One document matched: draft-ietf-ecrit-lost-sync-18.xml
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<rfc ipr="trust200902" category="exp" docName="draft-ietf-ecrit-lost-sync-18.txt">
<front>
<title abbrev="LoST Sync">Synchronizing Location-to-Service Translation (LoST) Protocol
based Service Boundaries and Mapping Elements</title>
<author initials="H." surname="Schulzrinne" fullname="Henning Schulzrinne">
<organization>Columbia University</organization>
<address>
<postal>
<street>Department of Computer Science</street>
<street>450 Computer Science Building</street>
<city>New York</city>
<region>NY</region>
<code>10027</code>
<country>US</country>
</postal>
<phone>+1 212 939 7004</phone>
<email>hgs+ecrit@cs.columbia.edu</email>
<uri>http://www.cs.columbia.edu</uri>
</address>
</author>
<author fullname="Hannes Tschofenig" initials="H." surname="Tschofenig">
<organization>Nokia Siemens Networks</organization>
<address>
<postal>
<street>Linnoitustie 6</street>
<city>Espoo</city>
<code>02600</code>
<country>Finland</country>
</postal>
<phone>+358 (50) 4871445</phone>
<email>Hannes.Tschofenig@gmx.net</email>
<uri>http://www.tschofenig.priv.at</uri>
</address>
</author>
<date year="2012"/>
<area>RAI</area>
<workgroup>ECRIT</workgroup>
<keyword>Internet-Draft</keyword>
<keyword>Location</keyword>
<abstract>
<t>The Location-to-Service Translation (LoST) protocol is an XML-based protocol for
mapping service identifiers and geodetic or civic location information to service
URIs and service boundaries. In particular, it can be used to determine the
location-appropriate Public Safety Answering Point (PSAP) for emergency services. </t>
<t>The <mapping> element is used to encapsulate
information about service boundaries is defined in the LoST protocol specification
and circumscribes the region within which all locations map to the same service
Uniform Resource Identifier (URI) or set of URIs for a given service.</t>
<t>This document defines an XML protocol to exchange these mappings between two nodes.
This mechanism is designed for the exchange of authoritative <mapping>
elements between two entities. Exchanging cached <mapping> elements,
i.e. non-authoritative elements, is possible but not envisioned. In any case, this
document can also be used without the LoST protocol even though the format of the
<mapping> element is re-used from the LoST specification.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>Since the early days of emergency services there has been a desire to route emergency calls to Public Safety Answering Points (PSAPs) that are nearest to the location of the emergency caller. For this purpose each PSAP discloses one or multiple service boundaries so that this information can be used to select the appropriate PSAP and to route the call to it. RFC 5222 <xref target="RFC5222"/> defines this data structure in the following way:
<list style="empty">
<t>A service boundary circumscribes the region within which all
locations map to the same service Uniform Resource Identifier (URI) or set of URIs for a given
service. A service boundary may consist of several non-contiguous
geometric shapes.
</t>
</list>
</t>
<t>RFC 5222 <xref target="RFC5222"/> not only defines the term but it also specifies the data structure itself: the <mapping> element.</t>
<t>This document re-uses this existing data structure and defines an XML-based protocol to exchange authoritative service boundaries between two entities (the LoST Sync source and the LoST Sync destination). This protocol can be used with and without the actual LoST protocol.</t>
<t>The rest of the document is structured as follows: <xref target="example"/> starts with an example usage of the LoST protocol. In <xref target="query"/>, <xref target="push"/>, <xref target="transport"/>, and <xref target="schema"/> we describe the protocol semantics, transport considerations and the schema. Finally, we conclude with operational and security considerations in <xref target="ops"/>, and in <xref target="security"/>.</t>
</section>
<!-- ******************************************************************************** -->
<section anchor="terminology" title="Terminology">
<t>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 RFC 2119 <xref target="RFC2119"/>.</t>
<t>This document reuses terminology introduced by the <xref target="RFC5582">mapping
architecture document</xref>, such as 'coverage region', 'forest guide', 'mapping',
'authoritative mapping server', and 'ESRP'.</t>
<t>Throughout this document we use the term LoST Sync source and LoST Sync destination
to denote the protocol end points of the exchange. The protocol is referred as LoST
Sync within the text.</t>
</section>
<!-- ******************************************************************************** -->
<section anchor="example" title="A Motivating Example">
<t> The LoST Sync mechanism can, for example, be used in the LoST architecture, as
specified in the <xref target="RFC5582"/>. There, LoST servers act in different
roles that cooperate to provide an ubiquitous, globally scalable and resilient
mapping service. In the LoST mapping architecture, LoST servers can peer, i.e., have
an on-going data exchange relationship. Peering relationships are set up manually,
based on local policies. A LoST server may peer with any number of other LoST servers.
