GEOPRIV WG J. Winterbottom Internet-Draft M. Thomson Expires: July 5, 2006 Andrew B. Stark BellSouth January 2006 HTTP Enabled Location Delivery (HELD) - Sighting draft-winterbottom-geopriv-held-sighting-00.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 July 5, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract A Geopriv sighting protocol 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 supports mobile and nomadic devices through Location URIs and location update URIs, which enables generation of location information at the Device. The protocol is an Winterbottom, et al. Expires July 5, 2006 [Page 1] Internet-Draft HELD Sighting January 2006 application-layer protocol that is independent of session-layer; an HTTP, web services binding is specified. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Exclusions . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Device or Target . . . . . . . . . . . . . . . . . . . . . 5 1.3. The Bigger Picture . . . . . . . . . . . . . . . . . . . . 5 2. Conventions used in this document . . . . . . . . . . . . . . 7 2.1. GEOPRIV Terminology . . . . . . . . . . . . . . . . . . . 7 3. HELD Sighting Overview . . . . . . . . . . . . . . . . . . . . 9 3.1. Acquiring Location Information . . . . . . . . . . . . . . 9 3.1.1. Shaping the PIDF-LO . . . . . . . . . . . . . . . . . 10 3.2. Requesting a Location URI . . . . . . . . . . . . . . . . 10 3.2.1. Establishing a Location Server Context . . . . . . . . 11 3.2.2. Locating Mobile Devices . . . . . . . . . . . . . . . 12 4. Protocol Description . . . . . . . . . . . . . . . . . . . . . 13 4.1. Protocol Binding . . . . . . . . . . . . . . . . . . . . . 13 4.2. Location Request . . . . . . . . . . . . . . . . . . . . . 14 4.3. Contexts . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3.1. Creating Contexts . . . . . . . . . . . . . . . . . . 15 4.3.2. Updating Contexts . . . . . . . . . . . . . . . . . . 15 4.3.3. Terminating Contexts . . . . . . . . . . . . . . . . . 16 4.4. Indicating Errors . . . . . . . . . . . . . . . . . . . . 16 5. Protocol Parameters . . . . . . . . . . . . . . . . . . . . . 18 5.1. "responseTime" Attribute . . . . . . . . . . . . . . . . . 19 5.2. "assert" Element . . . . . . . . . . . . . . . . . . . . . 19 5.2.1. "method" Attribute . . . . . . . . . . . . . . . . . . 19 5.2.2. "timestamp" Attribute . . . . . . . . . . . . . . . . 19 5.2.3. "expires" Attribute . . . . . . . . . . . . . . . . . 20 5.3. "locationType" Element . . . . . . . . . . . . . . . . . . 20 5.4. "exact" Attribute . . . . . . . . . . . . . . . . . . . . 21 5.5. "profile" Element . . . . . . . . . . . . . . . . . . . . 21 5.5.1. "presentity" Element . . . . . . . . . . . . . . . . . 21 5.5.2. SAML "Assertion" or "EncryptedAssertion" Element . . . 22 5.5.3. "retentionExpiry" Element . . . . . . . . . . . . . . 22 5.5.4. "retentionInterval" Element . . . . . . . . . . . . . 22 5.5.5. "retransmission" Element . . . . . . . . . . . . . . . 23 5.5.6. "rulesetURI" Element . . . . . . . . . . . . . . . . . 23 5.6. "signed" Attribute . . . . . . . . . . . . . . . . . . . . 23 5.7. "lifetime" Element . . . . . . . . . . . . . . . . . . . . 23 5.8. "rules" Element . . . . . . . . . . . . . . . . . . . . . 24 5.8.1. "rulesetURI" Element . . . . . . . . . . . . . . . . . 24 5.8.2. Common-Policy "ruleset" Element . . . . . . . . . . . 24 5.9. "updates" Element . . . . . . . . . . . . . . . . . . . . 25 5.9.1. "responseTime" Attribute . . . . . . . . . . . . . . . 25 Winterbottom, et al. Expires July 5, 2006 [Page 2] Internet-Draft HELD Sighting January 2006 5.10. "code" Attribute . . . . . . . . . . . . . . . . . . . . . 25 5.11. "message" Attribute . . . . . . . . . . . . . . . . . . . 26 5.12. "context" Element . . . . . . . . . . . . . . . . . . . . 27 5.12.1. "locationURI" Element . . . . . . . . . . . . . . . . 27 5.12.2. "password" Element . . . . . . . . . . . . . . . . . . 27 5.12.3. "expires" Attribute . . . . . . . . . . . . . . . . . 27 6. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 29 7. HTTP Binding . . . . . . . . . . . . . . . . . . . . . . . . . 36 7.1. HTTP Binding WSDL . . . . . . . . . . . . . . . . . . . . 36 8. Security Considerations . . . . . . . . . . . . . . . . . . . 39 8.1. Return Routability . . . . . . . . . . . . . . . . . . . . 39 8.2. Transaction Layer Security . . . . . . . . . . . . . . . . 40 8.3. Veracity of Asserted LI . . . . . . . . . . . . . . . . . 40 9. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 9.1. Simple HTTP Binding Example Messages . . . . . . . . . . . 41 9.2. Location Request Examples . . . . . . . . . . . . . . . . 43 9.3. Context Creation and Update Examples . . . . . . . . . . . 45 9.4. Sample LG WSDL Document . . . . . . . . . . . . . . . . . 49 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50 10.1. IANA Registry for HELD Result Codes . . . . . . . . . . . 50 10.2. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held . . . . . . . . . . . 50 10.3. XML Schema Registration . . . . . . . . . . . . . . . . . 51 10.4. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held:http . . . . . . . . . 51 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 53 11.1. Normative References . . . . . . . . . . . . . . . . . . . 53 11.2. Informative References . . . . . . . . . . . . . . . . . . 54 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 56 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 57 Intellectual Property and Copyright Statements . . . . . . . . . . 58 Winterbottom, et al. Expires July 5, 2006 [Page 3] Internet-Draft HELD Sighting January 2006 1. Introduction The location of a Device is information that is useful for a number of applications. A Device might be able to determine this information using its own resources, but more often than not, the Device must rely on its access network to provide this information. This document describes a protocol that can be used to acquire Location Information (LI) from a service within an access network. This specification identifies two methods for acquiring LI. Location may be retrieved from a Location Generator (LG) by-value, that is, the Device may acquire LI directly. Alternatively, the Device may request that the LG provide a location URI so that LI can be distributed by-reference. Both of these methods are compatible, and both can be provided concurrently from the same LG so that application needs can be addressed individually. This specification defines an XML-based protocol that enables the retrieval of LI from a LG. This protocol can be bound to any session-layer protocol, particularly those capable of MIME transport; an HTTP binding is included as a minimum requirement. The protocol described has specific support for mobile devices through the assertion of LI to the LG and update URIs, which allow the LG to query a Device for its current location. This feature, in combination with Location URIs enables location determination at the time that it is needed by the Location Recipient (LR), and in the form requested by the LR. 1.1. Exclusions This document defines a protocol for sighting only; that is, a protocol for requesting (and receiving) the information necessary to use LI. This document does not define a Geopriv Using Protocol. The LG is assumed to be present within the same administrative domain as the Device (the access network), which limits the security threats that this protocol is exposed to. This document does not specify how LI is derived. Determination of the physical location of a device is dependent on the type of access network and the capabilities of the device. The specific methods that could be used are innumerable, therefore this is left to individual network and device implementations. Providing LI by-reference implies that a server is able to provide the Device with a public, globally-routable URI. How this URI is provided is not covered by this specification. This includes any interactions between the LG and LS necessary to facilitate the Winterbottom, et al. Expires July 5, 2006 [Page 4] Internet-Draft HELD Sighting January 2006 provision of a Location URI. This document does not define how an LG is discovered or configured. 