GEOPRIV WG M. Barnes, Ed. Internet-Draft Nortel Intended status: Standards Track Expires: May 20, 2008 November 17, 2007 HTTP Enabled Location Delivery (HELD) draft-ietf-geopriv-http-location-delivery-03.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 20, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract A Layer 7 Location Configuration Protocol (L7 LCP) is described that is used for retrieving location information from a server within an access network. The protocol includes options for retrieving location information either by-value or by-reference. The protocol is an application-layer protocol that is independent of session- layer. This document describes the use of Hypertext Transfer Barnes, et al. Expires May 20, 2008 [Page 1] Internet-Draft HELD November 2007 Protocol (HTTP) as a delivery mechanism for the protocol. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions & Terminology . . . . . . . . . . . . . . . . . . 4 3. Overview and Scope . . . . . . . . . . . . . . . . . . . . . . 5 4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Device Identifiers, NAT and VPNs . . . . . . . . . . . . . 7 4.1.1. Devices and VPNs . . . . . . . . . . . . . . . . . . . 8 4.1.2. LIS Handling of NATs and VPNs . . . . . . . . . . . . 8 5. Protocol Description . . . . . . . . . . . . . . . . . . . . . 8 5.1. Delivery Protocol . . . . . . . . . . . . . . . . . . . . 9 5.2. Location Request . . . . . . . . . . . . . . . . . . . . . 9 5.3. Location Response . . . . . . . . . . . . . . . . . . . . 10 5.4. Indicating Errors . . . . . . . . . . . . . . . . . . . . 10 6. Protocol Parameters . . . . . . . . . . . . . . . . . . . . . 10 6.1. "responseTime" Parameter . . . . . . . . . . . . . . . . . 11 6.2. "locationType" Parameter . . . . . . . . . . . . . . . . . 11 6.2.1. "exact" Attribute . . . . . . . . . . . . . . . . . . 12 6.3. "code" Parameter . . . . . . . . . . . . . . . . . . . . . 12 6.4. "message" Parameter . . . . . . . . . . . . . . . . . . . 13 6.5. "locationURI" Parameter . . . . . . . . . . . . . . . . . 13 6.5.1. "expires" Parameter . . . . . . . . . . . . . . . . . 13 7. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8. HTTP Binding . . . . . . . . . . . . . . . . . . . . . . . . . 17 9. Security Considerations . . . . . . . . . . . . . . . . . . . 18 9.1. Return Routability . . . . . . . . . . . . . . . . . . . . 18 9.2. Transaction Layer Security . . . . . . . . . . . . . . . . 19 10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 10.1. HTTP Example Messages . . . . . . . . . . . . . . . . . . 19 10.2. Simple Location Request Example . . . . . . . . . . . . . 22 10.3. Location Request Example for Multiple Location Types . . . 23 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 11.1. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held . . . . . . . . . . . 24 11.2. XML Schema Registration . . . . . . . . . . . . . . . . . 25 11.3. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held:http . . . . . . . . . 25 11.4. MIME Media Type Registration for 'application/held+xml' . 26 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 27 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 27 14. Changes since last Version . . . . . . . . . . . . . . . . . . 27 15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 15.1. Normative References . . . . . . . . . . . . . . . . . . . 29 15.2. Informative References . . . . . . . . . . . . . . . . . . 31 Appendix A. HELD Compliance to IETF LCP requirements . . . . . . 31 Barnes, et al. Expires May 20, 2008 [Page 2] Internet-Draft HELD November 2007 A.1. L7-1: Identifier Choice . . . . . . . . . . . . . . . . . 31 A.2. L7-2: Mobility Support . . . . . . . . . . . . . . . . . . 32 A.3. L7-3: ASP and Access Network Provider Relationship . . . . 32 A.4. L7-4: Layer 2 and Layer 3 Provider Relationship . . . . . 33 A.5. L7-5: Legacy Device Considerations . . . . . . . . . . . . 33 A.6. L7-6: VPN Awareness . . . . . . . . . . . . . . . . . . . 33 A.7. L7-7: Network Access Authentication . . . . . . . . . . . 34 A.8. L7-8: Network Topology Unawareness . . . . . . . . . . . . 34 A.9. L7-9: Discovery Mechanism . . . . . . . . . . . . . . . . 34 A.10. L7-10: PIDF-LO Creation . . . . . . . . . . . . . . . . . 34 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 35 Intellectual Property and Copyright Statements . . . . . . . . . . 37 Barnes, et al. Expires May 20, 2008 [Page 3] Internet-Draft HELD November 2007 1. Introduction The location of a Device is information that is useful for a number of applications. The L7 Location Configuration Protocol (LCP) problem statement and requirements document [11] provides some scenarios in which a Device might rely on its access network to provide the location information, such as fixed environments (e.g., DSL/Cable), mobile networks and wireless access networks. This document describes a protocol that can be used to acquire Location Information (LI) from a Location Information Server (LIS) within an access network. This specification identifies two methods for acquiring LI. Location may be retrieved from a LIS by-value, that is, the Device may acquire a literal location object describing the location of the Device. Alternatively, the Device may request that the LIS provide a location reference in the form of a location URI or set of location URIs, allowing the Device to distribute its LI by-reference. Both of these methods are compatible, and both can be provided concurrently from the same LIS so that application needs can be addressed individually. This specification defines an XML-based protocol that enables the retrieval of LI from a LIS by a Device. This protocol can be bound to any session-layer protocol, particularly those capable of MIME transport. This document describes the use of Hypertext Transfer Protocol (HTTP) as a delivery mechanism for the protocol. 