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xeps/xep-0068.xml
Peter Saint-Andre 76458a46cd harmony with XEP-0060 for examples
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2009-04-05 17:19:29 +00:00

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<?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>Field Standardization for Data Forms</title>
<abstract>This document specifies how to standardize field variables used in the context of jabber:x:data forms.</abstract>
&LEGALNOTICE;
<number>0068</number>
<status>Active</status>
<type>Informational</type>
<sig>Standards</sig>
<dependencies>
<spec>XMPP Core</spec>
<spec>XEP-0004</spec>
</dependencies>
<supersedes/>
<supersededby/>
<shortname>formtypes</shortname>
<registry/>
&hildjj;
&stpeter;
<revision>
<version>1.1</version>
<date>2004-07-07</date>
<initials>psa</initials>
<remark>Specified ability to standardize field option values.</remark>
</revision>
<revision>
<version>1.0</version>
<date>2003-08-18</date>
<initials>psa</initials>
<remark>Per a vote of the Jabber Council, advanced status to Active.</remark>
</revision>
<revision>
<version>0.3</version>
<date>2003-06-05</date>
<initials>psa</initials>
<remark>Specified rules regarding registration and naming of FORM_TYPEs and associated fields.</remark>
</revision>
<revision>
<version>0.2</version>
<date>2003-05-09</date>
<initials>psa</initials>
<remark>Clarified the relation of FORM_TYPE to registered namespaces; defined registry format; added IQ example.</remark>
</revision>
<revision>
<version>0.1</version>
<date>2003-01-22</date>
<initials>jjh</initials>
<remark>Initial version.</remark>
</revision>
</header>
<section1 topic='Introduction' anchor='intro'>
<p>Now that &xep0004; has been finalized, several uses of jabber:x:data forms have been put on the standards track, including &xep0045;. These protocols typically need a way to gather data from both humans (using a GUI format) and computer processes (using a pre-defined but flexible format).</p>
<p>The 'jabber:x:data' namespace provides an adequate mechanism for both of these uses, as long as computer processes can rely on the var=&quot;&quot; names on a particular type of form.</p>
<p>This document proposes a specific mechanism for the &REGISTRAR; to standardize these form field variable names. Thus this document enables existing clients to process forms as they have to this point, but enables protocol authors to specify a mechanism for non-GUI processors of those forms to determine the semantic meanings of those forms.</p>
</section1>
<section1 topic='Requirements' anchor='reqs'>
<ol>
<li>Forms must continue to be presentable to humans for data entry.</li>
<li>Jabber clients that know how to process generic jabber:x:data messages must be supported; the basic format of jabber:x:data must not change.</li>
<li>If a form type is used in the context of a standards-track protocol, it should be standardized and registered; however, there is no requirement that all form types must be registered (e.g., form types used in custom applications).</li>
<li>If a form type is standardized and registered, field names used in the context of that form type must either be standardized as well or else be clearly labeled as unregistered.</li>
<li>Forms that are not directed <em>to</em> an entity must be able to traverse the entity (e.g., a form sent to a MUC room, intended for the participants of the room, and not the room itself).</li>
<li>Forms must continue to be flexible for implementations; unknown future expansion fields must not be limited.</li>
<li>The chosen approach must work for forms embedded in messages as well as in IQs.</li>
</ol>
</section1>
<section1 topic='Approach' anchor='approach'>
