ECRIT T. Hardie Internet-Draft Qualcomm, Inc. Intended status: Standards Track A. Newton Expires: August 15, 2007 SunRocket H. Schulzrinne Columbia U. H. Tschofenig Siemens Networks GmbH & Co KG February 11, 2007 LoST: A Location-to-Service Translation Protocol draft-ietf-ecrit-lost-04.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 August 15, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Hardie, et al. Expires August 15, 2007 [Page 1] Internet-Draft LoST February 2007 Abstract This document describes an XML-based protocol for mapping service identifiers and geodetic or civic location information to service contact URIs. In particular, it can be used to determine the location-appropriate PSAP for emergency services. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology and Requirements Notation . . . . . . . . . . . . 6 3. Overview of Protocol Usage . . . . . . . . . . . . . . . . . . 7 4. LoST servers and Their Resolution . . . . . . . . . . . . . . 8 5. The Element . . . . . . . . . . . . . . . . . . . . 9 5.1. Data source and version: The 'source', 'sourceId' and 'version' Attributes . . . . . . . . . . . . . . . . . . . 9 5.2. Time of Last Update: The 'lastUpdated' Attribute . . . . . 9 5.3. Validity: The 'expires' Attribute . . . . . . . . . . . . 9 5.4. Describing the Service with the Element . . 10 5.5. The Mapped Service: the Element . . . . . . . . 10 5.6. Defining the Service Region with the Element . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.7. Service Boundaries by Reference: the Element . . . . . . . . . . . . 11 5.8. The Service Number Element . . . . . . . . . . . . . . . . 11 5.9. Service URLs: the Element . . . . . . . . . . . . . 12 6. Path of Request: Element . . . . . . . . . . . . . . . 13 7. Mapping a Location and Service to URLs: . . . . 14 7.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.2.1. Example Using Geodetic Coordinates . . . . . . . . . . 14 7.2.2. Civic Address Mapping Example . . . . . . . . . . . . 15 7.3. Components of the Request . . . . . . . . . 17 7.3.1. The Element . . . . . . . . . . . . . . . . 17 7.3.2. Identifying the Service: The Element . . . 18 7.3.3. Recursion . . . . . . . . . . . . . . . . . . . . . . 18 7.3.4. Service Boundary . . . . . . . . . . . . . . . . . . . 18 7.3.5. Requesting Civic Location Validation . . . . . . . . . 18 7.4. Components of the Mapping Response . . . . . . . . . . . . . . . . . . 20 7.4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . 20 7.4.2. Civic Address Validation: the Element . . . . . . . . . . . . . 21 8. Retrieving the Service Boundary via . . . 22 9. List Services: . . . . . . . . . . . . . . . . 25 10. List Services By Location: . . . . . 26 11. Location Profiles . . . . . . . . . . . . . . . . . . . . . . 28 Hardie, et al. Expires August 15, 2007 [Page 2] Internet-Draft LoST February 2007 11.1. Location Profile Usage . . . . . . . . . . . . . . . . . . 29 11.2. Two Dimensional Geodetic Profile . . . . . . . . . . . . . 32 11.3. Basic Civic Profile . . . . . . . . . . . . . . . . . . . 33 12. Errors, Warnings, and Redirects . . . . . . . . . . . . . . . 34 12.1. Errors . . . . . . . . . . . . . . . . . . . . . . . . . . 34 12.2. Warnings . . . . . . . . . . . . . . . . . . . . . . . . . 35 12.3. Redirects . . . . . . . . . . . . . . . . . . . . . . . . 36 13. LoST Transport . . . . . . . . . . . . . . . . . . . . . . . . 37 14. Relax NG Schema . . . . . . . . . . . . . . . . . . . . . . . 38 15. Internationalization Considerations . . . . . . . . . . . . . 45 16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46 16.1. U-NAPTR Registrations . . . . . . . . . . . . . . . . . . 46 16.2. Content-type registration for 'application/lost+xml' . . . 46 16.3. LoST Relax NG Schema Registration . . . . . . . . . . . . 48 16.4. LoST Namespace Registration . . . . . . . . . . . . . . . 48 16.5. LoST Location Profile Registry . . . . . . . . . . . . . . 49 17. Security Considerations . . . . . . . . . . . . . . . . . . . 50 18. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 51 19. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 53 20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 54 20.1. Normative References . . . . . . . . . . . . . . . . . . . 54 20.2. Informative References . . . . . . . . . . . . . . . . . . 55 Appendix A. Non-Normative RELAX NG Schema in XML Syntax . . . . . 56 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 70 Intellectual Property and Copyright Statements . . . . . . . . . . 71 Hardie, et al. Expires August 15, 2007 [Page 3] Internet-Draft LoST February 2007 1. Introduction This document describes a protocol for mapping a service identifier [10] and location information compatible with PIDF-LO [7], namely revised civic location information [11] and GML [13]) to one or more service URL. Example service URL schemes include sip [14], xmpp [15], and tel [16]. While the initial focus is on providing mapping functions for emergency services, it is likely that the protocol is applicable to any service URN. For example, in the United States, the "2-1-1" and "3-1-1" service numbers follow a similar location-to- service behavior as emergency services. This document names this protocol "LoST", for Location-to-Service Translation. LoST Satisfies the requirements [18] for mapping protocols. LoST provides a number of operations, centered around mapping locations and service URNs to service URLs and associated information. LoST mapping queries can contain either civic or geodetic location information. For civic addresses, LoST can indicate which parts of the civic address are known to be valid or invalid, thus providing address validation (see Section 3.5 of [18] for a description of validation). LoST indicates errors in the location data to facilitate debugging and proper user feedback, but also provides best-effort answers. LoST queries can be resolved recursively or iteratively. To minimize round trips and to provide robustness against network failures, LoST caches individual mappings and indicates the region for which the same answer would be returned ("service region"). As defined in this document, LoST messages are carried in HTTP and HTTPS protocol exchanges, facilitating use of TLS for protecting the integrity and confidentiality of requests and responses. Later documents may describe how LoST messages could be carried over other transports. This document focuses on the description of the protocol between the mapping client and the mapping server. The relationship between other functions, such as discovery of mapping servers, data replication and the overall mapping server architecture are described in a separate document [19]. The query message carries location information and a service identifier encoded as a Uniform Resource Name (URN) (see [10]) from the LoST client to the LoST server. The LoST server uses its database to map the input values to one or more Uniform Resource Identifiers (URI) and returns those URIs along with optional information, such as hints about the service boundary, in a response message to the LoST client. If the server cannot resolve the query Hardie, et al. Expires August 15, 2007 [Page 4] Internet-Draft LoST February 2007 itself, it may in turn query another server or return the address of another LoST server, identified by a LoST server name. In addition to the mapping function described in Section 7, the protocol also allows to retrieve the service boundary (see Section 8) and to list the services available for a particular location (see Section 10) or supported by a particular server (see Section 9). Hardie, et al. Expires August 15, 2007 [Page 5] Internet-Draft LoST February 2007 2. Terminology and Requirements Notation 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 furthermore uses the terminology defined in [18]. Hardie, et al. Expires August 15, 2007 [Page 6] Internet-Draft LoST February 2007 3. Overview of Protocol Usage The client may perform the mapping at any time. Among the common triggers for mapping requests are: 1. When the client initially starts up or attaches to a network. 