2. Conventions & 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 [1]. This document uses the terms (and their acronym forms) Access Provider (AP), Location Information (LI), Location Object (LO), Device, Target, Location Generator (LG), Location Recipient (LR), Rule Maker (RM) and Rule Holder (RH) as defined in RFC 3693, GEOPRIV Requirements [7] . The terms Location Information Server (LIS), Access Network, Access Provider (AP) and Access Network Provider are used in the same context as defined in the L7 LCP Problem statement and Requirements document [11]. The usage of the terms, Civic Location/Address and Geodetic Location follows the usage in many of the referenced documents. Barnes, et al. Expires May 20, 2008 [Page 4] Internet-Draft HELD November 2007 3. Overview and Scope This document describes an interface between a Device and a Location Information Server (LIS). The LIS is present within the same administrative domain as the Device (the access network). An Access Provider (AP) operates the LIS so that Devices (and Targets) can retrieve LI. The LIS exists because not all Devices are capable of determining LI, and because, even if a device is able to determine its own LI, it may be more efficient with assistance. This document does not specify how LI is derived. This document is based on the attribution of the LI to a Device and not specifically a person (end user) or Target, based on the premise that location determination technologies are generally designed to locate a device and not a person. It is expected that, for most applications, LI for the device can be used as an adequate substitute for the end user's LI. Since revealing the location of the device almost invariably reveals some information about the location of the user of the device, the same level of privacy protection demanded by a user is required for the device. This approach may require either some additional assurances about the link between device and target, or an acceptance of the limitation that unless the device requires active user authentication, there is no guarantee that any particular individual is using the device at that instant. Barnes, et al. Expires May 20, 2008 [Page 5] Internet-Draft HELD November 2007 The following diagram shows the logical configuration of some of the functional elements identified in [7] and the LIS defined in [11] and where this protocol applies, with the Rule Maker and Target represented by the role of the Device. +---------------------------------------------+ | Access Network Provider | | | | +--------------------------------------+ | | | Location Information Server | | | | | | | | | | | | | | | | | | | +------|---------------------'---------+ | +----------|---------------------'------------+ | ' | ' HELD APP | ' Rule Maker - _ +-----------+ +-----------+ o - - | Device | | Location | and as specified in [8] MUST be applied. A default value of "no" SHALL be used for the element. A default value of 24 hours SHALL be used for value of any generated PIDF-LO documents. A LIS MAY provide a shorter value for but MUST NOT provide a value longer than 24 hours. Requesting location directly does not always address the requirements of an application. A Device can request a location URI instead of literal location. A Location URI is a URI [21] of any scheme, which a Location Recipient (LR) can use to retrieve LI. A location URI provided by a LIS can be assumed to be globally-addressable; that is, anyone in possession of the URI can access the LIS. This does not in any way suggest that the LIS is bound to reveal the location associated with the location URI. This issue is deemed out of scope for this document. The merits and drawbacks of using a Location URI approach are discussed in [15]. 4.1. Device Identifiers, NAT and VPNs Use of the HELD protocol is subject to the viability of the identifier used by the LIS to determine location. As described in Section 3, this document describes the use of the IP address of the Device as the identifier. When Network Address Translation (NAT), a Virtual Private Network (VPN) or other forms of address modification occur between the Device and the LIS, the location returned could be inaccurate. This is not always the case. For example, a NAT used in a residential Local Area Network (LAN) is typically not a problem. The external IP address used on the Wide Area Network (WAN) side of the NAT is an acceptable identifier for all of the devices in the Barnes, et al. Expires May 20, 2008 [Page 7] Internet-Draft HELD November 2007 residence since the covered geographical area is small. On the other hand, if there is a VPN between the Device and the LIS, for example for a teleworker, then the address seen by the LIS might not be the right address to identify the location of the Device. 4.1.1. Devices and VPNs To minimize the impact of VPNs, Devices SHOULD perform their HELD query prior to establishing a VPN tunnel. It is RECOMMENDED that discovery [14] and an initial query are performed before establishing the VPN. Devices that establish VPN connections for use by other devices inside a LAN or other closed network MAY act as a HELD LIS for those other devices. Devices within the closed network are not necessarily able to detect the presence of the VPN and are reliant on the VPN device. To this end, a VPN device SHOULD provide the address, of the LIS server it provides, in response to discovery queries. It could also be useful for a VPN device to act as a LIS for other location configuration options such as Dynamic Host Configuration Protocol (DHCP)[20] or Link Layer Discovery Protocol - Media Endpoint Discovery (LLDP-MED) [23]. VPN devices that act as a LIS MAY acquire their own location using HELD. 4.1.2. LIS Handling of NATs and VPNs A LIS MUST NOT provide location information to a Device if it cannot provide accurate information. This applies where the Device uses a VPN connection or is behind a NAT that serves a large geographic area or multiple geographic locations (for example, a NAT used by an enterprise to connect their private network to the Internet). The LIS needs to be configured to recognize identifiers that represent these conditions. LIS operators have a large role in ensuring the best possible environment for location determination. The LIS operator needs to ensure that the LIS is properly configured with identifiers that fall within NATs and VPNs. In order to serve a Device on a remote side of a NAT or VPN a LIS needs to have a presence on the side of the NAT or VPN nearest the Device. 