<section2 topic='Overview' anchor='approach-overview'>
<p>Within Jabber, namespaces are used to scope data that conforms to a schema (often data that extends the core protocol in some fashion). In addition, namespaces can also provide context for the field variable names used in jabber:x:data forms and reports. This proposal makes that link explicit by defining a mechanism for linking a namespace name with a form and the field names and types used in that form. Specifically, the namespace name is specified in the form as the value of a hidden variable called "FORM_TYPE".</p>
</section2>
<section2 topic='Whether to Register' anchor='approach-register'>
<p>The first decision-point is whether a FORM_TYPE needs to be registered with the XMPP Registrar. The following rules apply:</p>
<ol>
<li>If the FORM_TYPE is used in the context of a form defined in a XEP published by the &XSF;, it MUST be registered.</li>
<li>If the FORM_TYPE is used in the context of some other XMPP protocol but the form is not defined in a XEP, it MAY be registered.</li>
<li>If the FORM_TYPE is used in the context of a custom protocol, it MAY be registered.</li>
</ol>
</section2>
<section2 topic='Naming Convention' anchor='approach-naming'>
<p>While the value of the FORM_TYPE attribute SHOULD be considered an opaque string from the application perspective, the following rules apply:</p>
<ol>
<li>For custom protocols, the name SHOULD be an HTTP URI that is managed by the namespace "owner".</li>
<li>For all new protocols approved by the XSF, the name MUST be an HTTP URI or IETF-style URN.</li>
<li>For "legacy" protocols managed by the XSF, the name SHOULD use the old-style "jabber:*:*" format.</li>
</ol>
</section2>
<section2 topic='Field Names' anchor='approach-fieldnames'>
<p>For FORM_TYPEs that are registered with the XMPP Registrar, the field names MUST conform to one of the following two conditions:</p>
<ol>
<li>If the field name is defined by the relevant XEP or by registration, the field name MUST be registered with the XMPP Registrar and MAY have any name (except a name that begins with "x-"), subject to approval by the XMPP Registrar.</li>
<li>If the field name is unregistered, the field name MUST begin with "x-".</li>
</ol>
<p>If the FORM_TYPE is not registered, the field name MAY have any name (presumably managed by the namespace "owner").</p>
</section2>
<section2 topic='Field Values' anchor='approach-values'>
<p>Field values may also be registered; refer to the <link url='registrar'>XMPP Registrar</link> section of this document.</p>
</section2>
</section1>
<section1 topic='Use Cases' anchor='usecases'>
<section2 topic='Unspecified Form' anchor='usecases-unspecified'>
<p>These are forms that do not have a hidden field of name FORM_TYPE.
Existing processing rules still apply.</p>
<example caption='Message with no FORM_TYPE'><![CDATA[
<message
from='juliet@capulet.com/balcony'
to='romeo@montague.net/garden'>
<thread>vote-thread-reatmon-134</thread>
<x xmlns='jabber:x:data' type='form'>
<title>Vote #134</title>
<instructions>
This is the vote to pick a new mascot.
Thanks for your time!
</instructions>
<field var='mascot' type='list-single'>
<required/>
<option label='Light Bulb'><value>light_bulb</value></option>
<option label='Penguin'><value>penguin</value></option>
<option label='Moose'><value>moose</value></option>
<option label='Triangle Man'><value>triangle_man</value></option>
<option label='Other'><value>other</value></option>
</field>
</x>
</message>
]]></example>
</section2>
<section2 topic='Correctly Specified FORM_TYPE' anchor='usecases-correct'>
