--- 1/draft-ietf-ecrit-lost-05.txt 2007-08-13 21:12:06.000000000 +0200 +++ 2/draft-ietf-ecrit-lost-06.txt 2007-08-13 21:12:06.000000000 +0200 @@ -1,23 +1,23 @@ ECRIT T. Hardie Internet-Draft Qualcomm, Inc. Intended status: Standards Track A. Newton -Expires: September 5, 2007 SunRocket +Expires: February 11, 2008 TranTech, Inc. H. Schulzrinne - Columbia U. + Columbia University H. Tschofenig - Siemens Networks GmbH & Co KG - March 4, 2007 + Nokia Siemens Networks + August 10, 2007 LoST: A Location-to-Service Translation Protocol - draft-ietf-ecrit-lost-05.txt + draft-ietf-ecrit-lost-06.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 @@ -28,135 +28,136 @@ 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 September 5, 2007. + This Internet-Draft will expire on February 11, 2008. Copyright Notice Copyright (C) The IETF Trust (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 . . . . . . . . . . . . . . 9 + 4. LoST Servers and Their Resolution . . . . . . . . . . . . . . 9 5. The Element . . . . . . . . . . . . . . . . . . . . 10 - 5.1. The Data Source: 'source', 'sourceId' and + 5.1. The Mapping Data Source: 'source', 'sourceId' and 'lastUpdated' Attributes . . . . . . . . . . . . . . . . . 10 - 5.2. Validity: The 'expires' Attribute . . . . . . . . . . . . 10 + 5.2. Mapping Validity: The 'expires' Attribute . . . . . . . . 10 5.3. Describing the Service with the Element . . 11 5.4. The Mapped Service: the Element . . . . . . . . 11 5.5. Defining the Service Region with the Element . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.6. Service Boundaries by Reference: the Element . . . . . . . . . . . . 12 - 5.7. The Service Number Element . . . . . . . . . . . . . . . . 13 + 5.7. The Service Number: the Element . . . . . 13 5.8. Service URLs: the Element . . . . . . . . . . . . . 13 - 6. Path of a Request: Element . . . . . . . . . . . . . . 14 - 7. Mapping a Location and Service to URLs: . . . . 15 - 7.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 15 - 7.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 15 - 7.2.1. Example Using Geodetic Coordinates . . . . . . . . . . 15 - 7.2.2. Civic Address Mapping Example . . . . . . . . . . . . 16 - 7.3. Components of the Request . . . . . . . . . 18 - 7.3.1. The Element . . . . . . . . . . . . . . . . 18 - 7.3.2. Identifying the Service: The Element . . . 19 - 7.3.3. Recursion and Iteration . . . . . . . . . . . . . . . 19 - 7.3.4. Service Boundary . . . . . . . . . . . . . . . . . . . 19 - 7.3.5. Requesting Civic Location Validation . . . . . . . . . 19 - 7.4. Components of the Mapping Response - . . . . . . . . . . . . . . . . . . 21 - 7.4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . 21 - 7.4.2. Civic Address Validation: the - Element . . . . . . . . . . . . . 22 - 8. Retrieving the Service Boundary via . . . 23 - 9. List Services: . . . . . . . . . . . . . . . . 26 - 10. List Services By Location: . . . . . 27 - 11. Location Profiles . . . . . . . . . . . . . . . . . . . . . . 29 - 11.1. Location Profile Usage . . . . . . . . . . . . . . . . . . 30 - 11.2. Two Dimensional Geodetic Profile . . . . . . . . . . . . . 33 - 11.3. Basic Civic Profile . . . . . . . . . . . . . . . . . . . 34 - 12. Errors, Warnings, and Redirects . . . . . . . . . . . . . . . 35 - 12.1. Errors . . . . . . . . . . . . . . . . . . . . . . . . . . 35 - 12.2. Warnings . . . . . . . . . . . . . . . . . . . . . . . . . 36 - 12.3. Redirects . . . . . . . . . . . . . . . . . . . . . . . . 37 - 13. LoST Transport . . . . . . . . . . . . . . . . . . . . . . . . 38 - 14. Relax NG Schema . . . . . . . . . . . . . . . . . . . . . . . 39 - 15. Internationalization Considerations . . . . . . . . . . . . . 46 - 16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47 - 16.1. U-NAPTR Registrations . . . . . . . . . . . . . . . . . . 47 - 16.2. Content-type registration for 'application/lost+xml' . . . 47 - 16.3. LoST Relax NG Schema Registration . . . . . . . . . . . . 49 - 16.4. LoST Namespace Registration . . . . . . . . . . . . . . . 49 - 16.5. LoST Location Profile Registry . . . . . . . . . . . . . . 50 - 17. Security Considerations . . . . . . . . . . . . . . . . . . . 51 - 18. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 52 - 19. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 54 - 20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 55 - 20.1. Normative References . . . . . . . . . . . . . . . . . . . 55 - 20.2. Informative References . . . . . . . . . . . . . . . . . . 56 - Appendix A. Non-Normative RELAX NG Schema in XML Syntax . . . . . 57 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 70 - Intellectual Property and Copyright Statements . . . . . . . . . . 71 + 6. Path of a Request: the Element . . . . . . . . . . . . 14 + 7. Identifying the Location Element Used for Mapping: + . . . . . . . . . . . . . . . . . . . . . . . . 15 + 8. Mapping a Location and Service to URLs: . . . . 16 + 8.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 16 + 8.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 16 + 8.2.1. Example Using Geodetic Coordinates . . . . . . . . . . 16 + 8.2.2. Civic Address Mapping Example . . . . . . . . . . . . 17 + 8.3. Components of the Request . . . . . . . . . 19 + 8.3.1. The Element . . . . . . . . . . . . . . . . 19 + 8.3.2. Identifying the Service: The Element . . . 20 + 8.3.3. Recursion and Iteration . . . . . . . . . . . . . . . 20 + 8.3.4. Service Boundary . . . . . . . . . . . . . . . . . . . 20 + 8.3.5. Requesting Civic Location Validation . . . . . . . . . 20 + 8.4. Components of the Mapping Response + . . . . . . . . . . . . . . . . . . 22 + 8.4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . 22 + 8.4.2. Civic Address Validation: the + Element . . . . . . . . . . . . . 23 + 9. Retrieving the Service Boundary via . . . 24 + 10. List Services: . . . . . . . . . . . . . . . . 27 + 11. List Services By Location: . . . . . 28 + 12. Location Profiles . . . . . . . . . . . . . . . . . . . . . . 30 + 12.1. Location Profile Usage . . . . . . . . . . . . . . . . . . 31 + 12.2. Two Dimensional Geodetic Profile . . . . . . . . . . . . . 34 + 12.3. Basic Civic Profile . . . . . . . . . . . . . . . . . . . 35 + 13. Errors, Warnings, and Redirects . . . . . . . . . . . . . . . 37 + 13.1. Errors . . . . . . . . . . . . . . . . . . . . . . . . . . 