5. Protocol Description As discussed in Section 4, this protocol provides for the retrieval of a Location or a Location URI from a LIS. Three messages are Barnes, et al. Expires May 20, 2008 [Page 8] Internet-Draft HELD November 2007 defined to support the location retrieval: locationRequest, locationResponse and error. Messages are defined as XML documents. The Location Request (locationRequest) message is described in Section 5.2. A Location Request message from a Device indicates whether a Location (and the specific type of location) and/or a Location URI should be returned. The LIS replies with a response (locationResponse), including a PIDF-LO document and/or one or more Location URIs in case of success, or an error message in case of an error. A MIME type "application/held+xml" is registered in Section 11.4 to distinguish HELD messages from other XML document bodies. This specification follows the recommendations and conventions described in [18], including the naming convention of the type ('+xml' suffix) and the usage of the 'charset' parameter. Section 6 contains a more thorough description of the protocol parameters, valid values, and how each should be handled. Section 7 contains a more specific definition of the structure of these messages in the form of an XML Schema [12]. 5.1. Delivery Protocol The HELD protocol is an application-layer protocol that is defined independently of any lower layers. This means that any protocol can be used to transport this protocol providing that it can provide a few basic features: o The protocol must have acknowledged delivery. o The protocol must be able to correlate a response with a request. o The protocol must provide authentication, privacy and protection against modification. This document describes the use of a combination of HTTP [3], TLS [2] and TCP [16] in Section 8 . 5.2. Location Request A location request message is sent from the Device to the LIS when it requires LI. The type of LI that a Device requests is determined by the type of LI that is included in the "locationType" element. The location request is made by sending a document formed of a "locationRequest" element. The LIS uses the source IP address of the location request message as the primary source of identity for the requesting device or target. It is anticipated that other Device identities MAY be provided through schema extensions. The successful response to a location request message is a document formed of a "locationResponse" element, unless the request fails, in which case Barnes, et al. Expires May 20, 2008 [Page 9] Internet-Draft HELD November 2007 the LIS MUST provide an error indication document. The LIS MUST ignore any part of a location request message that it does not understand. 5.3. Location Response The response to a Location request MUST contain either a PIDF-LO and/or Location URI(s), depending upon the requested "locationType". 5.4. Indicating Errors In the event of an error, the LIS MUST respond to the Device with an error document. The error response applies to all request types and MUST also be sent in response to any unrecognized request. An error indication document consists of an "error" element. The "error" element MUST include a "code" attribute that indicates the type of error. A set of predefined error codes are included in Section 6.3. Error responses MAY also include a "message" attribute that can include additional information. This information SHOULD be for diagnostic purposes only, and MAY be in any language. The language of the message SHOULD be indicated with an "xml:lang" attribute. 6. Protocol Parameters This section describes, in detail the parameters that are used for this protocol. Table 1 lists the top-level components used within the protocol and where they are mandatory or optional for each of the messages. +------------------------+----------------+-----------------+-------+ | Parameter | Location | Location | Error | | | Request | Response | | +------------------------+----------------+-----------------+-------+ | responseTime | o | | | | (Section 6.1) | | | | | locationType | o | | | | (Section 6.2) | | | | | exact (Section 6.2.1) | o | | | | code (Section 6.3) | | m | m | | message (Section 6.4) | | | o | | locationURI | | o | | | (Section 6.5) | | | | Barnes, et al. Expires May 20, 2008 [Page 10] Internet-Draft HELD November 2007 | expires | | m | | | (Section 6.5.1) | | | | +------------------------+----------------+-----------------+-------+ Table 1: Message Parameter Usage 6.1. "responseTime" Parameter The "responseTime" parameter is optional and indicates to the LIS how long the Device is prepared to wait for a response and/or the purpose for which the Device needs the location. In the case of emergency services, the purpose of obtaining the LI could be either for routing a call to the appropriate PSAP or indicating the location to which responders should be dispatched. The time values defined for those purposes, emergencyRouting and emergencyDispatch, will likely be governed by jurisdictional policies, and SHOULD be configurable on the LIS. The value of the "responseTime" parameter is indicative only and the LIS is under no obligation to strictly adhere to the time limit implied; any enforcement of the time limit is left to the requesting Device. The "responseTime" parameter is expressed with a decimal seconds value, which may include a decimal point. It is RECOMMENDED that systems support millisecond precision for this parameter. The LIS SHOULD provide the most accurate LI that can be determined within the specified interval for the specific service. The LIS MAY use the value of the "responseTime" parameter as input when selecting the method of location determination, where multiple such methods exist. If this parameter is absent, then the LIS MUST return the most precise LI it is capable of determining, with the time interval being implementation dependent. 6.2. "locationType" Parameter The "locationType" element MAY be included in a location request message. It contains a list of LI types that are requested by the Device. The following list describes the possible values: any: The LIS SHOULD attempt to provide LI in all forms available to it. This value MUST be assumed as the default if no "locationType" is specified. The LIS SHOULD return location information in a form that is suited for routing and responding to an emergency call in its jurisdiction. The LIS MAY alternatively or additionally return a location URI. Barnes, et al. Expires May 20, 2008 [Page 11] Internet-Draft HELD November 2007 geodetic: The LIS SHOULD return a geodetic location for the Target. civic: The LIS SHOULD return a civic address for the Target. Any type of civic address may be returned. locationURI: The LIS SHOULD return a location URI for the Target. The LIS SHOULD return the requested location type or types. The LIS MAY provide additional