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XMPP Ping This specification defines an XMPP protocol extension for sending application-level pings over XML streams. Such pings can be sent from a client to a server, from one server to another, or end-to-end. &LEGALNOTICE; 0199 Draft Standards Track Standards Council XMPP Core XEP-0030 ping http://www.xmpp.org/schemas/ping.xsd &stpeter; 1.0 2007-06-12 psa

Per a vote of the XMPP Council, advanced status to Draft; XMPP Registrar issued urn:xmpp:ping namespace.

 0.5 2007-05-30 psa

Clarified error handling and recommended against sending to bare JIDs.

 0.4 2007-05-21 psa

Modified security considerations to ensure coherence of error handling between client and server.

 0.3 2007-05-07 psa

Added use case for client pinging server; changed namespace to conform to XMPP Registrar requirements, with namespace to be issued upon advancement to Draft; added section on discovering support.

 0.2 2006-11-22 psa

Changed IQ-set to IQ-get; clarified requirements; specified protocol description; added use cases.

 0.1 2006-11-21 psa

Initial version.

As specified in &rfc3920;, the XML streams used in XMPP are bound to TCP. Unfortunately, TCP connections can go down without the application (XMPP) layer knowing about it. The traditional approach to solving this issue has been to periodically send so-called "whitespace pings" over the XML stream. This document recommends a more XML-friendly approach, which can be used over more than one hop in the communication path (e.g., from one client to another) and can also be used with other bindings such as the &xep0124; method for which &xep0206; is the XMPP profile.

This specification addresses the following requirements:

  1. Determining the viability of an XML stream (i.e., its underlying binding) between a client and a server, or between two servers.
  2. Determining end-to-end connectivity between any two XMPP entities (e.g., two clients).

The number of "hops" for which the ping tests connectivity depends on how far the pinged entity is from the pinging entity, as shown in the following use cases. However, this specification does not provide per-hop information similar to that provided by the traceroute protocol (&rfc1393;); a future specification may define such functionality for XMPP.

The XMPP ping protocol is extremely simple:

  1. The pinging entity sends an IQ-get containing a <ping/> element qualified by the 'urn:xmpp:ping' namespace.
  2. The pinged entity returns either an IQ-result (if it supports the namespace) or an IQ-error (if it does not).

One popular usage is for a server to test the viability of the underlying stream connection by pinging a connected client. This is done by sending an &IQ; get over the stream from the server to the client.

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If the client supports the ping namespace, it MUST return an IQ-result, which functions as a "pong":

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If the client does not support the ping namespace, it MUST return a &unavailable; error:

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The other error conditions defined in RFC 3920 could also be returned if appropriate.

A client may also ping its server by sending an IQ-get over the stream between the two entities.

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Note: The client MAY include a 'to' address of the client's bare JID &LOCALBARE;, in this instance "juliet@capulet.lit" or MAY include no 'to' address (this signifies that the stanza shall be handled by the server on behalf of the connected user's bare JID, which in the case of &IQ; stanzas is equivalent to directing the IQ-get to the server itself).

If the server supports the ping namespace, it MUST return an IQ-result:

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If the server does not support the ping namespace, it MUST return a &unavailable; error:

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The other error conditions defined in RFC 3920 could also be returned if appropriate.

Pings can also be used to test a server-to-server connection. This is done by sending an IQ-get over the stream from one server to another.

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If the other party to the stream supports the ping namespace, it MUST return an IQ-result:

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If the other party to the stream does not support the ping namespace, it MUST return a &unavailable; error:

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The other error conditions defined in RFC 3920 could also be returned if appropriate.

Pings can also be used for client-to-client (i.e., end-to-end) pings.

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Note: The 'to' address should be a full JID &LOCALFULL;, since a ping sent to a bare JID &LOCALBARE; will be handled by the server on behalf of the client.

If the pinged entity supports the ping namespace, it SHOULD return an IQ-result:

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If the pinged entity does not support the ping namespace, it MUST return a &unavailable; error:

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The other error conditions defined in RFC 3920 could also be returned if appropriate.

Pings can also be used for component-to-client pings, for example from a &xep0045; component to a client.

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Note: The 'to' address should be a full JID &LOCALFULL;, since a ping sent to a bare JID &LOCALBARE; will be handled by the server on behalf of the client.

If the pinged entity supports the ping namespace, it SHOULD return an IQ-result:

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If the pinged entity does not support the ping namespace, RFC 3920 requires it to return a &unavailable; error:

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The other error conditions defined in RFC 3920 could also be returned if appropriate.

If an entity supports the XMPP Ping protocol, it MUST report that fact by including a service discovery feature of "urn:xmpp:ping" in response to a &xep0030; information request:

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If a server receives a ping request directed to a full JID &LOCALFULL; associated with a registered account but there is no connected resource matching the 'to' address, RFC 3920 requires it to reply with a &unavailable; error and set the 'from' address of the IQ-error to the full JID provided in the 'to' address of the ping request. If a connected resource receives a ping request but it does not want to reveal its network availability to the sender for any reason (e.g., because the sender is not authorized to know the connected resource's availability), then it too MUST reply with a &unavailable; error. This consistency between the server response and the client response helps to prevent presence leaks.

No interaction with &IANA; is necessary as a result of this document.

The ®ISTRAR; includes "urn:xmpp:ping" in its registry of protocol namespaces (see &NAMESPACES;).

 The protocol documented by this schema is defined in XEP-0199: http://www.xmpp.org/extensions/xep-0199.html ]]>