37 + 13.2. Warnings . . . . . . . . . . . . . . . . . . . . . . . . . 39 + 13.3. Redirects . . . . . . . . . . . . . . . . . . . . . . . . 40 + 14. LoST Transport: HTTP . . . . . . . . . . . . . . . . . . . . . 42 + 15. Relax NG Schema . . . . . . . . . . . . . . . . . . . . . . . 43 + 16. Internationalization Considerations . . . . . . . . . . . . . 50 + 17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 51 + 17.1. U-NAPTR Registrations . . . . . . . . . . . . . . . . . . 51 + 17.2. Content-type registration for 'application/lost+xml' . . . 51 + 17.3. LoST Relax NG Schema Registration . . . . . . . . . . . . 53 + 17.4. LoST Namespace Registration . . . . . . . . . . . . . . . 53 + 17.5. LoST Location Profile Registry . . . . . . . . . . . . . . 54 + 18. Security Considerations . . . . . . . . . . . . . . . . . . . 55 + 19. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 56 + 20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 58 + 20.1. Normative References . . . . . . . . . . . . . . . . . . . 58 + 20.2. Informative References . . . . . . . . . . . . . . . . . . 59 + Appendix A. Non-Normative RELAX NG Schema in XML Syntax . . . . . 60 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 74 + Intellectual Property and Copyright Statements . . . . . . . . . . 75 1. Introduction - Numerous techniques have been specified for the discovery of servers - for a particular service, including NAPTR records, SVRLOC and similar - protocols. However, there are an important class of services where - the specific service instance that is to be connected to depends on - the identity of the service and the location of the entity that needs - to reach it. An example of this is emergency telecommunications - services, where the service instance is a Public Safety Answering - Point (PSAP) that has jurisdiction over the location of the user - making the call. Here, the desired PSAP isn't necessarily the one - that is topologically or even line-of-sight closest to the caller; - rather, it is the one that serves the callers location based on - geopolitical boundaries. For this reason, the selected service - instance is a function of location and the desired service. + Protocols such as NAPTR records and the Service Location Protocol + (SLP) can be used to discover servers offering a particular service. + However, for an important class of services the appropriate specific + service instance depends both on the identity of the service and the + geographic location of the entity that needs to reach it. Emergency + telecommunications services are an important example; here, the + service instance is a Public Safety Answering Point (PSAP) that has + jurisdiction over the location of the user making the call. The + desired PSAP isn't necessarily the one that is topologically or even + line-of-sight closest to the caller; rather, it is the one that + serves the callers location based on jurisdictional boundaries. This document describes a protocol for mapping a service identifier - [9] and location information compatible with PIDF-LO [6], namely - revised civic location information [10] and GML [12]) 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. + (service URNs) [9] and location information compatible with PIDF-LO + [6], namely revised civic location information [10] and a subset of + the PIDF-LO profile [13] and consequently with the Geo-Shapes [12] + defined for GML [11]) to one or more service URLs. 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 other + service URNs. 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. + invalid, thus providing address validation, as described in Section + 3.5 of [18]. 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 supports caching of 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. @@ -168,131 +169,123 @@ The query message carries location information and a service identifier encoded as a Uniform Resource Name (URN) (see [9]) 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 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). + to the mapping function described in Section 8, the protocol also + allows to retrieve the service boundary (see Section 9) and to list + the services available for a particular location (see Section 11) or + supported by a particular server (see Section 10). 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 uses the following terms: - Mapping: - - Mapping is a process that takes a location and a service - identifier as inputs and returns one or more URIs that point to a - host providing that service or acting as an intermediary to - establish communication with the serving entity. This definition + Mapping: Mapping is a process that takes a location and a service + identifier as inputs and returns one or more URIs. Those URIs can + either point to a host providing that service or to a host that in + turn routes the request to the final destination. This definition is a generalization of the term "mapping" as used in [18], because - of the potential for LoST to be used for non-emergency services. + LoST can be used for non-emergency services. - LoST Client and Server: + LoST client: A host acts as a LoST client if it sends LoST query + messages and receives LoST response messages. - "LoST client" is the role played by an entity that sends LoST - query messages and receives LoST response messages. "LoST server" - is the role played by an entity that receives LoST query messages - and sends LoST response messages. In recursive operation, the - same entity may play both roles. This document also uses the term - "authoritative server" to designate an entity that acts in the - LoST server role only and successfully resolves the input location - and service identifier to a URI or set of URIs. + LoST server: A host acts as a LoST server if it receives LoST query + messages and sends LoST response messages. In recursive + operation, the same entity may be both a client and a server. - Service Boundary: + Authoritative LoST server: An authoritative server acts only as a + server and successfully resolves the input location and service + identifier to a URI or set of URIs. - A service boundary is the boundary or set of boundaries of a - geographic region, respectively set of geographic regions, within - which all locations will map to the same URI or set of URIs for a - given service. + Service boundary: A service boundary circumscribes the region within + which all locations map to the same service URI or set of URIs for + a given service. A service boundary may consist of several non- + contiguous geometric shapes. Validation: - The term "validation" as used in this document is a concrete - realization of the term "location validation" as defined in - Section 3.5 of [18]. + The term "validation" describes the behavior defined as "location + validation" in Section 3.5 of [18]. Additional emergency service terminology can be found in [18]. 