ecrit                                                           B. Rosen
Internet-Draft                                                   Neustar
Intended status: Standards Track                           July 18, 2016
Expires: January 19, 2017

            Validation of Locations Around a Planned Change


   This document defines an extension to LoST (RFC5222) that allows a
   planned change to the data in the LoST server to occur.  Records that
   previously were valid will become invalid at a date in the future,
   and new locations will become valid after the date.  The extension
   adds two elements to the <findservice> request: a URI to be used to
   inform the LIS that previously valid locations will be invalid after
   the planned change date, and add a date which requests the server to
   perform validation as of the date specified.  It also adds an
   optional TTL element to the response, which informs all queriers the
   current expected lifetime of the validation.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on January 19, 2017.

Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents

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   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  <plannedChange> element . . . . . . . . . . . . . . . . . . .   4
   4.  <locationInvalidated> object  . . . . . . . . . . . . . . . .   4
   5.  uri Not Stored Warning  . . . . . . . . . . . . . . . . . . .   4
   6.  TTL in Response . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Relax NG Schema . . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Relax NG Schema Registration  . . . . . . . . . . . . . .   8
     9.2.  LoST Namespace Registration . . . . . . . . . . . . . . .   9
   10. Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   This document describes an update to the LoST protocol [RFC5222]
   which allows a <findservice> request to optionally add a URI and a
   date to be used with planned changes to the underlying location
   information in the server.  The URI is retained by the LoST server,
   associated with the data record that was validated, and used to
   notify the LIS (the LoST client) when a location which was previously
   valid will become invalid.  The date is used by the client to ask the
   server to perform validation as of a future date.  In addition to
   this mechanism, the lt;findserviceResponse> is also extended to
   provide a TTL for validation, after which the client should
   revalidate the location.

   Validation of civic locations involves dealing with data that changes
   over time.  A typical example is a portion of a county or province
   that was not part of a municipality is "annexed" to a municipality.
   Prior to the change, the content of the PIDF A3 element would be
   blank, or represent some other value and after the change would be
   the municipality that annexed that part of the county/province.  This
   kind of annexation has an effectivity date and time (typically 00:00
   on the first or last day of a month).

   Records in a LIS must change around these kinds of events.  The old
   record must be discarded, and a new, validated record must be loaded
   into the LIS.  It is often difficult for the LIS operator to know

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   that records must be changed around such events.  There are other
   circumstances where locations that were previously valid become
   invalid, such as a street renaming or renumbering event.  As RFC5222
   defines validation, the only way for a LIS to discover such changes
   was to periodically revalidate its entire database.  Of course, this
   would not facilitate timely changes, is not coordinated with the
   actual change event, and also adds significant load to the LoST
   server.  Even if re-validation is contemplated, the server has no
   mechanism to control, or even suggest the time period for

   This extension allows the client to provide a stable URI that is
   retained by the server associated with the location information used
   in the request.  In the event of a planned change, or any other
   circumstance where the LI becomes invalid, the server sends a
   notification to the URI informing it of a change.  The notification
   contains the date and time when the LI becomes invalid.

   Ideally, following such a notification, the LIS will prepare a new
   record to be inserted in its active database, that becomes active at
   the precise planned event date and time, at which point it would also
   delete the old record.  However, the new record has to be valid, and
   the LIS would like to validate it prior to the planned change event.
   If it requests validation before the planned event, the server
   (without this extension) would inform the client that the location
   was invalid.  This extension includes an optional "asOf" date and
   time in the request that allows the LoST server to provide validation
   as of the date and time specified, as opposed to the "as of now"
   implied in the current LoST protocol.

   When it is not practical or advisable for the LIS to maintain stable
   URIs for all of its records, periodic revalidation can be still used
   to maintain the data in the LIS.  However, the server should be able
   to control the rate of such revalidation.  For this purpose, a new
   TTL element is included in the lt;findserviceResponse> which provides
   advice from the server to the LIS of when validation is suggested.

2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

   "Server" in this document refers to the LoST server and "Client" is
   the LoST client, even when the server is performing an operation on
   the client.