Forest
guides peer with other forest guides; authoritative mapping servers peer with forest
guides and other authoritative servers, either in the same cluster or above or below
them in the tree. Authoritative mapping servers push coverage regions "up" the tree,
i.e., from child nodes to parent nodes. The child informs the parent of the
geospatial or civic region that it covers for a specific service.</t>
<t>Consider a hypothetical deployent of LoST in two countries, for example Austria and
Finland. Austria, in our example, runs three authoritative mapping servers labeled as
'East', 'West' and 'Vienna' whereby the former two cover the entire country expect
for Vienna, which is covered by a separate LoST server. There may be other caching
LoST servers run by ISPs, universities, and VSPs but they are not relevant for this
illustration. Finland, on the other hand, decided to only deploy a single LoST
server that also acts as a Forest Guide. For this simplistic illustration we assume
that only one service is available, namely 'urn:service:sos' since otherwise the
number of stored mappings would have to be multiplied by the number of used
services.</t>
<t>
<xref target="example-deployment"/> shows the example deployment. <figure
anchor="example-deployment" title="LoST Deployment Example">
<artwork><![CDATA[
+---LoST-Sync-->\\ //<--LoST-Sync----+
| ----- |
| |
\/ \/
----- -----
// \\ // \\
/ \ / \
| Forest | | Forest |
| Guide | | Guide |
| Austria | | Finland
\ / \ /
+--------->\\ //<--------+ \\ //
| ----- | -----
| /\ | |
LoST | LoST //------\\
Sync LoST Sync |Co-Located|
| Sync | | LoST |
\/ | \/ | Server |
//----\\ \/ //----\\ \\------//
| LoST | //----\\ | LoST |
| Server | | LoST | | Server |
| (East) | | Server | |(Vienna)|
\\----// | (West) | \\----//
\\----//
]]></artwork>
</figure>
</t>
<t>The configuration of these nodes would therefore be as follows: <list style="hanging">
<t hangText="Forest Guide Austria:">This forest guide would contain mappings for
the three authoritative mapping servers (East, West and Vienna) describing what
area they are responsible for. Note that each mapping would contain a
service URN and these mappings point to LoST servers rather than to PSAPs or
ESRPs.</t>
<t hangText="LoST Server 'East':">This LoST server would contain all the
mappings to PSAPs covering one half of the country. <vspace blankLines="1"/>
Additionally, the LoST server aggregates all the information it has and
provides an abstracted view towards the Forest Guide indicating that it is
responsible for a certain area (for a given service, and for a given
location profile). Such a mapping could have the following structure:
<figure anchor="fg-austria" title="Forest Guide Austria Mapping XML Snippet">
<artwork><![CDATA[
<mapping
xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:gml="http://www.opengis.net/gml"
expires="2009-01-01T01:44:33Z"
lastUpdated="2009-12-01T01:00:00Z"
source="east-austria.lost-example.com"
sourceId="e8b05a41d8d1415b80f2cdbb96ccf109">
<displayName xml:lang="en">LoST Server 'East'</displayName>
<service>urn:service:sos</service>
<serviceBoundary profile="geodetic-2d">
<gml:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
<gml:exterior>
<gml:LinearRing>
<gml:pos> ... </gml:pos>
..... list of coordinates for
boundary of LoST server 'East'
<gml:pos> ... </gml:pos>
</gml:LinearRing>
</gml:exterior>
</gml:Polygon>
</serviceBoundary>
<uri/>
</mapping>
]]></artwork>
</figure>Note that the XML code snippet in <xref target="fg-austria"/> serves illustrative purposes only
and does not validate. As it can be seen in this example the <uri>
element is absent and the 'source' attribute identifies the LoST server,
namely "east-austria.lost-example.com". <vspace
blankLines="1"/> The above-shown mapping is what is the LoST server
"east-austria.lost-example.com" provides to the Austrian Forest Guide. </t>
<t hangText="LoST Server 'West':">This LoST server would contain all the
mappings to PSAPs covering the other half of the country.</t>
<t hangText="LoST Server 'Vienna':">This LoST server would contain all the
mappings to PSAPs in the area of Vienna.</t>
<t hangText="Forest Guide Finland:">In our example we assume that Finland would
deploy a single ESRP for the entire country as their IP-based emergency
services solution. There is only a single LoST server and it is co-located
with the Forest Guide, as shown in <xref target="example-deployment"/>. The
mapping data this FG would distribute via LoST sync is shown in <xref
target="fg-finland"/>. <figure anchor="fg-finland"
title="Forest Guide Finland Mapping XML Snippet">
<artwork><![CDATA[
<mapping xmlns="urn:ietf:params:xml:ns:lost1"
expires="2007-01-01T01:44:33Z"
lastUpdated="2006-11-01T01:00:00Z"