3. Overview of Protocol Usage The LoST protocol supports the following type of queries and responses: and - This message pattern allows to perform retrieve contact URIs based - on location information together with a service identifier. The - same query type may also ask for location validation and for - service numbers, either integrated into mapping request or - separately. The details can be found in Section 7 and - Section 7.4. + A LoST client retrieves contact URIs based on location information + and a service identifier with this request and response. The same + query type may also ask for location validation and for service + numbers, either combined with a mapping request or separately. + The details can be found in Section 8 and Section 8.4. and - This message pattern allows query for a service boundary. The - details can be found in Section 8. + A LoST client obtains a service boundary with this request and + response, as described in Section 9. and - This message pattern enables a LoST client to ask a LoST server - for the services it supports. The details can be found in - Section 9. + With this request and response, a LoST client can find out which + services a LoST server supports, as described in Section 10. and - This message pattern provides the LoST client with the services - that are available for a specific location region. The details - can be found in Section 10. + A LoST client can determine with this request and response which + services are available for a specific location region. Section 11 + describes the details. LoST clients may initiate any of the above queries at any time. Among the common triggers are: - 1. When the client initially starts up or attaches to a network. + 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. + 2. when the client detects that its location has changed + sufficiently that it is outside the bounds of the service region; - 3. An incoming message at a SIP proxy in a location-based routing - scenario that requires a routing decision to be made. + 3. when a SIP message arrives at a SIP proxy performing location- + based call routing; - 4. When cached mapping information has expired. + 4. when cached mapping information has expired; - 5. When invoking a particular service. At that time, a client may + 5. 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 5.2), or they become invalid if the caller's device moves beyond the boundaries of the service region. -4. LoST servers and Their Resolution - - LoST servers are identified by U-NAPTR/DDDS [11] application unique - strings, in the form of a DNS name. +4. LoST Servers and Their Resolution - An example is 'lostserver.example.com' + LoST servers are identified by U-NAPTR/DDDS [8] application unique + strings, in the form of a DNS name. An example is + 'lostserver.example.com'. - Clients need to use the U-NAPTR [11] specification described below to + Clients need to use the U-NAPTR [8] 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 "example.com" to the HTTPS URL https://lostserv.example.com/secure or the HTTP URL http://lostserver.example.com, with the former being preferred. @@ -306,47 +299,47 @@ Clients learn the LoST server's host name by means beyond the scope of this specification, such as SIP configuration and DHCP. 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. The Data Source: 'source', 'sourceId' and 'lastUpdated' Attributes +5.1. The Mapping Data Source: 'source', 'sourceId' and 'lastUpdated' + Attributes The 'source', the 'sourceId' and the 'lastUpdated' attributes uniquely identify a particular mapping record. They are created by - the authoritative source for a mapping and never modified when a + the authoritative source for a mapping and are 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 more recent - datum in 'lastUpdated'. + time in 'lastUpdated'. The 'source' attribute contains a LoST application unique string - identifying the authoritative generator of the mapping. See - Section 4. + identifying the authoritative generator of the mapping (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 'lastUpdated' attribute describes when a specific instance of mapping, identified by the combination of 'source' and 'sourceId', 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. -5.2. Validity: The 'expires' Attribute +5.2. Mapping 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. The 'expires' attribute is REQUIRED to be included in the element. Optionally, this attribute may contain the values of 'NO-CACHE' and 'NO-EXPIRATION' instead of a dateTime value. The value 'NO-CACHE' is @@ -354,211 +347,219 @@ 'NO-EXPIRATION' is an indication that the mapping does not expire. 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. Since the expired mapping will be returned to the client as a non-error/non-warning response it is the responsibility of the client to check the 'expires' attribute - associated with mapping data returned in a LoST response to detemine + associated with mapping data returned in a LoST response to determine whether the mapping is fresh. 5.3. 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. 5.4. 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: + The mandatory 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 [9] in the element of the request, exists for the location - indicated, then the LoST server puts the service URN from the + indicated, then the LoST server copies the service URN from the request into the element. 2. If, however, the requested service, identified by the service URN [9] 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 + (Section 13.1) 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. - 5.5. 