XEP-0472: Pubsub Social Feed

Abstract
This specification defines a way of publishing social content over XMPP.
Author
Timothée Jaussoin
Copyright
© 2022 – 2023 XMPP Standards Foundation. SEE LEGAL NOTICES.
Status

Experimental

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 are advised to carefully consider whether it is appropriate to deploy implementations of this protocol before it advances to a status of Draft.
Supersedes
XEP-0277
Type
Standards Track
Version
0.2.0 (2023-04-03)
Document Lifecycle
  1. Experimental
  2. Proposed
  3. Stable
  4. Final

1. Introduction

Social Networking plaftorms are often built around the concept of feeds. XMPP offers, through Publish-Subscribe (XEP-0060) [1], a really generic way of Publishing and Subscribing elements on XMPP nodes. This extension defines a way to publish social content on Pubsub nodes using RFC 4287 [2]

Social features in XMPP were historically built on the Microblogging Over XMPP (XEP-0277) [3] specifications. However, in practice, Microblogging was not clearly defined in more common cases such as on generic Pubsub nodes and it was not easy to differentiate social nodes from the other ones. The current XEP defines a more generic way of handling Social Feeds on XMPP by declaring a secific pubsub#type for those Pubsub nodes and by keeping Microblogging Over XMPP (XEP-0277) [3] as a subset of it.

2. Glossary

Profile
Defined by a specific Pubsub type (pubsub#type) a profile is a Pubsub Social Feed with some constraints. See the Profiles section.

3. Discovery

If an entity implements Pubsub Social Feed, it MUST specify the 'urn:xmpp:pubsub-social-feed:1' feature in its service discovery information features as specified in Service Discovery (XEP-0030) [4] and the Entity Capabilities profile specified in Entity Capabilities (XEP-0115) [5].

If the entity is also implementing specific profiles, it MUST expose the specific feature defined in the related Pubsub type.

Example 1. The entity responds with specific features profiles
  <iq type='result'
      id='disco1'
      from='juliet@capulet.lit/sabo239'
      to='romeo@montegue.lit/30d3d8'>
    <query xmlns='http://jabber.org/protocol/disco#info'>
      ...
      <feature var='urn:xmpp:pubsub-social-feed:1'/>
      <feature var='urn:xmpp:pubsub-social-feed:gallery:1'/>
      ...
    </query>
  </iq>

4. Protocol

4.1 Location

A Pubsub Social Feed can be located on any Pubsub node on the XMPP network. Some specific use cases, such as the personal eventing (PEP) node Microblog is defined in the Profiles section.

4.2 Publishing a Post

The publication of a Post consist of a valid RFC 4287 [2] entry embeded in a Publish-Subscribe (XEP-0060) [1] item.

The post content itself can be either text (content element without "type" attribute or with "type" attribute with "text" value) or XHTML ("content" element "type" attribute with "xhtml" value). If Romeo publishes XHTML content, his client MUST publish two "content" elements: a text one, and a XHTML one. For XHTML publishing, see Publish-Subscribe (XEP-0060) [1].

Example 2. Publishing a post
<iq from='romeo@montague.lit/pda'
    id='pub1'
    to='new.montague.lit'
    type='set'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='montague-family'>
      <item id='1cb57d9c-1c46-11dd-838c-001143d5d5db'>
        <entry xmlns='http://www.w3.org/2005/Atom'>
          <title type='text'>hanging out at the Caf&amp;#233; Napolitano</title>
          <id>tag:montague.lit,2008-05-08:posts-1cb57d9c-1c46-11dd-838c-001143d5d5db</id>
          <published>2008-05-08T18:30:02Z</published>
          <updated>2008-05-08T18:30:02Z</updated>
        </entry>
      </item>
    </publish>
  </pubsub>
</iq>

Note: The "title" element is required to be included in an "atom:entry" element according to RFC 4287 [2]. An implementation MAY provide also "atom:summary" and/or "atom:content" elements too if it needs.

