Network Working Group C. Daboo Internet-Draft Apple Inc. Updates: 5545 (if approved) January 31, 2013 Intended status: Standards Track Expires: August 4, 2013 New Properties for iCalendar draft-daboo-icalendar-extensions-06 Abstract This document defines a set of new properties for iCalendar data. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://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 August 4, 2013. Copyright Notice Copyright (c) 2013 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Daboo Expires August 4, 2013 [Page 1]
Internet-Draft iCalendar Property Extensions January 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 3. Backwards Compatible Extension Properties . . . . . . . . . . 3 4. Modifications to Calendar Components . . . . . . . . . . . . . 4 5. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1. NAME Property . . . . . . . . . . . . . . . . . . . . . . 5 5.2. DESCRIPTION Property . . . . . . . . . . . . . . . . . . . 6 5.3. UID Property . . . . . . . . . . . . . . . . . . . . . . . 6 5.4. URL Property . . . . . . . . . . . . . . . . . . . . . . . 7 5.5. TIMEZONE-ID Property . . . . . . . . . . . . . . . . . . . 7 5.6. REFRESH-INTERVAL Property . . . . . . . . . . . . . . . . 8 5.7. VALID Property . . . . . . . . . . . . . . . . . . . . . . 9 5.8. COLOR Property . . . . . . . . . . . . . . . . . . . . . . 10 5.9. IMAGE Property . . . . . . . . . . . . . . . . . . . . . . 11 6. Property Parameters . . . . . . . . . . . . . . . . . . . . . 13 6.1. ALTURI Property Parameter . . . . . . . . . . . . . . . . 13 6.2. DISPLAY Property Parameter . . . . . . . . . . . . . . . . 13 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8.1. Property Registrations . . . . . . . . . . . . . . . . . . 14 8.2. Parameter Registrations . . . . . . . . . . . . . . . . . 15 8.3. Display Types Registry . . . . . . . . . . . . . . . . . . 15 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 10.1. Normative References . . . . . . . . . . . . . . . . . . . 15 10.2. Informative References . . . . . . . . . . . . . . . . . . 16 Appendix A. Change History (To be removed by RFC Editor before publication) . . . . . . . . . . . . . . . . . 16 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 17 Daboo Expires August 4, 2013 [Page 2]
Internet-Draft iCalendar Property Extensions January 2013 1. Introduction The iCalendar [RFC5545] data format is used to represent calendar data and is used with iTIP [RFC5546] to handle scheduling operations between calendar users. iCalendar is in widespread use, and in accordance with provisions in that specification, extension elements have been added by various vendors to the data format in order to support and enhance capabilities. This specification collects a number of these ad-hoc extensions and uses the new IANA registry capability defined in [RFC5545] to register standard variants with clearly defined definitions and semantics. In addition, some new elements are introduced for features that vendors have recently been requesting. 2. 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]. The notation used in this memo is the ABNF notation of [RFC5234] as used by iCalendar [RFC5545]. Any syntax elements shown below that are not explicitly defined in this specification come from iCalendar [RFC5545]. 3. Backwards Compatible Extension Properties iCalendar defines properties which can have different value types indicated by a "VALUE" parameter. The definition of a property specifies a "default" value type that is assumed to be used when no "VALUE" parameter is present. However, this poses a problem to iCalendar parser/generator software that does not know about the default values for new properties. For example, if a new property "FOO" were defined with a default value type of URI, and a URI value with a comma was used, an iCalendar generator not aware of this fact would likely treat the property value as "TEXT" and apply backslash escaping to the comma in the value, effectively making it an invalid URI value. To avoid this problem, this specification recommends that all properties not defined in [RFC5545], always include a "VALUE" parameter, if the type is other than "TEXT". i.e., in the example above, the "FOO" property would have a "VALUE=URI" parameter. This allows iCalendar parser/generator software to track the correct types of unknown properties. Daboo Expires August 4, 2013 [Page 3]