1.2. Device or Target LI provided for a device is often represented as the location of a user. However, in this document LI is attributed to a device and not a person. Primarily, this is because location determination technologies are generally designed to locate a device and not a person. In addition to this, unless the device requires active user authentication, there is no guarantee that any particular individual is using the device at that instant. Thus, if any claim of veracity is to be made for LI, the distinction between user and device must be made explicit. This distinction should not lead to the impression that the location of a device does not impact the privacy constraints required by this protocol. Revealing the location of a device almost invariably reveals some information about the location of the user of that device, therefore the same level of privacy protection demanded by a user is required for their device. It is expected that, for most applications, this distinction will be unnecessary and LI for a device will be used as an adequate substitute for the user's LI. This requires either some additional assurances about the link between device and user, or an acceptance of the aforementioned limitations. This document assumes that the Device is responsible for the protocol interactions described and that it does so with the authority of the Target and Rule Maker (RM). 1.3. The Bigger Picture This document describes an interface between a Device and a Location Generator (LG). Detailing the interactions between these two entities requires a wider understanding of other interested parties. For the Device, the most important consideration is the Target. In some cases, this is the same as the Device, but it is more likely to be a human user. The foundation of this protocol is that the Target is able to direct the dissemination of LI, that is, the Target provides authorization policies and otherwise controls how LI is granted to Location Recipients (LRs). This extends to when a Location Server (LS) is employed to provide a Location URI; the LS cannot provide LI to an LR without express permission from the Target. Winterbottom, et al. Expires July 5, 2006 [Page 5] Internet-Draft HELD Sighting January 2006 The LG exists as an access network service. An Access Provider (AP) operates this service so that Devices (and Targets) can retrieve LI. The LG 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 interface between Device and LG includes some features that could be equally described by a direct interface between Device and LS. Communication with the LS is directed through the LG because it places the complexity on the LG; this enables the implementation of a very simple client in the Device. The following diagram shows one possible configuration of the roles identified in [RFC3693] and where this protocol applies. +-----------+ +-----------+ | Location | | Location | | Generator | - - - - | Server | | | | | +-----------+ +-----------+ | | HELD Sighting | | | Rule Maker - _ +-----------+ +-----------+ o - - | Device | | Location | | (Target) |----Object--->| Recipient | | | (Sighting) | (LS, RH) | (Applic.) | | +-----------+ +----------+ +-----------+ Figure 2: Simple Location Request Model In this model, the Device in this scenario acts as a Location Server (LS) and Rule Holder (RH); it is responsible for making authorization decisions about which Location Recipients are given LOs. The LG needs to uniquely identify the Device within the access network. The source address of the request message is sufficient in most cases. Once the Device is identified, the LG uses network domain-specific information to determine the location of the Device. An LI request does not need to include any identification information other than return addressing. In fact, the HTTP binding (Section 7) includes the option for a GET request. Return routability also addresses a number of security concerns, see Section 8. The response from the LG is a PIDF-LO document [RFC4119], unless there were errors in processing the request. The interface between Device (acting as LS) and Location Recipient (LR) is application-specific and outside the scope of this specification. Winterbottom, et al. Expires July 5, 2006 [Page 9] Internet-Draft HELD Sighting January 2006 3.1.1. Shaping the PIDF-LO A Device can include additional information in an LI request that controls how the LG populates the fields in a PIDF-LO document. Related to privacy, a presentity URI and usage rules can be specified. The Device can also include a location estimate, or request a specific type of location information, including a request for a signed PIDF-LO. When requesting LI, the Device can include a presentity URI for the Target and a ruleset reference. The LG incorporates this information in the PIDF-LO document, or modifies the document accordingly. LI contained within a PIDF-LO document can be either geodetic (coordinates using latitude and longitude or some other coordinate system) or civic (street or postal addresses). The Device can request that the LG provide a specific type of LI, including whether a jurisdictional or postal civic address is required. If a Device is capable of providing its own location it can include this in a request. The LG is then able to include this LI in the returned PIDF-LO. The type of LI is inferred from the request when LI is provided. The PIDF-LO document generated by an LG MUST follow the rules in [I-D.ietf-geopriv-pdif-lo-profile]. The LI sent in a request MUST follow the rules relating to the construction of the "location-info" element. 3.2. Requesting a Location URI Requesting LI directly does not always address the requirements of an application. A Location URI is a URI [RFC3986] of any scheme, which a Location Recipient (LR) can use to retrieve LI. A Device can request a Location URI instead of LI. Figure 3 illustrates how this usage of HELD Sighting fits within the model presented in [RFC3693]. The first aspect of the diagram shows how the Device acts as an agent for the Target and retrieves a Location URI, which it then provides to the Location Recipient. The second aspect has the Device acting as an agent for the Rule Maker; the Device forwards rules to the LG, which forwards them to the LS. Winterbottom, et al. Expires July 5, 2006 [Page 10] Internet-Draft HELD Sighting January 2006 +-----------+ Location +--------------+ | Location |------URI------>| Device | | Generator | | (Target) | | |<-----Rules-----| (Rule Maker) | +-----------+ (Sighting) +--------------+ | | LO & Rules Location URI (Publish) (Application) | | V V +----------+ +------------+ | Location | Location | Location | | Server |------Object----->| Recipient | | | (Notification) | | +----------+ +------------+ Figure 3: Location URI Usage Model Note that the Location Server takes the role of a (Private) Rule Holder when the rules are provided by-value. The rules may also be provided to the LG and LS by-reference, in which case, a Public Rule Holder is required; the Public Rule Holder is not shown in this diagram. The interface between Device (acting as LS) and Location Recipient (LR) is application-specific and outside the scope of this specification. Also, any interface between Device (acting as RM) and a Public Rule Holder is not relevant to this specification. The merits and drawbacks of using a Location URI approach are discussed in [I-D.winterbottom-location-uri]. 3.2.1. Establishing a Location Server Context A Location URI is allocated for a Device by the LS. If the LS is to be able to service queries for location directed at the Location URI, it must maintain certain information. When the LG receives a request for a Location URI, it requests that the LS allocate a URI for a particular Device. As a part of providing a Location URI, the LS also creates a _context_, which contains the information that it requires to properly service requests to the URI. This document does not make any normative statements about the interface between the LG and LS. Any assumptions that are made about the nature of this interface are stated where necessary. A context contains sufficient information for the LS to identify the Device to the LG, so that LI can be generated as required, which Winterbottom, et al. Expires July 5, 2006 [Page 11] Internet-Draft HELD Sighting January 2006 could be on a per-request basis. The context also includes instructions from the Device on how the PIDF-LO is to be generated, as described in Section 3.1.1. Most importantly, the context contains an authorization policy that describes to whom, and how, LI is granted. This is a common-policy document [I-D.ietf-geopriv-common-policy] that is provided by the Device in the context creation request, either directly, or by reference. 