4.2.1 Publishing a Post with Rich Content

It's possible to insert some rich content in the post. It can be some text formatting, images, etc. Only "xhtml" content type is supported for the moment by this document but possibly it will be extended later.

Example 3. Publishing a post with rich content
<iq from='romeo@montague.lit/pda'
    id='pub2'
    to='news.montague.lit'
    type='set'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='montague-family'>
      <item id='1cb57d9c-1c46-11dd-838c-001143d5d5db'>
        <entry xmlns='http://www.w3.org/2005/Atom'>
          <title type='xhtml'>
            <div xmlns="http://www.w3.org/1999/xhtml">
              <p>hanging out at the <strong>Caf&amp;#233; Napolitano</strong></p>
            </div>
          </title>
          <id>tag:montague.lit,2008-05-08:posts-1cb57d9c-1c46-11dd-838c-001143d5d5db</id>
          <published>2008-05-08T18:30:02Z</published>
          <updated>2008-05-08T18:30:02Z</updated>
          <generator uri='https://capu.chat' version='42'>CapuChat</generator>
        </entry>
      </item>
    </publish>
  </pubsub>
</iq>

4.3 Receiving a Post

Because Juliet is subscribed to some Romeo's family Pubsub service nodes. Romeo's XMPP server will send a Pubsub notification to Juliet. The notification can include an XMPP message body for backwards-compatibility with Jabber clients that are not pubsub-capable (see Message Body ).

Example 4. Receiving a post
<message from='news.montague.lit'
         to='juliet@capulet.lit'
         type='headline'>
  <body>hanging out at the Caf&amp;#233; Napolitano</body>
  <event xmlns='http://jabber.org/protocol/pubsub#event'>
    <items node='montague-family'>
      <item id='1cb57d9c-1c46-11dd-838c-001143d5d5db' publisher='romeo@montague.lit'>
        <entry xmlns='http://www.w3.org/2005/Atom'>
          <title type='text'>hanging out at the Caf&amp;#233; Napolitano</title>
          <link rel='alternate'
                type='text/html'
                href='http://montague.lit/romeo/posts/1cb57d9c-1c46-11dd-838c-001143d5d5db'/>
          <link rel='alternate'
                href='xmpp:news.montague.lit?;node=montague-family;item=1cb57d9c-1c46-11dd-838c-001143d5d5db'/>
          <id>tag:montague.lit,2008-05-08:posts-1cb57d9c-1c46-11dd-838c-001143d5d5db</id>
          <published>2008-05-08T18:30:02Z</published>
          <updated>2008-05-08T18:30:02Z</updated>
          <generator uri='https://capu.chat' version='42'>CapuChat</generator>
        </entry>
      </item>
    </items>
  </event>
</message>

Note: these alternate links were not posted by the original client because some clients can't compute them themselves. These things SHOULD be inserted at server side though.

4.4 Replying to a Post

Anyone can publish a post in reply to Romeo's post. Here we assume that a reply comes from Benvolio.

Note: Inclusion of the "thr:in-reply-to" element defined in RFC 4685 [6] indicates the post to which the user is replying. This reply includes two such elements (one pointing to the HTTP URL for the post and the other pointing to the XMPP URI for the post.

Note: The post can be a reply to more than the only one another.

