XEP-0083: Nested Roster Groups

1. Introduction¶

In many modern instant messaging clients, client authors implement a way to nest contact groups within other contact groups. Usually this is implemented on the client side, since many instant messaging networks do not support nesting contact groups in this manner. The limitation of this system is that if the user changes from one client to another, or even a second installation of the same client, the user loses all of his or her sub-group information. This document aims to solve that problem within Jabber, by providing for a way to store sub-groups on the Jabber roster without breaking existing clients.

2. roster:delimiter Namespace¶

Jabber already provides a useful method for storing client data on the server using Private XML Storage (XEP-0049) [1]. All we need to do is create a new roster element and a namespace to store the delimiter for nested groups, roster:delimiter. This element MUST contain XML character data that defines a string to be used as a delimiter in the roster groups. [2]

A single-character roster delimiter (e.g., "/") would make client implementation easier, but be more limiting to the end-user in terms of choices for naming roster groups, so a string is ideal. Therefore, the delimiter SHOULD contain multiple characters in order to avoid inconveniencing the user, but single-character delimiters MUST be honored by the client. The exception is if the delimiter is a single alphanumeric character (a-z, A-Z, 0-9); in this case compliant clients MUST treat the situation as if nesting were disabled, to avoid malicious use of this element by setting 'e' or 'm' or some other common single character as a delimiter.

A compliant client SHOULD ask for the nested delimiter before requesting the user's roster, in order to know whether or not to parse the roster 'group' fields accordingly. If there is no delimiter stored, a client MAY set a delimiter but MUST either prompt the user for a delimiter, or use a user-configurable default.

3. Use Cases¶

Use cases for this extension are straightforward, and are shown below as examples.

CLIENT:
<iq type='get'
    id='1'>
  <query xmlns='jabber:iq:private'>
    <roster xmlns='roster:delimiter'/>
  </query>
</iq>

SERVER:
<iq type='result'
    id='1'
    from='bill@shakespeare.lit/Globe'
    to='bill@shakespeare.lit/Globe'>
  <query xmlns='jabber:iq:private'>
    <roster xmlns='roster:delimiter'>::</roster>
  </query>
</iq>

CLIENT:
<iq type='get'
    id='2'>
  <query xmlns='jabber:iq:roster'/>
</iq>

SERVER:
<iq type='result'
    to='bill@shakespeare.lit/Globe'
    id='2'>
  <query xmlns='jabber:iq:roster'>
    <item jid='bottom@athens.gr' subscription='both'>
      <group>Midsummer::Actors</group>
    </item>
    <item jid='quince@athens.gr' subscription='both'>
      <group>Midsummer::Actors</group>
    </item>
    <item jid='snug@athens.gr' subscription='both'>
      <group>Midsummer::Actors</group>
    </item>
    <item jid='theseus@athens.gr' subscription='both'>
      <group>Midsummer::Royalty</group>
    </item>
    <item jid='hippolyta@athens.gr' subscription='both'>
      <group>Midsummer::Royalty</group>
    </item>
    <item jid='robin@faeries.underhill.org' subscription='both'>
      <group>Midsummer</group>
    </item>
    <item jid='hamlet@denmark.net' subscription='both'>
      <group>Hamlet</group>
    </item>
    <item jid='gertrude@denmark.net' subscription='both'>
      <group>Hamlet</group>
    </item>
  </query>
</iq>

4. Security Considerations¶

There are no security features or concerns related to this proposal above and beyond those specified for roster management in XMPP IM [3] and for private XML storage in XEP-0049.

5. IANA Considerations¶

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [4].

6. XMPP Registrar Considerations¶

7. Schema¶

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='roster:delimiter'
    xmlns='roster:delimiter'>

  <xs:annotation>
    <xs:documentation>
      The protocol documented by this schema is defined in
      XEP-0083: http://www.xmpp.org/extensions/xep-0083.html
    </xs:documentation>
  </xs:annotation>

  <xs:element name='roster' type='xs:string'/>

</xs:schema>

Appendices

Appendix A: Document Information¶

Series

XEP

Number

0083

Publisher

XMPP Standards Foundation

Status

Active

Type

Informational

Version

1.0

Last Updated

2004-10-11

Approving Body

XMPP Council

Dependencies

XMPP Core, XMPP IM, XEP-0049

Supersedes

None

Superseded By

None

Short Name

nestedgroups

Schema

<http://www.xmpp.org/schemas/delimiter.xsd>

Source Control

HTML

This document in other formats: XML  PDF

Appendix B: Author Information¶

Rachel Blackman

Email

rcb@ceruleanstudios.com

JabberID

sparks@jabber.org

Appendix C: Legal Notices¶

Appendix D: Relation to XMPP¶

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.

Appendix E: Discussion Venue¶

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Discussion on other xmpp.org discussion lists might also be appropriate; see <https://xmpp.org/community/> for a complete list.

Errata can be sent to <editor@xmpp.org>.

Appendix F: Requirements Conformance¶

The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".

Appendix G: Notes¶

Appendix H: Revision History¶

Note: Older versions of this specification might be available at https://xmpp.org/extensions/attic/

1. Version 1.0 (2004-10-11)¶
   Per a vote of the Jabber Council, advanced to a status of Active.
   psa
2. Version 0.1 (2003-05-05)¶
   Initial version.
   rcb

Appendix I: Bib(La)TeX Entry

@report{blackman2003nestedgroups,
  title = {Nested Roster Groups},
  author = {Blackman, Rachel},
  type = {XEP},
  number = {0083},
  version = {1.0},
  institution = {XMPP Standards Foundation},
  url = {https://xmpp.org/extensions/xep-0083.html},
  date = {2003-05-05/2004-10-11},
}

END