location types, or it MAY provide alternative types if the request cannot be satisfied for a requested location type. If the "exact" attribute is present and set to "true" in a location request, then a successful LIS response MUST provide the requested location type only, with no additional location information. The "exact" attribute has no effect when this element is set to "any". The "SHOULD"-strength requirement on this parameter is included to allow for soft-failover. This enables a fixed client configuration that prefers a specific location type without causing location requests to fail when that location type is unavailable. Unless the "exact" attribute is set, the LIS MUST provide LI in any available form if it is unable to comply with the request. For example, a notebook computer could be configured to retrieve civic addresses, which is usually available from typical home or work situations. However, when using a wireless modem, the LIS might be unable to provide a civic address and thus provides a geodetic address. 6.2.1. "exact" Attribute When the "exact" attribute is set to "true", it indicates to the LIS that the contents of the "locationType" parameter MUST be strictly followed. The default value of "false" allows the LIS the option of returning something beyond what is specified, such as a location URI when only a civic location was requested. A value of "true" indicates that the LIS MUST provide a location of the requested type or types or MUST provide an error. The LIS MUST provide the requested types only. The LIS MUST handle an exact request that includes a "locationType" element set to "any" as if the "exact" attribute were set to "false". 6.3. "code" Parameter All "error" responses MUST contain a response code. All errors are application-level errors, and MUST only be provided in successfully processed transport-level responses. For example where HTTP is used as the transport, HELD error messages MUST be accompanied by a 200 OK HTTP response. Barnes, et al. Expires May 20, 2008 [Page 12] Internet-Draft HELD November 2007 HELD error responses may be one of the following tokens: requestError: This code indicates that the request was badly formed in some fashion. xmlError: This code indicates that the XML content of the request was either badly formed or invalid. generalLisError: This code indicates that an unspecified error occurred at the LIS. locationUnknown: This code indicates that the LIS could not determine the location of the Device. unsupportedMessage: This code indicates that the request was not supported or understood by the LIS. timeout: This code indicates that the LIS could not satisfy the request within the time specified in the "responseTime" parameter. cannotProvideLiType: This code indicates that the LIS was unable to provide LI of the type or types requested. This code is used when the "exact" attribute on the "locationType" parameter is set to "true". 6.4. "message" Parameter The "error" message MAY include a "message" attribute to convey some additional, human-readable information about the result of the request. This message MAY be included in any language, which SHOULD be indicated by the "xml:lang", attribute. The default language is assumed to be English. 6.5. "locationURI" Parameter The "locationURI" element includes a single Location URI. Each Location URI that is allocated by the LIS is unique to the device that is requesting it. A "locationResponse" message MAY contain any number of "locationURI" elements. It is RECOMMENDED that the LIS allocate a Location URI for each scheme that it supports and that each scheme is present only once. URI schemes and their secure variants such as http and https MUST be regarded as two separate schemes. A "locationURI" MUST NOT contain any information that could be used to identify the Device or Target. It is RECOMMENDED that a "locationURI" contain a public address for the LIS and an anonymous identifier, such as a local identifer or unlinked pseudonym. 6.5.1. "expires" Parameter The "expires" attribute is optional and is only included in a "locationResponse" message when a Location URI is included. The "expires" attribute indicates the time at which the Location URI Barnes, et al. Expires May 20, 2008 [Page 13] Internet-Draft HELD November 2007 provided by the LIS will expire. Responses to Locations requests for Location URIs MUST include the expiry time of the Location URI. 7. XML Schema This section gives the XML Schema Definition [12] of the "application/held+xml" format. This is presented as a formal definition of the "application/held+xml" format. Note that the XML Schema definition is not intended to be used with on-the-fly validation of the presence XML document. This document defines HELD messages. Barnes, et al. Expires May 20, 2008 [Page 14] Internet-Draft HELD November 2007 Barnes, et al. Expires May 20, 2008 [Page 15] Internet-Draft HELD November 2007 8. HTTP Binding This section describes the use of HTTP [3] as a delivery mechanism for this protocol, which all conforming implementations MUST support. The request is carried in the body of an HTTP POST request. The MIME type of both request and response bodies should be "application/held+xml". The LIS populates the HTTP headers so that they are consistent with the contents of the message. In particular, the "expires" and cache control headers are used to control the caching of any PIDF-LO Barnes, et al. Expires May 20, 2008 [Page 17] Internet-Draft HELD November 2007 document or Location URIs. The HTTP status code SHOULD indicate a 2xx series response when a PIDF-LO document or Location URI is included. The use of HTTP also includes a default behaviour, which is triggered by a GET request, or a POST with no request body. If either of these queries are received, the LIS MUST attempt to provide either a PIDF-LO document or a Location URI, as if the request was a location request. The implementation of HTTP as a delivery mechanism MUST implement TLS as described in [4]. TLS provides message integrity and privacy between Device and LIS. The LIS MUST use the server authentication method described in [4]; the Device MUST fail a request if server authentication fails, except in the event of an emergency. 