| Abstract: | This document specifies how to standardize field variables used in the context of jabber:x:data forms. |
| Authors: | Joe Hildebrand, Peter Saint-Andre |
| Copyright: | © 1999 - 2011 XMPP Standards Foundation. SEE LEGAL NOTICES. |
| Status: | Active |
| Type: | Informational |
| Version: | 1.2pre1 |
| Last Updated: | 2011-10-18 |
NOTICE: This Informational specification defines a best practice or protocol profile that has been approved by the XMPP Council and/or the XSF Board of Directors. Implementations are encouraged and the best practice or protocol profile is appropriate for deployment in production systems.
1. Introduction
2. Requirements
3. Approach
3.1. Overview
3.2. Whether to Register
3.3. FORM_TYPE Names
3.4. Field Names
3.5. Field Values
4. Use Cases
4.1. Unspecified Form
4.2. Correctly Specified FORM_TYPE
4.3. Incorrectly Specified FORM_TYPE
4.4. IQ Example
5. Implementation Notes
6. Security Considerations
7. IANA Considerations
8. XMPP Registrar Considerations
8.1. Registries
8.1.1. FORM_TYPEs Registry
8.1.1.1. Process
Appendices
A: Document Information
B: Author Information
C: Legal Notices
D: Relation to XMPP
E: Discussion Venue
F: Requirements Conformance
G: Notes
H: Revision History
Now that Data Forms [1] has been finalized, several uses of jabber:x:data forms have been put on the standards track, including Multi-User Chat [2]. 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).
The 'jabber:x:data' namespace provides an adequate mechanism for both of these uses, as long as computer processes can rely on the var="" names on a particular type of form.
This document proposes a specific mechanism for the XMPP Registrar [3] 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.
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".
The first decision-point is whether a FORM_TYPE needs to be registered with the XMPP Registrar. The following rules apply:
While the value of the FORM_TYPE attribute SHOULD be considered an opaque string from the application perspective, the following rules apply:
For FORM_TYPEs that are registered with the XMPP Registrar, the following rules apply:
If the FORM_TYPE is not registered, the field MAY have any name (managed by the namespace owner).
Note: Older versions of this specification mandated that unregistered field names had to begin with the prefix "x-". In accordance with X-Dash [6], that mandate has been removed.
Field values may also be registered; refer to the XMPP Registrar section of this document.
These are forms that do not have a hidden field of name FORM_TYPE. Existing processing rules still apply.
Example 1. Message with no FORM_TYPE
<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>
In the following example, the FORM_TYPE is 'http://jabber.org/protocol/pubsub', all of the fields whose names start with "pubsub#" are registered with the XMPP Registrar (see Publish-Subscribe [7]), and the custom "time_restrictions" field defined by the organization at example.com uses Clark Notation [8] in the field name.
Example 2. Message with FORM_TYPE
<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="{http://example.com/pubsub}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>
If the FORM_TYPE field is not hidden, it MUST be ignored as a context indicator.
Example 3. Message with bad FORM_TYPE
<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>
The following example shows a user's interaction with a Multi-User Chat room in order to register with the room.
Example 4. User Requests Registration Requirements
<iq
from='hag66@shakespeare.lit/pda'
to='darkcave@macbeth.shakespeare.lit'
type='get'
id='reg1'>
<query xmlns='jabber:iq:register'/>
</iq>
Example 5. Service Returns Registration Form
<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 6. User Submits Registration Form
<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>
If the FORM_TYPE field is not type="hidden", it does not have the special meaning defined herein.
If the form is used in an IQ, the namespace of the <query/> element SHOULD match the base namespace of the FORM_TYPE. (One possible way of solving this problem would have been to reuse the <query/> 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.)
Security-conscious programs that are using this approach should be careful to process only agreed-upon fields with agreed-upon types.
This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [9] for now.
The XMPP Registrar shall maintain a registry of information about submitted FORM_TYPEs.
In order to submit new values to this registry, the registrant shall define an XML fragment of the following form and either include it in the relevant XMPP Extension Protocol or send it to the email address <registrar@xmpp.org>:
<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>
The registrant MAY register more than one FORM_TYPE at a time, each contained in a separate <form_type/> element. The registrant MAY also register more than one field at a time, each contained in a separate <field/> 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 <field/> 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.
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:
<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>
Series: XEP
Number: 0068
Publisher: XMPP Standards Foundation
Status:
Active
Type:
Informational
Version: 1.2pre1
Last Updated: 2011-10-18
Approving Body: XMPP Council
Dependencies: XMPP Core, XEP-0004
Supersedes: None
Superseded By: None
Short Name: formtypes
Registry:
<http://xmpp.org/registrar/formtypes.html>
Source Control:
HTML
This document in other formats:
XML
PDF
Email:
jhildebr@cisco.com
JabberID:
hildjj@jabber.org
Email:
stpeter@jabber.org
JabberID:
stpeter@jabber.org
URI:
https://stpeter.im/
The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 3920) and XMPP IM (RFC 3921) 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 <http://xmpp.org/about/discuss.shtml> 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. XEP-0004: Data Forms <http://xmpp.org/extensions/xep-0004.html>.
2. XEP-0045: Multi-User Chat <http://xmpp.org/extensions/xep-0045.html>.
3. 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 <http://xmpp.org/registrar/>.
4. The XMPP Standards Foundation (XSF) is an independent, non-profit membership organization that develops open extensions to the IETF's Extensible Messaging and Presence Protocol (XMPP). For further information, see <http://xmpp.org/xsf/>.
5. XEP-0053: XMPP Registrar Function <http://xmpp.org/extensions/xep-0053.html>.
6. Deprecating Use of the "X-" Prefix in Application Protocols <http://tools.ietf.org/html/draft-ietf-appsawg-xdash>. Work in progress.
7. XEP-0060: Publish-Subscribe <http://xmpp.org/extensions/xep-0060.html>.
8. Clark Notation, a syntax to allow universal names written as a URI in curly brackets followed by the local name; developed by James Clark. <http://www.jclark.com/xml/xmlns.htm>.
9. 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/>.
Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/
END