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3.  <plannedChange> element

   This document defines a new element to <findService> called
   'plannedChange'.  This element contains two attributes: 'uri' and
   'asOf'.  The 'uri' attribute MUST be a URI with a scheme of https.
   The URI will be stored by the server against the location in the
   request for subsequent use with the notification function defined
   below.  To minimize storage requirements of at the server, the length
   of the URI MUST be less than 256 bytes.  Each client of the server
   may only store one URI against a location, where "location" is
   defined by policy at the server, since a given unique location may
   have many combinations of LI elements that resolve to the same
   location.  If the server receives a 'uri' for the same location from
   the same client, the URI in the request replaces the URI it
   previously retained.  Policy at the server may limit how many uris it
   retains for a given location.  A new warning is defined below to be
   used to indicate that the URI has not been stored.  If the location
   in the request is invalid, the uri will not be stored and the warning
   will be returned.

   The 'asOf' attribute contains a date and time.  The server will
   validate the location in the request as of the date specified, taking
   into account planned changes.  This allows the client to verify that
   it can make changes in the LIS commensurate with changes in the LoST
   server by validating locations in advance of a change.

4.  <locationInvalidated> object

   When the server needs to invalidate a location where the client
   provided a URI in <plannedChange>, the server executes an HTTPS POST
   containing <locationInvalidated> to the URI previously provided.
   This is the notice from the server to the client that the location
   may be invalid and should be revalidated.  <locationInvalidated>
   contains an asOf attribute that specifies when the location may
   become invalid.  If the date/time in asOf is earlier than the time
   the <locationInvalidated> was sent, the location may already be
   invalid and the LIS should take immediate action.  If the POST
   operation fails, the server MAY retry the operation immediately, and
   if it fails again, retry the operation at a later time.

5.  uri Not Stored Warning

   A new warning is added to the exceptionContainer, 'uriNotStored'.
   This warning MUST NOT be returned unless the plannedChange element
   was found in the corresponding request.  The warning is returned when
   the server decides not to store the URI found in the plannedChange
   element.  As discussed above, this may occur because, among other
   reasons, the policy at the server limits how many URIs will be stored

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   against a specific location, the uri is not well formed or the policy
   at the server has some other restriction on the feature.

6.  TTL in Response

   A new 'ttl' element is added to the lt;findserviceResponse>.  The ttl
   element contains a date and time after which the client may wish to
   revalidate the location at the server.  This element MAY be added by
   the server if validation is requested in the response.  The form of
   the element is the 'expires' pattern, which allows explicit 'No
   Cache' and 'No Expiration' values to be returned.  'No Cache' has no
   meaning and MUST NOT be returned in TTL.  'No Expiration' means the
   server does not have any suggested revalidation period.

   Selecting a revalidation interval is a complex balancing of
   timeliness, server load, stability of the underlying data, and policy
   of the LoST server.  Too short, and load on the server may overwhelm
   it.  Too long and invalid data may persist in the server for too
   long.  The URI mechanism provides timely notice to coordinate
   changes, but even with it, it is often advisable to revalidate data

   In areas that have little change in data, such as fully built out,
   stable communities already part of a municipality, it may be
   reasonable to set revalidation periods of 6 months or longer,
   especially if the URI mechanism is widely deployed at both the server
   and the clients.  In areas that are quickly growing, 20-30 day
   revalidation may be more appropriate even though such revalidation
   would be the majority of the traffic on the LoST server.

   When a planned change is made, typically the TTL for the affected
   records is lowered, so that revalidation is forced soon after the
   change is implemented.  It is not advisable to set the expiration
   precisely at the planned change time if a large number of records
   will be changed, since that would cause a large spike in traffic at
   the change time.  Rather, the expiration time should have a random
   additional time added to it to spread out the load.

