Gathering information on many implementations has always been a chore, there exist various lists or comparisons for XMPP clients, servers and libraries, but these are often out of date, inaccurate, incomplete, or generally unmaintained.
This specification aims at solving this problem by putting the work of publishing and keeping up to date said information onto the maintainers of the software. Given many already do maintain this kind of list, the inconvenience should be minimal.
The information listed SHOULD include, but isn’t limited to, the project name, homepage, description, logo, screenshots if relevant, specifications supported (RFCs and XEPs). A full list of supported properties is described in RDF format at http://usefulinc.com/ns/doap#.
A central point should be defined to gather the list of implementations publishing their information, this specifications proposes xmpp.org for this purpose.
Creating, publishing and maintaining a project description should be as easy as possible for producers.
Fetching, parsing and using a project description should be as easy as possible for consumers.
These two requirements have oriented the choice of technologies towards being as restrictive as possible:
A user might want to know which compliance suite level a given client supports before choosing it.
A sysadmin might want to know which compliance suite level a given server supports before choosing it.
An XMPP service might want to propose clients based on their advertised support of what they consider a modern client.
A specification author might want to know the list of projects implementing this specification, their support level and version.
An XMPP enthousiast website might want to automatically update their XMPP comparison page with up to date information.
This specification won’t list every property one could add to their DOAP file, that is the role of the DOAP specification, so it will start with examples.
Here is a minimal DOAP file, containing the same data as the XMPP Software Listing:
<?xml version='1.0' encoding='UTF-8'?>
<rdf:RDF xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'
xmlns='http://usefulinc.com/ns/doap#'>
<Project xml:lang='en'>
<name>Poezio</name>
<homepage rdf:resource='https://poez.io'/>
<os>Linux</os>
</Project>
</rdf:RDF>
But a lot more information can be added:
<?xml version='1.0' encoding='UTF-8'?>
<rdf:RDF xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'
xmlns='http://usefulinc.com/ns/doap#'
xmlns:xmpp='https://linkmauve.fr/ns/xmpp-doap#'
xmlns:schema='https://schema.org'>
<Project>
<name>poezio</name>
<created>2010-01-10</created>
<shortdesc xml:lang='en'>Free console XMPP client</shortdesc>
<shortdesc xml:lang='fr'>Client XMPP libre en console</shortdesc>
<description xml:lang='en'>Free and modern console XMPP client written in Python with the ncurses library</description>
<description xml:lang='fr'>Client console XMPP libre et moderne, écrit en Python avec la bibliothèque ncurses</description>
<homepage rdf:resource='https://poez.io/'/>
<schema:documentation rdf:resource='https://doc.poez.io/'/>
<download-page rdf:resource='https://poez.io/#download'/>
<bug-database rdf:resource='https://lab.louiz.org/poezio/poezio/-/issues'/>
<developer-forum rdf:resource='xmpp:poezio@muc.poez.io?join'/>
<support-forum rdf:resource='xmpp:poezio@muc.poez.io?join'/>
<license rdf:resource='https://git.poez.io/poezio/plain/COPYING'/>
<language>en</language>
<schema:logo rdf:resource='https://poez.io/img/logo.svg'/>
<schema:screenshot rdf:resource='https://poez.io/img/screenshot.png'/>
<programming-language>Python</programming-language>
<os>Linux</os>
<category rdf:resource='https://linkmauve.fr/ns/xmpp-doap#category-client'/>
<repository>
<GitRepository>
<browse rdf:resource='https://lab.louiz.org/poezio/poezio'/>
<location rdf:resource='https://lab.louiz.org/poezio/poezio.git'/>
</GitRepository>
</repository>
<implements rdf:resource='https://xmpp.org/rfcs/rfc6120.html'/>
<implements rdf:resource='https://xmpp.org/rfcs/rfc6121.html'/>
<implements rdf:resource='https://xmpp.org/rfcs/rfc6122.html'/>
<implements rdf:resource='https://xmpp.org/rfcs/rfc7590.html'/>
<implements>
<xmpp:SupportedXep>
<xmpp:xep rdf:resource='https://xmpp.org/extensions/xep-0030.html'/>
<xmpp:status>complete</xmpp:status>
<xmpp:version>2.5rc3</xmpp:version>
<xmpp:since>0.5</xmpp:since>
<xmpp:note xml:lang='en'>The 'disco' plugin can be loaded to make manual queries.</xmpp:note>
<xmpp:note xml:lang='fr'>Le plugin 'disco' peut être chargé pour faire des requêtes manuellement.</xmpp:note>
</xmpp:SupportedXep>
</implements>
<!-- And a lot more! -->
<release>
<Version>
<revision>0.13.1</revision>
<created>2020-05-31</created>
<file-release rdf:resource='https://lab.louiz.org/poezio/poezio/-/archive/v0.13.1/poezio-v0.13.1.tar.gz'/>
</Version>
</release>
</Project>
</rdf:RDF>
It is recommended to start from such an example and tweak it to correspond to your project.
As per the requirements, and as you may have seen in the previous example, we want to know the implementation status of each relevant XMPP specification, which isn’t covered by the DOAP specification.
In order to support that, the https://linkmauve.fr/ns/xmpp-doap# namespace defines the <SupportedXep/> element, which sports a few properties:
| Property | Description | Required |
|---|---|---|
| xep | The URL to the XEP document. | Required |
| status | The support status by this project, can be 'complete', 'partial', 'planned', 'deprecated', 'removed' or 'wontfix'. | Required |
| version | XEP version implemented by this software. | Optional |
| since | Software version this support first appeared in. | Optional |
| note | Any implementation note the project deems relevant. | Optional |
A project SHOULD publish the information it deems relevant in the format defined in this specification.
A project MAY maintain this information in another serialisation (JSON-LD, Turtle…), but MUST submit it in RDF/XML serialisation.
Once satisfied with it, a project SHOULD submit their DOAP file to xmpp.org following this process.
xmpp.org SHOULD cache and host the given files on the behalf of projects, so that if their website goes down for whichever reason other consumers can keep working as usual.
Projects with an existing internationalization process are encouraged to use it to translate user-facing strings in the DOAP file.
This document introduces no additional security considerations above and beyond those defined in the documents on which it depends.
This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [1].
This document requires no interaction with the XMPP Registrar [2].
https://schema.org/ was also considered, given the considerable overlap in features with DOAP, but it didn’t contain many properties useful for software projects. Parts of its properties are reused in this specification, where DOAP was lacking (namely for the logo, screenshot and documentation properties).
AppStream was also considered, but it lacks the extensibility and existing tooling of RDF, while being limited to being a description for software installers instead of a generic software description.
This document in other formats: XML PDF
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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).
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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.
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.
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. 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/>.
2. 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/>.
Note: Older versions of this specification might be available at https://xmpp.org/extensions/attic/
First draft.
@report{peyrot2021xepxxxx,
title = {DOAP usage in XMPP},
author = {Peyrot, Emmanuel Gil},
type = {XEP},
number = {xxxx},
version = {0.0.1},
institution = {XMPP Standards Foundation},
url = {https://xmpp.org/extensions/xep-xxxx.html},
date = {2021-01-10/2021-01-10},
}END