Internet-Draft iCalendar Property Extensions January 2013 New properties defined in this specification use the term "no default" in the "Value Type" definition to indicate that the "VALUE" parameter has to be included. 4. Modifications to Calendar Components The following changes to the syntax defined in iCalendar [RFC5545] are made here. New elements are defined in subsequent sections. calprops /= *( ; ; The following are OPTIONAL, ; but MUST NOT occur more than once. ; uid / url / timezid / refresh / valid / color / ; ; The following are OPTIONAL, ; and MAY occur more than once. ; name / description / image ; ) eventprop /= *( ; ; The following are OPTIONAL, ; but MUST NOT occur more than once. ; color / ; ; The following are OPTIONAL, ; and MAY occur more than once. ; image ; ) todoprop /= *( ; ; The following are OPTIONAL, ; but MUST NOT occur more than once. ; color / ; ; The following are OPTIONAL, Daboo Expires August 4, 2013 [Page 4]
Internet-Draft iCalendar Property Extensions January 2013 ; and MAY occur more than once. ; image ; ) jourprop /= *( ; ; The following are OPTIONAL, ; but MUST NOT occur more than once. ; color / ; ; The following are OPTIONAL, ; and MAY occur more than once. ; image ; ) 5. Properties 5.1. NAME Property Property Name: NAME Purpose: This property specifies the name of the calendar. Value Type: TEXT Property Parameters: IANA, non-standard, alternate text representation, and language property parameters can be specified on this property. Conformance: This property can be specified multiple times in an iCalendar object. However, each property MUST represent the name of the calendar in a different language. Description: This property is used to specify a name (a short, one- line description) of the iCalendar object that can be used by calendar user agents when presenting the calendar data to a user. Whilst a calendar only has a single name, multiple language variants can be specified by including this property multiple times with different "LANGUAGE" parameter values on each. Daboo Expires August 4, 2013 [Page 5]
Internet-Draft iCalendar Property Extensions January 2013 Format Definition: This property is defined by the following notation: name = "NAME" nameparam ":" text CRLF nameparam = *( ; ; The following are OPTIONAL, ; but MUST NOT occur more than once. ; (";" altrepparam) / (";" languageparam) / ; ; The following is OPTIONAL, ; and MAY occur more than once. ; (";" other-param) ; ) Example: The following is an example of this property: NAME:Company Vacation Days 5.2. DESCRIPTION Property This specification modifies the definition of the "DESCRIPTION" property to allow it to be defined on an iCalendar object. The following additions are made to the definition of this property. Purpose: This property specifies the description of the calendar. Conformance: This property can be specified multiple times in an iCalendar object. However, each property MUST represent the description of the calendar in a different language. Description: This property is used to specify a lengthy textual description of the iCalendar object that can be used by calendar user agents when describing the nature of the calendar data to a user. Whilst a calendar only has a single description, multiple language variants can be specified by including this property multiple times with different "LANGUAGE" parameter values on each. 5.3. UID Property This specification modifies the definition of the "UID" property to allow it to be defined on an iCalendar object. The following additions are made to the definition of this property. Daboo Expires August 4, 2013 [Page 6]
Internet-Draft iCalendar Property Extensions January 2013 Purpose: This property specifies the persistent, globally unique identifier for the iCalendar object. Conformance: This property can be specified once in an iCalendar object. 5.4. URL Property This specification modifies the definition of the "URL" property to allow it to be defined on an iCalendar object. The following additions are made to the definition of this property. Purpose: This property specifies a URL from where the calendar data was retrieved or where it can be refreshed. Conformance: This property can be specified once in an iCalendar object. Description: This property specifies a URL identifying the source of the calendar data and a location from where updates can be retrieved. 