mirror of https://github.com/moparisthebest/xeps
Merge pull request #1188 from mar-v-in/xep-0428
XEP-0428: Fallback Indication v0.2.0
This commit is contained in:
Kevin Smith
GitHub
commit
186c69bd89
91
xep-0428.xml
91
xep-0428.xml
|
|
@ -8,13 +8,14 @@
|
|||
<xep>
|
||||
<header>
|
||||
<title>Fallback Indication</title>
|
||||
<abstract>This specification proposes a mechanism by which message bodies can be marked as being purely for fallback
|
||||
purposes, and therefore to be ignored by intermediaries and anything that understands the remainder of the message.</abstract>
|
||||
<abstract>This specification proposes a mechanism by which message bodies or parts thereof can be marked as being for fallback
|
||||
purposes, and therefore to be ignored by anything that understands the original intent of the message.</abstract>
|
||||
&LEGALNOTICE;
|
||||
<number>0428</number>
|
||||
<status>Deferred</status>
|
||||
<status>Experimental</status>
|
||||
<type>Standards Track</type>
|
||||
<sig>Standards</sig>
|
||||
<approver>Council</approver>
|
||||
<dependencies>
|
||||
<spec>XMPP Core</spec>
|
||||
</dependencies>
|
||||
|
|
@ -23,6 +24,19 @@
|
|||
<shortname>fallback</shortname>
|
||||
&dcridland;
|
||||
&larma;
|
||||
<revision>
|
||||
<version>0.2.0</version>
|
||||
<date>2022-07-17</date>
|
||||
<initials>lmw</initials>
|
||||
<remark>
|
||||
<ul>
|
||||
<li>Add 'for' attribute such that entities can discover what the fallback is for.</li>
|
||||
<li>Allow to specify that only one of &SUBJECT; or &BODY; is meant as a fallback.</li>
|
||||
<li>Allow to specify the part of respective text that is meant as fallback where applicable.</li>
|
||||
<li>Don't use encryption example, which should use XEP-0380 instead.</li>
|
||||
</ul>
|
||||
</remark>
|
||||
</revision>
|
||||
<revision>
|
||||
<version>0.1.1</version>
|
||||
<date>2020-03-03</date>
|
||||
|
|
@ -48,17 +62,20 @@
|
|||
</header>
|
||||
|
||||
<section1 topic='Introduction' anchor='intro'>
|
||||
<p>A common and convenient practise for new extensions is to supply a fallback body. This provides immediate backwards
|
||||
<p>A common and convenient practise for new extensions is to supply a fallback in the body. This provides immediate backwards
|
||||
compatibility for naive clients, since - not understanding the new protocol - they will gracefully degrade to displaying
|
||||
the body as an instant message.</p>
|
||||
the body as an instant message.</p>
|
||||
<p>By way of example, a recent Reactions proposal suggested including the emoji as a <tt><body/></tt> element, so
|
||||
that existing clients would simply display it as a normal message.</p>
|
||||
<p>The downside of this approach is that servers and other intermediaries treat the presence of a <tt><body/></tt>
|
||||
as being an indicator that a message is indeed an instant message. They will then treat it this way for archival
|
||||
purposes, etc, which might not be appropriate.</p>
|
||||
<p>This specification tackles the problem by providing an element to be used as a hint that the supplied
|
||||
<tt><body/></tt> and <tt><subject/></tt> elements are only for fallback purposes, and the message SHOULD be
|
||||
treated as if they were not present for most purposes.</p>
|
||||
as being an indicator that a message is indeed an instant message. They may errornously treat a message this way
|
||||
for archival purposes, etc, that only has a <tt><body/></tt> for fallback purposes, which might not be appropriate.</p>
|
||||
<p>This specification tackles the problem by providing an element to be used as a hint that parts or all of the supplied
|
||||
<tt><body/></tt> and <tt><subject/></tt> elements are for fallback purposes, and the message may be treated as
|
||||
if they were not present if the processing entity understands what the message is a fallback for.</p>
|
||||
<p>Additionally, the specification allows for transporting information about which parts of a <tt><body/></tt> are used
|
||||
for fallback purposes and for which reason, such that supporting clients can hide or dim those parts when displaying them
|
||||
to the user or otherwise treat those parts special as intended or encouraged by other specifications.</p>
|
||||
</section1>
|
||||
|
||||
<section1 topic='Overview' anchor="overview">
|
||||
|
|
@ -67,25 +84,41 @@
|
|||
of <tt>&ns;</tt>. Note that lack of support will result in the desired fallback behaviour.</p>
|
||||
</section2>
|
||||
<section2 topic="Fallback Indicator">
|
||||
<p>The fallback indicator is an element <tt><fallback/></tt> qualified by the <tt>&ns;</tt> namespace. It has no