2. When the client detects that its location has changed sufficiently that it is outside the bounds of the service region returned in an earlier LoST query. 3. When cached mapping information has expired. 4. When invoking a particular service. At that time, a client may omit requests for service boundaries or other auxiliary information. A service-specific Best Current Practice (BCP) document, such as [20], governs whether a client is expected to invoke the mapping service just before needing the service or whether to rely on cached answers. Cache entries expire at their expiration time (see Section 5.3), or they become invalid if the caller's device moves beyond the boundaries of the service region. Hardie, et al. Expires August 15, 2007 [Page 7] Internet-Draft LoST February 2007 4. LoST servers and Their Resolution A LoST server may be discovered using a U-NAPTR/DDDS [12] application unique string (AUS), in the form of a DNS name. An example is 'lostserver.example.com' Clients need to use the U-NAPTR [12] specification described below to obtain a URI (indicating host and protocol) for the applicable LoST service. In this document, only the HTTP and HTTPS URL schemes are defined. Note that the HTTP URL can be any valid HTTP URL, including those containing path elements. The following two DNS entries show the U-NAPTR resolution for the AUS "example.com" to the HTTPS URL https://lostserv.example.com/secure or the HTTP URL http://lostserver.example.com, with the former being preferred. example.com. IN NAPTR 100 10 "u" "LoST:https" "!*.!https://lostserver.example.com/secure!" "" IN NAPTR 200 10 "u" "LoST:http" "!*.!http://lostserver.example.com!" "" Clients learn the LoST server's AUS by means beyond the scope of this specification, such as SIP configuration and DHCP. Hardie, et al. Expires August 15, 2007 [Page 8] Internet-Draft LoST February 2007 5. The Element The element is the core data element in LoST, describing a service region and the associated service URLs. Its attributes and elements are described in subsections below. 5.1. Data source and version: The 'source', 'sourceId' and 'version' Attributes The 'source', 'sourceId' and 'version' attributes uniquely identify a particular mapping record. They are created by the authoritative source for a mapping and never modified when a mapping is served from a cache. All three attributes are REQUIRED for all elements. A receiver can replace a mapping with another one having the same 'source' and 'sourceId' and a higher version number. The 'source' attribute contains a LoST application unique string identifying the authoritative generator of the mapping. See Section 4. The 'sourceId' attribute identifies a particular mapping and contains an opaque token that MUST be unique among all different mappings maintained by the authoritative source for that particular service. For example, a Universally Unique Identifier (UUID) is a suitable format. The 'version' attribute is a positive integer that is incremented for each change in the mapping. The XML data type does not specify an upper bound for this attribute and thus, the value MUST NOT wrap around. Thus, a higher version number refers to a more recent mapping. A mapping maintains its sourceId value as long as it remains logically the same, e.g., represents the same service boundary or replaces an earlier service boundary. 5.2. Time of Last Update: The 'lastUpdated' Attribute The 'lastUpdated' attribute describes when the mapping was last changed. The contents of this attribute has the XML data type dateTime in its timezoned form, using canonical UTC representation with the letter 'Z' as the timezone indicator. The attribute is REQUIRED. 5.3. Validity: The 'expires' Attribute The 'expires' attribute contains the absolute time at which the mapping becomes invalid. The contents of this attribute is a timezoned XML type dateTime, in canonical representation. See Section 3 regarding how this value is to be utilized with a cache. Hardie, et al. Expires August 15, 2007 [Page 9] Internet-Draft LoST February 2007 The 'expires' attribute is REQUIRED to be included in the element. On occasion, a server may be forced to return an expired mapping if it cannot reach the authoritative server or the server fails to return a usable answer. Clients and servers MAY cache the mapping so that they have at least some information available. Caching servers that have such stale information SHOULD re-attempt the query each time a client requests a mapping. 5.4. Describing the Service with the Element Zero or more elements describe the service with a string that is suitable for display to human users, each annotated with the 'xml:lang' attribute that contains a language tag to aid in the rendering of text. 5.5. The Mapped Service: the Element The element identifies the service for which this mapping applies. Two cases need to be distinguished when the LoST server sets the element in the response message: 1. If the requested service, identified by the service URN [10] in the element of the request, exists for the location indicated, then the LoST server puts the service URN from the request into the element. 2. If, however, the requested service, identified by the service URN [10] in the element in the request, does not exist for the location indicated, the server can either return an (Section 12.1) error or can provide an alternate service that approximates the desired service for that location. In the latter case, the server MUST include a element with the alternative service URN. The choice of service URN is left to local policy, but the alternate service should be able to satisfy the original service request. The element is optional but may also be required if the mapping is to be digitally signed. 