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 5.6). If a client moves outside the service area and wishes to obtain current service data, it sends a new query 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). If included in a response, the - element MUST contain at least one service boundary that uses 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. + to a specific location profile, identified by the 'profile' attribute + (see Section 12). serviceBoundary elements formatted according to + different location profiles are alternative representations of the + same area, not additive to one another; this allows a client + understanding only one of the profile types to be sure it has a + complete view of the serviceBoundary. Within a serviceBoundary + element there may, however, be multiple locations which _are_ + additive; this is necessary because some serviceBoundary areas could + not be easily expressed with a single shape or civic location. If + included in a response, the element MUST contain at + least one service boundary that uses the same profile as the request. - A service boundary is requested by the client (using the + A service boundary is requested by the client, using the 'serviceBoundary' attribute in the request with the value set to - "value"). - - 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. + "value". 5.6. 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 + can thus be quite large, clients may wish to conserve bandwidth by + requesting a reference to the service boundary instead of the value described in Section 5.5. 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. + getServiceBoundary (Section 9) request. A reference to a service boundary is requested by the client (using the 'serviceBoundary' attribute in the request with the value set to "reference"). A LoST server may decide, based on local policy, to return the service boundary per value or to omit the element in the response. 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. + the remainder of the mapping has become invalid. -5.7. The Service Number Element +5.7. The Service Number: the 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 service. 5.8. 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'. -6. Path of a Request: Element +6. Path of a Request: the 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 initially received the request from the client issuing the request. The element is inserted logically on receipt of the request, so that every server in a recursive query operation is included in the element. The server that answers the request instead of forwarding it, such as the authoritative server, copies the element verbatim into the response. The element is not modified in responses as the responses traverses the server chain back to the querying client. If a query is answered iteratively, the querier includes all servers that it has already contacted. + When a cached mapping is returned then the element cached + together with the mapping is returned. + The example in Figure 5 indicates that the answer was given to the client by the LoST server at esgw.ueber-110.de.example, which got the answer from the (authoritative) LoST server at polizei.muenchen.de.example. -7. Mapping a Location and Service to URLs: +7. Identifying the Location Element Used for Mapping: -7.1. Overview + Several of the requests can provide one or more elements, + among which the server gets to choose. It is useful for the client + to be able to determine which one was actually used in producing the + result. For that purpose, the tag MUST contain an 'id' + attribute that uniquely identifies the element. The + format of the identifier is left to the client; it could, for + example, use a hash of the location information. The server returns + the identifier for the element it used in the + tag. + +8. Mapping a Location and Service to URLs: + +8.1. 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 +8.2. Examples -7.2.1. Example Using Geodetic Coordinates +8.2.1. 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:nypd@example.com" and - "xmpp:nypd@example.com". The server has also given the client a + service to the New York City Police Department, instructing the + client that it may contact them via the URIs "sip:nypd@example.com" + and "xmpp:nypd@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. + sourceId="7e3f40b098c711dbb6060800200c9a66"> New York City Police Department urn:service:sos.police 37.775 -122.4194 37.555 -122.4194 @@ -567,41 +568,41 @@ 37.775 -122.4194 sip:nypd@example.com xmpp:nypd@example.com 911 - + + Figure 3: A geodetic answer -7.2.2. Civic Address Mapping Example +8.2.2. 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 + The example below shows how to map a service to a location much like + the example in Section 8.2.1, 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). - + Germany Bavaria Munich Otto-Hahn-Ring 6 81675 @@ -622,21 +623,21 @@ 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. + sourceId="e8b05a41d8d1415b80f2cdbb96ccf109"> Muenchen Polizei-Abteilung urn:service:sos.police Germany Bavaria @@ -645,280 +646,286 @@ sip:munich-police@example.com xmpp:munich-police@example.com 110 + Figure 5: A civic address answer -7.3. Components of the Request +8.3. 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 may be contained in the response. -7.3.1. The Element +8.3.1. 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 + (see Section 12). There MUST NOT be more than one location element + for each distinct location profile. The order of location elements + is significant; the server uses the first location element where it understands the location profile. -7.3.2. Identifying the Service: The Element +8.3.2. Identifying the Service: The Element The type of service desired is specified by the element. It contains service URNs from the registry established in [9]. -7.3.3. Recursion and Iteration +8.3.3. Recursion and Iteration LoST can operate in either recursive or iterative mode, on a request- by-request basis. In recursive mode, the LoST server initiates queries on behalf of the requester and returns the result to the requester. In iterative mode, the server contacted returns a redirection - response indicating the next server to be queried. + response indicating the next server to be queried if the server + contacted cannot provide an answer itself. For the queries defined in this document, only 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". -7.3.4. Service Boundary +8.3.4. 