Service Discovery Extensions (XEP-0128) [1] defines a way for an XMPP entity to include extended information in its responses to Service Discovery (XEP-0030) [2] information requests. This document specifies a usage of XEP-0128 whereby an XMPP entity can provide detailed data about itself in such responses. This protocol is intended to replace Software Version (XEP-0092) [3] for software information discovery (thus reducing or eliminating the need for distinct software version requests) and also provides a format that can be encapsulated into Entity Capabilities (XEP-0115) [4] notifications.
To illustrate this usage, consider the following example of a disco#info request-response interaction that includes detailed client information:
<iq from='romeo@montaguue.lit/orchard'
to='juliet@capulet.lit/chamber'
id='disco1'
type='get'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
Upon receiving the disco#info request, the software replies and includes extended information in a data form (Data Forms (XEP-0004) [5]), where the icon is communicated using the format defined in Data Forms Media Element (XEP-0221) [6].
<iq from='juliet@capulet.lit/chamber'
to='romeo@montague.lit/orchard'
id='disco1'
type='result'>
<query xmlns='http://jabber.org/protocol/disco#info'>
<identity category='client' name='Exodus' type='pc'/>
<feature var='http://jabber.org/protocol/disco'/>
<x xmlns='jabber:x:data' type='result'>
<field var='FORM_TYPE' type='hidden'>
<value>urn:xmpp:dataforms:softwareinfo</value>
</field>
<field var='icon'>
<media xmlns='urn:xmpp:media-element'
height='80'
width='290'>
<uri type='image/jpeg'>
http://www.shakespeare.lit/clients/exodus.jpg
</uri>
<uri type='image/jpeg'>
cid:sha1+f24030b8d91d233bac14777be5ab531ca3b9f102@bob.xmpp.org
</uri>
</media>
</field>
<field var='os'>
<value>Windows</value>
</field>
<field var='os_version'>
<value>XP</value>
</field>
<field var='software'>
<value>Exodus</value>
</field>
<field var='software_version'>
<value>0.9.1</value>
</field>
</x>
</query>
</iq>
The fields have the following meaning:
Service discovery information is typically world-readable. Therefore, care should be taken in exposing information that may make it easier for a potential attacker to target the publishing entity's system (e.g., the operating system on which the software is running).
This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [7].
The XMPP Registrar [8] shall include the following information in its registries.
Field Standardization for Data Forms (XEP-0068) [9] defines a process for standardizing the fields used within Data Forms qualified by a particular namespace, and XEP-0128 describes how to use field standardization in the context of service discovery. This section registers fields for software information scoped by the "urn:xmpp:dataforms:softwareinfo" FORM_TYPE.
<form_type>
<name>urn:xmpp:dataforms:softwareinfo</name>
<doc>XEP-0232</doc>
<desc>
Forms enabling the communication of detailed information
about an XMPP client.
</desc>
<field
var='icon'
type='text-single'
label='A URL for an icon representing the software, no matter the
presence or availability status of the XMPP entity'/>
<field
var='os'
type='text-single'
label='The operating system on which the XMPP software is running'/>
<field
var='os_version'
type='text-single'
label='The operating system version'/>
<field
var='software'
type='text-single'
label='The XMPP software running at the entity'/>
<field
var='software_version'
type='text-single'
label='The XMPP software version'/>
</form_type>
Thanks to Dave Cridland, Olivier Goffart, Joe Hildebrand, Etan Reisner, Remko Tronçon, and Jiří Zárevúcký for their comments.
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Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list.
Errata can be sent to <editor@xmpp.org>.
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".
1. XEP-0128: Service Discovery Extensions <https://xmpp.org/extensions/xep-0128.html>.
2. XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>.
3. XEP-0092: Software Version <https://xmpp.org/extensions/xep-0092.html>.
4. XEP-0115: Entity Capabilities <https://xmpp.org/extensions/xep-0115.html>.
5. XEP-0004: Data Forms <https://xmpp.org/extensions/xep-0004.html>.
6. XEP-0221: Data Forms Media Element <https://xmpp.org/extensions/xep-0221.html>.
7. 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/>.
8. 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 XMPP Standards Foundation. For further information, see <https://xmpp.org/registrar/>.
9. XEP-0068: Field Data Standardization for Data Forms <https://xmpp.org/extensions/xep-0068.html>.
Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/
Per Last Call feedback, removed icons for presence states; redefined the icon field to use media element per XEP-0221.
Added icon fields.
Initial published version.
Added software field; generalized to be software information, not client information.
Clarified relationship to Software Version (XEP-0092).
First draft.
END