5.5. TIMEZONE-ID Property Property Name: TIMEZONE-ID Purpose: This property specifies the default time zone identifier for the iCalendar object as a whole. Value Type: TEXT Property Parameters: IANA and non-standard property parameters can be specified on this property. Conformance: This property can be specified once in an iCalendar object. Description: This property specifies a time zone identifier that represents the default timezone for which floating time or all-day events in the iCalendar object can be assumed to be relative to. It can also be used to choose an initial time zone for use when creating new components in the iCalendar object. A "VTIMEZONE" component having a "TZID" property matching the value specified in this property MUST be present in the iCalendar object. Daboo Expires August 4, 2013 [Page 7]
Internet-Draft iCalendar Property Extensions January 2013 Format Definition: This property is defined by the following notation: timezid = "TIMEZONE-ID" timezidparam ":" text CRLF ;Same value syntax as "TZID" property. timezidparam = *(";" other-param) Example: The following is an example of this property: TIMEZONE-ID:America/New_York 5.6. REFRESH-INTERVAL Property Property Name: REFRESH-INTERVAL Purpose: This property specifies a suggested minimum interval for polling for changes of the calendar data from the original source of that data. Value Type: DURATION - no default Property Parameters: IANA and non-standard property parameters can be specified on this property. Conformance: This property can be specified once in an iCalendar object. Description: This property specifies a positive duration that gives a suggested minimum polling interval for checking for updates to the calendar data. The value of this property SHOULD be used by calendar user agents to limit the polling interval for calendar data updates to the minimum interval specified. Format Definition: This property is defined by the following notation: Daboo Expires August 4, 2013 [Page 8]
Internet-Draft iCalendar Property Extensions January 2013 refresh = "REFRESH-INTERVAL" refreshparam ":" dur-value CRLF ;consisting of a positive duration of time. refreshparam = *( ; ; The following is REQUIRED, ; but MUST NOT occur more than once. ; (";" "VALUE" "=" "DURATION") / ; ; The following is OPTIONAL, ; and MAY occur more than once. ; (";" other-param) ; ) Example: The following is an example of this property: REFRESH-INTERVAL;VALUE=DURATION:P1W 5.7. VALID Property Property Name: VALID Purpose: This property specifies when the calendar data is valid. Value Type: DATE-TIME or PERIOD Property Parameters: IANA and non-standard property parameters can be specified on this property. Conformance: This property can be specified once in an iCalendar object. Description: This property specifies a time period for which the calendar data can assumed to be valid. If a "PERIOD" value type is used, the validity is assumed to be a time range defined by the start and end of the period. If a "DATE-TIME" value is used, the date indicates when end date when the calendar data is no longer valid. Once the end date has been reached (or at some convenient time prior) clients SHOULD refresh the calendar data to determine whether an update is available, extending the range of validity. The value MUST be specified in UTC. Daboo Expires August 4, 2013 [Page 9]
Internet-Draft iCalendar Property Extensions January 2013 Format Definition: This property is defined by the following notation: valid = "VALID" validparam ":" validval CRLF validparam = *( ; ; The following is REQUIRED, ; but MUST NOT occur more than once. ; (";" "VALUE" "=" ("DATE-TIME" / "PERIOD")) / ; ; The following is OPTIONAL, ; and MAY occur more than once. ; (";" other-param) ; ) validval = date-time / period ;Value MUST match value type. Value MUST be in UTC. Example: The following is an example of this property: VALID;VALUE=DATE-TIME:20120609T000000Z VALID;VALUE=PERIOD:20120609T000000Z/P365D 5.8. COLOR Property Property Name: COLOR Purpose: This property specifies a color used for displaying the calendar, event, todo, or journal data. Value Type: TEXT. The value MUST be three COLON-separated INTEGER values. Property Parameters: IANA and non-standard property parameters can be specified on this property. Conformance: This property can be specified once in an iCalendar object, or "VEVENT", "VTODO", or "VJOURNAL" calendar components. Description: This property specifies a color that client MAY use when presenting the relevant data to a user. Typically this would appear as the "background" color of events or tasks. The value MUST be an RGB value with integer value components in the range 0..255. If a color is specified on a "VEVENT", "VTODO" or Daboo Expires August 4, 2013 [Page 10]