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. -7.3.5. Requesting Civic Location Validation +8.3.5. 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. + Section 8.4.2. The example in Figure 6 demonstrates address + validation. If the server chooses a geodetic location among the + locations provided in a request, the attribute is ignored. - + DE Bavaria Munich Otto-Hahn-Ring 6 81675 urn:service:sos.police Figure 6: A query with address validation request + sourceId="4db898df52b84edfa9b6445ea8a0328e"> 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 + HNO - + + Figure 7: A message with address validation information -7.4. Components of the Mapping Response +8.4. Components of the Mapping Response -7.4.1. Overview +8.4.1. 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 + (Section 13.2), location validation information (Section 8.4.2), and an indication of the path (Section 6) the response has taken. -7.4.2. Civic Address Validation: the Element +8.4.2. 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 SHOULD include this information if the 'validateLocation' attribute in the request was true but local policy at the server may allow this information to be omitted. Each element contains a list of tokens separated by white - space, enumerating the civic location lables used in child elements + space, enumerating the civic location labels 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. + civic address elements found in the list. Civic location + tokens that are neither listed in the , the and the + element belong to the class of unchecked tokens. 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. + The example shown in Figure 6 and in Figure 7 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. The 'HNO' token belongs to + the class of unchecked location tokens. -8. Retrieving the Service Boundary via +9. Retrieving the Service Boundary via As discussed in Section 5.5, 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 + the boundary by value. This is shown in the example in Figure 8 and + Figure 9. 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 + sourceId="7e3f40b098c711dbb6060800200c9a66"> New York City Police Department urn:service:sos.police sip:nypd@example.com xmpp:nypd@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. - + US New York New York - + Figure 11: Civic Address Service Boundary Response -9. List Services: +10. 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 - (Section 11) query below can be used to find out whether a particular service is offered for a specific location. An example request and response are shown in Figure 12. urn:service:sos Figure 12: Example of query @@ -935,54 +942,57 @@ urn:service:sos.marine urn:service:sos.physician urn:service:sos.poison urn:service:sos.police urn:service:sos.suicide Figure 13: Example of -10. List Services By Location: +11. 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. + location profile (Section 12), 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. + request. The query indicates the services that the server can + enumerate from within the forest structure of which it is a part. + Because LoST does not presume a single, overarching organization of + all potential service types, there may be services available within a + geographic area which could be described by other LoST servers + connected to other forest structures. As an example, the emergency + services forest for a region may be distinct from the forests that + locate commercial services within the same region 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. - + -34.407 150.883 urn:service:sos Figure 14: Example of query - + + Figure 15: Example of response -11. Location Profiles +12. 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 + is possible to standardize other profiles in the future. The three baseline profiles are: geodetic-2d: - a simple profile for two-dimensional geodetic location - information, as described in Section 11.2; + a profile for two-dimensional geodetic location information, as + described in Section 12.2; civic: a profile consisting of civic address location information, as - described in Section 11.3. + described in Section 12.3. 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: @@ -1047,244 +1058,303 @@ 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. -11.1. Location Profile Usage +12.1. Location Profile Usage A location profile is identified by a token in an IANA-maintained - registry (Section 16.5). Clients send location information compliant + registry (Section 17.5). 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. + element carries an optional 'profile' attribute that + indicates the location format of the child elements. A client may + obtain location information that does not conform to a profile it + recognizes or it may not have the capability to map XML to profiles. + In that case, a client MAY omit the profile attribute and the server + should interpret the XML location data to the best of its ability, + returning a "locationProfileUnrecognized" error if it is unable to do + so. + + The concept of location profiles are described in Section 12. 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. + contains location information conforming to the location profile + specified in the 'profile' attribute. A response MAY contain + multiple mappings or boundaries for the different + elements, subject to the restrictions below. Using the location profiles defined in this document, the following - rules insure basic interoperatiblity between clients and servers: + rules ensure interoperability 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. + profile other than the ones described in this document, 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. A client SHOULD NOT send multiple profiles of derived - from different baseline profiles. Or said another way, a client - should only send location profiles from the same baseline profile - in the same query. If a client has location information - primarily of geodetic nature and location information primarily - of a civic nature, it should send separate requests containing - each type of location