<p>In the following example, the FORM_TYPE is 'http://jabber.org/protocol/pubsub', and all of the fields whose var names start with "pubsub#" would be registered with the XMPP Registrar, associated with that namespace.</p>
<example caption='Message with FORM_TYPE'><![CDATA[
<message to="node-owner" from="pubsub.jabber.org">
<x xmlns="jabber:x:data" type="form">
<title>PubSub subscriber request</title>
<instructions>To approve this entity's subscription request,
click the OK button. To deny the request, click the
cancel button.</instructions>
<field var="FORM_TYPE" type="hidden">
<value>http://jabber.org/protocol/pubsub</value>
</field>
<field var="pubsub#node" type="hidden">
<value>generic/pgm-mp3-player</value>
</field>
<field var="pubsub#subscriber_jid" type="jid-single"
label="Jabber ID of Subscriber">
<value>sub1@foo.com</value>
</field>
<field var="x-time_restrictions" type="text-multi"
label="Limit to these time ranges">
<value>09:00-12:00</value>
<value>13:00-17:00</value>
</field>
</x>
</message>
]]></example>
</section2>
<section2 topic='Incorrectly Specified FORM_TYPE' anchor='usecases-incorrect'>
<p>If the FORM_TYPE field is not hidden, it MUST be ignored as a
context indicator.</p>
<example caption='Message with bad FORM_TYPE'><![CDATA[
<message to="juliet@capulet.com" from="romeo@montague.net/garden">
<x xmlns="jabber:x:data" type="form">
<title>Balcony Scene (Act 2, Scene 2)</title>
<instructions>But soft! What light through yonder window breaks?</instructions>
<!-- Not hidden. Treated as any other text-single field: -->
<field var="FORM_TYPE" type="text-single">
<value>http://jabber.org/protocol/shakespeare</value>
</field>
<field var="light" type="list-multi">
<option label="Juliet">Sun</option>
<option lable="Maid">Moon</option>
<option label="Eyes">Stars</option>
</field>
</x>
</message>
]]></example>
</section2>
<section2 topic='Message with Bad Field' anchor='usecases-badfield'>
<p>When a FORM_TYPE is specified correctly, and an unknown field is found whose name does not start with "x-", a receiver MAY respond with an "Not Acceptable" error.</p>
<example caption='Message with bad field'><![CDATA[
<message to="juliet@capulet.com" from="romeo@montague.net/garden">
<x xmlns="jabber:x:data" type="form">
<title>Balcony Scene (Act 2, Scene 2)</title>
<instructions>But soft! What light through yonder window breaks?</instructions>
<field var="FORM_TYPE" type="hidden">
<value>http://jabber.org/protocol/shakespeare</value>
</field>
<field var="light" type="list-multi">
<option label="Juliet">Sun</option>
<option lable="Maid">Moon</option>
<option label="Eyes">Stars</option>
</field>
</x>
</message>
<message from="juliet@capulet.com" to="romeo@montague.net/garden" type="error">
<error code="406" type='modify'>
<not-acceptable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<text xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
The field "light" is not acceptable.
</text>
</error>
</message>
]]></example>
</section2>
<section2 topic='IQ Example' anchor='usecases-IQ'>
<p>The following example shows a user's interaction with a Multi-User Chat room in order to register with the room.</p>
<example caption='User Requests Registration Requirements'><![CDATA[
<iq
from='hag66@shakespeare.lit/pda'
to='darkcave@macbeth.shakespeare.lit'
type='get'
id='reg1'>
<query xmlns='jabber:iq:register'/>
</iq>
]]></example>
<example caption='Service Returns Registration Form'><![CDATA[
<iq
type='result'
from='darkcave@macbeth.shakespeare.lit'
to='hag66@shakespeare.lit/pda'
id='reg1'>
<query xmlns='jabber:iq:register'>
<instructions>
To register on the web, visit http://shakespeare.lit/
</instructions>
<x xmlns='jabber:x:data' type='form'>
<title>Dark Cave Registration</title>
<instructions>
Please provide the following information
to register with this room.