3.2.2. Locating Mobile Devices This protocol expands support for mobile devices by allowing for the generation of LI at the time that an LR requests it. This is a feature of Location URIs that is enhanced through the use of a location update URI. The Device is able to provide a location update URI that is stored within its context. When the LG is determining the location of the Device, it is then able to query the Device for its location through the location update URI. A location update URI therefore enables location determination of the highest available precision at the time that an LR requires it. Winterbottom, et al. Expires July 5, 2006 [Page 12] Internet-Draft HELD Sighting January 2006 4. Protocol Description As discussed in Section 3, this protocol provides two basic functions: LI request and Location URI request. Messages are defined as XML documents. The Location Request message is described in Section 4.2. A Location Request from a Device results in a PIDF-LO document in case of success, or an error message. In requesting a Location URI, the Device requests that a context be created on the LS. The parameters for the create context request are described in Section 4.3.1. The response to a context creation request includes Location URIs and a password that can be used to update the information contained in the context. The details stored by the LS can be updated at any time after creation using the update context request, described in Section 4.3.2. Table 1 shows the basic set of messages supported by this protocol and their respective responses, successful or otherwise. +-----------+--------------------+------------------+---------------+ | Operation | Request Message | Successful | Error | | | | Response | Response | +-----------+--------------------+------------------+---------------+ | Request | locationRequest | PIDF-LO document | error | | Location | (Section 4.2) | [RFC4119] | (Section 4.4) | | | | | | | Create | createContext | contextResponse | error | | Context | (Section 4.3.1) | | (Section 4.4) | | | | | | | Update | updateContext | contextResponse | error | | Context | (Section 4.3.2) | | (Section 4.4) | +-----------+--------------------+------------------+---------------+ Table 1: HELD Sighting Operations Section 5 contains a more thorough description of the protocol parameters, valid values, and how each should be handled. Section 6 contains a more specific definition of the structure of these messages in the form of an XML Schema [W3C.REC-xmlschema-1-20041028]. 4.1. Protocol Binding The HELD sighting 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: Winterbottom, et al. Expires July 5, 2006 [Page 13] Internet-Draft HELD Sighting January 2006 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. Candidate protocols that could be used to address these purposes include: TCP [RFC0793], TLS [RFC2246], SASL [RFC2222], HTTP [RFC2616], SIP [RFC3261], BEEP [RFC3080] and SOAP [W3C.REC-soap12- part1-20030624] [W3C.REC-soap12-part2-20030624]. This document includes a binding that uses a combination of HTTP, TLS and TCP in Section 7. 4.2. Location Request A location request is sent from the Device to the LG when it requires LI. This request can be very simple, including no parameters; in fact, the HTTP binding includes a GET request that does not include a message body. A Device MAY make an assertion about its own location as part of a location request. Devices that have some means of acquiring LI, either from embedded technology like Global Positioning System (GPS) receivers or from user input, can use this to convey that information to the LG. The "assert" element can be used to convey this information. The type of LI that a Device requests is determined by the type of LI that is included in the "assert" element. When asserted LI is not provided, the Device MAY specify the type of location requested using the "locationType" element. LI provided by the Device is potentially more precise than that provided by the LG, therefore the LG MAY use this information to create a response. The LG SHOULD validate the LI provided for accuracy and precision before using this information. The Device MAY specify a "profile" element that instructs the LG on how to construct the LO. Alternatively, if the Device has created a profile in an LS context, the Device can provide a "context" element so that the LG can retrieve the profile from the LS. The location request is made by sending a document formed of a "locationRequest" element. The successful response to a location request is a PIDF-LO document, unless the request fails, in which case the LG SHOULD provide an error indication document. Winterbottom, et al. Expires July 5, 2006 [Page 14] Internet-Draft HELD Sighting January 2006 4.3. Contexts 4.3.1. Creating Contexts The Device uses the "createContext" message to request that the LG, and the LS, assign a Location URI. This establishes a context at the LS. The LS MUST maintain the information provided in the create context request. The create context request includes a time limit, which sets the maximum time that this context can be maintained. The response to a create context request contains information that the Device can use to identify a context. A set of Location URIs are included, each one MUST uniquely identify the context; that is, the LS MUST be able to identify a context based on a single Location URI. A Device can distribute a Location URI to an LR to allow it retrieve LI from the LS. A Location URI MUST NOT contain any information that could be used to identify the Device or Target. It is RECOMMENDED that a Location URI contain a public address for the LS and a random sequence of characters that the LS can use to identify a particular context. The presentity identifier included in a PIDF-LO document SHOULD NOT be used for either part or the entirety of a Location URI. The response to a create context request MUST include the time when the LS will terminate the context. The LS MUST NOT respond to any queries to the context beyond this time. A response to a context creation also includes a password that the Device uses to identify itself when updating the context at any time before the context expiry time. 4.3.2. Updating Contexts A Device can update any of the information it has provided for a context at any time. The update context request includes the same information as the create context request with the addition of information that identifies an existing context. A Device uses any one of the Location URIs provided to uniquely identify a context when updating context information. The context password MUST be provided when updating context information. If a Device includes an authorization policy (or ruleset) in an update context request, the LS MUST refresh any stored copy of the authorization policy. This is especially important for authorization policies that are provided by-reference; the LS MUST update the Winterbottom, et al. Expires July 5, 2006 [Page 15] Internet-Draft HELD Sighting January 2006 authorization policy, even if the URI has not changed. Updated authorization policies SHOULD be processed by the LG and LS immediately. The update context request is constructed using the "updateContext" element. A successful response is the "contextResponse" element, which is the same as the response to a create context response. The update context request can also indicate that data can be removed by the context by specifying a _nil_ value for any of the parameters, using the "xsi:nil" attribute. This applies to the profile (Section 5.5) and updates (Section 5.9) values. The response to an update context request is identical in form to the create context response, with updated information about the context. The Location URIs SHOULD be the same as those in the response to the initial create context request, but the password and expiry time MAY be changed. 