information. + 3. A client MUST NOT send multiple objects that are + derived from different baseline profiles. In other words, a + client MUST only send location objects according to the same + baseline profile in a query, but it MAY contain a location + element following a baseline profile in addition to some other + profile. - 4. There can only be one instance of each location profile in a + 4. If a client has both location information primarily of geodetic + nature and location information primarily of a civic nature, it + MUST send separate requests containing each type of location + information. + + 5. There can only be one instance of each location profile in a query. - 5. Servers MUST implement the geodetic-2d and civic profiles. + 6. Servers MUST implement all profiles described in this document. - 6. A server uses the first-listed location profile that it + 7. A server uses the first-listed location profile that it understands and ignores the others. - 7. If a server receives a request that only contains location + 8. 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). + responds with a (Section 13.1). - 8. The element MUST use the same location profile + 9. 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. + 'not-yet-standardized-prism-profile' location profile. Client X + sends location information to Server Y, which does not understand the + 'not-yet-standardized-prism-profile' 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. - - - 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 - + + + + + + + + 42.556844 -73.248157 36.6 + 42.656844 -73.248157 36.6 + 42.656844 -73.348157 36.6 + 42.556844 -73.348157 36.6 + 42.556844 -73.248157 36.6 + + + + + + + 2.4 + + - - 37.775 -122.422 - + + 42.656844 -73.348157 + urn:service:sos.police Figure 16: Example of a query with baseline profile interoperability + sourceId="cf19bbb038fb4ade95852795f045387d"> New York City 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 +12.2. Two Dimensional Geodetic Profile - The geodetic-2d location profile is identified by geodetic-2d. - Clients use this profile by placing a element, as described - in Section 7.2.1 of [13], within the element. Section - 7.2.1 of [13] describes the specification of a with either a - two dimensional position (latitude and longitude) or three - dimensional position (latitude, longitude, and altitude). A client - MAY use the three dimensional position, and servers MAY interpret a - three dimensional position as a two dimensional position by ignoring - altitude. + The "geodetic-2d" location profile is identified by "geodetic-2d". + Clients and servers use this profile by placing the following + location shapes into the or into the + element (unless indicated otherwise): - Servers use this profile by placing a element, as described - in Section 7.2.2 of [13], within the element. This - is defined by the 'polygon' pattern in the LoST schema (see - Section 14). + Point: - With respect to the description in Section 7.2.2 of [13] the - restriction to 16 points for a polygon is not applicable to this - document. With this profile servers MUST use WGS 84 (latitude, - longitude), i.e., the srsName set to 'urn:ogc:def:crs:EPSG::4326' - where altitude information is omitted. The orientation of the points - in the polygon is upward normal as described in Section 7.2.2 of - [13]. + The element is described in Section 5.2.1 of [13]. + Section 5.2.1 of [13] shows also the specification of a + with either a two dimensional position (latitude and longitude) or + three dimensional position (latitude, longitude, and altitude). A + client MAY use the three dimensional position, and servers MAY + interpret a three dimensional position as a two dimensional + position by ignoring the altitude value. A element is not + placed into a element. -11.3. Basic Civic Profile + Polygon: + + The element is described in Section 5.2.2 of [13]. The + restriction to 16 points for a polygon contained in Section 7.2.2 + of [12] is not applicable to this document. + + Circle: + + The element is described in Section 5.2.3 of [13]. + + Ellipse: + + The element is described in Section 5.2.4 of [13]. + + ArcBand: + + The element is described in Section 5.2.5 of [13]. + + When clients place a , , or + element within the element then it indicates that the + query is about any point contained in the given area; it is left to + the server to select an appropriate matching algorithm, such as using + computing the centroid. A server MAY return multiple + elements if the polygon extends across multiple service areas. + + When geodetic location information of this location profile is placed + in the element then the elements with geospatial + coordinates are alternative descriptions of the same service region, + not additive geometries. + +12.3. Basic Civic Profile The basic-civic location profile is identified by the token 'civic'. Clients use this profile by placing a element, defined in [10], within the element. Servers use this profile by placing a element, defined in [10], within the element. -12. Errors, Warnings, and Redirects + 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. Hence, a response may contain multiple + elements with civic and/or geodetic location + profiles. + +13. 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. This document - does not define warnings. 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. + 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 +13.1. 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.) + authoritative server and was refused. 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). + (see Section 12). + + locationInvalid + + The geodetic or civic location in the request was invalid. For + example, the longitude or latitude values fall outside the + acceptable ranges. + + SRSInvalid + + The spatial reference system (SRS) contained in the location + element was not recognized or does not match the location profile. 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. @@ -1307,69 +1377,151 @@ An example is below: Figure 18: Example of an error resonse -12.2. Warnings +13.2. 