</instructions>
<field
type='hidden'
var='FORM_TYPE'>
<value>http://jabber.org/protocol/muc#user</value>
</field>
<field
type='text-single'
label='First Name'
var='muc#user_first'>
<required/>
</field>
<field
type='text-single'
label='Last Name'
var='muc#user_last'>
<required/>
</field>
<field
type='text-single'
label='Desired Nickname'
var='muc#user_roomnick'>
<required/>
</field>
<field
type='text-single'
label='Your URL'
var='muc#user_url'/>
<field
type='text-single'
label='Email Address'
var='muc#user_email'/>
<field
type='text-multi'
label='FAQ Entry'
var='muc#user_faqentry'/>
</x>
</query>
</iq>
]]></example>
<example caption='User Submits Registration Form'><![CDATA[
<iq
type='set'
from='hag66@shakespeare.lit/pda'
to='darkcave@macbeth.shakespeare.lit'
id='reg2'>
<query xmlns='jabber:iq:register'>
<x xmlns='jabber:x:data' type='submit'>
<field var='FORM_TYPE'>
<value>http://jabber.org/protocol/muc#user</value>
</field>
<field var='muc#user_first'>
<value>Brunhilde</value>
</field>
<field var='muc#user_last'>
<value>Entwhistle-Throckmorton</value>
</field>
<field var='muc#user_roomnick'>
<value>thirdwitch</value>
</field>
<field var='muc#user_url'>
<value>http://witchesonline/~hag66/</value>
</field>
<field var='muc#user_email'>
<value>hag66@witchesonline</value>
</field>
<field var='muc#user_faqentry'>
<value>Just another witch.</value>
</field>
</x>
</query>
</iq>
]]></example>
</section2>
</section1>
<section1 topic='Implementation Notes' anchor='impl'>
<p>If the FORM_TYPE field is not type=&quot;hidden&quot;, it does not have the special meaning defined herein.</p>
<p>If the form is used in an IQ, the namespace of the &lt;query/&gt; element SHOULD match the base namespace of the FORM_TYPE. (One possible way of solving this problem would have been to reuse the &lt;query/&gt; tag from the IQ form of jabber:x:data within messages, but that would have meant that existing clients would not have been able to participate in these exchanges.)</p>
</section1>
<section1 topic='Error Codes' anchor='errors'>
<p>If the receiving entity believes that a specified field is invalid for the given FORM_TYPE, the receiver MAY respond to the sender with a "Not Acceptable" error; alternatively, the receiver MAY choose to ignore unknown fields.</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
<p>Security-conscious programs that are using this approach should be careful to process only agreed-upon fields, with agreed-upon types, or "x-" fields that are understood by a particular implementation and a user of that implementation.</p>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
<p>This document requires no interaction with &IANA; for now. However, if this document is submitted to the IETF later, IANA should be used to standardize the field names rather than the XMPP Registrar.</p>
</section1>
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
<section2 topic='Registries' anchor='registrar-reg'>
<section3 topic='FORM_TYPEs Registry' anchor='registrar-reg-formtypes'>
<p>The XMPP Registrar shall maintain a registry of information about submitted FORM_TYPEs.</p>
<section4 topic='Process' anchor='registrar-reg-formtypes-process'>
&REGPROCESS;
<code><![CDATA[
<form_type>
<name>FORM_TYPE namespace or namespace derivative</name>
<doc>associated specification</doc>
<desc>natural-language description of form type</desc>
<field
var='the_field_name'
type='the_field_type'
label='natural-language description of field'/>
</form_type>
]]></code>
<p>The registrant MAY register more than one FORM_TYPE at a time, each contained in a separate &lt;form_type/&gt; element. The registrant MAY also register more than one field at a time, each contained in a separate &lt;field/&gt; child element. Registrations of new fields within an existing FORM_TYPE MUST include the full XML snippet but SHOULD NOT include the FORM_TYPE description (only the name and the XEP number or other document identifier). Note that for ease of use the format for the &lt;field/&gt; element in the registry submission is the same as that defined in XEP-0004; in addition, the value of the 'type' attribute MUST be one of those defined in that XEP-0004.</p>
<p>In addition, a registrant MAY also register particular field option values for fields of type 'list-single' and 'list-multi'. The format for such submissions is as follows:</p>
<code><![CDATA[
<form_type>
<name>FORM_TYPE namespace or namespace derivative</name>
<doc>associated XEP or other document</doc>
<desc>natural-language description of form type</desc>
<field
var='the_field_name'
type='the_field_type'
label='natural-language description of field'>
<option label='natural-language description of option'>
<value>the_value</value>
</option>
</field>
</form_type>
]]></code>
</section4>
</section3>
</section2>
</section1>
</xep>