xep-0455.xml

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  <!ENTITY % ents SYSTEM 'xep.ent'>
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<xep>
<header>
  <title>Service Outage Status</title>
  <abstract>This document defines an XMPP protocol extension that enables server administrators
            to communicate issues with the server to all users in a semantic manner.</abstract>
  &LEGALNOTICE;
  <number>0455</number>
  <status>Experimental</status>
  <type>Standards Track</type>
  <sig>Standards</sig>
  <approver>Council</approver>
  <dependencies>
    <spec>XMPP Core</spec>
    <spec>XEP-0060</spec>
    <spec>XEP-0128</spec>
    <spec>XEP-0222</spec>
  </dependencies>
  <supersedes/>
  <supersededby/>
  <shortname>NOT_YET_ASSIGNED</shortname>
  <author>
    <firstname>Mathieu</firstname>
    <surname>Pasquet</surname>
    <email>mathieui@mathieui.net</email>
    <jid>mathieui@mathieui.net</jid>
  </author>
  <revision>
    <version>0.2.0</version>
    <date>2021-02-09</date>
    <initials></initials>
    <remark>Evolve the standard: Editorial restructuring, add business rules and security considerations and clarify some wording.</remark>
  </revision>
  <revision>
    <version>0.1.0</version>
    <date>2021-02-09</date>
    <initials>XEP Editor (jsc)</initials>
    <remark>Accepted by vote of Council on 2021-01-20.</remark>
  </revision>
  <revision>
    <version>0.0.1</version>
    <date>2021-01-18</date>
    <initials>mp</initials>
    <remark><p>First draft.</p></remark>
  </revision>
</header>
<section1 topic='Introduction' anchor='intro'>
  <p>The XMPP Network is a network of servers which each have their own administration policies, status reports, and other peculiarities. &xep0157; provides a consistent framework for reaching out to administrators and reporting abuse, incidents, or even giving feedback on the service, and the goal of this specification is to provide a similar framework for letting users (or other entities) know the server status in-band or out of band (in case of hard failures).</p>
  <p>Centralized systems usually control both the infrastructure and client code, making it easy to hardcode information retrieval one way or the other.</p>
  <p>The usual way of informing users of planned maintenance, partial or total outage was previously through "announce" modules that lets the admin broadcast server-wided messages. This approach has several drawbacks, as it will appear in most clients as a new discussion with the server JID, which can prove confusing. It also does not provide a way to reach the user when the XMPP server is offline.</p>
    <p>This XEP provides:</p>
    <ul>
        <li>An informational way of exposing an external service endpoint containing machine-readable data using &xep0128;</li>
        <li>A specification of the data this service should provide</li>
        <li>A normative way of providing such information in-band, when the outage is not complete</li>
        <li>A way to reference and archive such incidents, in a &xep0060; node</li>
    </ul>
</section1>
<section1 topic='External status' anchor='external-status'>
  <section2 topic='Discovery' anchor='external-disco'>
    <p>To make such discovery possible, we specify a &xep0128; mechanism that a server SHOULD return in response to service discovery information ("disco#info") requests sent to the bare domain of the server. This information MUST be scoped using a FORM_TYPE of "urn:xmpp:sos:0" (as already specified in &xep0128;) and data form fields registered for this purpose as defined in the <link url='#registrar'>XMPP Registrar Considerations</link> section of this document.</p>

    <p>Values of 'external-status-addresses' form field MUST be valid URIs, i.e. comply with the 'xs:anyURI' datatype of &w3xmlschema2;.</p>
    <example caption='Entity queries server for information'><![CDATA[
<iq from='thirdwitch@shakespeare.lit/chamber'
    to='shakespeare.lit'
    id='disco1'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
]]></example>

    <example caption='Server communicates information'><![CDATA[
<iq from='shakespeare.lit'
    to='thirdwitch@shakespeare.list/chamber'
    id='disco1'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <identity category='server' type='im'/>
    <feature var='http://jabber.org/protocol/disco'/>
    <x xmlns='jabber:x:data' type='result'>
      <field var='FORM_TYPE' type='hidden'>
        <value>urn:xmpp:sos:0</value>
      </field>
      <field var='external-status-addresses'>
        <value>http://secondary.shakespeare.lit/status.json</value>
      </field>
    </x>
  </query>
</iq>
]]></example>