source="finland.lost-example.com"
sourceId="7e3f40b098c711dbb6060800200c9a66">
<displayName xml:lang="en">Finland ESRP</displayName>
<service>urn:service:sos</service>
<serviceBoundary profile="civic">
<civicAddress
xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>FI</country>
</civicAddress>
</serviceBoundary>
<uri/>
</mapping>
]]></artwork>
</figure> An example mapping stored at the co-located LoST server is shown
in <xref target="lost-finland"/>. <figure anchor="lost-finland"
title="Forest Guide Finland / Co-Located LoST Server Mapping XML Snippet">
<artwork><![CDATA[
<mapping xmlns="urn:ietf:params:xml:ns:lost1"
expires="2007-01-01T01:44:33Z"
lastUpdated="2006-11-01T01:00:00Z"
source="finland.lost-example.com"
sourceId="7e3f40b098c711dbb6060800200c9a66">
<displayName xml:lang="en">Finland ESRP</displayName>
<service>urn:service:sos</service>
<serviceBoundary profile="civic">
<civicAddress
xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>FI</country>
</civicAddress>
</serviceBoundary>
<uri>sip:esrp@finland-example.com</uri>
<uri>xmpp:esrp@finland-example.com</uri>
<serviceNumber>112</serviceNumber>
</mapping>
]]></artwork>
</figure>
</t>
</list>
</t>
<t>The LoST sync mechanism described in this document could be run between the two
Forest Guides. Thereby, the three mappings stored in the Austria FG are sent to the
FG Finland and a single mapping in the FG Finland is sent to the FG Austria.
Additionally, the three Austrian LoST servers could utilize LoST sync to inform the
Austrian FG about their boundaries. These three authoritative mapping servers in
Austria would be responsible to maintain their own mapping information. Since the
amount of data being exchanged is small and the expected rate of change is low the
nodes are configured to always exchange all their mapping information whenever a
change happens. </t>
<t>This document defines two types of exchanges and those are best described by the
exchange between two nodes as shown in <xref target="overview1"/> and <xref
target="overview2"/>. The protocol exchange always runs between a LoST Sync
source and a LoST Sync destination. Node A in the examples of <xref
target="overview1"/> and <xref target="overview2"/> has mappings that Node B is
going to retrieve. Node A acts as the source for the data and Node B is the
destination.</t>
<t> The <getMappingsRequest> request allows a LoST Sync source to request
mappings from a LoST Sync destination.<figure anchor="overview1"
title="Querying for Mappings with a <getMappingsRequest> Message">
<artwork><![CDATA[
+---------+ +---------+
| Node B | | Node A |
| acting | | acting |
| as | | as |
| LoST | | LoST |
| Sync | | Sync |
| Dest. | | Source |
+---------+ +---------+
| |
| |
| |
| <getMappingsRequest> |
|----------------------------->|
| |
| <getMappingsResponse> |
|<-----------------------------|
| |
| |
| |
]]></artwork>
</figure>
</t>
<t>Note that in the exchange illustrated in <xref target="overview1"/> Node B is issuing
the first request and plays the role of the HTTPS client and Node A plays the role of the HTTPS server.</t>
<t> The <pushMappingsRequest> exchange allows a LoST Sync source to push mappings
to LoST Sync destination. In this example we assume that Node A has been configured maintain state about the mappings it had pushed to Node B.</t>
<t>No
publish/subscribe mechanism is defined in this document that would allow Node B to tell Node
A about what mappings it is interested in nor a mechanism for learning to which
entities mappings have to be pushed.</t>
<t><figure anchor="overview2"
title="Pushing Mappings with a <pushMappingsRequest> Message">
<artwork><![CDATA[
+---------+ +---------+
| Node A | | Node B |
| acting | | acting |
| as | | as |
| LoST | | LoST |
| Sync | | Sync |
| Source | | Dest. |
+---------+ +---------+
| |
| |
| |
| <pushMappingsRequest> |
|----------------------------->|
| |
| <pushMappingsResponse> |
|<-----------------------------|
| |
| |
| |
]]></artwork>
</figure>
</t>
<t>Node A issuing
the first request in <xref target="overview2"/> plays the role of the HTTPS client and Node B plays the role of the HTTPS server.</t>
</section>
<!-- ******************************************************************************** -->
<section anchor="query"
title="Querying for Mappings with a <getMappingsRequest> / <getMappingsResponse> Exchange ">
<section title="Behavior of the LoST Sync Destination">
<t>A LoST Sync destination has two ways to retrieve mapping elements from a LoST
Sync source. </t>
<t>
<list style="numbers">
<t>A mechanisms that is suitable when no mappings are available on the LoST
Sync destination is to submit an empty <getMappingsRequest>