4.3.3. Terminating Contexts The update context request can be used to instruct the LS to terminate a context. The "lifetime" element in the request is set to a zero duration. Once the context has been terminated, or it has expired, Location URIs that reference that context can no longer be used and the Device MUST NOT use the Location URIs or password relating to that context. The LS MAY terminate a context without notifying the Device. The LS SHOULD terminate contexts if it, or the LG, detect that any information relating to the Device changes in a way that invalidates the context. When the Device requests that a context be terminated, the LG responds with a "contextResponse" message that does not include any context information; this message SHOULD include the "201" response code. 4.4. Indicating Errors In the event of an error, the LG SHOULD respond to the Device with an error document. The error response applies to all request types and SHOULD 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 5.10. Winterbottom, et al. Expires July 5, 2006 [Page 16] Internet-Draft HELD Sighting January 2006 Reponses 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. Winterbottom, et al. Expires July 5, 2006 [Page 17] Internet-Draft HELD Sighting January 2006 5. Protocol Parameters This section describes, in detail the parameters that are used for this protocol. Table 2 lists the top-level components used within the protocol and where they are used. +---------------------+-------------+--------------+----------------+ | Parameter | Location | Create | Update Context | | | Request | Context | | +---------------------+-------------+--------------+----------------+ | responseTime | Request | Request | Request | | (Section 5.1) | | | | | | | | | | assert | Request | | | | (Section 5.2) | | | | | | | | | | locationType | Request | | | | (Section 5.3) | | | | | | | | | | exact (Section 5.4) | Request | | | | | | | | | profile | Request | Request | Request | | (Section 5.5) | | | | | | | | | | signed | Request | | | | (Section 5.6) | | | | | | | | | | lifetime | | Request | Request | | (Section 5.7) | | | | | | | | | | rules (Section 5.8) | | Request | Request | | | | | | | updates | | Request | Request | | (Section 5.9) | | | | | | | | | | code (Section 5.10) | Error | Error & | Error & | | | | Response | Response | | | | | | | message | Error | Error & | Error & | | (Section 5.11) | | Response | Response | | | | | | | context | Request | Response | Request & | | (Section 5.12) | | | Response | +---------------------+-------------+--------------+----------------+ Table 2: Message Parameter Usage Winterbottom, et al. Expires July 5, 2006 [Page 18] Internet-Draft HELD Sighting January 2006 5.1. "responseTime" Attribute The "responseTime" attribute indicates to the LG how long the Device is prepared to wait for a response. This attribute MAY be added to any request message, although it is primarily used with the location request. The value of this attribute is indicative only, the LG is under no obligation to strictly adhere to the time limit implied; any enforcement of the time limit is left to the Device. This attribute MAY be either a duration value as defined in XML Schema [W3C.REC-xmlschema-2-20041028], or a decimal seconds value, which may include a decimal point. It is RECOMMENDED that systems support millisecond precision for this parameter. The LG SHOULD provide the most accurate LI that can be determined within the specified interval. This parameter could be used as input when selecting the method of location determination, where multiple such methods exist. If this parameter is absent, then the LG SHOULD return the most precise LI it is capable of determining. 5.2. "assert" Element This attribute allows a Device to provide LI to the LG as part of a location request. Two types of content are allowed: a geodetic structure made up of a Geography Markup Language (GML) geometry object, "_Geometry" as defined by [OGC.GML-3.1.1]; and a civic address structure, "civicAddress" as defined by [I-D.ietf-geopriv- revised-civic-lo]. The contents of this element SHOULD follow the rules in [I-D.ietf-geopriv-pdif-lo-profile]. When used in combination with the "context" element, this LI MAY be used by the LS for requests to Location URIs for that context. This element is mutually exclusive with the "locationType" parameter, defined in Section 5.3. The type of LI requested is implied by the types included in the assertion. 5.2.1. "method" Attribute The "method" attribute SHOULD be attached to the "assert" element to indicate the means by which the LI was derived. This attribute follows the rules of the similarly named method element of the PIDF-LO. 5.2.2. "timestamp" Attribute The "timestamp" attribute SHOULD be attached to the "assert" element to indicate when the LI was generated. Winterbottom, et al. Expires July 5, 2006 [Page 19] Internet-Draft HELD Sighting January 2006 5.2.3. "expires" Attribute The "expires" attribute MAY be attached to the "assert" element to indicate when the included LI is no longer valid. The LG SHOULD set the "retention-expires" element in the returned PIDF-LO to no later than this time if it uses the LI. This attribute SHOULD NOT be included unless this time is definite. 5.3. "locationType" Element The "locationType" element is included in a location request. It contains a list of LI types that are requested by the Device. The following list describes the possible values: any: The LG SHOULD attempt to provide LI in all forms available to it. This value MUST be assumed as the default if no "locationType" is specified. geodetic: The LG SHOULD return a geodetic location for the Target. civic: The LG SHOULD return a civic address for the Target. Any type of civic address may be returned. The LG SHOULD ignore this value if a request for jurisdictional or postal civic address has been made and can be satisfied. jurisdictionalCivic: The LG SHOULD return a jurisdictional civic address for the Target. postalCivic: The LG SHOULD return a postal civic address for the Target. The "locationType" element is mutually exclusive with the "assert" element, defined in Section 5.2. The LG SHOULD return the requested location type or types. The LG 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 LG 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 LG is always able to provide LI in some Winterbottom, et al. Expires July 5, 2006 [Page 20] Internet-Draft HELD Sighting January 2006 form. 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 LG might be unable to provide a civic address. 5.4. "exact" Attribute The "exact" attribute is used for the location request message in conjunction with either the "locationType" or "assert" elements. When this value is set to "true", it indicates to the LG that the contents of these parameters MUST be strictly followed. The default value of "false" allows the LG the option of ignoring these values. When used with the "assert" element, this attribute indicates that the asserted LI MUST be included in the PIDF-LO response. If the LG cannot do this for any reason, which is usually because it determines that the LI was inaccurate or insufficiently precise, the LG MUST indicate an error. When used with the "locationType" element, a value of "true" indicates that the LG MUST provide a PIDF-LO that includes LI of the requested type or types. The LG MUST provide the requested types only and these types SHOULD be specified in the same order as they were requested. The LG SHOULD handle an exact request that includes a "locationType" element set to "any" as if the "exact" attribute were set to "false". 