a number of properties, and provides a way to differentiate multiple values. For example, it allows event producers to provide contact information for different purposes.

4.2. Level

This parameter is defined by the following notation: 

  levelparam    = "LEVEL" "=" (1*2DIGIT / "10")
                                ; An integer between 1 and 10.
Parameter name:
LEVEL
Purpose:
To define a level of sponsorship.
Format Definition:
Description:
This parameter MAY be specified on the SPONSOR property, and provides a way to assign a level of sponsorship with 1 being the highest level. .

4.3. Title

This parameter is defined by the following notation: 

  titleparam     = "TITLE" "=" text
Parameter name:
TITLE
Purpose:
To provide a human readable title.
Format Definition:
Description:
This parameter MAY be specified on all properties defined in this specification, and provides a human readable label, perhaps for icons or links..

5. New Properties

5.1. Structured-Contact

This property is defined by the following notation: 

  extcontact      = "STRUCTURED-CONTACT" extcontactparam (":" uri)  /
                    (
                      ";" "VALUE" "=" "TEXT"
                      ":" text
                    )
                    CRLF

  extcontactparam = *(

                  ; the following are OPTIONAL
                  ; but MUST NOT occur more than once

                  (";" fmttypeparam) /
                  (";" titleparam) /
                  (";" "TYPE" "=" ("PRIMARY" /   ; The default
                                   "BOOKING" /   ; Make reservations 
                                                 ; and/or pay
                                   "EMERGENCY" /
                                   "PUBLICITY" / 
                                   "PLANNER" /
                                   text)) /

                  ; the following is OPTIONAL
                  ; and MAY occur more than once

                  (";" other-param)

                  )

The following is an example of this property. It points to a VCARD providing information on the contact. 

                 STRUCTURED-CONTACT;FMTTYPE=text/vcard;
                   TITLE=A contact:
                   http://dir.example.com/vcard/contacts/contact1.vcf

The following is an example of the property used to link to VCARD information on the event planner. 

                 STRUCTURED-CONTACT;FMTTYPE=text/vcard;
                   TYPE=PLANNER;TITLE=ClownsIsUs:
                   http://dir.example.com/vcard/clowns-is-us.vcf
Property name:
STRUCTURED-CONTACT
Purpose:
This property provides a typed reference to external information about a contact or optionally a plain text typed value.
Value type:
The default value type for this property is URI. The value type can also be set to TEXT to indicate plain text content.
Property Parameters:
Non-standard, title, type or format type parameters can be specified on this property.
Conformance:
This property MAY be specified in any iCalendar component.
Description:
When used in a component the value of this property points to structured contact information, for example, it may reference a VCARD giving detailed information. A summary of the vcard value for the primary contact could be used to populate the CONTACT property.
Format Definition:
Example:
Example:

5.2.

This property is defined by the following notation: 

  sponsor         = "SPONSOR" sponsorparam (":" uri)  /
                    (
                      ";" "VALUE" "=" "TEXT"
                      ":" text
                    )
                    CRLF

  sponsorparam    = *(

                  ; the following are OPTIONAL
                  ; but MUST NOT occur more than once

                  (";" fmttypeparam) /
                  (";" titleparam) /
                  (";" levelparam) /
                  (";" "TYPE" "=" ("CORPORATE" /   ; The default
                                   "CHARITABLE" /
                                   text)) /

                  ; the following is OPTIONAL
                  ; and MAY occur more than once

                  (";" other-param)

                  )

The following is an example of this property. It points to a VCARD providing information on the sponsor. 

                 SPONSOR;TITLE=A sponsor:
                   http://dir.example.com/vcard/sponsor1.vcf
Property name:
SPONSOR
Purpose:
This property provides a typed reference to external information about a sponsor or optionally a plain text typed value.
Value type:
The default value type for this property is URI. The value type can also be set to TEXT to indicate plain text content.
Property Parameters:
Non-standard, title, type, level or format type parameters can be specified on this property.
Conformance:
This property MAY be specified in any iCalendar component.
Description:
When used in a component the value of this property points to information about an event sponsor. The level parameter allows for the flagging of various levels of sponsorship.
Format Definition:
Example:

5.3. Participant

This property is defined by the following notation: 

  participant     = "PARTICIPANT" partparam (":" uri)  /
                    (
                      ";" "VALUE" "=" "TEXT"
                      ":" text
                    )
                    CRLF

  partparam      = *(

                  ; the following are OPTIONAL
                  ; but MUST NOT occur more than once

                  (";" fmttypeparam) /
                  (";" titleparam) /
                  (";" "TYPE" "=" ("ACTIVE" /      ; The default
                                   "INACTIVE" /    ; e.g. the audience
                                   "PRINCIPAL_PERFORMER" /
                                       ; A principal performer
                                   "PERFORMER" /  
                                       ; Performer at an event
                                   text)) /

                  ; the following is OPTIONAL
                  ; and MAY occur more than once

                  (";" other-param)

                  )

The following is an example of this property. It points to a VCARD providing information on an event participant. 