7.  Relax NG Schema

   The Relax NG schema in [RFC5222] is extended to include:

   namespace a = ""
   default namespace ns1 = "urn:ietf:params:xml:ns:lost-plannedChange1"

   ##       Extension to Location-to-Service Translation (LoST) Protocol
   ##       to support a planned change to location data

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   ##       plannedChange is used in the extensionPoint of
   ##       commonRequestPattern in a findService request
   ##       locationInvalidated is used by the LoST server to notify a
   ##       LIS that a previously valid location may be (or will become)
   ##       invalid
   ##       ttl is used in the extensionPoint of
   ##       commonResponsePattern in a findService response
   ##       uriNotStored is a new warning to be used in a
   ##       exceptionContainer in the warnings element of a
   ##       findServiceResponse
   start =
     | locationInvalidated
     | uriNotStored
   ##       plannedChange
   div {
     plannedChange =
       element plannedChange {
         attribute uri {
           xsd:anyURI }?,
         attribute asOf {
           xsd:dateTime }?,

   ##       locationInvalidated
   div {
     locationInvalidated =
       element locationInvalidated {
         attribute asOf {
           xsd:dateTime }?,

   ##       ttl

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   div {
     ttl =
       element ttl {

   ##       uriNotStored
   div {
     uriNotStored =
       element uriNotStored { basicException }

   ##       Patterns for inclusion of elements from schemas in
   ##       other namespaces.
   div {

     ##         Any element not in the LoST namespace.
     notLostChange = element * - (ns1:* | ns1:*) { anyElement }

     ##         A wildcard pattern for including any element
     ##         from any other namespace.
     anyElement =
       (element * { anyElement }
        | attribute * { text }
        | text)*

     ##         A point where future extensions
     ##         (elements from other namespaces)
     ##         can be added.
     extensionPoint = notLostChanged*

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8.  Security Considerations

   As an extension to LoST, this document inherits the security issues
   raised in [RFC5222].  The server could be tricked into storing a
   malicious URI which, when sent the locationInvalidated object could
   trigger something untoward.  The server MUST NOT accept any data from
   the client in response to POSTing the locationInvalidated.

   The server is subject to abuse by clients because it is being asked
   to store something and may need to send data to an uncontrolled URI.
   Clients could request many URIs for the same location for example.
   The server MUST have policy that limits use of this mechanism by a
   given client.  If the policy is exceeded, the server returns the
   uriNotStored warning.  The server MUST validate that the content of
   the uri sent is syntactically valid and meets the 256 byte limit.
   When sending the locationInvalidated object to the uri stored, the
   server MUST protect itself against common http vulnerabilities.

   The mutual authentication between client and server when is
   RECOMMENDED for both the initial findService operation that requests
   storing the uri and the sending of the locationInvalidated object.
   The server should be well known to the client, and its credential
   should be learned in a reliable way.  For example, a public safety
   system operating the LoST server may have a credential traceable to a
   well known Certificate Authority known to provide credentials for
   public safety agencies.  Many of the clients will be operated by
   local ISPs or other service providers where the server operator can
   reasonably obtain a good credential to use for the URI.  Where the
   server does not recognize the client, its policy MAY limit the use of
   this feature beyond what it would limit a client it recognized.

9.  IANA Considerations

9.1.  Relax NG Schema Registration

      URI:  urn:ietf:params:xml:schema:lost-planedChange1

      Registrant Contact:  IETF ECRIT Working Group, Brian Rosen

      Relax NG Schema: The Relax NG schema to be registered is contained
         in Section 5.  Its first line is

      default namespace = "urn:ietf:params:xml:ns:lost-PlannedChange1

      and its last line is


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9.2.  LoST Namespace Registration

      URI:  urn:ietf:params:xml:ns:lost-plannedChange1

      Registrant Contact:  IETF ECRIT Working Group, Brian Rosen


   <?xml version="2.0"?>
   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
   <html xmlns="">
     <meta http-equiv="content-type"
     <title>LoST Planned Change Namespace</title>
     <h1>Namespace for LoST Planned Change extension</h1>
   <p>See <a href="">

10.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC5222]  Hardie, T., Newton, A., Schulzrinne, H., and H.
              Tschofenig, "LoST: A Location-to-Service Translation
              Protocol", RFC 5222, DOI 10.17487/RFC5222, August 2008,

Author's Address

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   Brian Rosen
   470 Conrad Dr
   Mars, PA  16046


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