xeps/xep-0453.xml

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE xep SYSTEM 'xep.dtd' [
  <!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
<header>
  <title>DOAP usage in XMPP</title>
  <abstract>This specification defines how XMPP projects can provide a machine-readable description of their abilities, and how external entities can interact with it.</abstract>
  &LEGALNOTICE;
  <number>0453</number>
  <status>Experimental</status>
  <type>Informational</type>
  <sig>Standards</sig>
  <approver>Council</approver>
  <dependencies>
    <spec>https://www.w3.org/TR/rdf11-concepts/</spec>
    <spec>http://usefulinc.com/ns/doap#</spec>
    <spec>https://linkmauve.fr/ns/xmpp-doap#</spec>
    <spec>https://schema.org/</spec>
  </dependencies>
  <supersedes/>
  <supersededby/>
  <shortname>NOT_YET_ASSIGNED</shortname>
  <author>
    <firstname>Emmanuel Gil</firstname>
    <surname>Peyrot</surname>
    <email>linkmauve@linkmauve.fr</email>
    <jid>linkmauve@linkmauve.fr</jid>
  </author>
  <revision>
    <version>0.1.0</version>
    <date>2021-01-26</date>
    <initials>XEP Editor (jsc)</initials>
    <remark>Accepted by vote of Council on 2021-01-13.</remark>
  </revision>
  <revision>
    <version>0.0.1</version>
    <date>2021-01-10</date>
    <initials>egp</initials>
    <remark><p>First draft.</p></remark>
  </revision>
</header>
<section1 topic='Introduction' anchor='intro'>
  <p>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been a chore, there exist various lists or comparisons for XMPP clients, servers and libraries, but these are often out of date, inaccurate, incomplete, or generally unmaintained.</p>
  <p>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.</p>
  <p>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 <link url='http://usefulinc.com/ns/doap#'>http://usefulinc.com/ns/doap#</link>.</p>
  <p>A central point should be defined to gather the list of implementations publishing their information, this specifications proposes <link url='https://xmpp.org'>xmpp.org</link> for this purpose.</p>
</section1>
<section1 topic='Requirements' anchor='reqs'>
  <p>Creating, publishing and maintaining a project description should be as easy as possible for producers.</p>
  <p>Fetching, parsing and using a project description should be as easy as possible for consumers.</p>
  <p>These two requirements have oriented the choice of technologies towards being as restrictive as possible:</p>
  <ul>
    <li>The chosen RDF serialisation format MUST be RDF/XML, assuming XMPP project authors are already familiar with XML as a serialisation format.</li>
    <li>The resulting file should be published over HTTPS, without access restrictions.</li>
  </ul>
</section1>
<section1 topic='Glossary' anchor='glossary'>
  <dl>
    <di>
      <dt>DOAP</dt>
      <dd>Description of a Project, the chosen RDF format used by this specification to describe the various properties of a project.</dd>
    </di>
    <di>
      <dt>RDF</dt>
      <dd>Resource Description Framework, a generic data model framework, supporting many serialisation formats and conversions between them.  For the purpose of this specification we will only consider RDF/XML, an XML serialisation format, with the rationale that all XMPP authors are already familiar with this serialisation format.</dd>
    </di>
  </dl>
</section1>
<section1 topic='Use Cases' anchor='usecases'>
  <p>A user might want to know which compliance suite level a given client supports before choosing it.</p>
  <p>A sysadmin might want to know which compliance suite level a given server supports before choosing it.</p>
  <p>An XMPP service might want to propose clients based on their advertised support of what they consider a modern client.</p>
  <p>A specification author might want to know the list of projects implementing this specification, their support level and version.</p>
  <p>An XMPP enthousiast website might want to automatically update their XMPP comparison page with up to date information.</p>
  <section2 topic='Examples' anchor='examples'>
    <p>This specification won’t list every property one could add to their DOAP file, that is the role of the <link url='https://github.com/ewilderj/doap/wiki'>DOAP specification</link>, so it will start with examples.</p>
    <p>Here is a minimal DOAP file, containing the same data as the <link url='https://xmpp.org/2017/03/new-xmpp-software-listing-rules/'>XMPP Software Listing</link>:</p>
    <example caption='A Minimal DOAP File'><![CDATA[
<?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>
]]></example>
    <p>But a lot more information can be added:</p>
    <example caption='A More Featureful DOAP File'><![CDATA[
<?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>
]]></example>
    <p>It is recommended to start from such an example and tweak it to correspond to your project.</p>
  </section2>
  <section2 topic='Extensions Specific to XMPP' anchor='extensions'>
    <p>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.</p>
    <p>In order to support that, the <link url='https://linkmauve.fr/ns/xmpp-doap#'>https://linkmauve.fr/ns/xmpp-doap#</link> namespace defines the <tt>&lt;SupportedXep/&gt;</tt> element, which sports a few properties:</p>
    <table>
      <tr>
        <th>Property</th>
        <th>Description</th>
        <th>Required</th>
      </tr>
      <tr>
        <td>xep</td>
        <td>The URL to the XEP document.</td>
        <td>Required</td>
      </tr>
      <tr>
        <td>status</td>
        <td>The support status by this project, can be 'complete', 'partial', 'planned', 'deprecated', 'removed' or 'wontfix'.</td>
        <td>Required</td>
      </tr>
      <tr>
        <td>version</td>
        <td>XEP version implemented by this software.</td>
        <td>Optional</td>
      </tr>
      <tr>
        <td>since</td>
        <td>Software version this support first appeared in.</td>
        <td>Optional</td>
      </tr>
      <tr>
        <td>note</td>
        <td>Any implementation note the project deems relevant.</td>
        <td>Optional</td>
      </tr>
    </table>
  </section2>
</section1>
<section1 topic='Business Rules' anchor='rules'>
  <p>A project SHOULD publish the information it deems relevant in the format defined in this specification.</p>
  <p>A project MAY maintain this information in another serialisation (JSON-LD, Turtle…), but MUST submit it in RDF/XML serialisation.</p>
  <p>Once satisfied with it, a project SHOULD submit their DOAP file to xmpp.org following <link url='https://github.com/xsf/xmpp.org/blob/master/data/README.rst'>this process</link>.</p>
  <p>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.</p>
</section1>
<section1 topic='Internationalization Considerations' anchor='i18n'>
  <p>Projects with an existing internationalization process are encouraged to use it to translate user-facing strings in the DOAP file.</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
  <p>This document introduces no additional security considerations above and beyond those defined in the documents on which it depends.</p>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
  <p>This document requires no interaction with &IANA;.</p>
</section1>
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
  <p>This document requires no interaction with the &REGISTRAR;.</p>
</section1>
<section1 topic='Design Considerations' anchor='design'>
  <p><link url='https://schema.org/'>https://schema.org/</link> 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).</p>
  <p><link url='https://www.freedesktop.org/software/appstream/docs/'>AppStream</link> 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.</p>
</section1>
</xep>