Protocol-Specific Profiles for JSContact
draft-ietf-calext-jscontact-profiles-00

calext                                                       R. Stepanek
Internet-Draft                                                  Fastmail
Intended status: Standards Track                             M. Loffredo
Expires: 17 October 2025                                         IIT-CNR
                                                           15 April 2025

                Protocol-Specific Profiles for JSContact
                draft-ietf-calext-jscontact-profiles-00

Abstract

   This document defines JSContact profiles, a named subsets of
   JSContact elements that are supported in context of a contact data
   exchange protocol or other use case.  It aims to facilitate using
   JSContact in contexts where supporting all of JSContact semantics is
   not appropriate.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 17 October 2025.

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   document authors.  All rights reserved.

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Table of Contents

   1.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  JSContact Profiles  . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Profile Name  . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Profile Version . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Supported Properties  . . . . . . . . . . . . . . . . . .   4
     3.4.  "uid" Property  . . . . . . . . . . . . . . . . . . . . .   5
     3.5.  PatchObject Keys  . . . . . . . . . . . . . . . . . . . .   5
   4.  Example Profile . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
   Appendix A.  ABNF definition for JSContact Profile Name . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The ABNF definitions in this document use the notations of [RFC5234].
   ABNF rules not defined in this document are defined in either
   [RFC5234] (such as the ABNF for CRLF, WSP, DQUOTE, VCHAR, ALPHA, and
   DIGIT) or [RFC6350].

2.  Introduction

   The JSContact [RFC9553] contact card data model and format is
   designed for use in address book applications and directory services.
   Intended as an alternative to the prevalent vCard [RFC6350] data
   format, it covers vCard core semantics and extensions, and provides a
   rich model for personal names, postal addresses and localization.
   All JSContact elements are relevant for some contact card use case
   and, similar to vCard, implementations are expected to support these
   elements when exchanging contact card information using protocols
   such as CardDAV [RFC6352] and JMAP for Contacts [RFC9610].

   In contrast, other protocols and internet standards might require to
   exchange _some_ contact card information, but not need all of what
   JSContact provides.  Section 1.7.4 of [RFC9553] outlines how
   JSContact implementations may ignore unknown JSContact elements, but
   this only applies to future extensions of [RFC9553]; they are still

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   expected to implement all elements of the core specification.  Also,
   the extensibility of JSContact and the requirement to preserve
   arbitrary contact elements might not be adequate for some protocols.

   To make use of JSContact under these circumstances, this document
   defines a new IANA registry for JSContact that allows to register
   named subsets of JSContact elements.  These subsets are referred to
   as "JSContact profiles" and are meant to bring the following
   benefits:

   *  Protocol designers might be encouraged to use JSContact, rather
      than coming up with their own contacts format.  This facilitates
      cross-protocol data exchange and migration.

   *  Different protocols use the same IANA registry to express which
      JSContact elements they support.  This facilitates understanding
      their commonalities and reusing existing profiles.

   *  A central registry provides implementors of JSContact libraries
      with a consistent format documenting which profile supports what
      elements, rather than having to look up that information from
      possibly distinctly organized internet drafts.

   This document is organized as follows: Section 3 defines JSContact
   profiles, Section 4 illustrates JSContact profiles by example,
   Section 5 summarizes the relevant information for IANA to establish
   the JSContact Profiles registry.

3.  JSContact Profiles

   A JSContact profile is a named subset of JSContact properties.  The
   JSContact properties MUST be registered in the IANA JSContact
   registry.  A JSContact extension MAY define both a new profile and
   new properties, as long as they are registered at the same time.

   A JSContact object conforms to a profile if all its properties are in
   the subset of properties defined by that profile and its property
   values comply with the profile restrictions.

   A JSContact profile MUST be registered at IANA (see Section 5).

3.1.  Profile Name

   A JSContact profile MUST have a unique name.  The name MUST only
   contain ASCII lowercase alphabetic and numeric characters, optionally
   separated by a hyphen.  Formally, it MUST be a valid "profile-name"
   defined in the appendix section in Figure 1.

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3.2.  Profile Version

   A JSContact profile MUST define its current version.  That version
   identifier MUST be a valid "jsversion" value as defined in
   Section 1.9.1 of [RFC9553].  Any addition to the list of JSContact
   properties supported by that profile (Section 3.3) MUST update the
   current version.

   Should the semantic versioning scheme not be adequate for protocol
   designers making use of JSContact profiles, then an alternative
   approach is to register a new JSContact profile for each new version.

3.3.  Supported Properties

   The subset of JSContact object properties supported by a profile is
   defined by a list of object properties.  A JSContact property of an
   object type is part of this subset if one of the following conditions
   apply:

   1.  It explicitly is listed as supported for that object type in that
       profile.

   2.  It is defined for an object type which is the value type of an
       explicitly listed property and no properties are listed
       explicitly for this object type.

   3.  It is defined for the Card object and no properties are listed
       explicitly for the Card object type.

   A profile MUST explicitly list at least one property.

   If at least one property is listed explicitly for an object type,
   then all mandatory properties of that object type MUST be listed
   (this is to allow a profile restrict an object type to only its
   mandatory properties).

   The following properties need not be listed, they are always
   supported:

   *  The "@type" of any object type that is supported by this profile.

   *  The "version" property of the Card object.

   The "uid" property of the Card object is implicitly supported, unless
   it is explicitly not supported as outlined in Section 3.4.

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   For each supported property, a profile MAY define an optional
   property to be mandatory for that profile.  It also MAY restrict the
   value type signature of a multi-typed property e.g. only allow the
   value type "A" for a property having value type "A|B".

