XEP-XXXX: Last Presence using Delayed Delivery

Abstract:This specification defines a way to determine the time when a XMPP entity has last changed its presence.
Author:Tobias Markmann
Copyright:© 1999 - 2013 XMPP Standards Foundation. SEE LEGAL NOTICES.
Status:ProtoXEP
Type:Informational
Version:0.0.1
Last Updated:2013-02-20

WARNING: This document has not yet been accepted for consideration or approved in any official manner by the XMPP Standards Foundation, and this document is not yet an XMPP Extension Protocol (XEP). If this document is accepted as a XEP by the XMPP Council, it will be published at <http://xmpp.org/extensions/> and announced on the <standards@xmpp.org> mailing list.


Table of Contents


1. Introduction
2. Use Cases
    2.1. Last Presence of a XMPP Entity
    2.2. Uptime Reporting of Servers and Components
3. Acknowledgements
4. Security Considerations
5. IANA Considerations
6. XMPP Registrar Considerations

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

This protocol describes a way to communicate time of last presence change with other XMPP entities over presence stanzas. This is done extending presence stanzas with delayed delivery information according to Delayed Delivery [1] and can be used to determine the time of last presence change for XMPP entities includeing servers. For users on the same server, the server also adds delyed delivery information to the presence responses.

The time of the delayed delivery information attatched to the presence indicates the time a XMPP entity has last changed to this presence.

2. Use Cases

2.1 Last Presence of a XMPP Entity

This section describes how to determine the time a user when offline or, in general, changed to her current presence state. This is merly a description since the protocol is already described in RFC 6121 [2], section 4.3.2.

The following example show a possible incoming presence in response to going online by sending your own available presence.

Example 1. Incoming Presence with Delayed Delivery

<presence from='romeo@montague.com/kitchen' to='juliet@capulet.com/balcony' type'unavailable'>
  <delay xmlns='urn:xmpp:delay' stamp='2002-09-10T23:41:07Z'/>
</presence>

2.2 Uptime Reporting of Servers and Components

Reqesting the uptime of a server or component is done by sending a directed presence probe to the XMPP entity of interest. The request is shown in the following example.

Example 2. Request for Uptime Reporting using Presence Probe

<presence from='juliet@capulet.com/balcony' to='montague.com' type='probe' />

The server or component then responds with an available presence, extended with delayed delivery information, according to Delayed Delivery [3], indicating its startup time. This is shown below:

Example 3. Response to the Presence Probe

<presence from='montague.com' to='juliet@capulet.com/balcony'>
  <delay xmlns='urn:xmpp:delay' stamp='2002-09-10T23:41:07Z'/>
</presence>

3. Acknowledgements

Thanks to Kim Alvefur and Lance Stout for their helpful comments.

4. Security Considerations

Adding delayed delivery notation to the presence probe responses exposes information a user might not expect to have exposed. However the information about last presence change is known to all entities subscribed to one's presence which are online. This extension just provides this information to XMPP entities which have been offline during the course of presence change.

It's worth to note that the security considerations of XMPP Date and Time Profiles [4] apply here.

5. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [5].

6. XMPP Registrar Considerations

This document requires no interaction with the XMPP Registrar [6].


Appendices


Appendix A: Document Information

Series: XEP
Number: XXXX
Publisher: XMPP Standards Foundation
Status: ProtoXEP
Type: Informational
Version: 0.0.1
Last Updated: 2013-02-20
Approving Body: XMPP Council
Dependencies: XMPP Core, XMPP IM, XEP-0203
Supersedes: None
Superseded By: None
Short Name: last-presence
This document in other formats: XML  PDF


Appendix B: Author Information

Tobias Markmann

Email: tmarkmann@googlemail.com
JabberID: tm@ayena.de


Appendix C: Legal Notices

Copyright

This XMPP Extension Protocol is copyright © 1999 - 2013 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/about-xmpp/xsf/xsf-ipr-policy/> 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 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 <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-0203: Delayed Delivery <http://xmpp.org/extensions/xep-0203.html>.

2. RFC 6121: Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence <http://tools.ietf.org/html/rfc6121>.

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

4. XEP-0082: XMPP Date and Time Profiles <http://xmpp.org/extensions/xep-0082.html>.

5. 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/>.

6. 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/>.


Appendix H: Revision History

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

Version 0.0.1 (2013-02-20)

Initial version.

(tobias)

END