9. Security Considerations The threat model for this protocol assumes that the LIS exists within the same administrative domain as the Device. The LIS requires access to network information so that it can determine Location. Therefore, the LIS can use network information to protect against a number of the possible attacks. Specific requirements and security considerations for location acquisition protocols are provided in [11] including that the LCP MUST NOT assume prior network access authentication, which is addressed in Section 9.2 An in-depth discussion of the security considerations applicable to the use of Location URIs and by-reference provision of LI is included in [15]. 9.1. Return Routability It is RECOMMENDED that Location Information Servers use return routability rather than requiring Device authentication. Device authentication SHOULD NOT be required due to the administrative challenge of issuing and managing of client credentials, particularly when networks allow visiting users to attach devices. However, the LIS MAY require any form of authentication as long as these factors are considered. Addressing information used in a request to the LIS is used to determine the identity of the Device, and to address a response. This ensures that a Device can only request its own LI. Barnes, et al. Expires May 20, 2008 [Page 18] Internet-Draft HELD November 2007 A temporary spoofing of IP address could mean that a device could request a Location URI that would result in another Device's location. One or more of the follow approaches are RECOMMENDED to limit this exposure: o Location URIs SHOULD have a limited lifetime, as reflected by the value for the expires element (Section 6.5.1). o The network SHOULD have mechanisms that protect against IP address spoofing. o The LIS SHOULD ensure that requests can only originate from within its administrative domain. o The LIS and network SHOULD be configured so that the LIS is made aware of Device movement within the network and addressing changes. If the LIS detects a change in the network, then all location URIs MUST be invalidated. The above measures are dependent on network configuration and SHOULD be considered with circumstances in mind. For instance, in a fixed internet access, providers may be able to restrict the allocation of IP addresses to a single physical line, ensuring that spoofing is not possible; in such an environment, other measures may not be necessary. 9.2. Transaction Layer Security All bindings for this protocol MUST ensure that messages are adequately protected against eavesdropping and modification. Bindings MUST also provide a means of authenticating the LIS. It is RECOMMENDED that all bindings also use TLS [2]. For the HTTP binding, TLS MUST be used. TLS provides protection against eavesdropping and modification. The server authentication methods described in HTTP on TLS [4] MUST be used. 10. Examples 10.1. HTTP Example Messages The examples in this section show a complete HTTP message that includes the HELD request or response document. Barnes, et al. Expires May 20, 2008 [Page 19] Internet-Draft HELD November 2007 This example shows the most basic request for a LO. This uses the GET feature described by the HTTP binding. This example assumes that the LIS service exists at the URL "https://lis.example.com/location". GET /location HTTP/1.1 Host: lis.example.com Accept:application/held+xml, application/xml;q=0.8, text/xml;q=0.7 Accept-Charset: UTF-8,* The GET request is exactly identical to a minimal POST request that includes an empty "locationRequest" element. POST /location HTTP/1.1 Host: lis.example.com Accept: application/held+xml, application/xml;q=0.8, text/xml;q=0.7 Accept-Charset: UTF-8,* Content-Type: application/held+xml Content-Length: 87 Barnes, et al. Expires May 20, 2008 [Page 20] Internet-Draft HELD November 2007 The successful response to either of these requests is a PIDF-LO document. The following response shows a minimal PIDF-LO response. HTTP/1.x 200 OK Server: Example LIS Date: Tue, 10 Jan 2006 03:42:29 GMT Expires: Tue, 10 Jan 2006 03:42:29 GMT Cache-control: private Content-Type: application/held+xml Content-Length: 594 -34.407 150.88001 2006-01-11T03:42:28+00:00 2006-01-10T03:42:28+00:00 Barnes, et al. Expires May 20, 2008 [Page 21] Internet-Draft HELD November 2007 The error response to either of these requests is an error document. The following response shows an example error response. HTTP/1.x 200 OK Server: Example LIS Expires: Tue, 10 Jan 2006 03:49:20 GMT Cache-control: private Content-Type: application/held+xml Content-Length: 135 Note: To focus on important portions of messages, all examples following this note do not show HTTP headers or the XML prologue. In addition, sections of XML not relevant to the example are replaced with comments. 10.2. Simple Location Request Example The location request shown below doesn't specify any location types or response time. The response to this location request is a list of Location URIs. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o sips:9769+357yc6s64ceyoiuy5ax3o@ls.example.com An error response to this location request is shown below: Barnes, et al. Expires May 20, 2008 [Page 22] Internet-Draft HELD November 2007 10.3. Location Request Example for Multiple Location Types The following Location Request message includes a request for geodetic, civic and any Location URIs. geodetic civic locationURI The corresponding Location Response message includes the requested location information, including two location URIs. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o sips:9769+357yc6s64ceyoiuy5ax3o@ls.example.com: -34.407242 150.882518 30 AU NSW Wollongong Gwynneville Northfield Avenue Barnes, et al. Expires May 20, 2008 [Page 23] Internet-Draft HELD November 2007 University of Wollongong 2 Andrew Corporation 2500 39 WS-183 U40 false 2007-05-25T12:35:02+10:00 Wiremap 2007-05-24T12:35:02+10:00 11. IANA Considerations This document registers an XML namespace and schema and the "application/held+xml" MIME type. 11.1. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held This section registers a new XML namespace, "urn:ietf:params:xml:ns:geopriv:held", as per the guidelines in [6]. URI: urn:ietf:params:xml:ns:geopriv:held Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), Mary Barnes (mary.barnes@nortel.com). XML: Barnes, et al. Expires May 20, 2008 [Page 24] Internet-Draft HELD November 2007 BEGIN HELD Messages

Namespace for HELD Messages

urn:ietf:params:xml:ns:geopriv:held

[[NOTE TO IANA/RFC-EDITOR: Please update RFC URL and replace XXXX with the RFC number for this specification.]]