    <p>Links present inside the 'external-status-addresses' field SHOULD use HTTP/HTTPS protocol and the resources referenced MUST be available without authentication.</p>

  </section2>
  <section2 topic='External status format' anchor='json-schema'>
    <p>TODO: do we want this to be XML or json? I have no real preference, in any case it should be preferably generated by a tool but easy to write by hand, as this needs to be usable in situations where time is the essence.</p>
    <p>The format used for the external status is defined here, to allow a wide range
       of compatibility across services and clients.</p>
    <p>A client MUST ignore unknown extra fields present in the JSON file, to allow extensibility, and implementations MAY add other fields.</p>
    <example caption='Example status'><![CDATA[
{
  "outage": "complete",
  "planned": true,
  "beginning": "2021-01-12T01:01:01Z",
  "expected_end": "2021-01-12T05:00:00Z",
  "message": {
    "default": "Mise à jour du serveur",
    "en": "The serveur is being updated"
  }
}
  ]]></example>

    <p>The "message" field MUST contain at least a message on the "default" key, that will be
        used by the client if the current user language is not found. It is left to the
        operator to determine which language is more relevant as a default, according to the
        server’s user base.</p>

    <p>When the outage is over, the file SHOULD be replaced with an empty JSON object.</p>

    <example caption='Empty file after resolution of the issue'><![CDATA[
{}
]]></example>

    <p>The following JSON schema is provided as a means to describe and validate the
       file exposed by the external service:</p>

    <code><![CDATA[
{
  "$id": "http://xmpp.org/server-outage-schema.json",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "XMPP Server Outage Format",
  "type": "object",
  "required": ["beginning"],
  "additionalProperties": true,
  "properties": {
    "outage": {
      "type": "string",
      "enum": ["partial", "complete"],
      "description": "The outage status (partial or complete)."
    },
    "planned": {
      "type": "boolean",
      "description": "If the outage was planned or not."
    },
    "beginning": {
      "type": "string",
      "format": "date-time",
      "description": "Approximate time of the start of the outage."
    },
    "expected_end": {
      "type": "string",
      "format": "date-time",
      "description": "Estimated time of the end of the outage (if known)."
    },
    "message": {
    "type": "object",
      "description": "Textual message to service users, each key being 'defaul' or a BCP47 language tag.",
      "required": ["default"],
      "properties": {
        "default": { "type": "string"}
      },
      "patternProperties": {
        "default": {"type": "string"},
        ".*": {"type": "string"}
      }
    }
  }
}
]]></code>
  </section2>

</section1>
<section1 topic="In-band status" anchor="in-band-status">
  <section2 topic='PubSub Node' anchor='pubsubnode'>
    <p>For in-band notifications of server issues, a service with this extension SHOULD expose a 'urn:xmpp:sos:0'
       pubsub node with the acess model defined in &xep0222; on its bare JID.
       This pubsub node contains items describing outages and outage resolutions, and each item MUST have an 'id' attribute value containing
       the outage date and time, in &xep0082; format.</p>
    <p>Clients implementing this extension SHOULD subscribe to the '+notify' on that node, as defined in &xep0060;.</p>
    <p>Entities from other servers MAY be allowed to subscribe to other server nodes, to allow external services
        to monitor the server. Doing so allows aggregation of XMPP outage events across the network, for a better
        transparency.</p>
  </section2>
  <section2 topic='Outage event' anchor='outage-event'>

    <example caption='Server operator publishes an outage event'><![CDATA[
  <iq from='firstwitch@shakespeare.lit/broom' to='shakespeare.lit' type='set' id='pub1'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='urn:xmpp:sos:0'>
      <item id="2021-01-01T01:01:01Z">
        <outage xmlns='urn:xmpp:sos:0'>
          <description xml:lang='en'>The ICQ and MSN gateways are down</description>
          <description xml:lang='fr'>Les passerelles ICQ et MSN sont mortes</description>
          <planned>false</planned>
          <expected_end>2021-01-01T05:00:00Z</expected_end>
        </outage>
      </item>
    </publish>
  </pubsub>
</iq>
]]></example>