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. + To provide human readable text in an appropriate language the HTTP + content negotiation capabilities (see Section 14) MAY be utilized by + a server. - This version of the specification does not define any warning - elements. + This version of the specification defines the following warnings: -12.3. Redirects + locationValidationUnavailable + + The element MAY be returned when a + server wishes to notify a client that it cannot fulfill a location + validation request. This warning allows a server to return + mapping information while signalling this exception state. + + serviceSubstitution + + The element MAY be returned when a server + was not able to fulfill a request for a given + service URN. For example, a request with the + 'urn:service:sos.police' service URN for a location in Uruguay may + cause the LoST service to return a mapping for the + 'urn:service:sos' service URN since Uruguay does not make use of + the sub-services police, fire and ambulance. If this warning is + returned then the element in the response provides + information about the service URN that refers to the mapping. + + defaultMappingReturned + + The element MAY be returned when a server + was not able to fulfill a request for a given + location but is able to respond with a default URI. For example, + a nearby PSAP may be returned. + + An example of a warning is shown below: + + + + + + New York City 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 19: Example of an warning resonse + +13.3. 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 + Figure 20: Example of a redirect response -13. LoST Transport +14. LoST Transport: HTTP 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 + POST method. The HTTP request MUST use the Cache-Control response + directive "no-cache" to HTTP-level "caching even by caches that have + been configured to return stale responses to client requests." -14. Relax NG Schema + All LoST responses, including those indicating a LoST warning or + error, are carried in 2xx responses, typically 200 (OK). Other 2xx + responses, in particular 203 (Non-authoritative information) may be + returned by HTTP caches that disregard the caching instructions. 3xx, + 4xx and 5xx HTTP response codes indicates that the HTTP request + itself failed or was redirected; these responses do not contain any + LoST XML elements. + + The HTTP URL is derived from the LoST server name via U-NAPTR + application, as discussed above. + +15. 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. namespace a = "http://relaxng.org/ns/compatibility/annotations/1.0" default namespace ns1 = "urn:ietf:params:xml:ns:lost1" ## ## Location-to-Service Translation Protocol (LoST) ## @@ -1449,21 +1601,21 @@ div { commonResponsePattern = warnings*, path, extensionPoint } ## ## Location Information ## div { locationInformation = extensionPoint+, - attribute profile { xsd:NMTOKEN } + attribute profile { xsd:NMTOKEN }? } ## ## Service Boundary ## div { serviceBoundary = element serviceBoundary { locationInformation }+ } ## @@ -1539,67 +1691,74 @@ element invalid { qnameList }?, element unchecked { qnameList }?, extensionPoint } } ## ## Errors and Warnings Container. ## div { - errorContainer = + exceptionContainer = (badRequest? & internalError? & serviceSubstitution? + & defaultMappingReturned? & forbidden? & notFound? & loop? & serviceNotImplemented? & serverTimeout? & serverError? + & locationInvalid? & locationProfileUnrecognized?), extensionPoint, source - errors = element errors { errorContainer } - warnings = element warnings { errorContainer } + errors = element errors { exceptionContainer } + warnings = element warnings { exceptionContainer } } ## -## Basic Errors +## Basic Exceptions ## div { ## - ## Error pattern. + ## Exception pattern. ## - basicError = message, extensionPoint - badRequest = element badRequest { basicError } - internalError = element internalError { basicError } - serviceSubstitution = element serviceSubstitution { basicError } - forbidden = element forbidden { basicError } - notFound = element notFound { basicError } - loop = element loop { basicError } - serviceNotImplemented = element serviceNotImplemented { basicError } - serverTimeout = element serverTimeout { basicError } - serverError = element serverError { basicError } + basicException = message, extensionPoint + badRequest = element badRequest { basicException } + internalError = element internalError { basicException } + serviceSubstitution = element serviceSubstitution { basicException } + defaultMappingReturned = + element defaultMappingReturned { basicException } + forbidden = element forbidden { basicException } + notFound = element notFound { basicException } + loop = element loop { basicException } + serviceNotImplemented = + element serviceNotImplemented { basicException } + serverTimeout = element serverTimeout { basicException } + serverError = element serverError { basicException } + locationInvalid = element locationInvalid { basicException } + locationValidationUnavailable = + element locationValidationUnavailable { basicException } locationProfileUnrecognized = element locationProfileUnrecognized { attribute unsupportedProfiles { xsd:NMTOKENS }, - basicError + basicException } } ## ## Redirect. ## div { - ## ## Redirect pattern ## redirect = element redirect { attribute target { appUniqueString }, source, message, extensionPoint } @@ -1634,51 +1793,49 @@ notLost = element * - (ns1:* | ns1:*) { anyElement } ## ## A wildcard pattern for including any element ## from any other namespace. ## anyElement = (element * { anyElement } | attribute * { text } | text)* - ## ## A point where future extensions ## (elements from other namespaces) ## can be added. ## extensionPoint = notLost* - } - Figure 20: RelaxNG schema + Figure 21: RelaxNG schema -15. Internationalization Considerations +16. 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. + The LoST protocol is mostly meant for machine-to-machine + communications; 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 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. -16. IANA Considerations +17. IANA Considerations -16.1. U-NAPTR Registrations +17.1. 