|
||||
attributes, content, or child elements.</p>
|
||||
<p>The fallback indicator is an element <tt><fallback/></tt> qualified by the <tt>&ns;</tt> namespace. It has an attribute
|
||||
<tt>for</tt> that indicates the specification that the fallback is meant to replace. This is typically the primary namespace
|
||||
of the respective specification, but may be specified otherwise. The <tt><fallback/></tt> element may have one or multiple
|
||||
<tt><body/></tt> or <tt><subject/></tt> child elements, that indicate the part of the message, that is a fallback. Both
|
||||
of these child elements may have a <tt>start</tt> and <tt>end</tt> attribute which point to the start and end of a fallback
|
||||
character sequence as defined in &xep0426; in the respective element in the message. If <tt>start</tt> and <tt>end</tt>
|
||||
attribute are not supplied, the whole respective message element should be assumed to be there for fallback purposes. If
|
||||
the <tt><fallback/></tt> element does not have any childs, it is assumed to apply to every message <tt><body/></tt> and
|
||||
<tt><subject/></tt> present in the message.</p>
|
||||
<p class="box">A previous version of this specification had an example using an encrypted message. It is suggested to use &xep0380;
|
||||
instead of this specification for that usecase.</p>
|
||||
<example><![CDATA[
|
||||
<message from="alice@example.org" to="bob@example.net" type="chat">
|
||||
<fallback xmlns="]]>&ns;<![CDATA["/>
|
||||
<encrypted xmlns="urn:example:crypto">Abobql jvyy rire qrpelcg bhe fhcre-frperg zrffntr!</encrypted>
|
||||
<body>This message is encrypted.</body>
|
||||
<message to='anna@example.com' id='message-id2' type='groupchat'>
|
||||
<body>
|
||||
> Anna wrote:
|
||||
> Hi, how are you?
|
||||
Great
|
||||
</body>
|
||||
<reply to='anna@example.com' id='message-id1' xmlns='urn:xmpp:reply:0' />
|
||||
<fallback xmlns='urn:xmpp:fallback:0' for='urn:xmpp:reply:0'>
|
||||
<body start='0' end='33' />
|
||||
</fallback>
|
||||
</message>
|
||||
]]></example>
|
||||
<p>Receiving the above message, a naive client will naturally display only the <tt><body/></tt> element text, but
|
||||
a client or server which supports this specification will know this is merely a fallback placeholder, and to ignore
|
||||
(and not display) the content therein.</p>
|
||||
<p>Receiving the above message, a naive client will naturally display the full <tt><body/></tt> element text, but
|
||||
a client which supports this specification and the specification for <tt>urn:xmpp:reply:0</tt> will know that a part of the
|
||||
message is merely a fallback placeholder, and to ignore (and not display) that part, if it has other ways to convey the
|
||||
intended meaning.</p>
|
||||
</section2>
|
||||
<section2 topic="Alternatives">
|
||||
<ul>
|
||||
<li>&xep0334; was considered, and would probably be ideal - servers often examine these elements and alter
|
||||
behaviour accordingly, but the specification was rejected by Council.</li>
|
||||
<li>&xep0334; was considered to inform intermediaries, and would probably be ideal - servers often examine these elements
|
||||
and alter behaviour accordingly, but the specification was rejected by Council.</li>
|
||||
<li>Placing fallback elements within the <tt><fallback/></tt> element would shift the onus from server to
|
||||
client, but this is likely to be less useful.</li>
|
||||
client, but this is likely to be less useful.</li>
|
||||
</ul>
|
||||
</section2>
|
||||
</section1>
|
||||
|
|
@ -94,10 +127,20 @@
|
|||
<code>
|
||||
<![CDATA[
|
||||
<?xml version="1.0" encoding="UTF-8"?>
|
||||
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="]]>&ns;<![CDATA[" xmlns:xs="http://www.w3.org/2001/XMLSchema">
|
||||
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="]]>&ns;<![CDATA[" xmlns="]]>&ns;<![CDATA[" xmlns:xs="http://www.w3.org/2001/XMLSchema">
|
||||
<xs:element name="fallback">
|
||||
<xs:complexType/>
|
||||
<xs:complexType>
|
||||
<xs:sequence>
|
||||
<xs:element name="subject" type="region" minOccurs="0" maxOccurs="unbounded" />
|
||||
<xs:element name="body" type="region" minOccurs="0" maxOccurs="unbounded" />
|
||||
</xs:sequence>
|
||||
<xs:attribute name="for" type="xs:string" />
|
||||
</xs:complexType>
|
||||
</xs:element>
|
||||
<xs:complexType name="region">
|
||||
<xs:attribute name="start" type="xs:integer" />
|
||||
<xs:attribute name="end" type="xs:integer" />
|
||||
</xs:complexType>
|
||||
</xs:schema>
|
||||
]]>
|
||||
</code>
|
||||
|
|
|
|||
Loading…
Reference in New Issue