5.5. "profile" Element The "profile" element contains a presentity identifier and usage rules information. All fields are optional within this element, but when these fields are included, the LG MUST use these parameters when constructing the PIDF-LO document. This element MAY be included in location requests, create context requests and update context requests. When included in a location request, the profile is used immediately; when used in create context or update context requests, the profile is stored on the LS and is provided to the LG when the LS responds to requests from LRs. 5.5.1. "presentity" Element The "presentity" element contains a presentity identifier that the LG SHOULD include in the "pres" attribute of the PIDF-LO document. Winterbottom, et al. Expires July 5, 2006 [Page 21] Internet-Draft HELD Sighting January 2006 The LG MAY require authentication of the presentity through any means; the LG SHOULD ignore this parameter if authentication information is not present or authentication information cannot be verified. A SAML assertion MAY be provided in place of this element. 5.5.2. SAML "Assertion" or "EncryptedAssertion" Element The "Assertion" or "EncryptedAssertion" element MAY be included in place of the "presentity" element to carry identity information. This element is taken from SAML 2.0 Core [OASIS.saml-core-2.0-os], which allows for an assertion about identity to be made by an external entity. The assertion MUST include a "Subject" that identifies a user. For _addr-spec_ -type addresses, such as are used in "pres" and "sip" URIs, the name identifier format identifier SHOULD be "urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress". To use this element, the Device SHOULD support the web browser single sign-on profile of SAML, identified by "urn:oasis:names:tc:SAML:2.0:profiles:SSO:browser". This profile is defined in [OASIS.saml-profiles-2.0-os]. The LG or LS MAY choose not to support this method for authentication. Requests including this element MAY be rejected with an error response; alternatively the element MAY be ignored. 5.5.3. "retentionExpiry" Element The "retentionExpiry" element contains an absolute "dateTime" [W3C.REC-xmlschema-2-20041028] value for the "retention-expires" element of the PIDF-LO usage rules. This element is mutually exclusive with the "retentionInterval" element. The LG MAY use a different value than that specified (or the suggested default) as circumstances dictate, but MUST NOT use a value later than specified. If this value indicates a time that has already passed, the request MUST be rejected with an error. See retentionInterval (Section 5.5.4) for more details. 5.5.4. "retentionInterval" Element The "retentionInterval" element contains a time duration value that is specified in the same fashion as the responseTime attribute (Section 5.1). This value MUST be added to the time at which the PIDF-LO document is created to set the value of the "retention-expires" element. This Winterbottom, et al. Expires July 5, 2006 [Page 22] Internet-Draft HELD Sighting January 2006 element enables the Target to set an interval over which a LR can retain a LO, rather than an absolute time. This element is mutually exclusive with the "retentionExpires" element. If neither "retentionExpiry" nor "retentionInterval" are specified, the LG SHOULD provide a default value for the "retention-expires" element of the generated PIDF-LO document. The default for this value SHOULD be 24 hours from the receipt of the location request as defined in [RFC4119]. The LG MAY use a different value than that specified (or the suggested default) as circumstances dictate, but MUST NOT use a value larger than specified. 5.5.5. "retransmission" Element The "retransmission" element contains a boolean value that MUST be included in the "retransmission-allowed" element of the generated PIDF-LO usage rules. When this element is not provided, the LG MUST set the "retransmission-allowed" element to "false". 5.5.6. "rulesetURI" Element The "rulesetURI" element contains a URI value that MUST be included in the "ruleset-reference" element of the generated PIDF-LO usage rules. This datum is only used to construct the PIDF-LO document. Within the context of a profile, this ruleset is not used by either LG or LS, and the LS does not apply the rules found at the URI. 5.6. "signed" Attribute The "signed" attribute indicates whether the Device requires a digitally signed PIDF-LO. When present and set to "true", the LG MUST provide a PIDF-LO document that is signed according to XML- Signature [RFC3275]. 5.7. "lifetime" Element The "lifetime" element specifies the maximum time that a context should be maintained by the LS. This parameter MUST be included in the context creation request to indicate to the LS the latest time that the context is allowed to be retained. The parameter MAY be included in context update requests to modify this time; when included in an update request with a zero value, it indicates that the context MUST be removed immediately. Winterbottom, et al. Expires July 5, 2006 [Page 23] Internet-Draft HELD Sighting January 2006 The "lifetime" element is a duration value that is specified in the same fashion as the "responseTime" attribute. This value MUST be added to the current time when received by the LS to determine the time at which the context expires. An LS MAY use any value less than or equal to this value, but MUST NOT use a longer value. The actual expiry time of the context MUST be indicated in the context response. 5.8. "rules" Element The "rules" element contains the authorization policy of the Target that dictates how and to whom LI is provided by the LS. This policy MUST be applied by the LS when providing LI to LRs. Authorization policies MUST conform to [I-D.ietf-geopriv-common- policy]. If the authorization policy is invalid, cannot be retrieved, or is otherwise not understood by the LS, the LG SHOULD fail the request. Note that this implies that the LS SHOULD attempt to retrieve an authorization policy that is provided by-reference at the time of a create context request; however, an LS MAY choose to do this later, if the requested response time might be exceeded. In the absence of an authorization policy, the LS MUST NOT provide LI to any LR. Note that in certain jurisdictions an LS might be required to provide LI to specific parties irrespective of the authorization policy, as mandated by legislation; for example, emergency services in some countries. 5.8.1. "rulesetURI" Element The "rulesetURI" element contains a URI that references the Target's authorization policy. This URI should reference a document of type "application/auth-policy+xml" as defined in [I-D.ietf-geopriv-common- policy]. It is RECOMMENDED that a ruleset URI use the "https" scheme. It is anticipated that, to improve responsiveness and reduce network usage, an LS could cache an authorization policy, consistent with the rules specified by the Rule Holder. For instance, the Rule Holder could specified retention times using the "Expires" header in HTTP [RFC2616]. The impact of changes to authorization policies are discussed in Section 4.3.2. 5.8.2. Common-Policy "ruleset" Element The "ruleset" element, which is in the "urn:ietf:params:xml:ns:common-policy" namespace [I-D.ietf-geopriv- Winterbottom, et al. Expires July 5, 2006 [Page 24] Internet-Draft HELD Sighting January 2006 common-policy], allows for providing an authorization policy directly as part of a request. It is RECOMMENDED that this method is only used where the "rulesetURI" element cannot be provided. 5.9. "updates" Element The "updates" element is provided by a Device that has some ability to generate its own location. This consists of the URI where the LG can request LI. Typically, the update URI is served by the Device, but it MAY be served by any entity that can determine the location of the Device. The request to the update URI is a HELD Sighting location request only. The entity serving the update URI SHOULD use the same binding as was used to contact the LG. Requests to an update URI MUST NOT contain any reference to contexts, or request signed LI. The entity serving a request to an update URI MAY ignore all parameters included in requests. Therefore, a simple location request is RECOMMENDED where supported by the binding; for the HTTP binding, this is the GET request. 