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 @@ -1689,99 +1846,95 @@ 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' +17.2. Content-type registration for 'application/lost+xml' This specification requests the registration of a new MIME type according to the procedures of RFC 4288 [7] 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. - 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: + Encoding considerations: Uses XML, which can employ 8-bit + characters, depending on the character encoding used. See RFC + 3023 [5], Section 3.2. - This content type is designed to carry LoST protocol payloads. + 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: + replace XXXX with the RFC number of this specification.] - Emergency and Location-based Systems + 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 + Tschofenig, Hannes.Tschofenig@nsn.com Intended usage: LIMITED USE Author: This specification is a work item of the IETF ECRIT working group, with mailing list address . Change controller: The IESG -16.3. LoST Relax NG Schema Registration +17.3. LoST Relax NG Schema Registration URI: urn:ietf:params:xml:ns:lost1 Registrant Contact: IETF ECRIT Working Group, Hannes Tschofenig - (Hannes.Tschofenig@siemens.com). + (Hannes.Tschofenig@nsn.com). Relax NG Schema: The Relax NG schema to be registered is contained - in Section 14. Its first line is + in Section 15. Its first line is default namespace = "urn:ietf:params:xml:ns:lost1" and its last line is } -16.4. LoST Namespace Registration +17.4. LoST Namespace Registration URI: urn:ietf:params:xml:ns:lost1 Registrant Contact: IETF ECRIT Working Group, Hannes Tschofenig - (Hannes.Tschofenig@siemens.com). + (Hannes.Tschofenig@nsn.com). XML: BEGIN 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 +17.5. 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 + Defined in Section 12.2. civic: - Defined in Section 11.3 + Defined in Section 12.3. -17. Security Considerations +18. Security Considerations - There are multiple threats to the overall system of which service + There are several 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]. -18. Acknowledgments +19. 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) @@ -1859,20 +2012,22 @@ reviewer) o Jonathan Rosenberg (Review February 2007) o Tom Taylor (Review February 2007) o Theresa Reese (Review February 2007) o Shida Schubert (Review February 2007) + o James Winterbottom (Review July 2007) + 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) @@ -1907,23 +2062,34 @@ URN) o Otmar Lendl (LoST aggregation) o Tom Taylor (Terminology) 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. -19. Open Issues + Early implementation efforts lead to good feedback by two open source + implementation groups. We would like to thank the implementers for + their work and for helping us to improve the quality of the + specification: - Please find open issues at: http://www.ietf-ecrit.org:8080/lost/ + o Wonsang Song + + o Jong-Yul Kim + + o Anna Makarowska + + o Krzysztof Rzecki + + o Blaszczyk Piotr 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, @@ -1937,84 +2103,86 @@ [5] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [6] Peterson, J., "A Presence-based GEOPRIV Location Object Format", RFC 4119, December 2005. [7] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005. - [8] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and - Registration Procedures for New URI Schemes", BCP 115, - RFC 4395, February 2006. + [8] Daigle, L., "Domain-Based Application Service Location Using + URIs and the Dynamic Delegation Discovery Service (DDDS)", + RFC 4848, April 2007. [9] Schulzrinne, H., "A Uniform Resource Name (URN) for Services", - draft-ietf-ecrit-service-urn-05 (work in progress), - August 2006. + draft-ietf-ecrit-service-urn-06 (work in progress), March 2007. [10] Thomson, M. and J. Winterbottom, "Revised Civic Location Format for PIDF-LO", draft-ietf-geopriv-revised-civic-lo-05 (work in progress), February 2007. - [11] Daigle, L., "Domain-based Application Service Location Using - URIs and the Dynamic Delegation Discovery Service (DDDS)", - draft-daigle-unaptr-02 (work in progress), February 2007. - - [12] Cox, S., Daisey, P., Lake, R., Portele, C., and A. Whiteside, + [11] Cox, S., Daisey, P., Lake, R., Portele, C., and A. Whiteside, "Geographic information - Geography Markup Language (GML)", OGC Standard OpenGIS 03-105r1, April 2004. - [13] Reed, C. and M. Thomson, "GML 3.1.1 PIDF-LO Shape Application + [12] Reed, C. and M. Thomson, "GML 3.1.1 PIDF-LO Shape Application Schema for use by the Internet Engineering Task Force (IETF)", Candidate OpenGIS Implementation Specification , December 2006. 20.2. Informative References + [13] Tschofenig, H., "GEOPRIV PIDF-LO Usage Clarification, + Considerations and Recommendations", + draft-ietf-geopriv-pdif-lo-profile-08 (work in progress), + July 2007. + [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. + Call Marking and Mapping", draft-ietf-ecrit-security-threats-04 + (work in progress), April 2007. [18] Schulzrinne, H. and R. Marshall, "Requirements for Emergency Context Resolution with Internet Technologies", - draft-ietf-ecrit-requirements-12 (work in progress), - August 2006. + draft-ietf-ecrit-requirements-13 (work in progress), + March 2007. [19] Schulzrinne, H., "Location-to-URL Mapping Architecture and - Framework", draft-ietf-ecrit-mapping-arch-01 (work in - progress), December 2006. + Framework", draft-ietf-ecrit-mapping-arch-02 (work in + progress), July 2007. [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. + draft-ietf-ecrit-phonebcp-01 (work in progress), March 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. @@ -2162,31 +2333,32 @@
Location Information + +
Service Boundary -
@@ -2334,21 +2506,21 @@
Errors and Warnings Container. - + @@ -2364,122 +2536,137 @@ + + + + - + - +
- Basic Errors + Basic Exceptions - + - Error pattern. + Exception pattern. - + - + - - + - + - + - + - + - + - + + + + + + + + + + + + - +
Redirect. + Redirect pattern @@ -2585,58 +2773,57 @@ can be added.
- - Figure 24 + Figure 25 Authors' Addresses Ted Hardie Qualcomm, Inc. Email: hardie@qualcomm.com Andrew Newton - SunRocket - 8045 Leesburg Pike, Suite 300 - Vienna, VA 22182 + TranTech, Inc. + 4900 Seminary Road, Suite 215 + Alexandria, VA 22311 US - Phone: +1 703 636 0852 + Phone: +1 703 671 9873 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 + Nokia Siemens Networks Otto-Hahn-Ring 6 Munich, Bavaria 81739 Germany Phone: +49 89 636 40390 - Email: Hannes.Tschofenig@siemens.com + Email: Hannes.Tschofenig@nsn.com URI: http://www.tschofenig.com 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.