5.6. Defining the Service Region with the Element A response MAY indicate the region for which the service URL returned would be the same as in the actual query, the so-called _service region_. The service region can be indicated by value or by reference (see Section 5.7). If a client moves outside the service area and wishes to obtain current service data, it sends a new query Hardie, et al. Expires August 15, 2007 [Page 10] Internet-Draft LoST February 2007 with its current location. The service region is described by value in one or more elements, each formatted according to a different location profile, identified by the 'profile' atribute (see Section 11). The response MUST contain at least one service boundary using the same profile as the request. The client only processes the first element that it can understand according to its list of supported location profiles. Thus, elements with geospatial coordinates are alternative descriptions of the same service region, not additive geometries. A response MAY contain more than one element with profile 'civic'. Each element describes a set of civic addresses that fall within the service boundary, namely all addresses that textually match the civic address elements provided, regardless of the value of other address elements. A location falls within the mapping's service boundary if it matches any of the elements. 5.7. Service Boundaries by Reference: the Element Since geodetic service boundaries may contain thousands of points and thus be quite large, clients may opt to conserve bandwidth and request a reference to the service boundary instead of the value described in Section 5.6. The identifier of the service boundary is returned as an attribute of the element, along with a LoST application unique string (see Section 4) identifying the server from where it can be retrieved. The actual value of the service boundary is then retrieved with the getServiceBoundary (Section 8) request. The identifier is a random token with at least 128 bits of entropy and can be assumed to be globally unique. It uniquely references a particular boundary. If the boundary changes, a new identifier MUST be chosen. Because of these properties, a client receiving a mapping response can simply check if it already has a copy of the boundary with that identifier. If so, it can skip checking with the server whether the boundary has been updated. Since service boundaries are likely to remain unchanged for extended periods of time, possibly exceeding the normal lifetime of the service URL, this approach avoids unnecessarily refreshing the boundary information just because the the remainder of the mapping has become invalid. 5.8. The Service Number Element The service number is returned in the optional element. It contains a string of digits, * and # that a user on a device with a 12-key dial pad could use to reach that particular Hardie, et al. Expires August 15, 2007 [Page 11] Internet-Draft LoST February 2007 service. 5.9. Service URLs: the Element The response returns the service URLs in one or more elements. The URLs MUST be absolute URLs. The ordering of the URLs has no particular significance. Each URL scheme MUST only appear at most once, but it is permissible to include both secured and regular versions of a protocol, such as both 'http' and 'https' or 'sip' and 'sips'. Hardie, et al. Expires August 15, 2007 [Page 12] Internet-Draft LoST February 2007 6. Path of Request: Element To prevent loops and to allow tracing of request and response paths, all requests that allow recursion include a element that contains one or more elements, each possessing an attribute containing a LoST application unique string (see Section 4). The order of elements corresponds to the order of LoST servers, i.e., the first element identifies the server that first received the request from the client. The authoritative server copies the element verbatim into the response. If a query is answered iteratively, the querier includes all servers that it has already contacted. The example in Figure 5 indicates that the answer was given to the responding server by the LoST server at esgw.ueber-110.de.example, which got the answer from the LoST server at polizei.muenchen.de.example. Hardie, et al. Expires August 15, 2007 [Page 13] Internet-Draft LoST February 2007 7. Mapping a Location and Service to URLs: 7.1. Overview The query constitutes the core of the LoST functionality, mapping civic or geodetic locations to URLs and associated data. After giving an example, we enumerate the elements of the query and response. 7.2. Examples 7.2.1. Example Using Geodetic Coordinates The following is an example of mapping a service to a location using geodetic coordinates, for the service associated with the police (urn:service:sos.police). 37.775 -122.422 urn:service:sos.police Figure 2: A geodetic query Given the query above, a server would respond with a service, and information related to that service. In the example below, the server has mapped the location given by the client for a police service to the New York City Police Deparment, instructing the client that it may contact them via the URIs "sip:sfpd@example.com" and "xmpp:sfpd@example.com". The server has also given the client a geodetic, two-dimensional boundary for this service. The mapping was last updated on November 1, 2006 and expires on January 1, 2007. If the client's location changes beyond the given service boundary or the expiration time has been reached, it may want to requery for this information, depending on the usage environment of LoST. Hardie, et al. Expires August 15, 2007 [Page 14] Internet-Draft LoST February 2007 San Francisco Police Department urn:service:sos.police 37.775 -122.4194 37.555 -122.4194 37.555 -122.4264 37.775 -122.4264 37.775 -122.4194 sip:sfpd@example.com xmpp:sfpd@example.com 911 Figure 3: A geodetic answer 7.2.2. Civic Address Mapping Example The following is an example of mapping a service to a location much like the example in Section 7.2.1, but using civic address location information. In this example, the client requests the service associated with police (urn:service:sos.police) along with a specific civic address (house number 6 on a street named Otto-Hahn-Ring in Munich, Germany). Hardie, et al. Expires August 15, 2007 [Page 15] Internet-Draft LoST February 2007 Germany Bavaria Munich Otto-Hahn-Ring 6 81675 urn:service:sos.police Figure 4: A civic address query Given the query above, a server would respond with a service, and information related to that service. In the example below, the server has mapped the location given by the client for a police service to the Muenchen Polizei-Abteilung, instructing the client that it may contact them via the URIs sip:munich-police@example.com and xmpp:munich-police@example.com. The server has also given the client a civic address boundary (the city of Munich) for this service. The mapping was last updated on November 1, 2006 by the authoritative source "polizei.muenchen.de.example" and expires on January 1, 2007. This instructs the client to requery for the information if its location changes beyond the given service boundary (i.e., beyond the city of Munich) or after January 1, 2007. Hardie, et al. Expires August 15, 2007 [Page 16] Internet-Draft LoST February 2007 Muenchen Polizei-Abteilung urn:service:sos.police Germany Bavaria Munich 81675 sip:munich-police@example.com xmpp:munich-police@example.com 110 Figure 5: A civic address answer 7.3. Components of the Request The request includes attributes that govern whether the request is handled iteratively or recursively, whether location validation is performed and which elements must be contained in the response. 