                 PARTICIPANT;TYPE=PRINCIPAL_PERFORMER:
                   http://dir.example.com/vcard/aviolinist.vcf
Property name:
PARTICIPANT
Purpose:
This property provides a typed reference to external information about participants in an event or optionally a plain text typed value.
Value type:
The default value type for this property is URI. The value type can also be set to TEXT to indicate plain text content.
Property Parameters:
Non-standard, title, type or format type parameters can be specified on this property.
Conformance:
This property MAY be specified in any iCalendar component.
Description:
When used in a component the value of this property points to information about an event participant. This is NOT an attendee in a scheduling sense and the ATTENDEE property may in fact be specified in addition. Participants in events can be individuals or organizations, for example a soccer team, the spectators, or the musicians.
Format Definition:
Example:

5.4. Structured-Location

This property is defined by the following notation: 

  extloc         = "STRUCTURED-LOCATION" extlocparam (":" uri)  /
                    (
                      ";" "VALUE" "=" "TEXT"
                      ":" text
                    )
                    CRLF

  extlocparam    = *(

                  ; the following are OPTIONAL
                  ; but MUST NOT occur more than once

                  (";" fmttypeparam) /
                  (";" titleparam) /
                  (";" "TYPE" "=" ("VENUE" /      ; The default
                                   "PARKING" /
                                   "DINING" /     ; restaurant
                                   "LODGING" /    ; hotels
                                   "TRANSPORT" /  
                                     ; shuttles, stations
                                   "VIRTUAL" / 
                                     ; A Virtual World Space
                                   text)) /

                  ; the following is OPTIONAL
                  ; and MAY occur more than once

                  (";" other-param)

                  )

The following is an example of this property. It points to a venue. 

                 STRUCTURED-LOCATION;TITLE="The venue":
                   http://dir.example.com/venues/big-hall.vcf
Property name:
STRUCTURED-LOCATION
Purpose:
This property provides a typed reference to external information about the location of an event or optionally a plain text typed value.
Value type:
The default value type for this property is URI. The value type can also be set to TEXT to indicate plain text content.
Property Parameters:
Non-standard, title, type or format type parameters can be specified on this property.
Conformance:
This property MAY be specified zero or more times in any iCalendar component.
Description:
When used in a component the value of this property provides information about the event venue or of related services such as parking, dining, stations etc..
Format Definition:
Example:

6. Extended examples

The following are some examples of the use of the properties defined in this specification. They include additional properties defined in [I-D.daboo-icalendar-extensions] which includes IMAGE and LIVEFEED.

6.1. Example 1

The following is an example of a VEVENT describing a concert. It includes location information for the venue itself as well as references to parking and restaurants. There is also an available live feed which allows clients to prompt the user as the time for the concert approaches. 

BEGIN:VEVENT
CREATED:20101116T145739Z
DESCRIPTION: Piano Sonata No 3\n
 Piano Sonata No 30
DTSTAMP:20101116T145739Z
DTSTART;TZID=America/New_York:20110315T150000Z
DTEND;TZID=America/New_York:20110315T163000Z
LAST-MODIFIED:20101116T145739Z
SUMMARY:Beethoven Piano Sonatas
UID:123456
STRUCTURED-LOCATION;TITLE="The venue":
 http://dir.example.com/venues/big-hall.vcf
SPONSOR:http://example.com/sponsor.vcf 
LIVEFEED:http://www.examplebroadcasting.net/big-hall.pls
PARTICIPANT;TYPE=PRINCIPAL_PERFORMER:
 http://www.example.com/people/johndoe.vcf
END:VEVENT

7. Security Considerations

Applications using these property need to be aware of the risks entailed in using the URIs provided as values. See [RFC3986] for a discussion of the security considerations relating to URIs.

8. IANA Considerations

8.1. Property Registrations

This document defines the following new iCalendar properties to be added to the registry defined in Section 8.2.3 of [RFC5545]:

Property Status Reference
STRUCTURED-CONTACT Current RFCXXXX, Section 5.1
SPONSOR Current RFCXXXX, Section 5.2
PARTICIPANT Current RFCXXXX, Section 5.3
STRUCTURED-LOCATION Current RFCXXXX, Section 5.4

8.2. Parameter Registrations

This document defines the following new iCalendar property parameters to be added to the registry defined in Section 8.2.4 of [RFC5545]:

Property Parameter Status Reference
LEVEL Current RFCXXXX, Section 4.2
TYPE Current RFCXXXX, Section 4.1
TITLE Current RFCXXXX, Section 4.3

9. Acknowledgements

The author would like to thank Chuck Norris of eventful.com for his work which led to the development of this RFC.

The author would also like to thank the members of the Calendaring and Scheduling Consortium public events technical committee and the following individuals for contributing their ideas and support:

Cyrus Daboo, Dan Mendell

The authors would also like to thank the Calendaring and Scheduling Consortium for advice with this specification.

10. References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5545] Desruisseaux, B., "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", RFC 5545, September 2009.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005.
[W3C.REC-xml-20060816] Bray, T., Paoli, J., Sperberg-McQueen, C., Yergeau, F. and E. Maler, "Extensible Markup Language (XML) 1.0 (Fourth Edition)", World Wide Web Consortium FirstEdition REC-xml-20060816, August 2006.
[I-D.daboo-icalendar-extensions] Daboo, C, "New Properties for iCalendar", Internet-Draft draft-daboo-icalendar-extensions-04, April 2011.

Appendix A. Change log

v00 2007-10-19 MD Initial version

2011-01-07

  • Remove MEDIA - it's going in the Cyrus RFC
  • Rename EXTENDED-... to STRUCTURED-...
  • Add TYPE parameter to SPONSOR

Author's Address

Michael Douglass Rensselaer Polytechnic Institute 110 8th Street Troy, NY 12180 USA EMail: douglm@rpi.edu URI: http://www.rpi.edu/