Example 5. Publishing a reply
<iq from='benvolio@montague.lit/mobile'
    id='uv2x37s5'
    to='news.montague.lit'
    type='set'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='montague-family'>
      <item id='c4145006-1c53-11dd-b2d5-000bcd82471e'>
        <entry xmlns='http://www.w3.org/2005/Atom'
               xmlns:thr='http://purl.org/syndication/thread/1.0'>
          <author>
            <name>Benvolio Montague</name>
            <uri>xmpp:romeo@montague.lit</uri>
          </author>
          <title type='text'>@romeo cappuccino this late in the day?</title>
          <link rel='alternate'
                type='text/html'
                href='http://montague.lit/benvolio/posts/c4145006-1c53-11dd-b2d5-000bcd82471e'/>
          <link rel='alternate'
                href='xmpp:news.montague.lit?;
                      node=montague-family;
                      item=c4145006-1c53-11dd-b2d5-000bcd82471e'/>
          <id>tag:montague.lit,2008-05-08:posts-c4145006-1c53-11dd-b2d5-000bcd82471e</id>
          <published>2008-05-08T18:31:21Z</published>
          <updated>2008-05-08T18:31:21Z</updated>
          <thr:in-reply-to
               ref='tag:montague.lit,2008-05-08:posts-1cb57d9c-1c46-11dd-838c-001143d5d5db'
               type='application/xhtml+xml'
               href='http://montague.lit/romeo/posts/1cb57d9c-1c46-11dd-838c-001143d5d5db'/>
          <thr:in-reply-to
               ref='tag:montague.lit,2008-05-08:posts-1cb57d9c-1c46-11dd-838c-001143d5d5db'
               href='xmpp:news.montague.lit?;node=montague-family;item=1cb57d9c-1c46-11dd-838c-001143d5d5db'/>
        </entry>
      </item>
    </publish>
  </pubsub>
</iq>

Assuming that Romeo has also subscribed to the same node he will receive the reply that Benvolio sent.

4.5 Repeating a Post

When Benvolio wants to repeat a Romeo's post, his client publishes the same post under a different name. But to be able to track the repeated post original author, Benvolio's client MAY use specific "atom:author" child node, "atom:name" and "atom:uri", containing, respectively, the name of the original post author, and his XMPP URI (JID).

The client SHOULD also put an "atom:link" element with "rel" attribute set to "via" and point it to the original post.

Example 6. Repeating a Post
<iq from='benvolio@montague.lit/mobile'
    id='pub2'
    to='news.montague.lit'
    type='set'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='montague-family'>
      <item id='1re57d3c-1q46-11dd-748r-024943d2d5rt'>
        <entry xmlns='http://www.w3.org/2005/Atom'>
          <author>
            <name>Romeo Montague</name>
            <uri>xmpp:romeo@montague.lit</uri>
          </author>
          <title type='text'>hanging out at the Caf&amp;#233; Napolitano</title>
          <link rel='alternate'
                type='text/html'
                href='http://montague.lit/benvolio/posts/1re57d3c-1q46-11dd-748r-024943d2d5rt'/>
          <link rel='alternate'
                href='xmpp:news.montague.lit?;node=montague-family;item=1re57d3c-1q46-11dd-748r-024943d2d5rt'/>
          <link rel='via'
                href='xmpp:rnews.montague.lit?;node=montague-family;item=1cb57d9c-1c46-11dd-838c-001143d5d5db'
                ref='tag:montague.lit,2008-05-08:posts-1cb57d9c-1c46-11dd-838c-001143d5d5db'/>
          <id>tag:montague.lit,2008-05-08:posts-1re57d3c-1q46-11dd-748r-024943d2d5rt</id>
          <published>2008-05-08T18:30:02Z</published>
          <updated>2008-05-08T18:32:02Z</updated>
        </entry>
      </item>
    </publish>
  </pubsub>
</iq>

Thus, a different author JID value lets the client know the item has been repeated from another one.

It's also possible for Benvolio to add his own thougths to the repost. To do this he SHOULD wrap the original content in the "xhtml:blockquote" element and after it add his own content. Also, the client MAY post reply without quotation to the original thread to inform users about the repost.

4.6 Atom and XMPP integration

4.6.1 Pubsub Item ID vs. Atom Entry id

There are two different things that carry a similar sense: the XMPP Pubsub Item ID and the "atom:id" element. This section is devoted to make a separation between them.

The pubsub Item ID MUST be used when linking to an entry with an XMPP channel (i.e. by including it in the URI with the "xmpp" schema). the Atom entry ID MUST be built according to RFC 4287 [2] and used in aggregators with the aim of revealing of post duplicates, reposts, mentions, syndications, etc.