7.3.1. The Element The query communicates location information using one or more elements, which MUST conform to a location profile (see Section 11). There MUST NOT be more than one location element for each distinct location profile. The order of location objects is significant; the server uses the first location object where it understands the location profile. Hardie, et al. Expires August 15, 2007 [Page 17] Internet-Draft LoST February 2007 7.3.2. Identifying the Service: The Element The type of service desired is specified by the element. It contains service URNs from the registry established in [10]. 7.3.3. Recursion LoST and queries can be recursive, as indicated by the 'recursive' attribute. A value of "true" indicates a recursive query, with the default being "false" when the attribute is omitted. Regardless of the attribute, a server MAY always answer a query by providing a LoST application unique string (see Section 4), i.e., indirection, however, it MUST NOT recurse if the attribute is "false". In recursive mode, the LoST server initiates queries on behalf of the requester and returns the result to the requester, inserting a element to track the response chain. The elements are appended in responses in order of visit, i.e., the first element contains the authoritative server and elements below indicate servers that the response traversed on its way back to the original querier. 7.3.4. Service Boundary LoST elements can describe the service boundary either by value or by reference. Returning a service boundary reference is generally more space-efficient for geospatial (polygon) boundaries and if the boundaries change rarely, but does incur an additional request. The querier can express a preference for one or the other modality with the 'serviceBoundary' attribute in the request, but the server makes the final decision as to whether to return a reference or a value. Servers SHOULD NOT return a by-value service boundaries if the querier requested a reference. 7.3.5. Requesting Civic Location Validation Civic address validation is requested by setting the optional attribute 'validateLocation' to true. If the attribute is omitted, it is assumed to be false. The response is described in Section 7.4.2. The example in Figure 6 demonstrates address validation, omitting the standard response elements. Hardie, et al. Expires August 15, 2007 [Page 18] Internet-Draft LoST February 2007 DE Bavaria Munich Otto-Hahn-Ring 6 81675 urn:service:sos.police Figure 6: A query with address validation request Hardie, et al. Expires August 15, 2007 [Page 19] Internet-Draft LoST February 2007 Muenchen Polizei-Abteilung urn:service:sos.police Germany Bavaria Munich 81675 sip:munich-police@example.com xmpp:munich-police@example.com 110 country A1 A3 A6 PC Figure 7: A message with address validation information 7.4. Components of the Mapping Response 7.4.1. Overview Mapping responses consist of the element (Section 5) describing the mapping itself, possibly followed by warnings (Section 12.2), location validation information (Section 7.4.2), and an indication of the path (Section 6) the response has taken. Hardie, et al. Expires August 15, 2007 [Page 20] Internet-Draft LoST February 2007 7.4.2. Civic Address Validation: the Element A server can indicate in its response which civic address elements it has recognized as valid, which ones it has ignored and which ones it has checked and found to be invalid. The server MUST include this information if the 'validateLocation' attribute in the request was true. Each element contains a list of tokens separated by white space, enumerating the civic location lables used in child elements of the element. The element enumerates those civic address elements that have been recognized as valid by the LoST server and that have been used to determine the mapping. The elements enumerates the civic address elements that the server did not check and that were not used in determining the response. The element enumerate civic address elements that the server attempted to check, but that did not match the other civic address elements found in the list. Note that the same address can yield different responses if parts of the civic address contradict each other. For example, if the postal code does not match the city, local server policy determines whether the postal code or the city is considered valid. The mapping naturally corresponds to the valid elements. The example (Figure 6) indicates that the tokens 'country', 'A1', 'A3', and 'A6' have been validated by the LoST server. The server considered the postal code 81675 in the element as not valid for this location. Hardie, et al. Expires August 15, 2007 [Page 21] Internet-Draft LoST February 2007 8. Retrieving the Service Boundary via As discussed in Section 5.6, the can return a globally unique identifier in the 'serviceBoundary' attribute that can be used to retrieve the service boundary, rather than returning the boundary by value. This is shown in the example in Figure 8. The client can then retrieve the boundary using the request and obtains the boundary in the , illustrated in the example in Figure 10. The client issues the request to the server identified in the 'server' attribute of the element. These requests are always directed to the authoritative server and do not recurse. 37.775 -122.422 urn:service:sos.police Figure 8: request and response with service boundary reference Hardie, et al. Expires August 15, 2007 [Page 22] Internet-Draft LoST February 2007 San Francisco Police Department urn:service:sos.police sip:sfpd@example.com xmpp:sfpd@example.com 911 Figure 9: message with service boundary reference Figure 10: Requesting a service boundary with The request may also be used to retrieve service boundaries that are expressed as civic addresses, as illustrated in Figure 11. Hardie, et al. Expires August 15, 2007 [Page 23] Internet-Draft LoST February 2007 US New York New York Figure 11: Civic Address Service Boundary Response Hardie, et al. Expires August 15, 2007 [Page 24] Internet-Draft LoST February 2007 9. List Services: A LoST client can ask a LoST server for the list of services that it understands, primarily for diagnostic purposes. The query does not contain location information, as it simply provides an indication of which services the server can look up, not whether a particular service is offered for a particular area. Typically, only top-level services are included in the answer, implying support for all sub- services. Since the query is answered by the queried server, there is no notion of recursion or indirection and no path indication. The urn:service:sos Figure 12: Example of query urn:service:sos.ambulance urn:service:sos.animal-control urn:service:sos.fire urn:service:sos.gas urn:service:sos.mountain urn:service:sos.marine urn:service:sos.physician urn:service:sos.poison urn:service:sos.police urn:service:sos.suicide Figure 13: Example of Hardie, et al. Expires August 15, 2007 [Page 25] Internet-Draft LoST February 2007 10. List Services By Location: A LoST client can ask a LoST server for the list of services it knows about for a particular area. The query contains one or more elements, each from a different location profile (Section 11), and may contain the element. As for , the server selects the first location element that has a profile the server understands and it can operate either recursively or iteratively; < via> elements track the progress of the request. By its nature, the query can only indicate the services that a particular server can determine, not all possible services that might be offered. Unlike , the answer describes the services available at a specific location, not just those understood by the server. If the query contains the element, the LoST server returns only immediate child services of the queried service that are available for the provided location. If the element is absent, the LoST service returns all top-level services available for the provided location that it knows about. A server responds to this query with a response. This response MAY contain elements (see Section 6) and MUST contain a element, consisting of a whitespace-separated list of service URNs. The query and response are illustrated in Figure 14 and in Figure 15, respectively. 