Internet-Draft iCalendar Property Extensions January 2013 "VJOURNAL" that SHOULD override any color specified on the enclosing iCalendar object. Format Definition: This property is defined by the following notation: color = "COLOR" colorparam ":" colorvalue CRLF colorparam = *(";" other-param) colorvalue = integer ":" integer ":" integer ; Red, green, and blue values in the range ; 0 - 255. Example: The following is an example of this property: COLOR:255:0:255 5.9. IMAGE Property Property Name: IMAGE Purpose: This property specifies an image associated with the calendar or a calendar component. Value Type: URI or BINARY - no default. The value MUST refer to or be data with a media type of "image". Property Parameters: IANA, non-standard, display, inline encoding, and value data type property parameters can be specified on this property. The format type parameter can be specified on this property and is RECOMMENDED for inline binary encoded content information. Conformance: This property can be specified multiple times in an iCalendar object, or "VEVENT", "VTODO", or "VJOURNAL" calendar components. Description: This property specifies an image for an iCalendar object or a calendar component via a uri or directly with inline data that can be used by calendar user agents when presenting the calendar data to a user. Multiple properties MAY be used to specify alternative sets of images with, for example, varying media subtypes, resolutions or sizes. When multiple properties are present, calendar user agents SHOULD display only one of them, picking one that provides the most appropriate image quality, or display none. The "DISPLAY" parameter is used to indicate the intended display mode for the image. An "ALTURI" parameter is Daboo Expires August 4, 2013 [Page 11]
Internet-Draft iCalendar Property Extensions January 2013 used to provide a "clickable" image where the URI in the parameter value can be "launched" by a click on the image in the calendar user agent. Format Definition: This property is defined by the following notation: image = "IMAGE" imageparam ( ":" uri ) / ( ";" "ENCODING" "=" "BASE64" ";" "VALUE" "=" "BINARY" ":" binary ) CRLF imageparam = *( ; ; The following is REQUIRED, ; but MUST NOT occur more than once. ; (";" "VALUE" "=" "URI") / ; ; The following is OPTIONAL for a URI value, ; RECOMMENDED for a BINARY value, ; and MUST NOT occur more than once. ; (";" fmttypeparam) / ; ; The following are OPTIONAL, ; and MUST NOT occur more than once. ; (";" alturiparam) / (";" displayparam) / ; ; The following is OPTIONAL, ; and MAY occur more than once. ; (";" other-param) ; ) Example: The following is an example of this property: IMAGE;VALUE=URI;DISPLAY=BACKGROUND;FMTTYPE=image/png:h ttp://example.com/images/party.png Daboo Expires August 4, 2013 [Page 12]
Internet-Draft iCalendar Property Extensions January 2013 6. Property Parameters 6.1. ALTURI Property Parameter Parameter Name: ALTURI Purpose: To specify a URI alternative to a property value. Format Definition: This property parameter is defined by the following notation: alturiparam = "ALTURI" "=" DQUOTE uri DQUOTE Description: This property parameter MAY be specified on "IMAGE" properties. Example: IMAGE;VALUE=URI;FMTTYPE=image/png:ALTURI="http://example.co m/clicked-image1":http://example.com/images/party.png 6.2. DISPLAY Property Parameter Parameter Name: DISPLAY Purpose: To specify different ways in which an image for a calendar or component can be displayed. Format Definition: This property parameter is defined by the following notation: displayparam = "DISPLAY" "=" ("BADGE" / ; A small "badge" image "BACKGROUND" / ; Use as a background image "OVERLAY" / ; Use as an overlay image "BANNER" / ; Use as a "banner" across the top x-name / ; Experimental type iana-token) ; Other IANA registered type ; ; Default is BADGE Description: This property parameter MAY be specified on "IMAGE" or "IMAGE" properties. In the absence of this parameter, the value "BADGE" MUST be used for the default behavior. The value determines how a client ought to present an image supplied in iCalendar data to the user. Daboo Expires August 4, 2013 [Page 13]