See RFCXXXX.

END 11.2. XML Schema Registration This section registers an XML schema as per the guidelines in [6]. URI: urn:ietf:params:xml:schema:geopriv:held Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), Mary Barnes (mary.barnes@nortel.com). Schema: The XML for this schema can be found as the entirety of Section 7 of this document. 11.3. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held:http This section registers a new XML namespace, "urn:ietf:params:xml:ns:geopriv:held:http", as per the guidelines in [6]. URI: urn:ietf:params:xml:ns:geopriv:held:http Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), Mary Barnes (mary.barnes@nortel.com). XML: Barnes, et al. Expires May 20, 2008 [Page 25] Internet-Draft HELD November 2007 BEGIN HELD HTTP Binding WS

Namespace for HELD HTTP Binding WS

urn:ietf:params:xml:ns:geopriv:held:http

[[NOTE TO IANA/RFC-EDITOR: Please update RFC URL and replace XXXX with the RFC number for this specification.]]

See RFCXXXX.

END 11.4. MIME Media Type Registration for 'application/held+xml' This section registers the "application/held+xml" MIME type. To: ietf-types@iana.org Subject: Registration of MIME media type application/held+xml MIME media type name: application MIME subtype name: held+xml Required parameters: (none) Optional parameters: charset Indicates the character encoding of enclosed XML. Default is UTF-8. Encoding considerations: Uses XML, which can employ 8-bit characters, depending on the character encoding used. See RFC 3023 [18], section 3.2. Security considerations: This content type is designed to carry protocol data related to the location of an entity, which could include information that is considered private. Appropriate precautions should be taken to limit disclosure of this information. Interoperability considerations: This content type provides a basis for a protocol Published specification: RFC XXXX [[NOTE TO IANA/RFC-EDITOR: Please replace XXXX with the RFC number for this specification.]] Applications which use this media type: Location information providers and consumers. Additional Information: Magic Number(s): (none) File extension(s): .xml Macintosh File Type Code(s): (none) Barnes, et al. Expires May 20, 2008 [Page 26] Internet-Draft HELD November 2007 Person & email address to contact for further information: Mary Barnes Intended usage: LIMITED USE Author/Change controller: This specification is TBD Other information: This media type is a specialization of application/xml [18], and many of the considerations described there also apply to application/held+xml. 12. Contributors James Winterbottom, Martin Thomson and Barbara Stark are the authors of the original document, from which this WG document was derived. Their contact information is included in the Author's address section. In addition, they also contributed to the WG document, including the XML schema. 13. Acknowledgements The author/contributors would like to thank the participants in the GEOPRIV WG and the following people for their constructive input and feedback on this document (in alphabetical order): Nadine Abbott, Eric Arolick, Richard Barnes, Peter Blatherwick, Guy Caron, Martin Dawson, Lisa Dusseault, Jerome Grenier, Ted Hardie, Neil Justusson, Tat Lam, Marc Linsner, Patti McCalmont, Roger Marshall, Perry Prozeniuk, Carl Reed, Brian Rosen, John Schnizlein, Shida Schubert, Henning Schulzrinne, Ed Shrum, Doug Stuard, and Hannes Tschofenig. 14. Changes since last Version NOTE TO THE RFC-Editor: Please remove this section prior to publication as an RFC. Changes from WG 02 to 03: 1) Added text to address concern over use of IP address as device identifier, per long email thread - changes to section 3 (overview) and section 4 (protocol overview). 2) Removed WSDL (section 8 updated, section 8.1 and 10.4 removed) 3) Added extensibility to baseRequestType in the schema (an oversight from previous edits), along with fixing some other nits in schema (section 7) 4) Moved discussion of Location URI from section 5.3 (Location Barnes, et al. Expires May 20, 2008 [Page 27] Internet-Draft HELD November 2007 Response) to where it rightly belonged in Section 6.5 (Location URI Parameter). 5) Clarified text for "expires" parameter (6.5.1) - it's an optional parm, but required for LocationURIs 6) Clarified responseTime parameter: when missing, then the LCS provides most precise LI, with the time required being implementation specific. 7) Clarified that the MUST use in section 8 (HTTP binding) is a MUST implement. 8) Updated references (removed unused/added new). Changes from WG 01 to 02: 1) Updated Terminology to be consistent with WG agreements and other documents (e.g., LCS -> LIS and removed duplicate terms). In the end, there are no new terms defined in this document. 2) Modified definition of responseTime to reflect WG consensus. 3) Removed jurisdictionalCivic and postalCivic locationTypes (leaving just "civic"). 4) Clarified text that locationType is optional. Fixed table 1 and text in section 5.2 (locationRequest description). Text in section 6.2 (description of locationType element) already defined the default to be "any". 5) Simplified error responses. Separated the definition of error response type from the locationResponse type thus no need for defining an error code of "success". This simplifies the schema and processing. 6) Updated schema/examples for the above. 7) Updated Appendix A based on updates to requirements document, specifically changes to A.1, A.3 and adding A.10. 8) Miscellaneous editorial clarifications. Changes from WG 00 to 01: 1) heldResponse renamed to locationResponse. 2) Changed namespace references for the PIDF-LO geoShape in the Barnes, et al. Expires May 20, 2008 [Page 28] Internet-Draft HELD November 2007 schema to match the agreed GML PIDF-LO Geometry Shape Application Schema. 