37:46:30N 122:25:10W urn:service:sos Figure 14: Example of query Hardie, et al. Expires August 15, 2007 [Page 26] Internet-Draft LoST February 2007 urn:service:sos.ambulance urn:service:sos.animal-control urn:service:sos.fire urn:service:sos.gas urn:service:sos.mountain urn:service:sos.marine urn:service:sos.physician urn:service:sos.poison urn:service:sos.police urn:service:sos.suicide Figure 15: Example of response Hardie, et al. Expires August 15, 2007 [Page 27] Internet-Draft LoST February 2007 11. Location Profiles LoST uses location information in elements in requests and elements in responses. Such location information may be expressed in a variety of ways. This variety can cause interoperability problems where a request or response contains location information in a format not understood by the server or the client, respectively. To achieve interoperability, this document defines two mandatory-to-implement baseline location profiles to define the manner in which location information is transmitted. It possible to standardize other profiles in the future. The two baseline profiles are: geodetic-2d: a simple profile for two-dimensional geodetic location information, as described in Section 11.2; civic: a profile consisting of civic address location information, as described in Section 11.3. Requests and responses containing or elements MUST contain location information in exactly one of the two baseline profiles, in addition to zero or more additional profiles. The ordering of location information indicates a preference on the part of the sender. Standards action is required for defining new profiles. A location profile MUST define: 1. The token identifying it in the LoST location profile registry; 2. The formal definition of the XML to be used in requests, i.e., an enumeration and definition of the XML child elements of the element; 3. The formal definition of the XML to be used in responses, i.e., an enumeration and definition of the XML child elements of the element; 4. The declaration of whether geodetic-2d or civic is to be used as the baseline profile. It is necessary to explicitly declare the baseline profile as future profiles may be combinations of geodetic and civic location information. Hardie, et al. Expires August 15, 2007 [Page 28] Internet-Draft LoST February 2007 11.1. Location Profile Usage A location profile is identified by a token in an IANA-maintained registry (Section 16.5). Clients send location information compliant with a location profile, and servers respond with location information compliant with that same location profile. When a LoST client sends a request that provides location information, it includes one or more elements. A element carries a mandatory 'profile' attribute that indicates the location format of the child elements. The concept of location profiles are described in Section 11. With the ability to specify more than one element the client is able to convey location information for multiple location profiles in the same request. When a LoST server sends a response that contains location information, it uses the elements much like the client uses the elements. Each element contains location information conformant to the location profile specified in the 'profile' attribute. When multiple elements are included then it enables the server to send location information compliant with multiple location profiles. Using the location profiles defined in this document, the following rules insure basic interoperatiblity between clients and servers: 1. A client MUST be capable of understanding the response for the baseline profiles it used in the request. 2. If a client sends location information conformant to any location profile other than geodetic-2d or civic, it MUST also send, in the same request, location information conformant to one of the baseline profiles. Otherwise, the server might not be able to understand the request. 3. There can only be one instance of each location profile in a query. 4. Servers MUST implement the geodetic-2d and civic profiles. 5. A server uses the first-listed location profile that it understands and ignores the others. 6. If a server receives a request that only contains location information using profiles it does not understand, the server responds with a (Section 12.1). Hardie, et al. Expires August 15, 2007 [Page 29] Internet-Draft LoST February 2007 7. The element MUST use the same location profile that was used to retrieve the answer and indicates which profile has been used with the 'profile' attribute. These rules enable the use of location profiles not yet specified, while ensuring baseline interoperability. Take, for example, this scenario. Client X has had its firmware upgraded to support the uber-complex-3D location profile. Client X sends location information to Server Y, which does not understand the uber-complex-3D location profile. If Client X also sends location information using the geodetic-2D baseline profile, then Server Y will still be able to understand the request and provide an understandable response, though with location information that might not be as precise or expressive as desired. This is possible because both Client X and Server Y understand the baseline profile. Hardie, et al. Expires August 15, 2007 [Page 30] Internet-Draft LoST February 2007 37.775 -122.422 37.775 -122.4194 37.555 -122.4194 37.555 -122.4264 37.775 -122.4264 37.775 -122.4194 -122.422 37.775 37.775 -122.422 urn:service:sos.police Figure 16: Example of a query with baseline profile interoperability Hardie, et al. Expires August 15, 2007 [Page 31] Internet-Draft LoST February 2007 San Francisco Police Department urn:service:sos.police 37.775 -122.4194 37.555 -122.4194 37.555 -122.4264 37.775 -122.4264 37.775 -122.4194 sip:nypd@example.com Figure 17: Example of a message with baseline profile interoperability 11.2. Two Dimensional Geodetic Profile The geodetic-2d location profile is identified by geodetic-2d. Clients use this profile by placing a GML [13] element within the element. This is defined by the 'point2D' pattern in the LoST schema (see Section 14). Servers use this profile by placing a GML [13] element within the element. This is defined by the 'polygon' pattern in the LoST schema (see Section 14). Hardie, et al. Expires August 15, 2007 [Page 32] Internet-Draft LoST February 2007 11.3. Basic Civic Profile The basic-civic location profile is identified by the token 'civic'. Clients use this profile by placing a element, defined in [11], within the element. Servers use this profile by placing a element, defined in [11], within the element. Hardie, et al. Expires August 15, 2007 [Page 33] Internet-Draft LoST February 2007 12. Errors, Warnings, and Redirects When a LoST server cannot fulfill a request completely, it can return either an error or a warning, depending on the severity of the problem. It returns an error element if no useful response can be returned for the query. It returns a element as part of another response element if it was able to respond in part, but the response may not be quite what the client had desired. For both elements, the 'source' attribute names the server that originally generated the error or warning, such as the authoritative server. Unless otherwise noted, all elements below can be either an error or a warning, depending on whether a default response, such as a mapping, is included. 