XEP-0184: Message Receipts

This document specifies an XMPP protocol extension for message receipts.

WARNING: This Standards-Track document is Experimental. Publication as an XMPP Extension Protocol does not imply approval of this proposal by the XMPP Standards Foundation. Implementation of the protocol described herein is encouraged in exploratory implementations, but production systems should not deploy implementations of this protocol until it advances to a status of Draft.

Document Information

Series: XEP
Number: 0184
Publisher: XMPP Standards Foundation
Status: Experimental
Type: Standards Track
Version: 0.3
Last Updated: 2006-11-06
Approving Body: XMPP Council
Dependencies: XMPP Core
Supersedes: XEP-0022 (in part)
Superseded By: None
Short Name: TO BE ASSIGNED
Wiki Page: <http://wiki.jabber.org/index.php/Message Receipts (XEP-0184)>

Author Information

Legal Notice

This XMPP Extension Protocol is copyright 1999 - 2007 by the XMPP Standards Foundation (XSF) and is in full conformance with the XSF's Intellectual Property Rights Policy <http://www.xmpp.org/extensions/ipr-policy.shtml>. This material may be distributed only subject to the terms and conditions set forth in the Creative Commons Attribution License (<http://creativecommons.org/licenses/by/2.5/>).

Discussion Venue

The preferred venue for discussion of this document is the Standards discussion list: <http://mail.jabber.org/mailman/listinfo/standards>.

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.

Conformance Terms

The following 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".

Table of Contents

1. Introduction

While Advanced Message Processing [1] provides message acknowledgements at the server level, it does not extend that model all the way to the client. However, sometimes client-level acknowledgements are needed, for example to provide "receipts". This document defines a mechanism for XMPP message receipts, which are functionally equivalent to the "delivered" or "displayed" event in Message Events [2], which this specification in part obsoletes. [3]

2. Requirements

This document addresses the following requirements:

1. Enable a sender to request notification that an XMPP message stanza has been received.
2. Enable a recipient to provide message receipts if desired.

Note: This document explicitly does not define a protocol for "guaranteed delivery", since that term (like "security") means different things to different people. Instead, we define a more focused protocol that addresses the need for message receipts, thus solving one problem that falls under the heading of "guaranteed delivery".

3. Protocol Format

In order to make it possible for senders to request and for recipients to generate message receipts, we define a new Advanced Message Processing rule: "receipt". In accordance with XEP-0079, we provide the following information about the receipt rule:

• The namespace shall be "http://jabber.org/protocol/amp?condition=receipt".
• The condition applies only to final receipt by the intended recipient; therefore, the per-hop flag does not apply.
• The only defined value of the receipt rule is "received".
• This condition is met if a message processing application (client) controlled by the intended recipient has received and processed the message; the term "processed" is understood to include presentation to a human user if appropriate or any other application-specific client-side processing, including generation of an error response if the application determines that the message contents cannot be handled.
• Although any defined action may be triggered, the only action needed in order to support message receipts is the "notify" action.

The following is an example of a message that includes a request for return receipt.

Example 1. A message with receipt requested

<message
    from='northumberland@shakespeare.lit/westminster'
    id='richard2-4.1.247'
    to='kingrichard@royalty.england.lit/throne'>
  <body>My lord, dispatch; read o'er these articles.</body>
  <amp xmlns='http://jabber.org/protocol/amp'>
    <rule condition='receipt' action='notify' value='received'/>
  </amp>
</message>
  

The recipient MUST generate a receipt if and only if it meets all of the following criteria:

1. It supports Advanced Message Processing.
2. It supports the "receipt" rule.
3. It is configured to return receipts, either globally or for this recipient.

Example 2. A message receipt

<message
    from='kingrichard@royalty.england.lit/throne'
    id='richard2-4.1.247'
    to='northumberland@shakespeare.lit/westminster'>
  <amp xmlns='http://jabber.org/protocol/amp' status='notify'>
    <rule condition='receipt' action='notify' value='received'/>
  </amp>
</message>
  

If the recipient does not meet all of the foregoing criteria, it MUST NOT return a receipt and MUST NOT return an error.

4. Business Rules

The general business rules specified for Advanced Message Processing in XEP-0079 apply to any rule; in addition, the following business rules apply specifically to the receipt rule:

1. A sender SHOULD NOT include a request for message receipts when sending a message to the bare JID (<node@domain.tld>) of the recipient, only when sending to a full JID (<node@domain.tld/resource>).

2. A sender SHOULD NOT include a request for message receipts unless it knows (via Service Discovery [4] or Entity Capabilities [5]) that the intended recipient supports the protocol described herein or unless the use of message receipts is negotiated via Stanza Session Negotiation [6].

Naturally, the receipt rule can be combined wiith rules specified in XEP-0079 (e.g., the deliver rule) for more complete reporting.