3) Removed "options" element - leaving optionality/extensibility to XML mechanisms. 4) Changed error codes to be enumerations and not redefinitions of HTTP response codes. 5) Updated schema/examples for the above and removed some remnants of the context element. 6) Clarified the definition of "Location Information (LI)" to include a reference to the location (to match the XML schema and provide consistency of usage throughout the document). Added an additional statement in section 7.2 (locationType) to clarify that LCS MAY also return a Location URI. 7) Modifed the definition of "Location Configuration Server (LCS)" to be consistent with the current definiton in the requirements document. 8) Updated Location Response (section 6.3) to remove reference to context and discuss the used of a local identifier or unlinked pseudonym in providing privacy/security. 9) Clarified that the source IP address in the request is used as the identifier for the target/device for the HELD protocol as defined in this document. 10) Miscellaneous editorial clarifications. 15. References 15.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [3] 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. [4] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. Barnes, et al. Expires May 20, 2008 [Page 29] Internet-Draft HELD November 2007 [5] Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup Language) XML-Signature Syntax and Processing", RFC 3275, March 2002. [6] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. [7] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J. Polk, "Geopriv Requirements", RFC 3693, February 2004. [8] Peterson, J., "A Presence-based GEOPRIV Location Object Format", RFC 4119, December 2005. [9] Thomson, M. and J. Winterbottom, "Revised Civic Location Format for PIDF-LO", draft-ietf-geopriv-revised-civic-lo-06 (work in progress), October 2007. [10] Winterbottom, J., Thomson, M., and H. Tschofenig, "GEOPRIV PIDF-LO Usage Clarification, Considerations and Recommendations", draft-ietf-geopriv-pdif-lo-profile-10 (work in progress), October 2007. [11] Tschofenig, H. and H. Schulzrinne, "GEOPRIV Layer 7 Location Configuration Protocol; Problem Statement and Requirements", draft-ietf-geopriv-l7-lcp-ps-05 (work in progress), September 2007. [12] Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn, "XML Schema Part 1: Structures Second Edition", World Wide Web Consortium Recommendation REC-xmlschema-1-20041028, October 2004, . [13] Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes Second Edition", World Wide Web Consortium Recommendation REC- xmlschema-2-20041028, October 2004, . [14] Thomson, M. and J. Winterbottom, "Discovering the Local Location Information Server (LIS)", draft-thomson-geopriv-lis-discovery-03 (work in progress), September 2007. [15] Marshall, R., "Requirements for a Location-by-Reference Mechanism", draft-ietf-geopriv-lbyr-requirements-01 (work in progress), October 2007. Barnes, et al. Expires May 20, 2008 [Page 30] Internet-Draft HELD November 2007 15.2. Informative References [16] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981. [17] Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000. [18] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [19] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [20] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host Configuration Protocol Option for Coordinate-based Location Configuration Information", RFC 3825, July 2004. [21] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [22] Polk, J. and B. Rosen, "Location Conveyance for the Session Initiation Protocol", draft-ietf-sip-location-conveyance-08 (work in progress), July 2007. [23] TIA, "ANSI/TIA-1057 Link Layer Discovery Protocol - Media Endpoint Discovery". Appendix A. HELD Compliance to IETF LCP requirements This appendix describes HELD's compliance to the requirements specified in the [11]. A.1. L7-1: Identifier Choice "The L7 LCP MUST be able to carry different identifiers or MUST define an identifier that is mandatory to implement. Regarding the latter aspect, such an identifier is only appropriate if it is from the same realm as the one for which the location information service maintains identifier to location mapping." COMPLY HELD uses the IP address of the location request message as the primary source of identity for the requesting device or target. This Barnes, et al. Expires May 20, 2008 [Page 31] Internet-Draft HELD November 2007 identity can be used with other contextual network information to provide a physical location for the Target for many network deployments. There may be network deployments where an IP address alone is insufficient to identify a Target in a network. However, any necessary identity extensions for these networks is beyond the scope of this document. A.2. L7-2: Mobility Support "The GEOPRIV Layer 7 Location Configuration Protocol MUST support a broad range of mobility from devices that can only move between reboots, to devices that can change attachment points with the impact that their IP address is changed, to devices that do not change their IP address while roaming, to devices that continuously move by being attached to the same network attachment point." COMPLY Mobility support is inherently a characteristic of the access network technology and HELD is designed to be access network agnostic. Consequently HELD complies with this requirement. In addition HELD provides specific support for mobile environments by providing an optional responseTime attribute in location request messages. Wireless networks often have several different mechanisms at their disposal for position determination (e.g. Assisted GPS versus location based on serving base station identity), each providing