5.9.1. "responseTime" Attribute The "responseTime" attribute of the "updates" element indicates a reasonable maximum time that a request to the given update URI is expected to take. This provides assistance to the LG that uses this URI in deciding whether or not to use the update URI when given time constraints. This value is indicative only and the LG is responsible for ensuring that responses are received in a timely manner. The "responseTime" attribute of the "updates" element is a duration value that is specified in the same fashion as the responseTime attribute (Section 5.1). For example, a GPS-enabled device might provide an update URI where the LG can request a GPS-determined location; if the device generally takes less than 45 seconds to determine its location, that value is used for the "responseTime" attribute. 5.10. "code" Attribute All responses, except a PIDF-LO document, MUST contain a response code. The "code" attribute applies to the "error" and "contextResponse" messages. The following response codes follow a three decimal form similar to that in HTTP [RFC2616] and SIP [RFC3261]: Winterbottom, et al. Expires July 5, 2006 [Page 25] Internet-Draft HELD Sighting January 2006 200 (Success): This code indicates that the request was successful. This code MUST not be used for an error response. 201 (Context Terminated): This code indicates that the request to terminate a context was successful. 400 (Request Error): This code indicates that the request was badly formed in some fashion. 401 (XML Error): This code indicates that the XML content of the request was either badly formed or invalid. 402 (Authentication Error): This code indicates that the request either did not contain authentication information, or the authentication provided was not accepted. 403 (Asserted Location Error): This code indicates that the LI that was asserted in the request was not acceptable to the LG. This code is used when the "exact" attribute is set to "true". 404 (Context Not Found): This code indicates that the context identified in the request was not found. This code MAY also be used if the password provided was incorrect. 500 (General LG Error): This code indicates that an unspecified error occurred at the LG. 501 (Location Unknown): This code indicates that the LG could not determine the location of the Device. 502 (Unsupported Message): This code indicates that the request was not supported or understood by the LG. 503 (Timeout): This code indicates that the LG could not satisfy the request within the time specified in the "requestTime" parameter. 504 (Cannot Provide LI Type): This code indicates that the LG was unable to provide LI of the type or types requested. This code is used when the "exact" attribute is set to "true". Additional response codes within the x00 to x79 range MUST be specified in published RFCs; the range from x80 to x99 is reserved for private usage. 5.11. "message" Attribute The "contextResponse" and "error" messages MAY include a "message" attribute to convey some additional, human-readable information about Winterbottom, et al. Expires July 5, 2006 [Page 26] Internet-Draft HELD Sighting January 2006 the result of the request. This message MAY be included in any language, which SHOULD be indicated by the "xml:lang", attribute. 5.12. "context" Element The "context" element includes information that is used to identify a context and control access to it. The context is identified by one or more Location URIs and a Device is granted a password which MUST be provided when accessing the context to update the information contained. When a context is created, the LG provides a "contextResponse" message that contains the "context" element. This element contains all of the Location URIs that can be used for the context, a password, and an expiry time. To update the details in a context, or reuse profile information stored in the context, the Device provides a "context" element. When identifying a context in this manner, the Device MUST provide only one Location URI and the password. 5.12.1. "locationURI" Element The "locationURI" element includes a single Location URI. Each Location URI is allocated by the LS so that it is able to uniquely identify the context. A "contextResponse" message contains any number of "locationURI" elements. It is RECOMMENDED that the LS allocate a Location URIs for all schemes that it supports and that no scheme is present twice. All "updateContext" request messages MUST contain only one "locationURI" element. The Device MAY select any of the provided Location URIs provided by the LS. 5.12.2. "password" Element The "password" element carries a password that is used to access the context after it has been created. The LS generates this value when creating a context and the Device MUST use the exact same value when it wishes to access the context. This value acts as a shared secret between Device and LS. This element MAY contain any valid XML character data. 5.12.3. "expires" Attribute The "expires" attribute indicates the time at which the context Winterbottom, et al. Expires July 5, 2006 [Page 27] Internet-Draft HELD Sighting January 2006 created by the LS will expire. This attribute is included in the "contextResponse" message only. Responses to create and update context requests MUST include the expiry time of the context. If the LS has expired a context in response to an update context request, this value SHOULD include a time in the past to avoid problems that could be caused by a slow clock in the Device. Winterbottom, et al. Expires July 5, 2006 [Page 28] Internet-Draft HELD Sighting January 2006 6. XML Schema This document defines HELD Sighting messages. Winterbottom, et al. Expires July 5, 2006 [Page 29] Internet-Draft HELD Sighting January 2006 Winterbottom, et al. Expires July 5, 2006 [Page 30] Internet-Draft HELD Sighting January 2006 Winterbottom, et al. Expires July 5, 2006 [Page 31] Internet-Draft HELD Sighting January 2006 Winterbottom, et al. Expires July 5, 2006 [Page 33] Internet-Draft HELD Sighting January 2006 Winterbottom, et al. Expires July 5, 2006 [Page 34] Internet-Draft HELD Sighting January 2006 Winterbottom, et al. Expires July 5, 2006 [Page 35] Internet-Draft HELD Sighting January 2006 7. HTTP Binding This section defines an HTTP [RFC2616] binding for this protocol, which all conforming implementations MUST support. This binding takes the form of a Web Service (WS) that can be described by the Web Services Description Language (WSDL) document in Section 7.1. The three request messages are carried in this binding as the body of an HTTP POST request. The MIME type of both request and response bodies should be "application/xml", except that a PIDF-LO document SHOULD have the MIME type "application/pidf+xml". The LG SHOULD populate the HTTP headers so that they are consistent with the contents of the message. In particular, the "Expires" and cache control headers SHOULD be used to control the caching of any PIDF-LO document. The HTTP status code SHOULD have the same first digit as any "contextResponse" or "error" body included, and it SHOULD indicate a 2xx series response when a PIDF-LO document is included. This binding also includes a default behaviour, which is triggered by a GET request, or a POST with no request body. In this case, the LG MUST attempt to provide a PIDF-LO document, as if the request was a location request. This binding MUST use TLS as described in [RFC2818]. TLS provides message integrity and privacy between Device and LG. It is RECOMMENDED that the LG also use the server authentication method described in [RFC2818]. When making a request to a location update URI, the LG SHOULD use the same authentication credentials that are used to respond to a client. 