12.1. Errors LoST defines a pattern for errors, defined as elements in the Relax NG schema. This pattern defines a 'message' attribute containing human readable text and an 'xml:lang' attribute denoting the language of the human readable text. One or more such error elements are contained in the element. The following errors follow this basic pattern: badRequest The server could not parse or otherwise understand a request, e.g., because the XML was malformed. forbidden The server refused to send an answer. This generally only occurs for recursive queries, namely if the client tried to contact the authoritative server and was refused. (For HTTP as the underlying protocol, an HTTP 401 error would be returned.) internalError The server could not satisfy a request due to misconfiguration or other operational and non-protocol related reasons. locationProfileUnrecognized None of the profiles in the request were recognized by the server (see Section 11). Hardie, et al. Expires August 15, 2007 [Page 34] Internet-Draft LoST February 2007 loop During a recursive query, the server was about to visit a server that was already in the server list in the element, indicating a request loop. notFound The server could not find an answer to the query. serverError An answer was received from another LoST server, but it could not be parsed or otherwise understood. This error occurs only for recursive queries. serverTimeout A time out occurred before an answer was received. serviceNotImplemented The requested service URN is not implemented and no substitution was available. An example is below: Figure 18: Example of an error resonse 12.2. Warnings A response MAY contain zero or more warnings. This pattern defines a 'message' attribute containing human readable text and an 'xml:lang' attribute denoting the language of the human readable text. One or more such warning elements are contained in the element. Hardie, et al. Expires August 15, 2007 [Page 35] Internet-Draft LoST February 2007 This version of the specification does not define any warning elements. 12.3. Redirects A LoST server can respond indicating that the querier should redirect the query to another server, using the element. The element includes a 'target' attribute indicating the LoST application unique string (see Section 4) that the client SHOULD be contacting next, as well as the 'source' attribute indicating the server that generated the redirect response and a 'message' attribute explaining the reason for the redirect response. During a recursive query, a server receiving a response can decide whether it wants to follow the redirection or simply return the response to its upstream querier. An example is below: Figure 19: Example of a redirect resonse Hardie, et al. Expires August 15, 2007 [Page 36] Internet-Draft LoST February 2007 13. LoST Transport LoST needs an underlying protocol transport mechanisms to carry requests and responses. This document defines the use of LoST over HTTP and LoST over HTTP-over-TLS; other mechanisms are left to future documents. The available transport mechanisms are determined through the use of the LoST U-NAPTR application. In protocols that support content type indication, LoST uses the media type application/ lost+xml. When using HTTP [3] and HTTP-over-TLS [4], LoST requests use the HTTP POST method. All HTTP responses are applicable. The HTTP URL is derived from the LoST server name via U-NAPTR application, as discussed above Hardie, et al. Expires August 15, 2007 [Page 37] Internet-Draft LoST February 2007 14. Relax NG Schema This section provides the Relax NG schema used by LoST protocol in the compact form. The verbose form is included in Appendix A. default namespace = "http://www.opengis.net/gml" namespace a = "http://relaxng.org/ns/compatibility/annotations/1.0" namespace ns1 = "urn:ietf:params:xml:ns:lost1" ## ## Location-to-Service Translation Protocol (LoST) ## ## A LoST XML instance has three request types, each with ## a cooresponding response type: find service, list services, ## and get service boundary. ## start = findService | listServices | listServicesByLocation | getServiceBoundary | findServiceResponse | listServicesResponse | listServicesByLocationResponse | getServiceBoundaryResponse | errors | redirect ## ## The queries. ## div { findService = element ns1:findService { element ns1:location { locationInformation }+, commonRequestPattern, attribute validateLocation { xsd:boolean >> a:defaultValue [ "false" ] }?, attribute serviceBoundary { ("reference" | "value") >> a:defaultValue [ "reference" ] }?, attribute recursive { xsd:boolean >> a:defaultValue [ "true" ] }? } listServices = element ns1:listServices { commonRequestPattern } Hardie, et al. Expires August 15, 2007 [Page 38] Internet-Draft LoST February 2007 listServicesByLocation = element ns1:listServicesByLocation { element ns1:location { locationInformation }*, commonRequestPattern, attribute recursive { xsd:boolean >> a:defaultValue [ "true" ] }? } getServiceBoundary = element ns1:getServiceBoundary { serviceBoundaryKey, extensionPoint } } ## ## The responses. ## div { findServiceResponse = element ns1:findServiceResponse { mapping+, locationValidation?, commonResponsePattern } listServicesResponse = element ns1:listServicesResponse { serviceList, commonResponsePattern } listServicesByLocationResponse = element ns1:listServicesByLocationResponse { serviceList, commonResponsePattern } getServiceBoundaryResponse = element ns1:getServiceBoundaryResponse { serviceBoundary, commonResponsePattern } } ## ## A pattern common to some of the queries. ## div { commonRequestPattern = service, extensionPoint } ## ## A pattern common to responses. ## div { commonResponsePattern = warnings*, path, extensionPoint } Hardie, et al. Expires August 15, 2007 [Page 39] Internet-Draft LoST February 2007 ## ## Location Information ## div { locationInformation = extensionPoint+, attribute profile { xsd:NMTOKEN } } ## ## Service Boundary ## div { serviceBoundary = element ns1:serviceBoundary { locationInformation }+ } ## ## Service Boundary Reference ## div { serviceBoundaryReference = element ns1:serviceBoundaryReference { source, serviceBoundaryKey, extensionPoint } serviceBoundaryKey = attribute key { xsd:token } } ## ## Path - ## Contains a list of via elements - ## places through which information flowed ## div { path = element ns1:path { element ns1:via { source, extensionPoint }* } } ## ## Expires pattern ## div { expires = attribute expires { xsd:dateTime } } ## ## A QName list Hardie, et al. Expires August 15, 2007 [Page 40] Internet-Draft LoST February 2007 ## div { qnameList = list { xsd:QName* } } ## ## A location-to-service mapping. ## div { mapping = element ns1:mapping { element ns1:displayName { xsd:string, attribute xml:lang { xsd:language } }*, service, (serviceBoundary | serviceBoundaryReference)?, element ns1:uri { xsd:anyURI }*, element ns1:serviceNumber { xsd:string { pattern = "[0-9*#]+" } }?, extensionPoint, expires, attribute lastUpdated { xsd:dateTime }, source, attribute sourceId { xsd:token }, attribute version { xsd:positiveInteger }, message } } ## ## Location validation ## div { locationValidation = element ns1:locationValidation { element ns1:valid { qnameList }?, element ns1:invalid { qnameList }?, element ns1:unchecked { qnameList }?, extensionPoint } } ## ## Errors and Warnings Container. ## div { Hardie, et al. Expires August 15, 2007 [Page 41] Internet-Draft LoST February 2007 errorContainer = (badRequest? & internalError? & serviceSubstitution? & forbidden? & notFound? & loop? & serviceNotImplemented? & serverTimeout? & serverError? & locationProfileUnrecognized?), extensionPoint, source errors = element ns1:errors { errorContainer } warnings = element ns1:warnings { errorContainer } } ## ## Basic Errors ## div { ## ## Error pattern. ## basicError = message, extensionPoint badRequest = element ns1:badRequest { basicError } internalError = element ns1:internalError { basicError } serviceSubstitution = element ns1:serviceSubstitution { basicError } forbidden = element ns1:forbidden { basicError } notFound = element ns1:notFound { basicError } loop = element ns1:loop { basicError } serviceNotImplemented = element ns1:serviceNotImplemented { basicError } serverTimeout = element ns1:serverTimeout { basicError } serverError = element ns1:serverError { basicError } locationProfileUnrecognized = element ns1:locationProfileUnrecognized { attribute unsupportedProfiles { xsd:NMTOKENS }, basicError } } ## ## Redirect. ## div { Hardie, et al. Expires August 15, 2007 [Page 42] Internet-Draft LoST February 2007 ## ## Redirect pattern ## redirect = element ns1:redirect { attribute target { appUniqueString }, source, message, extensionPoint } } ## ## Some common patterns. ## div { message = (attribute message { xsd:string }, attribute xml:lang { xsd:language })? service = element ns1:service { xsd:anyURI }? appUniqueString = xsd:string { pattern = "([a-zA-Z0-9\-]+\.)+[a-zA-Z0-9]+" } source = attribute source { appUniqueString } serviceList = element ns1:serviceList { list { xsd:anyURI* } } } ## ## Patterns for inclusion of elements from schemas in ## other namespaces. ## div { ## ## Any element not in the LoST namespace. ## notLost = element * - (ns1:* | ns1:*) { anyElement } ## ## A wildcard pattern for including any element ## from any other namespace. ## anyElement = (element * { anyElement } | attribute * { text } | text)* Hardie, et al. Expires August 15, 2007 [Page 43] Internet-Draft LoST February 2007 ## ## A point where future extensions ## (elements from other namespaces) ## can be added. ## extensionPoint = notLost* ## ## A 2D point from GML. ## point2d = element Point { attribute srsName { "urn:ogc:def:crs:EPSG::4326" }, pos } ## ## A GML position ## pos = element pos { list { xsd:double } } ## ## A Linear Ring from GML. ## linearRing = element LinearRing { pos, pos, pos, pos+ } ## ## A Polygon from GML. ## polygon = element Polygon { attribute srsName { "urn:ogc:def:crs:EPSG::4326" }, element exterior { linearRing }, element interior { linearRing }* } } Figure 20: RelaxNG schema Hardie, et al. Expires August 15, 2007 [Page 44] Internet-Draft LoST February 2007 15. Internationalization Considerations This mechanism is largely for passing protocol information from one subsystem to another; as such, most of its elements are tokens not meant for direct human consumption. If these tokens are presented to the end user, some localization may need to occur. The content of the element and the 'message' attributes may be displayed to the end user, and they are thus a complex types designed for this purpose. LoST exchanges information using XML. All XML processors are required to understand UTF-8 and UTF-16 encodings, and therefore all LoST clients and servers MUST understand UTF-8 and UTF-16 encoded XML. Additionally, LoST servers and clients MUST NOT encode XML with encodings other than UTF-8 or UTF-16. Hardie, et al. Expires August 15, 2007 [Page 45] Internet-Draft LoST February 2007 16. IANA Considerations 16.1. U-NAPTR Registrations This document registers the following U-NAPTR application service tag: Application Service Tag: LoST Defining Publication: The specification contained within this document. This document registers the following U-NAPTR application protocol tags: o Application Protocol Tag: http Defining Publication: RFC 2616 [3] o Application Protocol Tag: https Defining Publication: RFC 2818 [4] 16.2. Content-type registration for 'application/lost+xml' This specification requests the registration of a new MIME type according to the procedures of RFC 4288 [8] and guidelines in RFC 3023 [5]. MIME media type name: application MIME subtype name: lost+xml Mandatory parameters: none Optional parameters: charset Indicates the character encoding of enclosed XML. Hardie, et al. Expires August 15, 2007 [Page 46] Internet-Draft LoST February 2007 Encoding considerations: Uses XML, which can employ 8-bit characters, depending on the character encoding used. See RFC 3023 [5], Section 3.2. Security considerations: This content type is designed to carry LoST protocol payloads. Interoperability considerations: None Published specification: RFCXXXX [NOTE TO IANA/RFC-EDITOR: Please replace XXXX with the RFC number of this specification.] this document Applications which use this media type: Emergency and Location-based Systems Additional information: Magic Number: None File Extension: .lostxml Macintosh file type code: 'TEXT' Personal and email address for further information: Hannes Tschofenig, Hannes.Tschofenig@siemens.com Intended usage: LIMITED USE Author: This specification is a work item of the IETF ECRIT working group, with mailing list address . Hardie, et al. Expires August 15, 2007 [Page 47] Internet-Draft LoST February 2007 Change controller: The IESG delegated to the IETF ECRIT working group, if it is still active. 16.3. LoST Relax NG Schema Registration URI: urn:ietf:params:xml:ns:lost1 Registrant Contact: IETF ECRIT Working Group, Hannes Tschofenig (Hannes.Tschofenig@siemens.com). Relax NG Schema: The Relax NG schema to be registered is contained in Section 14. Its first line is default namespace = "urn:ietf:params:xml:ns:lost1" and its last line is } 16.4. LoST Namespace Registration URI: urn:ietf:params:xml:ns:lost1 Registrant Contact: IETF ECRIT Working Group, Hannes Tschofenig (Hannes.Tschofenig@siemens.com). XML: Hardie, et al. Expires August 15, 2007 [Page 48] Internet-Draft LoST February 2007 BEGIN LoST Namespace

