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GEOPRIV                                                       M. Thomson
Internet-Draft                                                    Andrew
Intended status: Standards Track                            May 27, 2010
Expires: November 28, 2010


       Using HTTP GET with HTTP-Enabled Location Delivery (HELD)
                   draft-thomson-geopriv-held-get-02

Abstract

   This document describes how an HTTP GET request to an HTTP-Enabled
   Location Delivery (HELD) resource is handled by the server
   responsible for that resource.  This ensures that requests generated
   by user agents that are unaware of the special status of a URI do not
   result in unhelpful responses and enables the use of HTTP GET for
   location configuration and dereference.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 28, 2010.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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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



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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  HTTP GET Behaviour  . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 4
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 5







































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1.  Introduction

   The HTTP-Enabled Location Delivery (HELD) protocol
   [I-D.ietf-geopriv-http-location-delivery] prohibits the use of the
   HTTP GET method.  It does this because a HELD request is not always
   safe and idempotent [RFC2616], an attribute necessary for use of GET.

   The behaviour that is expected when a client makes an HTTP GET
   request to the a HELD URI is therefore undefined.  GET is the method
   assumed by generic user agents, therefore unless context identifies
   an "https:" URI as a HELD URI, such a user agent might simply send an
   HTTP GET.

   Rather than providing an HTTP 405 (Method Not Allowed) response
   indicating that POST is the only permitted method, this document
   describes a way for a LIS to provide a HELD location response if it
   receives an HTTP GET request.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  HTTP GET Behaviour

   A HELD URI is an "https:" or "http:" URI that is either the product
   of LIS discovery [I-D.ietf-geopriv-lis-discovery] or a location URI
   generated by a LIS [I-D.winterbottom-geopriv-deref-protocol].

   An HTTP GET request to a HELD URI produces a HELD response as if the
   following HELD request had been sent using HTTP POST:

     <locationRequest xmlns="urn:ietf:params:xml:ns:geopriv:held">
       <locationType exact="false">
         geodetic civic
       </locationType>
     </locationRequest>

   If the URI is a location URI, this request complies with the limited
   profile of HELD described in
   [I-D.winterbottom-geopriv-deref-protocol].  However, a location URI
   MUST NOT be provided in response to a location dereferencing request.

   HTTP GET requests must be safe and idempotent - that is, there are no
   side-effects of making the request and repeating the request does not
   change the result.  If the response provides a location object, this
   does not pose a problem.  Changes in the location information do not



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   occur as a result of requests, they are a result of a change in the
   value of the resource (the resource being the location of the
   Target).

   To ensure that these requests are idempotent, a LIS MUST NOT generate
   a location URI as a result of serving a GET request.  However, if a
   location URI for the target already exists, it MAY be provided.  This
   approach only works as long as the location URI operates on the
   "authorization by possession" authorization model ([RFC5808]).

4.  Security Considerations

   The security considerations of HELD
   [I-D.ietf-geopriv-http-location-delivery] apply.  This document
   introduces no further security considerations.

5.  IANA Considerations

   This document has no IANA actions.

   [RFC Editor: please remove this section prior to publication.]

6.  References

6.1.  Normative References

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

   [RFC2616]                                  Fielding, R., Gettys, J.,
                                              Mogul, J., Frystyk, H.,
                                              Masinter, L., Leach, P.,
                                              and T. Berners-Lee,
                                              "Hypertext Transfer
                                              Protocol -- HTTP/1.1",
                                              RFC 2616, June 1999.

   [I-D.ietf-geopriv-http-location-delivery]  Barnes, M., Winterbottom,
                                              J., Thomson, M., and B.
                                              Stark, "HTTP Enabled
                                              Location Delivery (HELD)",
                                              draft-ietf-geopriv-http-
                                              location-delivery-16 (work
                                              in progress), August 2009.




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6.2.  Informative References

   [RFC5808]                                  Marshall, R.,
                                              "Requirements for a
                                              Location-by-Reference
                                              Mechanism", RFC 5808,
                                              May 2010.

   [I-D.ietf-geopriv-lis-discovery]           Thomson, M. and J.
                                              Winterbottom, "Discovering
                                              the Local Location
                                              Information Server (LIS)",
                                              draft-ietf-geopriv-lis-
                                              discovery-15 (work in
                                              progress), March 2010.

   [I-D.winterbottom-geopriv-deref-protocol]  Winterbottom, J.,
                                              Tschofenig, H.,
                                              Schulzrinne, H., Thomson,
                                              M., and M. Dawson, "A
                                              Location Dereferencing
                                              Protocol Using HELD", draf
                                              t-winterbottom-geopriv-
                                              deref-protocol-05 (work in
                                              progress), January 2010.

Author's Address

   Martin Thomson
   Andrew
   Andrew Building (39)
   University of Wollongong
   Northfields Avenue
   Wollongong, NSW  2522
   AU

   Phone: +61 2 4221 2915
   EMail: martin.thomson@andrew.com
   URI:   http://www.andrew.com/












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