Implementations have been able to declare a pubsub#type attribute on PubSub nodes for about as long as Publish-Subscribe (XEP-0060) [1] has existed. This attribute doesn’t seem to be widely used in the community though, maybe due to the vagueness of its description, that has recently changed, or the lack of features associated with it.
This specification provides a way for implementations to allow filtering on this attribute when discovering items on a PubSub service.
Filtering is particularly useful for example combined with Microblogging Over XMPP (XEP-0277) [2] and comment nodes that are created on the same service. When listing content nodes of a service, one may want to filter out comment nodes.
A service implementing this specification MUST advertize through Service Discovery (XEP-0030) [3] a urn:xmpp:pubsub-filter:0 feature.
While requesting disco#items on a PubSub service, an entity might want to only get nodes of certain pubsub#type. To do so, it may add a filter child of namespace urn:xmpp:pubsub-filter:0 to the query element, containing a Data Forms (XEP-0004) [4] form with FORM_TYPE set to urn:xmpp:pubsub-filter:0 and an included-types or excluded-types list-multi type field containing the various types it wants to filter.
When included-types is specified, a PubSub service MUST return nodes of matching pubsub#type in its response.
When excluded-types is specified, a PubSub service MUST return every node but those of matching pubsub#types in its response.
Both included and excluded fields MAY contain an empty value to designate nodes with an empty pubsub#type.
<iq type='get'
from='rosa@com.int/desktop'
to='news.commons.social'
id='disco1'>
<query xmlns='http://jabber.org/protocol/disco#items>
<filter xmlns='urn:xmpp:pubsub-filter:0'>
<x xmlns='jabber:x:data' type='submit'>
<field var='FORM_TYPE' type='hidden'>
<value>urn:xmpp:pubsub-filter:0</value>
</field>
<field type='list-multi' var='included-types'>
<value>urn:xmpp:microblog:0</value>
<value/>
</field>
</x>
</filter>
</query>
</iq>If both the included and excluded fields are specified, a service MUST return an error of type modify containing a bad-request element in the urn:ietf:params:xml:ns:xmpp-stanzas namespace.
<iq type='error'
from='news.com.int'
to='peter@commons.social/desktop'
id='error1'>
<error type='modify'>
<bad-request xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
</error>
</iq>None.
None.
<xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema'
xmlns:xdata='jabber:x:data'
targetNamespace='urn:xmpp:pubsub-filter:0'
xmlns='urn:xmpp:pubsub-filter:0'
elementFormDefault='qualified'>
<xs:annotation>
<xs:documentation>
The protocol documented by this schema is defined in
XEP-XXXX: http://xmpp.org/extensions/xep-xxxx.html
</xs:documentation>
</xs:annotation>
<xs:element name='filter'>
<xs:complexType>
<xs:choice xmlns:xdata='jabber:x:data'>
<xs:element ref='xdata:x'/>
</xs:choice>
</xs:complexType>
</xs:element>
</xs:schema>This document in other formats: XML PDF
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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.
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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-0060: Publish-Subscribe <https://xmpp.org/extensions/xep-0060.html>.
2. XEP-0277: Microblogging over XMPP <https://xmpp.org/extensions/xep-0277.html>.
3. XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>.
4. XEP-0004: Data Forms <https://xmpp.org/extensions/xep-0004.html>.
Note: Older versions of this specification might be available at https://xmpp.org/extensions/attic/
First draft.
@report{jaussoin2022xepxxxx,
title = {PubSub Type Filtering},
author = {Jaussoin, Timothée and Buquet, Maxime},
type = {XEP},
number = {xxxx},
version = {0.0.1},
institution = {XMPP Standards Foundation},
url = {https://xmpp.org/extensions/xep-xxxx.html},
date = {2022-02-01/2022-02-01},
}END