Namespace for LoST

urn:ietf:params:xml:ns:lost1

See RFCXXXX [NOTE TO IANA/RFC-EDITOR: Please replace XXXX with the RFC number of this specification.].

END 16.5. LoST Location Profile Registry This document seeks to create a registry of location profile names for the LoST protocol. Profile names are XML tokens. This registry will operate in accordance with RFC 2434 [2], Standards Action. geodetic-2d: Defined in Section 11.2 civic: Defined in Section 11.3 Hardie, et al. Expires August 15, 2007 [Page 49] Internet-Draft LoST February 2007 17. Security Considerations There are multiple threats to the overall system of which service mapping forms a part. An attacker that can obtain service contact URIs can use those URIs to attempt to disrupt those services. An attacker that can prevent the lookup of contact URIs can impair the reachability of such services. An attacker that can eavesdrop on the communication requesting this lookup can surmise the existence of an emergency and possibly its nature, and may be able to use this to launch a physical attack on the caller. To avoid that an attacker can modify the query or its result, the use of channel security, such as TLS, is RECOMMENDED. Generally, authentication and authorization is not required for mapping queries. If it is, authentication mechanism of the underlying transport mechanism, such as HTTP basic and digest authentication, MAY be used. (Basic authentication SHOULD only be used in combination with TLS.) A more detailed description of threats and security requirements are provided in [17]. Hardie, et al. Expires August 15, 2007 [Page 50] Internet-Draft LoST February 2007 18. Acknowledgments We would like to the thank the following working group members for the detailed review of previous LoST document versions: o Martin Thomson (Review July 2006) o Jonathan Rosenberg (Review July 2006) o Leslie Daigle (Review September 2006) o Shida Schubert (Review November 2006) o Martin Thomson (Review December 2006) o Barbara Stark (Review January 2007) o Patrik Faeltstroem (Review January 2007 o Shida Schubert (Review January 2007 as a designated expert reviewer) We would also like to thank the following working group members for their input to selected design aspects of the LoST protocol: o Leslie Daigle and Martin Thomson (DNS-based LoST discovery procedure) o John Schnizlein (authoritive LoST answers) o Rohan Mahy (display names) o James Polk (error handling) o Ron Watro and Richard Barnes (expiry of cached data) o Stephen Edge, Keith Drage, Tom Taylor, Martin Thomson and James Winterbottom (Indication of PSAP Confidence Level) o Martin Thomson (service boundary references) o Martin Thomson (service URN in LoST response message) o Cullen Jennings (service boundaries) o Clive D.W. Feather, Martin Thomson (Validation Functionality) Hardie, et al. Expires August 15, 2007 [Page 51] Internet-Draft LoST February 2007 o Roger Marshall (PSAP Preference in LoST response) o James Winterbottom, Marc Linsner, Keith Drage, Tom-PT Taylor, Martin Thomson, John Schnizlein, Shida Schubert, Clive D.W. Feather, Richard Stastny, John Hearty, Roger Marshall, Jean- Francois Mule, Pierre Desjardins (Location Profiles) o Michael Hammer, Patrik Faeltstroem, Stastny Richard, Thomson, Martin, Roger Marshall, Tom-PT Taylor, Spencer Dawkins, Drage, Keith (List Services functionality) o Thomson, Martin, Michael Hammer (Mapping of Services) o Shida Schubert, James Winterbottom, Keith Drage (default service URN) o Otmar Lendl (LoST aggregation) Klaus Darilion and Marc Linsner provided miscellaneous input to the design of the protocol. Finally, we would like to thank Brian Rosen who participated in almost every discussion thread. Hardie, et al. Expires August 15, 2007 [Page 52] Internet-Draft LoST February 2007 19. Open Issues Please find open issues at: http://www.ietf-ecrit.org:8080/lost/ Hardie, et al. Expires August 15, 2007 [Page 53] Internet-Draft LoST February 2007 20. References 20.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [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. [5] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [6] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [7] Peterson, J., "A Presence-based GEOPRIV Location Object Format", RFC 4119, December 2005. [8] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005. [9] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and Registration Procedures for New URI Schemes", BCP 115, RFC 4395, February 2006. [10] Schulzrinne, H., "A Uniform Resource Name (URN) for Services", draft-ietf-ecrit-service-urn-05 (work in progress), August 2006. [11] Thomson, M. and J. Winterbottom, "Revised Civic Location Format for PIDF-LO", draft-ietf-geopriv-revised-civic-lo-04 (work in progress), September 2006. [12] Daigle, L., "Domain-based Application Service Location Using URIs and the Dynamic Delegation Discovery Service (DDDS)", draft-daigle-unaptr-01 (work in progress), October 2006. [13] OpenGIS, "Open Geography Markup Language (GML) Implementation Specification", OGC OGC 02-023r4, January 2003. Hardie, et al. Expires August 15, 2007 [Page 54] Internet-Draft LoST February 2007 20.2. Informative References [14] 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. [15] Saint-Andre, P., Ed., "Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence", RFC 3921, October 2004. [16] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, December 2004. [17] Taylor, T., "Security Threats and Requirements for Emergency Call Marking and Mapping", draft-ietf-ecrit-security-threats-03 (work in progress), July 2006. [18] Schulzrinne, H. and R. Marshall, "Requirements for Emergency Context Resolution with Internet Technologies", draft-ietf-ecrit-requirements-12 (work in progress), August 2006. [19] Schulzrinne, H., "Location-to-URL Mapping Architecture and Framework", draft-ietf-ecrit-mapping-arch-01 (work in progress), December 2006. [20] Rosen, B. and J. Polk, "Best Current Practice for Communications Services in support of Emergency Calling", draft-ietf-ecrit-phonebcp-00 (work in progress), October 2006. Hardie, et al. Expires August 15, 2007 [Page 55] Internet-Draft LoST February 2007 Appendix A. Non-Normative RELAX NG Schema in XML Syntax Location-to-Service Translation Protocol (LoST) A LoST XML instance has three request types, each with a cooresponding response type: find service, list services, and get service boundary.

The queries. false Hardie, et al. Expires August 15, 2007 [Page 56] Internet-Draft LoST February 2007 reference value reference true true Hardie, et al. Expires August 15, 2007 [Page 57] Internet-Draft LoST February 2007

The responses.

Hardie, et al. Expires August 15, 2007 [Page 58] Internet-Draft LoST February 2007 A pattern common to some of the queries.

A pattern common to responses.

Location Information

Service Boundary Hardie, et al. Expires August 15, 2007 [Page 59] Internet-Draft LoST February 2007

Service Boundary Reference

Path - Contains a list of via elements - places through which information flowed

Hardie, et al. Expires August 15, 2007 [Page 60] Internet-Draft LoST February 2007 Expires pattern

A QName list

A location-to-service mapping. Hardie, et al. Expires August 15, 2007 [Page 61] Internet-Draft LoST February 2007 [0-9*#]+

Location validation Hardie, et al. Expires August 15, 2007 [Page 62] Internet-Draft LoST February 2007

Errors and Warnings Container. Hardie, et al. Expires August 15, 2007 [Page 63] Internet-Draft LoST February 2007

Basic Errors Error pattern. Hardie, et al. Expires August 15, 2007 [Page 64] Internet-Draft LoST February 2007

Redirect. Hardie, et al. Expires August 15, 2007 [Page 65] Internet-Draft LoST February 2007 Redirect pattern

Some common patterns. ([a-zA-Z0-9\-]+\.)+[a-zA-Z0-9]+ Hardie, et al. Expires August 15, 2007 [Page 66] Internet-Draft LoST February 2007

Patterns for inclusion of elements from schemas in other namespaces. Any element not in the LoST namespace. A wildcard pattern for including any element from any other namespace. Hardie, et al. Expires August 15, 2007 [Page 67] Internet-Draft LoST February 2007 A point where future extensions (elements from other namespaces) can be added. A 2D point from GML. urn:ogc:def:crs:EPSG::4326 A GML position A Linear Ring from GML. Hardie, et al. Expires August 15, 2007 [Page 68] Internet-Draft LoST February 2007 A Polygon from GML. urn:ogc:def:crs:EPSG::4326

Figure 24 Hardie, et al. Expires August 15, 2007 [Page 69] Internet-Draft LoST February 2007 Authors' Addresses Ted Hardie Qualcomm, Inc. Email: hardie@qualcomm.com Andrew Newton SunRocket 8045 Leesburg Pike, Suite 300 Vienna, VA 22182 US Phone: +1 703 636 0852 Email: andy@hxr.us Henning Schulzrinne Columbia University Department of Computer Science 450 Computer Science Building New York, NY 10027 US Phone: +1 212 939 7004 Email: hgs+ecrit@cs.columbia.edu URI: http://www.cs.columbia.edu Hannes Tschofenig Siemens Networks GmbH & Co KG Otto-Hahn-Ring 6 Munich, Bavaria 81739 Germany Phone: +49 89 636 40390 Email: Hannes.Tschofenig@siemens.com URI: http://www.tschofenig.com Hardie, et al. Expires August 15, 2007 [Page 70] Internet-Draft LoST February 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). Hardie, et al. Expires August 15, 2007 [Page 71]