Note that the rules of comparing, building and security notes for "atom:id" are listed in the RFC 4287 [2].

4.6.2 Message Body

Depending on service policies and the value of the "pubsub#include_body" node configuration option, Pubsub Social Feed notifications SHOULD include a message "body" element for backwards-compatibility with Jabber clients that are not pubsub-capable. It is RECOMMENDED for the XML character value of the "body" element to be the same as that of the "atom:title" child of the "atom:entry".

4.6.3 Geotagging

Juliet may want to know which places are Romeo's notices related to. That's why Romeo's client MAY geotag microblog entries, using the User Geolocation (XEP-0080) [7] protocol for storing geolocation information.

Romeo's client MUST create a "geoloc" element, with the User Geolocation (XEP-0080) [7] reference namespace: "http://jabber.org/protocol/geoloc".

Example 7. Geotagging a Post
<iq from='romeo@montague.lit/mobile'
    id='pub7'
    to='romeo@montague.lit'
    type='set'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='urn:xmpp:microblog:0'>
      <item id='1zr23z8a-3g12-34fh-750b-120867gjc1sqh'>
        <entry xmlns='http://www.w3.org/2005/Atom'>
          <author>
            <name>Romeo Montague</name>
            <uri>xmpp:romeo@montague.lit</uri>
          </author>
          <title type='text'>Is lost in the forest. Need help!</title>
          <id>tag:montague.lit,2008-05-08:posts-1zr23z8a-3g12-34fh-750b-120867gjc1sqh</id>
          <published>2008-05-08T18:43:01Z</published>
          <updated>2008-05-08T18:43:01Z</updated>
          <geoloc xmlns="http://jabber.org/protocol/geoloc">
            <lat>48.171761</lat>
            <lon>-3.3667986</lon>
            <country>France</country>
            <countrycode>FR</countrycode>
            <region>Brittany</region>
          </geoloc>
        </entry>
      </item>
    </publish>
  </pubsub>
</iq>

5. Profiles

Pubsub Social feeds are specified under profiles. Those profiles are constraints applied to nodes and defined by a specific Pubsub type (see Publish-Subscribe (XEP-0060) [1]#registrar-formtypes-metadata)

All the profiles MUST base their default configuration on the Base profile .

5.1 Base profile

This profile is specified by the Pubsub type "urn:xmpp:pubsub-social-feed:1" and define a generic Pubsub Social Feed that can be hosted on any Pubsub service node or Personal Eventing Protocol (XEP-0163) [8] node.

Those restrictions MUST be used by all the other profiles defined bellow and in other XEPs based on Pubsub Social Feed.

5.1.1 Pubsub Node Configuration

  1. The "pubsub#notify_retract" MUST be set to "true" to provide clients the ability to track if some items were retracted and reflect such changes in the UI correctly.
  2. The "pubsub#max_items" MUST be set to the "max" value, as defined in the Publish-Subscribe (XEP-0060) [1].
  3. The "pubsub#persist_items" MUST be set to "true".
  4. The "pubsub#send_last_published_item" SHOULD be set to "never".
  5. The "pubsub#deliver_payloads" SHOULD be set to "false". The social content can be quite large so it is advised to let the clients to manually query the content if it is not already cached.

5.2 Microblog profile

This profile is defined by the Pubsub type "urn:xmpp:microblog:0" as defined in Microblogging Over XMPP (XEP-0277) [3] and MUST be created and configured under the PEP "urn:xmpp:microblog:0" node.

This profile is defined by the Pubsub type "urn:xmpp:pubsub-social-feed:gallery:1" and can be hosted on any Pubsub service.

All the items published in a gallery node MUST only have at least one attached picture. This picture MUST be of type "enclosure" as specified in RFC 4287 [2].

