XEP-0199: XMPP Ping

This document defines an XMPP protocol extension for sending pings over XML streams.

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: 0199
Publisher: XMPP Standards Foundation
Status: Experimental
Type: Standards Track
Version: 0.2
Last Updated: 2006-11-22
Approving Body: XMPP Council
Dependencies: XMPP Core
Supersedes: None
Superseded By: None
Short Name: ping
Wiki Page: <http://wiki.jabber.org/index.php/XMPP Ping (XEP-0199)>

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

As specified in RFC 3920 [1], 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 also be used with other bindings such as the HTTP Binding [2].

2. Requirements

This document 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).

3. Protocol

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). [3]

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.

4. Use Cases

<iq from='capulet.com' to='juliet@capulet.com/balcony' id='ping123' type='get'>
  <ping xmlns='urn:xmpp:ping'/>
</iq>
    

<iq from='juliet@capulet.com/balcony' to='capulet.com' id='ping123' type='result'/>
    

<iq from='juliet@capulet.com/balcony' to='capulet.com' id='ping123' type='error'>
  <ping xmlns='urn:xmpp:ping'/>
  <error type='cancel'>
    <service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
  </error>
</iq>
    

<iq from='capulet.com' to='montague.net' id='ping234' type='get'>
  <ping xmlns='urn:xmpp:ping'/>
</iq>
    

<iq from='montague.net' to='capulet.com' id='ping234' type='result'/>
    

<iq from='montague.net' to='capulet.com' id='ping234' type='error'>
  <ping xmlns='urn:xmpp:ping'/>
  <error type='cancel'>
    <service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
  </error>
</iq>
    

<iq from='romeo@montague.net/home' 
    to='juliet@capulet.com/chamber'
    type='get' 
    id='ping345'>
  <ping xmlns='urn:xmpp:ping'/>
</iq>
    

<iq from='juliet@capulet.com/chamber'
    to='romeo@montague.net/home' 
    id='ping345'
    type='result'/>
    

<iq from='juliet@capulet.com/chamber'
    to='romeo@montague.net/home' 
    id='ping345'
    type='result'>
  <ping xmlns='urn:xmpp:ping'/>
  <error type='cancel'>
    <service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
  </error>
</iq>
    

<iq from='chat.shakespeare.lit'
    to='juliet@capulet.com/chamber'
    type='get' 
    id='ping456'>
  <ping xmlns='urn:xmpp:ping'/>
</iq>
    

<iq from='juliet@capulet.com/chamber'
    to='chat.shakespeare.lit'
    id='ping456'
    type='result'/>
    

<iq from='juliet@capulet.com/chamber'
    to='chat.shakespeare.lit'
    id='ping456'
    type='error'>
  <ping xmlns='urn:xmpp:ping'/>
  <error type='cancel'>
    <service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
  </error>
</iq>
    

5. Security Considerations

A pinged entity MAY ignore the IQ (i.e., return neither a result nor an error) if doing so would reveal its presence information to an entity that is not authorized to view that information; this mainly applies to client-to-client pings.

6. IANA Considerations

No interaction with the Internet Assigned Numbers Authority (IANA) [5] is necessary as a result of this document.

7. XMPP Registrar Considerations

8. XML Schema

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:ping'
    xmlns='urn:xmpp:ping'
    elementFormDefault='qualified'>

  <xs:element name='ping' type='empty'/>

  <xs:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>
  

Notes

Revision History

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