XEP-0350: Data Forms Geolocation Element

WARNING: This Standards-Track document is Experimental. Publication as an XMPP Extension Protocol does not imply approval of this proposal by the XMPP Standards Foundation. Implementation of the protocol described herein is encouraged in exploratory implementations, but production systems are advised to carefully consider whether it is appropriate to deploy implementations of this protocol before it advances to a status of Draft.

Table of Contents

1. Introduction

In certain protocols that make use of Data Forms (XEP-0004) [1], it can be helpful to include geolocation data. One example of such a "using protocol" is Form Discovery and Publishing (XEP-0346) [2]. This document defines a method for including geolocation data in a Data Form for something you manage and want to publish. This XEP leaves it open to developers how such a <geoloc/> form element will be rendered; possibilities might include editing Latitude and Longitude manually or through a rendered map.

There may also be the need to gather location data from both humans (using a GUI format) and computer processes (using a pre-defined but flexible format). This document defines a flexible mechanism for the XMPP Registrar [3] to standardize geographical location field names in data forms, thus enabling XMPP clients to process location fields in forms while giving protocol authors a way to specify additional location data types for non-GUI processors to determine the semantic meanings of a location field.

2. Requirements

This proposal addresses the following requirements:

• Integrate geolocation data with XEP-0004.
• Allow a potential receiver (rather than the sender) to validate geolocation data.

3. Integrate Geolocation Element with XEP-0004

The root element for geolocation data is <geoloc/> as defined in User Geolocation (XEP-0080) [4]. The information is structured by means of a <geoloc/> element that is qualified by the 'http://jabber.org/protocol/geoloc' namespace. The <geo/> element MUST be contained within a <field/> element qualified by the 'jabber:x:data' namespace.

The following example is provided only for the purpose of illustration; consult the specifications for using protocols (e.g., XEP-0080) to see canonical examples.

Example 1. Inclusion in Data Form

<x xmlns='jabber:x:data' type='form'>
  [ ... ]
   <field var='location'>
     <geoloc xmlns="http://jabber.org/protocol/geoloc">
        <text>Venice, Italy</text>
        <locality>Venice</locality>
        <country>Italy</country>
        <lat>45.44</lat>
        <lon>12.33</lon>
     </geoloc>
   </field>
   [ ... ]
</x>

4. Allow Receiver to Valdidate Geolocation Data

All elements associated with location fields MUST be qualified by the 'http://jabber.org/protocol/geoloc' namespace. The use of namespace prefixes is RECOMMENDED for large forms, to reduce the data size. To maintain the highest level of compatibility, implementations sending the form using prefixes SHOULD use the namespace prefix "geo:", and SHOULD declare the namespace prefix mapping in the ancestor <x xmlns='jabber:x:data'/> element:

The following example is provided only for the purpose of illustration; consult the specifications for using protocols (e.g. XEP-0080, XEP-0122) to see canonical examples.

Example 2. Validation of Geolocation Data

<x xmlns='jabber:x:data'
   xmlns:geo= http://jabber.org/protocol/geoloc'
   xmlns:xdv='http://jabber.org/protocols/xdata-validate'
   type='form'>
  <title>Sample Location Form</title>
  <instructions>
    Please provide information for the following location fields...
  </instructions>
  <field type='text-single' var='name' label='Event Name'/>
  <field type='text-single' var='time' label='Event Date/Time'>
    <xdv:validate datatype='xs:dateTime'>
      <basic/>
    </xdv:validate>
  </field>
  <field type='text-single' var='latitude' label='Latitude'>
    <xdv:validate datatype='geo:lat'>
      <basic/>
    </xdv:validate>
  </field>
  <field type='text-single' var='longitude' label='Longitude'>
    <xdv:validate datatype='geo:lon'>
      <basic/>
    </xdv:validate>
  </field>
</x>

5. Security Considerations

It is imperative to control access to location information, at least by default. Imagine that a stalker got unauthorized access to this information, with enough accuracy and timeliness to be able to find the target person. This scenario could lead to loss of life, so please take access control checks seriously. If an error is deliberately added to a location, the error SHOULD be the same for all receivers, to minimize the likelihood of triangulation. In the case of deliberate error, the <accuracy /> element SHOULD NOT be included.

6. IANA Considerations

This document requires no interaction with the the Internet Assigned Numbers Authority (IANA) [6].

7. XMPP Registrar Considerations

<datatype>
  <name>geo:lat</name>
  <desc>Datatype for publishing the latitude of a geographic location</desc>
  <doc>XEP-0080</doc>
</datatype>

<field type='text-single' var='latitude' label='Latitude'>
  <xdv:validate datatype='geo:lat'>
    <range min='-90'
           max='90'/>
  </xdv:validate>
  <value>45.44</value>
</field>

<datatype>
  <name>geo:lon</name>
  <desc>Datatype for publishing the longitude of a geographic location</desc>
  <doc>XEP-0080</doc>
</datatype>

<field type='text-single' var='longitude' label='Longitude'>
  <xdv:validate datatype='geo:lon'>
    <range min='-180'
         max='180'/>
  </xdv:validate>
  <value>12.33</value>
</field>

<datatype>
  <name>geo:dms</name>
  <desc>Datatype for publishing a degrees, minutes, and seconds (DMS) location</desc>
  <doc>Degree Minutes and Seconds, 'http://en.wikipedia.org/wiki/Geographic_coordinate_system'.</doc>
</datatype>

<field type='text-single' var='dms_location'>
  <xdv:validate datatype='geo:dms'/>
    <regex>([-|\\+]?\\d{1,3}[d|D|\u00B0|\\s](\\s*\\d{1,2}['|\u2019|\\s])?(\\s*\\d{1,2}[\"|\u201d])?\\s*[N|n|S|s]?)?(\\s*|,|,\\s*)?([-|\\+]?\\d+?(\\.\\d+?)??\\s*[E|e|W|w]??)</regex>
  </xdv:validate>
  <value>52d18'24.4775"N 0d52'44.0625"W</value>
</field>

<datatype>
  <name>geo:mgrs</name>
  <desc>Datatype for publishing a MGRS location</desc>
  <doc>Military Grid Reference System, 'http://en.wikipedia.org/wiki/Military_grid_reference_system'.</doc>
</datatype>

<field type='text-single' var='mgrs_location'>
  <xdv:validate datatype='geo:mgrs'/>
    <regex>\\d{1,2}[A-Za-z]\\s*[A-Za-z]{2}\\s*\\d{1,5}\\s*\\d{1,5}</regex>
  </xdv:validate>
  <value>38SMB4484</value>
</field>

8. XML Schema

As this document only defines semantics for existing protocol, additional schemas are not required.

Appendices

Appendix A: Document Information

Series: XEP
Number: 0350
Publisher: XMPP Standards Foundation
Status: Experimental
Type: Standards Track
Version: 0.1
Last Updated: 2014-07-03
Approving Body: XMPP Council
Dependencies: XMPP Core, XEP-0004, XEP-0080, XEP-0122
Supersedes: None
Superseded By: None
Short Name: geolocation-element
Schema: <http://www.xmpp.org/schemas/geolocation-element.xsd>
Source Control: HTML
This document in other formats: XML  PDF

Appendix B: Author Information

Appendix C: Legal Notices

Appendix D: Relation to XMPP

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) 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.

Appendix E: Discussion Venue

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>.

Appendix F: Requirements Conformance

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".

Appendix G: Notes

Appendix H: Revision History

Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/

END