XEP-xxxx: Stanza Timestamps

Florian Schmaus
© 1999 – 2020 XMPP Standards Foundation. SEE LEGAL NOTICES.


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.
Standards Track
0.0.1 (2019-04-19)
Document Lifecycle
  1. Experimental
  2. Proposed
  3. Draft
  4. Final

1. Introduction

Entities receiving a Delayed Delivery (XEP-0203) [1] marked are unable to determine if the delay is missing because the stanza was not delayed or because the service does not add delay. This is due a missing service disco possiblity for 203 with the according semantics.

Furthermore xep203 appears to be designed to avoid an timestamp in case there is no delay. However this can be considered a premature and unnecessary optimization which causes confusion (see for example https://medium.com/miquido/successful-migration-to-a-custom-xmpp-solution-76fcdecb0928).

2. Stanza Timestamps

Extension element is added by entities. The 'stamp' attributes contians the timestamp when the entity received the stanza. A missing 'by' attribute determines the timestamp when the orignating entity send the message.

Example 1. A message stanza with a stanza timestamp.
<message xmlns='jabber:client'
  <body>Typical body text</body>
  <time-stamp xmlns='urn:xmpp:stanza-timestamps:0'
  <time-stamp xmlns='urn:xmpp:stanza-timestamps:0'

3. Business Rules

  1. Stanza timestamp generating entities, which encounter a <time-stamp/> element where the 'by' attribute matches the 'by' attribute they would otherwise set, MUST ovverride that element.
  2. Entities, which are routing stanzas, SHOULD NOT strip any elements qualified by the 'urn:xmpp:stanza-timestamps:0' namespace from stanzas unless.
  3. Stanzas MUST possess, in the direct child level of the stanza, at most one <time-stamp/> extension element with the same XMPP address as value of the 'by' attribute.
  4. The value of the 'by' attribute MUST be the XMPP address of the entity adding the timestap of the element. Note that XMPP addresses are normalized as defined in RFC 6122 [2]. TODO update RFC reference.

4. Discovering Support

An entity that follows the buisness rules and adds timestamps to its stanzas SHOULD announce the 'urn:xmpp:stanza-timestamps:0' namespace in its disco features.

Example 2. Client sends service discovery request to the room
<iq from='romeo@montague.tld/garden'
  <query xmlns='http://jabber.org/protocol/disco#info' />
Example 3. Servers include the stanza timestamps namespace in its features
<iq from='room@muc.example.com'
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:xmpp:stanza-timestamps:0'/>

5. Security Considerations

Avoid address leaks of originating entities. Entites should verify the timestap by checking if the entity whose address is found in the 'by' attribute announces the according XEP-0030 feature.

6. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [3].

7. XMPP Registrar Considerations

7.1 Protocol Namespaces

This specification defines the following XML namespaces:

The XMPP Registrar [4] shall include the foregoing namespaces in its registry of protocol namespaces (see <https://xmpp.org/registrar/namespaces.html>) and in its disco features registry (<https://xmpp.org/registrar/disco-features.html>) as defined in Service Discovery (XEP-0030) [5].

  <desc>Indicates that an entity adds stanza-ids and follows the business rules described in the XEP</desc>

8. XML Schema

REQUIRED for protocol specifications.

9. Acknowledgements

Thanks to Kim Alvefur.


Appendix A: Document Information

XMPP Standards Foundation
Standards Track
Last Updated
Approving Body
XMPP Council
Superseded By
Short Name

This document in other formats: XML  PDF

Appendix B: Author Information

Florian Schmaus


This XMPP Extension Protocol is copyright © 1999 – 2020 by the XMPP Standards Foundation (XSF).


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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 <https://xmpp.org/extensions/xep-0203.html>.

2. RFC 6122: Extensible Messaging and Presence Protocol (XMPP): Address Format <http://tools.ietf.org/html/rfc6122>.

3. 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/>.

4. 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 <https://xmpp.org/registrar/>.

5. XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>.

Appendix H: Revision History

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

  1. Version 0.0.1 (2019-04-19)

    First draft.