XEP-0224: Attention

Abstract:This document defines an XMPP protocol extension for getting the attention of another user.
Author:Andreas Monitzer
Copyright:© 1999 - 2010 XMPP Standards Foundation. SEE LEGAL NOTICES.
Status:Draft
Type:Standards Track
Version:1.0
Last Updated:2008-11-13

NOTICE: The protocol defined herein is a Draft Standard of the XMPP Standards Foundation. Implementations are encouraged and the protocol is appropriate for deployment in production systems, but some changes to the protocol are possible before it becomes a Final Standard.

Table of Contents


1. Introduction
2. Requirements
3. Protocol
4. Business Rules
5. Determining Support
6. Implementation Notes
7. Security Considerations
8. IANA Considerations
9. XMPP Registrar Considerations
    9.1. Protocol Namespaces
    9.2. Protocol Versioning
10. XML Schema
11. Acknowledgements

Appendices
    A: Document Information
    B: Author Information
    C: Legal Notices
    D: Relation to XMPP
    E: Discussion Venue
    F: Requirements Conformance
    G: Notes
    H: Revision History

1. Introduction

Even though a client might be available (as stated in the most recent presence stanza), the user this client belongs to might not be focused on the client currently. Presence Obtained via Kinesthetic Excitation (POKE) [1] defines a method for a physical test of user presence. Since this requires special hardware that cannot be assumed to be available, this XEP defines a software-only implementation where no direct feedback is expected. This feature is known as 'nudge' or 'buzz' in some non-XMPP IM protocols.

It was discussed whether this feature belongs in Chat State Notifications [2]. However, the semantics are inherently different, since Chat State Notifications describe the sender's state, not a request to change the receiver's. Thus, a separate extension is desirable.

2. Requirements

The specification addresses remotely getting the user's attention in a more assertive way than simple text messages.

3. Protocol

In the following conversation, a user talks to somebody, but this user doesn't respond. The second inquiry includes an attention extension.

Example 1. User sends a regular message

<message from='calvin@usrobots.lit/lab'
         to='herbie@usrobots.lit/home'
         type='chat'>
  <body>All right, then, Herbie, give! We're waiting.</body>
</message>

When no reply is received, the sending user might want to grab the other's attention. This is done by sending a message that includes an <attention/> element qualified by the 'urn:xmpp:attention:0' namespace (see Namespace Versioning regarding the possibility of incrementing the version number). Note: The message MAY include a <body/> element.

Example 2. User tries to capture the other's attention

<message from='calvin@usrobots.lit/lab'
         to='herbie@usrobots.lit/home'
         type='headline'>
  <attention xmlns='urn:xmpp:attention:0'/>
  <body>Why don't you answer, Herbie?</body>
</message>

Finally, the receiving user notices the urgency of the message and responds.

Example 3. The user whose attention has been captured responds.

<message from='herbie@usrobots.lit/home'
         to='calvin@usrobots.lit/lab'
         type='chat'>
  <body>I cannot. You know I cannot! Dr. Bogert and Dr. Lanning don't want me to.</body>
</message>

4. Business Rules

The following rules apply to generating and processing of the attention extension.

  1. Before sending an attention message stanza, the client SHOULD confirm support for it in the other client as described under Determining Support.
  2. The message stanza containing the attention extension MAY contain a body and/or other extensions, which is to be displayed along with executing the attention event.
  3. In message stanzas containing either Delayed Delivery [3] data, attention extensions MUST be ignored, since the attention request is an instant event which SHOULD NOT be replayed after a delay.
  4. Messages containing an attention extension SHOULD use the headline message type to avoid offline storage.
  5. The attention extension MUST NOT be sent in <iq/> stanzas, since use of this feature is part of a messaging conversation.

5. Determining Support

If an entity wishes to receive the attention extension, it MUST advertise that fact in its responses to Service Discovery [4] information ("disco#info") requests by returning a feature of "urn:xmpp:attention:0":

Example 4. A disco#info query

<iq type='get' 
    from='calvin@usrobots.lit/lab'
    to='herbie@usrobots.lit/home'
    id='disco1'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>

Example 5. A disco#info response

<iq type='result' 
    from='herbie@usrobots.lit/home'
    to='calvin@usrobots.lit/lab'
    id='disco1'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:xmpp:attention:0'/>
  </query>
</iq>

In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined in Entity Capabilities [5]. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.