   In contrast, a profile MUST NOT define mandatory properties to be
   optional, except for the "uid" Card object property as outlined in
   Section 3.4.  It also MUST NOT fully replace or expand the value type
   signature of a property, or change the default type of a multi-typed
   property.

3.4.  "uid" Property

   The "uid" property [RFC9553] (Section 2.1.9) is defined to be
   mandatory for the Card object.  This is preferable for use in
   addressbooks and other contact management systems.  For example, it
   helps deduplicating contact data when merging addressbooks, and to
   use the same identifier to represent contact data in both JSContact
   and vCard Format [RFC6350].

   Yet, protocol designer might prefer to set protocol-specific
   identifiers that are incompatible with the "uid" property value
   definition in some other Card property, or not to set any identifier
   at all.  For this, a JSContact profile MAY define the Card "uid"
   property to either be optional or not supported at all for that
   profile.

3.5.  PatchObject Keys

   The JSContact PatchObject value type [RFC9553] (Section 1.4.3) allows
   to patch both top-level properties and nested properties in a Card
   object.  This results in a compact representation, as only the
   actually changed property values are included in the patch.  Notably,
   the "localizations" property [RFC9553] (Section 2.7.1) of the Card
   object uses PatchObject values to localize Card properties.

   Yet, protocol designers might prefer not to support patching nested
   properties, typically the goal being to simplify the processing of
   JSContact data.  For this, a JSContact profile MAY define nested
   PatchObject keys to not be supported.  Each JSON Pointer key in a
   PatchObject then MUST consist of exactly one JSON Pointer reference
   token [RFC6901] (Section 3).  In context of the "localizations"
   property, this means that a localized Card replaces one or more top-
   level properties entirely.

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4.  Example Profile

   This section provides an example for a JSContact profile.  This
   profile is just for illustration, it is not registered at IANA.

   Name:
      jscontact-simple

   Profile Version:
      1.0

   "uid" Property:
      Not Supported

   Nested PatchObject Keys:
      Not Supported

   Property Registry:
      +===============+===============+==========+============+=======+
      | Property Name | Property      |Restricted| Restricted |Since  |
      |               | Context       |to be     | Property   |Profile|
      |               |               |Mandatory | Type       |Version|
      +===============+===============+==========+============+=======+
      | addresses     | Card          |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | emails        | Card          |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | kind          | Card          |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | localizations | Card          |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | name          | Card          |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | full          | Address       |Mandatory |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | components    | Name          |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | full          | Name          |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | kind          | NameComponent |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+
      | value         | NameComponent |          |            |1.0    |
      +---------------+---------------+----------+------------+-------+

            Table 1: Properties of the "jscontact-simple" profile

   This profile describes contact cards that can only contain:

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   *  Full postal address lines, but no address components or any other
      property of the Address object type.

   *  Full names and distinct name components, but no other properties
      of the Name object type.

   *  Email addresses, where all properties of the EmailAddress object
      are supported.

   *  Localizations, with the restriction that PatchObject keys must not
      patch nested properties.

   In addition, the profile defines that the "uid" property of the Card
   object type must not be set.

   The following Card object conforms to that profile:

   {
     "@type": "Card",
     "version": "1.0",
     "name": {
        "components": [
         { "kind": "given", "value": "Akiyo" },
         { "kind": "surname", "value": "Murakami" }
       ]
     },
     "addresses": {
       "a1": {
         "full": "71 Cherry Court, Somewhere, 123SO, UK"
       }
     },
     "emails": {
       "e1": {
         "address": "akiyo@example.com"
       }
     },
     "localizations": {
       "jp": {
         "name": {
           "components": [
            { "kind": "surname", "value": "村上" },
            { "kind": "given", "value": "啓代" }
           ]
         }
       }
     }
   }

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5.  IANA Considerations

   TBD

6.  Security Considerations

   This document does not provide new security considerations.  The
   security considerations of Section 4 of [RFC9553] apply.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

   [RFC6350]  Perreault, S., "vCard Format Specification", RFC 6350,
              DOI 10.17487/RFC6350, August 2011,
              <https://www.rfc-editor.org/info/rfc6350>.

   [RFC6352]  Daboo, C., "CardDAV: vCard Extensions to Web Distributed
              Authoring and Versioning (WebDAV)", RFC 6352,
              DOI 10.17487/RFC6352, August 2011,
              <https://www.rfc-editor.org/info/rfc6352>.

   [RFC6901]  Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed.,
              "JavaScript Object Notation (JSON) Pointer", RFC 6901,
              DOI 10.17487/RFC6901, April 2013,
              <https://www.rfc-editor.org/info/rfc6901>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC9553]  Stepanek, R. and M. Loffredo, "JSContact: A JSON
              Representation of Contact Data", RFC 9553,
              DOI 10.17487/RFC9553, May 2024,
              <https://www.rfc-editor.org/info/rfc9553>.

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   [RFC9610]  Jenkins, N., Ed., "JSON Meta Application Protocol (JMAP)
              for Contacts", RFC 9610, DOI 10.17487/RFC9610, December
              2024, <https://www.rfc-editor.org/info/rfc9610>.

Appendix A.  ABNF definition for JSContact Profile Name

   profile-name = LALPHA *[ ["-"] LALPHA ]

   LALPHA       = %x61-7A | DIGIT  ; a-z or 0-9

               Figure 1: ABNF Rule for JSContact Profile Name

Authors' Addresses

   Robert Stepanek
   Fastmail
   PO Box 234
   Collins St. West
   Melbourne VIC 8007
   Australia
   Email: rsto@fastmailteam.com

   Mario Loffredo
   IIT-CNR
   Via Moruzzi, 1
   56124 Pisa
   Italy
   Email: mario.loffredo@iit.cnr.it

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