5. Service Discovery

If a sender wishes to request message receipts, it SHOULD first discover whether the intended recipient supports message receipts. Support can be discovered indirectly via Entity Capabilities or directly via Service Discovery.

If an entity supports Advanced Message Processing, it MUST report that by including a service discovery feature of "http://jabber.org/protocol/amp" as described in XEP-0079:

Example 3. Initial Service Discovery information request

<iq from='northumberland@shakespeare.lit/westminster'
    to='kingrichard@royalty.england.lit/throne'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
  

Example 4. Service Discovery information response

<iq from='kingrichard@royalty.england.lit/throne'
    to='northumberland@shakespeare.lit/westminster'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    ...
    <feature var='http://jabber.org/protocol/amp'/>
    ...
  </query>
</iq>
  

An entity that supports Advanced Message Processing SHOULD also maintain a service discovery node named "http://jabber.org/protocol/amp", at which it advertises the individual actions and conditions it supports. If an entity supports message receipts, it SHOULD respond to service discovery information requests sent to that node with a reply that includes the 'http://jabber.org/protocol/amp?condition=receipt' condition:

Example 5. Request for information about individual actions and conditions

<iq from='northumberland@shakespeare.lit/westminster'
    to='kingrichard@royalty.england.lit/throne'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'
         node='http://jabber.org/protocol/amp'/>
</iq>
  

Example 6. Response for individual actions and conditions

<iq from='kingrichard@royalty.england.lit/throne'
    to='northumberland@shakespeare.lit/westminster'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'
         node='http://jabber.org/protocol/amp'>
    ...
    <feature var='http://jabber.org/protocol/amp?condition=receipt'/>
    ...
  </query>
</iq>
  

6. Negotiation

Two entities MAY negotiate the use of message receipts for a given session using Chat Session Negotiation. The parameter to be negotiated is named "http://jabber.org/protocol/amp?condition=receipt". Its use is illustrated in the following examples.

Example 7. User requests chat session

<message type='normal'
         from='northumberland@shakespeare.lit/westminster'
         to='kingrichard@royalty.england.lit/throne'
         id='init1'>
  <thread>ffd7076498744578d10edabfe7f4a866</thread>
  <feature xmlns='http://jabber.org/protocol/feature-neg'>
    <x xmlns='jabber:x:data' type='form'>
      <field var='FORM_TYPE' type='hidden'>
        <value>http://jabber.org/protocol/chatneg</value>
      </field>
      <field label='Accept this chat?'
             type='boolean' 
             var='accept'>
        <value>true</value>
        <required/>
      </field>
      <field label='Enable Message Receipts?'
             type='boolean' 
             var='http://jabber.org/protocol/amp?condition=receipt'>
        <value>0</value>
      </field>
    </x>
  </feature>
</message>
    

Example 8. Contact accepts offer and specifies parameters

<message type='normal'
         from='kingrichard@royalty.england.lit/throne'
         to='northumberland@shakespeare.lit/westminster'
         id='init1'>
  <thread>ffd7076498744578d10edabfe7f4a866</thread>
  <feature xmlns='http://jabber.org/protocol/feature-neg'>
    <x xmlns='jabber:x:data' type='submit'>
      <field var='FORM_TYPE' type='hidden'>
        <value>http://jabber.org/protocol/chatneg</value>
      </field>
      <field var='accept'>
        <value>true</value>
      </field>
      <field var='http://jabber.org/protocol/amp?condition=receipt'>
        <value>1</value>
      </field>
    </x>
  </feature>
</message>
    

7. Implementation Notes

Although a sender MAY attempt to resend a message if it knows that the recipient supports message receipts and it does not receive a reply within some configurable timeout period, resend logic is out of scope for this specification.

8. Security Considerations

It is possible for a recipient to leak its presence when returning message receipts; therefore, a recipient SHOULD NOT return message receipts to senders who are not otherwise authorized to view its presence.

9. IANA Considerations

No interaction with the Internet Assigned Numbers Authority (IANA) [7] is necessary as a result of this document.

10. XMPP Registrar Considerations

<condition>
  <name>receipt</name>
  <ns>http://jabber.org/protocol/amp?condition=receipt</ns>
  <per-hop>false</per-hop>
  <value>received</value>
  <processing>
    The condition is met if a message processing application (client)
    controlled by the intended recipient has received and processed
    the message, including presentation to a human user if appropriate.
  </processing>
  <doc>XEP-0184</doc>
</condition>
    

<form_type>
  <name>http://jabber.org/protocol/chatneg</name>
  <field
      var='http://jabber.org/protocol/amp?condition=receipt'
      type='boolean'
      label='Whether to enable Message Receipts per XEP-0184'/>
</form_type>
      

11. Acknowledgements

Thanks to Joe Kemp and Kevin Smith for their input.

Notes

Revision History

END