6. Implementation Notes

The implementation of the alert is up to the developer. Possible behavior includes:

Because some users might not want this feature to disturb them, a client MUST either (1) allow the user to disable support or (2) disable the feature by default and process attention requests only if the user has explicitly enabled support. When the feature is disabled, it MUST NOT be advertised in disco#info.

Rate-limiting might be desirable in some implementations.

Formal feedback in response to the attention request to the requesting user is not specified, and so the request might be silently dropped.

7. Security Considerations

It is RECOMMENDED that a client accept message stanzas containing the attention extension only contacts that are in the user's roster or with whom the user's client is currently sharing directed presence, mainly to prevent the user from being annoyed by attention requests from random entities on the network. A client could implement finer-grained control if desired (e.g., allow attention requests only from entities in a particular roster group).

8. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [6].

9. XMPP Registrar Considerations

9.1 Protocol Namespaces

This specification defines the following XML namespace:

The XMPP Registrar [7] includes this namespace in the registry located at <http://xmpp.org/registrar/namespaces.html>, as described in Section 4 of XMPP Registrar Function [8].

9.2 Protocol Versioning

If the protocol defined in this specification undergoes a revision that is not fully backwards-compatible with an older version, the XMPP Registrar shall increment the protocol version number found at the end of the XML namespaces defined herein, as described in Section 4 of XEP-0053.

10. XML Schema

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

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:attention:0'
    xmlns='urn:xmpp:attention:0'
    elementFormDefault='qualified'>

  <xs:annotation>
    <xs:documentation>
      The protocol documented by this schema is defined in
      XEP-0224: http://www.xmpp.org/extensions/xep-0224.html
    </xs:documentation>
  </xs:annotation>

  <xs:element name='attention' type='empty'/>

  <xs:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>

11. Acknowledgements

The quotes have been taken from Isaac Asimov's short story "Liar!" as published in the book The Complete Robot.

Appendices

Appendix A: Document Information

Series: XEP
Number: 0224
Publisher: XMPP Standards Foundation
Status: Draft
Type: Standards Track
Version: 1.0
Last Updated: 2008-11-13
Approving Body: XMPP Council
Dependencies: XMPP Core, XMPP IM, XEP-0030
Supersedes: None
Superseded By: None
Short Name: attention
Schema: <http://xmpp.org/schemas/attention.xsd>
Source Control: HTML  RSS
This document in other formats: XML  PDF

Appendix B: Author Information

Andreas Monitzer

Email: andy@monitzer.com
JabberID: andy@monitzer.com

Appendix C: Legal Notices

Copyright

This XMPP Extension Protocol is copyright © 1999 - 2010 by the XMPP Standards Foundation (XSF).

Permissions

Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation.

Disclaimer of Warranty

## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ##

Limitation of Liability

In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.

IPR Conformance

This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <http://xmpp.org/extensions/ipr-policy.shtml> or obtained by writing to XMPP Standards Foundation, 1899 Wynkoop Street, Suite 600, Denver, CO 80202 USA).

Appendix D: Relation to XMPP

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 3920) and XMPP IM (RFC 3921) 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 <http://xmpp.org/about/discuss.shtml> 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

1. XEP-0132: Presence Obtained via Kinesthetic Excitation (POKE) <http://xmpp.org/extensions/xep-0132.html>.

2. XEP-0085: Chat State Notifications <http://xmpp.org/extensions/xep-0085.html>.

3. XEP-0203: Delayed Delivery <http://xmpp.org/extensions/xep-0203.html>.

4. XEP-0030: Service Discovery <http://xmpp.org/extensions/xep-0030.html>.

5. XEP-0115: Entity Capabilities <http://xmpp.org/extensions/xep-0115.html>.

6. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>.

7. The XMPP Registrar maintains a list of reserved protocol namespaces as well as registries of parameters used in the context of XMPP extension protocols approved by the XMPP Standards Foundation. For further information, see <http://xmpp.org/registrar/>.

8. XEP-0053: XMPP Registrar Function <http://xmpp.org/extensions/xep-0053.html>.

Appendix H: Revision History

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

Version 1.0 (2008-11-13)

Per a vote of the XMPP Council, advanced specification to Draft.

(psa)

Version 0.2 (2008-10-01)

Modified namespace to incorporate namespace versioning.

(psa)

Version 0.1 (2007-08-08)

Initial published version.

(psa)

Version 0.0.1 (2007-07-03)

Initial version.

(am)

END