7.1. HTTP Binding WSDL The following WSDL 2.0 [W3C.CR-wsdl20-20060106] document describes the HTTP binding for this protocol. Actual service instances MUST provide a "service" with at least one "endpoint" that implements the "heldHTTP" binding. A service description document MAY include this schema directly or by using the "import" or "include" directives. This document describes the basic HELD sighting web service. Please refer to RFCXXXX for details. [[NOTE TO RFC-EDITOR: Please replace XXXX with the RFC number for this specification and remove this note.]] Winterbottom, et al. Expires July 5, 2006 [Page 37] Internet-Draft HELD Sighting January 2006 Winterbottom, et al. Expires July 5, 2006 [Page 38] Internet-Draft HELD Sighting January 2006 8. Security Considerations The threat model for this protocol assumes that the LG exists within the same administrative domain as the Device. The LG requires access to network information so that it can determine LI. Therefore, the LG can use network information to protect against a number of the possible attacks. An in-depth discussion of the security considerations applicable to the use of Location URIs and by-reference provision of LI is included in [I-D.winterbottom-location-uri]. 8.1. Return Routability It is RECOMMENDED that Location Generators 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 LG MAY require any form of authentication as long as these factors are considered, in particular see Section 6.3.2 of [I-D.winterbottom-location-uri]. Addressing information used in a request to the LG 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. 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, that is, the LG SHOULD enforce a maximum value for the lifetime element (Section 5.7). o The network SHOULD have mechanisms that protect against IP address spoofing. o The LG SHOULD ensure that requests can only originate from within its administrative domain. o The LG and network SHOULD be configured so that the LG is made aware of Device movement within the network and addressing changes. If the LG and LS detect a change in the network that invalidates a context, the context MUST be terminated. The above measures are dependent on network configuration and SHOULD be considered with circumstances in mind. For instance, in a fixed Winterbottom, et al. Expires July 5, 2006 [Page 39] Internet-Draft HELD Sighting January 2006 internet access providers may be able to restriction the allocation of IP addresses to a single physical line, ensuring that spoofing is not possible; in such an environment, the other measures are not necessary. An identity association can also be used to guard against the theft of a Location URI, as described in [I-D.winterbottom-location-uri]. 8.2. 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 LG. It is RECOMMENDED that all bindings also use TLS [RFC2246]. For the HTTP binding, TLS MUST be used. TLS provides protection against eavesdropping and modification. The server authentication methods described in HTTP on TLS [RFC2818] MUST be used. 8.3. Veracity of Asserted LI The assert element (Section 5.2) allows a Device the ability to provide LI. However, if an LG uses asserted LI, it is the LG that becomes responsible for the veracity of that information. Therefore, when the Device provides LI in a request, the LG MUST NOT use this information unless it can ensure its accuracy. This prevents the fraudulent provision of LI that could be caused by the LG accepting LI without any checks. It is unlikely that an LG is able to verify Device-provided LI beyond any uncertainty. The ability of an LG to verify LI is limited by its own capacity to determine the location of the Device. The LG SHOULD indicate the source of LI using the PIDF-LO "method" parameter so that users of LI can make appropriate judgments on its veracity. Winterbottom, et al. Expires July 5, 2006 [Page 40] Internet-Draft HELD Sighting January 2006 9. Examples 9.1. Simple HTTP Binding Example Messages The examples in this section show a complete HTTP message that includes the HELD Sighting request or response document. 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 LG service exists at the URL "https://lg.example.com/location". GET /location HTTP/1.1 Host: lg.example.com Accept: application/pidf+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: lg.example.com Accept: application/pidf+xml,application/xml;q=0.8,text/xml;q=0.7 Accept-Charset: UTF-8,* Content-Type: application/xml Content-Length: 87 Winterbottom, et al. Expires July 5, 2006 [Page 41] Internet-Draft HELD Sighting January 2006 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 LG Date: Tue, 10 Jan 2006 03:42:29 GMT Expires: Tue, 10 Jan 2006 03:42:29 GMT Cache-control: private Content-Type: application/pidf+xml Content-Length: 594 -34.407 150.88001 2006-01-11T03:42:28+00:00 2006-01-10T03:42:28+00:00 The error response to either of these requests is an error document. The following response shows an example error response. HTTP/1.x 500 Server Error Server: Example LG Date: Tue, 10 Jan 2006 03:49:20 GMT Expires: Tue, 10 Jan 2006 03:49:20 GMT Cache-control: private Content-Type: application/xml Content-Length: 135 Winterbottom, et al. Expires July 5, 2006 [Page 42] Internet-Draft HELD Sighting January 2006 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. 9.2. Location Request Examples The location request shown below specifies location types and provides a profile that the LG applies to the PIDF-LO document. The request specifies that a response is desired within 10.5 seconds. jurisdictionalCivic geodetic pres:user@example.com 1800 false https://example.com/~user/ruleset.xml Winterbottom, et al. Expires July 5, 2006 [Page 43] Internet-Draft HELD Sighting January 2006 The response to this location request is the following PIDF-LO document, which shows how the profile values are applied. false 2006-01-11T03:42:28+00:00 https://example.com/~user/ruleset.xml 2006-01-10T03:42:28+00:00 Winterbottom, et al. Expires July 5, 2006 [Page 44] Internet-Draft HELD Sighting January 2006 The following location request includes a location assertion that includes a user-provided civic address. This message also requests that the LG retrieve profile information from a context that exists on an LS. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o vs76e8cae9873a079888p9y4txwa Since this request includes the "exact" parameter set to "true", any successful response MUST include the provided LI. 9.3. Context Creation and Update Examples The following create context request shows the simplest form of this message, which sets a two hour lifetime on the context and includes a "rulesetURI" element for the LS. PT2H https://www.example.com/~user/privacy/ruleset.xml Winterbottom, et al. Expires July 5, 2006 [Page 45] Internet-Draft HELD Sighting January 2006 The following more complex create context request includes additional information. This includes a profile that sets the presentity and some of the "usage-rules" components in the PIDF-LO that the LS serves. This example also provides an update URI where the LG can query for LI. PT2H pres:user@example.com 2006-01-13T12:00:00+00:00 false https://www.example.com/~user/privacy/ruleset.xml https://192.168.1.245:8080/ A typical successful response to this message provides several Location URIs in different schemes (in this case: "https" and "sips"), the exact context expiry time, and a password that can be used to update the context. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o sips://ls.example.com:9769/357yc6s64ceyoiuy5ax3o 38cdj38mjcd-0-=54821kj28mp1qms.1 If any aspect of the data stored in a context changes, a "contextUpdate" request is sent to the LG to request that it update the information. This request includes the information necessary to access a context (the location URI and password) and only the information that has changed. Winterbottom, et al. Expires July 5, 2006 [Page 46] Internet-Draft HELD Sighting January 2006 The following request demonstrates how information stored in a context could be updated. For the context previously created, this provides the "retentionInterval" element, which overrides a previously configured "retentionExpiry" value. The request also removes the location update URI from the context. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o 38cdj38mjcd-0-=54821kj28mp1qms.1 600 To indicate success, the LG provides a "contextResponse" identical in form to the original request. The following request shows that a context lifetime can be extended or shortened by the Device by updating a context with a new "lifetime" element. The following message requests that the LS maintain the context for two hours beyond the current time. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o 38cdj38mjcd-0-=54821kj28mp1qms.1 PT2H Winterbottom, et al. Expires July 5, 2006 [Page 47] Internet-Draft HELD Sighting January 2006 The response to a request to extend the context includes the new expiry time of the context, if it has changed. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o sips://ls.example.com:9769/357yc6s64ceyoiuy5ax3o 38cdj38mjcd-0-=54821kj28mp1qms.1 A zero value for the "lifetime" element terminates the context. The following request terminates the context. https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o 38cdj38mjcd-0-=54821kj28mp1qms.1 PT0S The response to a message that requests the termination of a context appears as follows. Winterbottom, et al. Expires July 5, 2006 [Page 48] Internet-Draft HELD Sighting January 2006 9.4. Sample LG WSDL Document The following WSDL document demonstrates how a WSDL document can be created for a specific service, in this case, a service at the URI "https://lg.example.com/location". Winterbottom, et al. Expires July 5, 2006 [Page 49] Internet-Draft HELD Sighting January 2006 10. IANA Considerations According to the guidelines in [RFC3688], this document calls for an IANA registry for result codes and registers an XML namespace and schema. 10.1. IANA Registry for HELD Result Codes IANA will establish and maintain a registry of HELD result codes. Additional values are registered based on the "specification required" option in [RFC3688]. Specifications MUST specify the following information when registering new values in this registry: Code Value: A three-digit value from 000 to 679. The last 20 codes in each block of 100 (from x80 to x99) are reserved for private or experimental use and cannot be registered. Short Message: A brief message that describes the general reason for the code. Publication: A reference to any relevant publication or specification. Description and Usage: A longer description of the code and the circumstances where it applies. This description does not need to be exhaustive. The values in Section 5.10 are pre-registered in this registry. 10.2. 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 [RFC3688]. URI: urn:ietf:params:xml:ns:geopriv:held Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), Martin Thomson (martin.thomson@andrew.com). XML: Winterbottom, et al. Expires July 5, 2006 [Page 50] Internet-Draft HELD Sighting January 2006 BEGIN HELD Sighting Messages

Namespace for HELD Sighting 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 10.3. XML Schema Registration This section registers an XML schema as per the guidelines in [RFC3688]. URI: urn:ietf:params:xml:schema:geopriv:held Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), Martin Thomson (martin.thomson@andrew.com). Schema: The XML for this schema can be found as the entirety of Section 6 of this document. 10.4. 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 [RFC3688]. URI: urn:ietf:params:xml:ns:geopriv:held:http Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), Martin Thomson (martin.thomson@andrew.com). XML: Winterbottom, et al. Expires July 5, 2006 [Page 51] Internet-Draft HELD Sighting January 2006 BEGIN HELD Sighting HTTP Binding WS

Namespace for HELD Sighting 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 Winterbottom, et al. Expires July 5, 2006 [Page 52] Internet-Draft HELD Sighting January 2006 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [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. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [RFC3275] Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup Language) XML-Signature Syntax and Processing", RFC 3275, March 2002. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. [RFC3693] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J. Polk, "Geopriv Requirements", RFC 3693, February 2004. [RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object Format", RFC 4119, December 2005. [I-D.ietf-geopriv-revised-civic-lo] Thomson, M. and J. Winterbottom, "Revised Civic Location Format for PIDF-LO", draft-ietf-geopriv-revised-civic-lo-01 (work in progress), January 2006. [I-D.ietf-geopriv-pdif-lo-profile] Tschofenig, H., "GEOPRIV PIDF-LO Usage Clarification, Considerations and Recommendations", draft-ietf-geopriv-pdif-lo-profile-02 (work in progress), February 2006. [W3C.REC-xmlschema-2-20041028] Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes Second Edition", W3C REC REC-xmlschema-2-20041028, October 2004. [OGC.GML-3.1.1] Cox, S., Daisey, P., Lake, R., Portele, C., and A. Winterbottom, et al. Expires July 5, 2006 [Page 53] Internet-Draft HELD Sighting January 2006 Whiteside, "Geographic information - Geography Markup Language (GML)", OpenGIS 03-105r1, April 2004, . [OASIS.saml-core-2.0-os] Cantor, S., Kemp, J., Philpott, R., and E. Maler, "Assertions and Protocols for the OASIS Security Assertion Markup Language (SAML) V2.0", OASIS Security Services TC Standard saml-core-2.0-os, July 2002, . [OASIS.saml-profiles-2.0-os] Hughes, J., Cantor, S., Hodges, J., Hirsch, F., Mishra, P., Philpott, R., and E. Maler, "Profiles for the OASIS Security Assertion Markup Language (SAML) V2.0", OASIS Security Services TC Standard saml-profiles-2.0-os, July 2002, . 11.2. Informative References [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981. [RFC2222] Myers, J., "Simple Authentication and Security Layer (SASL)", RFC 2222, October 1997. [RFC3080] Rose, M., "The Blocks Extensible Exchange Protocol Core", RFC 3080, March 2001. [RFC3261] 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. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [I-D.ietf-geopriv-common-policy] Schulzrinne, H., "A Document Format for Expressing Privacy Preferences", draft-ietf-geopriv-common-policy-06 (work in progress), October 2005. [I-D.winterbottom-location-uri] Winterbottom, J., "Rationale for Location by Reference", draft-winterbottom-location-uri-01 (work in progress), Winterbottom, et al. Expires July 5, 2006 [Page 54] Internet-Draft HELD Sighting January 2006 January 2006. [W3C.REC-xmlschema-1-20041028] Maloney, M., Beech, D., Thompson, H., and N. Mendelsohn, "XML Schema Part 1: Structures Second Edition", W3C REC REC-xmlschema-1-20041028, October 2004. [W3C.REC-soap12-part1-20030624] Nielsen, H., Mendelsohn, N., Gudgin, M., Hadley, M., and J. Moreau, "SOAP Version 1.2 Part 1: Messaging Framework", W3C REC REC-soap12-part1-20030624, June 2003. [W3C.REC-soap12-part2-20030624] Nielsen, H., Hadley, M., Moreau, J., Mendelsohn, N., and M. Gudgin, "SOAP Version 1.2 Part 2: Adjuncts", W3C REC REC-soap12-part2-20030624, June 2003. [W3C.CR-wsdl20-20060106] Chinnici, R., Moreau, J., Ryman, A., and S. Weerawarana, "Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language", W3C CR CR-wsdl20-20060106, January 2006. Winterbottom, et al. Expires July 5, 2006 [Page 55] Internet-Draft HELD Sighting January 2006 Appendix A. Acknowledgements The authors would like to thank the following people for their contribution to this document (in alphabetical order): Nadine Abbott, Guy Caron, Martin Dawson, Jerome Grenier, Neil Justusson, Tat Lam, Patti McCalmont, Perry Prozeniuk, John Schnizlein, Henning Schulzrinne, Ed Shrum, and Hannes Tschofenig. Winterbottom, et al. Expires July 5, 2006 [Page 56] Internet-Draft HELD Sighting January 2006 Authors' Addresses 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/ Barbara Stark BellSouth Room 7A41 725 W Peachtree St. Atlanta, GA 30308 US Email: barbara.stark@bellsouth.com Winterbottom, et al. Expires July 5, 2006 [Page 57] Internet-Draft HELD Sighting January 2006 Intellectual Property Statement 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. Disclaimer of Validity 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 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. Copyright Statement Copyright (C) The Internet Society (2006). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Winterbottom, et al. Expires July 5, 2006 [Page 58]