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) (XEP-0132)  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 (XEP-0085) . 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.
The specification addresses remotely getting the user's attention in a more assertive way than simple text messages.
In the following conversation, a user talks to somebody, but this user doesn't respond. The second inquiry includes an attention extension.
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.
Finally, the receiving user notices the urgency of the message and responds.
The following rules apply to generating and processing of the attention extension.
If an entity wishes to receive the attention extension, it MUST advertise that fact in its responses to Service Discovery (XEP-0030)  information ("disco#info") requests by returning a feature of "urn:xmpp:attention:0":
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 (XEP-0115) . However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.
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.
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).
This document requires no interaction with the Internet Assigned Numbers Authority (IANA) .
This specification defines the following XML namespace:
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.
The quotes have been taken from Isaac Asimov's short story "Liar!" as published in the book The Complete Robot.
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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.
The primary venue for discussion of XMPP Extension Protocols is the <email@example.com> discussion list.
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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".
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/>.
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Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/
Per a vote of the XMPP Council, advanced specification to Draft.
Modified namespace to incorporate namespace versioning.
Initial published version.