Example 8. An Atom attached picture
<link rel='enclosure' href='https://capulet.lit/upload/romeo.jpg' type='image/jpeg' title='Romeo Portrait'/>

6. Security Considerations

There are no security features or concerns related to this proposal.

7. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [9].

8. XMPP Registrar Considerations

The XMPP Registrar [10] is requested to issue an initial namespace of "urn:xmpp:pubsub-social-feed:1" and "urn:xmpp:pubsub-social-feed:gallery:1".

9. XML Schema

This specification re-uses the schema for the Atom content format, i.e., the 'http://www.w3.org/2005/Atom' namespace (see RFC 4287 [2] ).

Appendices

Appendix A: Document Information

Series
XEP
Number
0472
Publisher
XMPP Standards Foundation
Status
Experimental
Type
Standards Track
Version
0.2.0
Last Updated
2023-04-03
Approving Body
XMPP Council
Dependencies
XMPP Core, XMPP IM, XEP-0060, RFC 4287
Supersedes
XEP-0277
Superseded By
None
Short Name
psf
Source Control
HTML

This document in other formats: XML  PDF

Appendix B: Author Information

Timothée Jaussoin
Email
edhelas@movim.eu
JabberID
edhelas@movim.eu
URI
https://edhelas.movim.eu

Copyright

This XMPP Extension Protocol is copyright © 1999 – 2024 by the XMPP Standards Foundation (XSF).

Permissions

Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation.

Disclaimer of Warranty

## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ##

Limitation of Liability

In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.

IPR Conformance

This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <https://xmpp.org/about/xsf/ipr-policy> or obtained by writing to XMPP Standards Foundation, P.O. Box 787, Parker, CO 80134 USA).

Visual Presentation

The HTML representation (you are looking at) is maintained by the XSF. It is based on the YAML CSS Framework, which is licensed under the terms of the CC-BY-SA 2.0 license.

Appendix D: Relation to XMPP

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.

Appendix E: Discussion Venue

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Discussion on other xmpp.org discussion lists might also be appropriate; see <https://xmpp.org/community/> for a complete list.

Given that this XMPP Extension Protocol normatively references IETF technologies, discussion on the <xsf-ietf@xmpp.org> list might also be appropriate.

Errata can be sent to <editor@xmpp.org>.

Appendix F: Requirements Conformance

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".

Appendix G: Notes

1. XEP-0060: Publish-Subscribe <https://xmpp.org/extensions/xep-0060.html>.

2. RFC 4287: The Atom Syndication Format <http://tools.ietf.org/html/rfc4287>.

3. XEP-0277: Microblogging over XMPP <https://xmpp.org/extensions/xep-0277.html>.

4. XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>.

5. XEP-0115: Entity Capabilities <https://xmpp.org/extensions/xep-0115.html>.

6. RFC 4685: Atom Threading Extensions <http://tools.ietf.org/html/rfc4685>.

7. XEP-0080: User Geolocation <https://xmpp.org/extensions/xep-0080.html>.

8. XEP-0163: Personal Eventing Protocol <https://xmpp.org/extensions/xep-0163.html>.

9. 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/>.

10. 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/>.

Appendix H: Revision History

Note: Older versions of this specification might be available at https://xmpp.org/extensions/attic/

  1. Version 0.2.0 (2023-04-03)
    tj
  2. Version 0.1.1 (2022-12-24)
    tj
  3. Version 0.1.0 (2022-12-13)
    Accepted by vote of Council on 2022-10-19.
    XEP Editor (jsc)
  4. Version 0.0.1 (2022-09-26)
    Initial version.
    tj

Appendix I: Bib(La)TeX Entry

@report{jaussoin2022psf,
  title = {Pubsub Social Feed},
  author = {Jaussoin, Timothée},
  type = {XEP},
  number = {0472},
  version = {0.2.0},
  institution = {XMPP Standards Foundation},
  url = {https://xmpp.org/extensions/xep-0472.html},
  date = {2022-09-26/2023-04-03},
}

END