Internet-Draft iCalendar Property Extensions January 2013 Values for this parameter are registered with IANA as per Section 8.3. New values can be added to this registry following the procedure outlined in Section 8.2.1 of [RFC5545]. Servers and clients MUST handle x-name and iana-token values they don't recognize by not displaying any image at all. Example: IMAGE;VALUE=URI;DISPLAY=BANNER;FMTTYPE=image/png:http://exa mple.com/images/weather-cloudy.png 7. Security Considerations Several of the new properties or parameters defined by this specification allow reference to "external" URIs. Care MUST be taken when accessing data at external URIs as malicious content could be present. In addition, access to those URIs could be tracked, leading to loss of privacy. 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 | +------------------+---------+--------------------------------------+ | NAME | Current | RFCXXXX, Section 5.1 | | DESCRIPTION | Current | RFC5545 Section 3.8.1.5, RFCXXXX, | | | | Section 5.2 | | UID | Current | RFC5545 Section 3.8.4.7, RFCXXXX, | | | | Section 5.3 | | URL | Current | RFC5545 Section 3.8.4.6, RFCXXXX, | | | | Section 5.4 | | TIMEZONE-ID | Current | RFCXXXX, Section 5.5 | | REFRESH-INTERVAL | Current | RFCXXXX, Section 5.6 | | VALID | Current | RFCXXXX, Section 5.7 | | COLOR | Current | RFCXXXX, Section 5.8 | | IMAGE | Current | RFCXXXX, Section 5.9 | +------------------+---------+--------------------------------------+ Daboo Expires August 4, 2013 [Page 14]
Internet-Draft iCalendar Property Extensions January 2013 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 | +--------------------+---------+----------------------+ | ALTURI | Current | RFCXXXX, Section 6.1 | | DISPLAY | Current | RFCXXXX, Section 6.2 | +--------------------+---------+----------------------+ 8.3. Display Types Registry This document defines the following new iCalendar value registry as per Section 8.2.6 of [RFC5545]: +--------------+---------+----------------------+ | Display Type | Status | Reference | +--------------+---------+----------------------+ | BADGE | Current | RFCXXXX, Section 6.2 | | BACKGROUND | Current | RFCXXXX, Section 6.2 | | OVERLAY | Current | RFCXXXX, Section 6.2 | | BANNER | Current | RFCXXXX, Section 6.2 | +--------------+---------+----------------------+ 9. Acknowledgments Thanks to the following for feedback: Bernard Desruisseaux, Mike Douglass, Arnaud Quillaud, and Dave Thewlis. This specification came about via discussions at the Calendaring and Scheduling Consortium. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. [RFC5545] Desruisseaux, B., "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", RFC 5545, September 2009. Daboo Expires August 4, 2013 [Page 15]
Internet-Draft iCalendar Property Extensions January 2013 10.2. Informative References [RFC5546] Daboo, C., "iCalendar Transport-Independent Interoperability Protocol (iTIP)", RFC 5546, December 2009. Appendix A. Change History (To be removed by RFC Editor before publication) Changes in -06: 1. Removed BROADCAST/CONFERENCE properties and related parameters. Changes in -05: 1. Added section with recommendation on handling extension properties. 2. Added VALID property. Changes in -04: 1. TZID changed to new property TIMEZONE-ID. 2. Minor formal syntax changes. Changes in -03: 1. Dropped CALENDAR- prefix 2. DESCRIPTION, UID and TZID now based on existing RFC5545 properties 3. COLOR now on both the calendar and component level 4. IMAGE now on both the calendar and component level 5. Added FEATURE and REGION parameters to CONFERENCE property 6. Added ALTURI parameter to IMAGE property 7. Added FEED value to FEATURE parameter 8. Added BROADCAST property and clarified that CONFERENCE is for bi- direction channels and BROADCAST is for uni-directional. Changes in -02: Daboo Expires August 4, 2013 [Page 16]
Internet-Draft iCalendar Property Extensions January 2013 1. Minor wording changes. 2. Interval is now described as the "minimum interval". 3. Added CONFERENCE property and INFO parameter. Changes in -01: 1. Fixed DISPLAY parameter handling of x- and iana tokens to state that clients ignore the image if the token is not recognized. 2. Allow language variants for CALENDAR-NAME and CALENDAR- DESCRIPTION. 3. Added registry for DISPLAY values. Author's Address Cyrus Daboo Apple Inc. 1 Infinite Loop Cupertino, CA 95014 USA Email: cyrus@daboo.name URI: http://www.apple.com/ Daboo Expires August 4, 2013 [Page 17]