different degrees of accuracy and taking different amounts of time to yield a result. The responseTime parameter provides the LIS with a criterion which it can use to select a location determination technique. A.3. L7-3: ASP and Access Network Provider Relationship "The design of the L7 LCP MUST NOT assume a business or trust relationship between the Application Service Provider (ASP) and the Access Network Provider. Requirements for resolving a reference to location information are not discussed in this document." COMPLY HELD describes a location acquisition protocol and has no dependencies on the business or trust relationship between the ASP and the Access Network Provider. Location acquisition using HELD is subject to the restrictions described in Section 9. Barnes, et al. Expires May 20, 2008 [Page 32] Internet-Draft HELD November 2007 A.4. L7-4: Layer 2 and Layer 3 Provider Relationship "The design of the GEOPRIV Layer 7 Location Configuration Protocol MUST assume that there is a trust and business relationship between the L2 and the L3 provider. The L3 provider operates the LIS and needs to obtain location information from the L2 provider since this one is closest to the end host. If the L2 and L3 provider for the same host are different entities, they cooperate for the purposes needed to determine end system locations." COMPLY HELD was specifically designed with this model in mind and readily allows itself to chaining requests between operators without a change in protocol being required. HELD is a webservices protocol it can be bound to transports other than HTTP. Using o offers the option of high request throughput over a dedicated connection between an L3 provider and an L2 provider without incurring the serial restriction imposed by HTTP. This is less easy to do with protocols that do not decouple themselves from the transport. A.5. L7-5: Legacy Device Considerations "The design of the GEOPRIV Layer 7 Location Configuration Protocol MUST consider legacy residential NAT devices and NTEs in an DSL environment that cannot be upgraded to support additional protocols, for example to pass additional information through DHCP." COMPLY HELD is an application protocol and operates on top of IP. A HELD request from a host behind a residential NAT will traverse the NAT acquiring the external address of the home router. The location provided to the host therefore will be the address of the home router in this circumstance. No changes are required to the home router in order to support this function, HELD was designed specifically to address this deployment scenario. A.6. L7-6: VPN Awareness "The design of the GEOPRIV Layer 7 Location Configuration Protocol MUST assume that at least one end of a VPN is aware of the VPN functionality. In an enterprise scenario, the enterprise side will provide the LIS used by the client and can thereby detect whether the LIS request was initiated through a VPN tunnel." COMPLY Barnes, et al. Expires May 20, 2008 [Page 33] Internet-Draft HELD November 2007 HELD does not preclude a LIS on the far end of a VPN tunnel being aware that the client request is occurring over that tunnel. It also does not preclude a client device from accessing a LIS serving the local physical network and subsequently using the location information with an application that is accessed over a VPN tunnel. A.7. L7-7: Network Access Authentication "The design of the GEOPRIV Layer 7 Location Configuration Protocol MUST NOT assume prior network access authentication." COMPLY HELD makes no assumptions about prior network access authentication. HELD strongly recommends the use of TLS with server-side certificates for communication between the end-point and the LIS. There is no requirement for the end-point to authenticate with the LIS. A.8. L7-8: Network Topology Unawareness "The design of the GEOPRIV Layer 7 Location Configuration Protocol MUST NOT assume end systems being aware of the access network topology. End systems are, however, able to determine their public IP address(es) via mechanisms such as STUN or NSIS NATFW NSLP." COMPLY HELD makes no assumption about the network topology. HELD doesn't require that the device know its external IP address, except where that is required for discovery of the LIS. A.9. L7-9: Discovery Mechanism "The L7 LCP MUST define a single mandatory to implement discovery mechanism." COMPLY HELD uses the discovery mechanism in [14]. A.10. L7-10: PIDF-LO Creation "When a LIS creates a PIDF-LO per RFC 4119 then it MUST put the element into the element of the presence document (see RFC 4479). This ensures that the resulting PIDF-LO document, which is subsequently distributed to other entities, conforms to the rules outlined in ". [10] Barnes, et al. Expires May 20, 2008 [Page 34] Internet-Draft HELD November 2007 COMPLY HELD protocol overview (Section 4 ) describes the requirements on the LIS in creating the PIDF-LO and prescribes that the PIDF-LO generated by the LIS MUST conform to [10]. Authors' Addresses Mary Barnes (editor) Nortel 2201 Lakeside Blvd Richardson, TX Email: mary.barnes@nortel.com James Winterbottom Andrew PO Box U40 Wollongong University Campus, NSW 2500 AU Phone: +61 2 4221 2938 Email: james.winterbottom@andrew.com URI: http://www.andrew.com/ Martin Thomson Andrew PO Box U40 Wollongong University Campus, NSW 2500 AU Phone: +61 2 4221 2915 Email: martin.thomson@andrew.com URI: http://www.andrew.com/ Barnes, et al. Expires May 20, 2008 [Page 35] Internet-Draft HELD November 2007 Barbara Stark BellSouth Room 7A41 725 W Peachtree St. Atlanta, GA 30308 US Email: barbara.stark@bellsouth.com Barnes, et al. Expires May 20, 2008 [Page 36] Internet-Draft HELD November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Barnes, et al. Expires May 20, 2008 [Page 37]