This document defines an XMPP protocol extension for sending pings over an XML stream.
WARNING: This Standards-Track document is Experimental. Publication as an XMPP Extension Protocol does not imply approval of this proposal by the Jabber Software 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.
Status:
Experimental
Type:
Standards Track
Number: 0199
Version: 0.1
Last Updated: 2006-11-21
Publishing Organization: Jabber Software Foundation
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Superseded By: None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)>
Email:
stpeter@jabber.org
JID:
stpeter@jabber.org
This XMPP Extension Protocol is copyright 1999 - 2006 by the Jabber Software Foundation (JSF) and is in full conformance with the JSF'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/>).
The preferred venue for discussion of this document is the Standards-JIG discussion list: <http://mail.jabber.org/mailman/listinfo/standards-jig>.
The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 3920) and XMPP IM (RFC 3921) specifications contributed by the Jabber Software 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 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".
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 and XMPP-friendly approach, which can also be used with other bindings such as HTTP Binding [2].
This document addresses the following requirements:
The typical usage for stream-level pings is for a server to test the viability of the underlying stream connection by pinging a connected client or server (however, a client may send pings as well). This is done by sending an <iq/> set over the stream, which SHOULD NOT include 'to' and 'from' addresses.
Example 1. Ping
<iq type='set' id='ping123'>
<ping xmlns='urn:xmpp:ping'/>
</iq>
If the other party to the stream supports the ping namespace, it MUST return an IQ result:
Example 2. Pong
<iq type='result' id='ping123'/>
If the other party to the stream does not support the ping namespace, it MUST return an IQ error, which SHOULD be <service-unavailable/>:
Example 3. Ping Not Supported
<iq type='error' id='ping123'>
<ping xmlns='urn:xmpp:ping'/>
<error type='cancel'>
<service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
</error>
</iq>
For end-to-end pings, the 'from' and 'to' addresses are necessary.
Example 4. Ping
<iq from='romeo@montague.net/home'
to='juliet@capulet.com/chamber'
type='set'
id='ping234'>
<ping xmlns='urn:xmpp:ping'/>
</iq>
</iq>
If the receiving entity supports the ping namespace, it SHOULD return an IQ result:
Example 5. Pong
<iq from='romeo@montague.net/home'
to='juliet@capulet.com/chamber'
type='result'
id='ping234'/>
If the receiving entity does not support the ping namespace, it SHOULD return an IQ error, which SHOULD be <service-unavailable/>:
Example 6. Ping Not Supported
<iq type='error' id='ping234'>
<ping xmlns='urn:xmpp:ping'/>
<error type='cancel'>
<service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
</error>
</iq>
However, the receiving entity MAY ignore the IQ (e.g., if doing so would reveal presence information to an entity that is not authorized to view that information).
This specification introduces no known security concerns above and beyond those specified in RFC 3920.
No interaction with the Internet Assigned Numbers Authority (IANA) [3] is necessary as a result of this document.
The XMPP Registrar [4] shall include 'urn:xmpp:ping' in its registry of protocol namespaces (see <http://www.xmpp.org/registrar/namespaces.html>).
<?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>
1. RFC 3920: Extensible Messaging and Presence Protocol (XMPP): Core <http://www.ietf.org/rfc/rfc3920.txt>.
2. XEP-0124: HTTP Binding <http://www.xmpp.org/extensions/xep-0124.html>.
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 Jabber Software Foundation. For further information, see <http://www.xmpp.org/registrar/>.
Initial version.
(psa)END