    <example caption='Client subscribed receives an outage event'><![CDATA[
<message from='shakespeare.lit'
         to='macbeth@shakespeare.lit/throne'
         type='headline'
         id='outagefoo'>
  <event xmlns='http://jabber.org/protocol/pubsub#event'>
    <items node='urn:xmpp:sos:0'>
      <item id="2021-01-01T01:01:01Z">
        <outage xmlns='urn:xmpp:sos:0'>
          <description xml:lang='en'>The ICQ and MSN gateways are down</description>
          <description xml:lang='fr'>Les passerelles ICQ et MSN sont mortes</description>
          <planned>false</planned>
          <expected_end>2021-01-01T05:00:00Z</expected_end>
        </outage>
      </item>
    </items>
  </event>
</message>
]]></example>

  </section2>
  <section2 topic='Outage End Event' anchor='outage-end-event'>

  <p>When the outage is over, servers operators SHOULD publish an &lt;outage-end/&gt; element
      with the item id matching the time at which the issue was resolved. It can optionally
      contain a description.</p>

  <example caption='Server operator publishes an end of outage event'><![CDATA[
  <iq from='firstwitch@shakespeare.lit/broom' to='shakespeare.lit' type='set' id='pub2'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='urn:xmpp:sos:0'>
      <item id="2021-01-01T02:05:01Z">
        <outage-end xmlns='urn:xmpp:sos:0'>
          <description xml:lang="en">Everything has been fixed!</description>
          <description xml:lang="fr">Tout a été corrigé !</description>
        </outage-end>
      </item>
    </publish>
  </pubsub>
</iq>
]]></example>

  <p>Clients receiving this notification SHOULD remove the information about the outage from the user’s view, and MAY
     display the new message briefly.</p>
  </section2>
</section1>
<section1 topic='Use Cases' anchor='usecases'>
  <p>This extension has been thought for several different cases of service outages:</p>
  <ul>
    <li>A client failing to connect to a server is able to display an informative message to the user if the server is having issues.</li>
    <li>A server experiencing difficulties is able to communicate it to the users, and clients can display the information prominently.</li>
    <li>An external service can keep track of the various outages, either for a single server or a number of them, and present the information in a structured manner.</li>
  </ul>
</section1>
<section1 topic='Business Rules' anchor='rules'>
  <p>A client implementing this extension MUST fetch the addresses of the external service and cache it
    for later use. Doing so allows the client to use this information when it is impossible to connect
    to the server.</p>
  <p>A client receiving an outage event for a time in the future SHOULD treat it as a planned event
     that is not already happening and adapt its display consequently.</p>
  <p>When connected, a client SHOULD NOT fetch the external file as the in-band notification provides
     the same information, if available.</p>
</section1>
<section1 topic='Internationalization Considerations' anchor='i18n'>
  <p>Both the JSON and the XML format defined in this document allow for internationalization in the fields that are expected to be presented to the user as-is. The other fields are machine-readable and their various values SHOULD be translated in the implementing applications.</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
  <p>Client implementations MUST check the provenance of the pubsub notifications before displaying a notification, otherwise malicious entities could send fake outage events.</p>
  <p>Server administrators MUST ensure the servers provided in 'external-status-addresses' are trusted, as malicious administrators of this server could use the referenced file
     to display arbitrary messages to users.</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>The &REGISTRAR; includes the following information in its registries.</p>
  <section2 topic='Field Standardization' anchor='registrar-formtype'>
    <p>&xep0068; defines a process for standardizing the fields used within Data Forms qualified by a particular namespace, and &xep0128; describes how to use field standardization in the context of service discovery. This section registers fields for server information scoped by the "urn:xmpp:sos:0" FORM_TYPE.</p>
    <code caption='Registry Submission'><![CDATA[
<form_type>
  <name>urn:xmpp:sos:0</name>
  <doc>XEP-XXXXX</doc>
  <desc>
    Form enabling a the registration of a machine-readable
    external file to describe a service status.
  </desc>
  <field
      var='external-status-addresses'
      type='list-multi'
      label='One or more addresses containing a file with the server status'/>
</form_type>
]]></code>
  </section2>
</section1>
<section1 topic='XML Schema' anchor='schema'>
  <p>REQUIRED for protocol specifications.</p>
</section1>
</xep>