message, as shown in <xref target="empty-request"/>. The intent by the
LoST Sync destination thereby is to retrieve all mappings from the LoST
Sync source. Note that the request does not propagate further to other
nodes.</t>
<t>In case a LoST Sync destination node has already obtained mappings in
previous exchanges then it may want to check whether these mappings have
been updated in the meanwhile. The policy when to poll for updated
mapping information is outside the scope of this document. The
<getMappingsRequest> message with one or multiple
<exists> child element(s) allows to reduce the number of
returned mappings to those that have been updated and also to those that
are missing. </t>
</list>
</t>
<t>In response to the <getMappingsRequest> message the LoST Sync destination
waits for the <getMappingsResponse> message. In case of a successful
response the LoST Sync destination stores the received mappings and determines
which mappings to update.</t>
</section>
<section title="Behavior of the LoST Sync Source">
<t>When a LoST Sync source receives an empty <getMappingsRequest> message
then all locally available mappings MUST be returned.</t>
<t>When a LoST Sync source receives a <getMappingsRequest> message with one
or multiple <exists> child element(s) then it MUST consult with
the local mapping database to determine whether any of the mappings of the
client is stale and whether there are mappings locally that the client does not
yet have. The former can be determined by finding mappings corresponding to the
'source' and 'sourceID' attribut where a mapping with a more recent lastUpdated
date exists. </t>
<t>Processing a <getMappingsRequest> message MAY lead to a successful
response in the form of a <getMappingsResponse> or an <errors>
message. Only the <badRequest>, <forbidden>,
<internalError>, <serverTimeout> errors, defined in <xref
target="RFC5222"/>, are utilized by this specification. Neither the
<redirect> nor the <warnings> messages are reused by this
message.</t>
</section>
<section title="Examples">
<t>The first example shows an empty <getMappingsRequest> message that would
retrieve all locally stored mappings at the LoST Sync source. <figure
anchor="empty-request"
title="Example of empty <getMappingsRequest> message">
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<getMappingsRequest xmlns="urn:ietf:params:xml:ns:lostsync1"/>
]]></artwork>
</figure>
</t>
<t>A further example request is shown in <xref target="getMappings"/> and the
corresponding response is depicted in <xref target="getMappingsResponse"/>. In
this example the <getMappingsRequest> element contains information about the mapping
that is locally available to the client inside the <mapping-fingerprint> element (with
source="authoritative.bar.example",
sourceId="7e3f40b098c711dbb6060800200c9a66", and lastUpdated="2006-11-01T01:00:00Z").
The query asks for mappings that are more recent than the available one as well as any
missing mapping. </t>
<t>
<figure anchor="getMappings" title="Example <getMappingsRequest> Message">
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<getMappingsRequest xmlns="urn:ietf:params:xml:ns:lostsync1">
<exists>
<mapping-fingerprint source="authoritative.bar.example"
sourceId="7e3f40b098c711dbb6060800200c9a66"
lastUpdated="2006-11-01T01:00:00Z">
</mapping-fingerprint>
</exists>
</getMappingsRequest>
]]></artwork>
</figure>
</t>
<t>The response to the above request is shown in <xref target="getMappingsResponse"
/>. A more recent mapping was available with the identification of
source="authoritative.bar.example" and
sourceId="7e3f40b098c711dbb6060800200c9a66". Only one mapping that matched
source="authoritative.foo.example" was found and returned. </t>
<t>
<figure anchor="getMappingsResponse"
title="Example <getMappingsResponse> Message">
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<sync:getMappingsResponse
xmlns:sync="urn:ietf:params:xml:ns:lostsync1"
xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:gml="http://www.opengis.net/gml">
<mapping source="authoritative.bar.example"
sourceId="7e3f40b098c711dbb6060800200c9a66"
lastUpdated="2008-11-26T01:00:00Z"
expires="2009-12-26T01:00:00Z">
<displayName xml:lang="en">Leonia Police Department
</displayName>
<service>urn:service:sos.police</service>
<serviceBoundary
profile="urn:ietf:params:lost:location-profile:basic-civic">
<civicAddress
xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>US</country>
<A1>NJ</A1>
<A3>Leonia</A3>
<PC>07605</PC>
</civicAddress>
</serviceBoundary>
<uri>sip:police@leonianj2.example.org</uri>
<serviceNumber>911</serviceNumber>
</mapping>
<mapping expires="2009-01-01T01:44:33Z"
lastUpdated="2008-11-01T01:00:00Z"
source="authoritative.foo.example"
sourceId="7e3f40b098c711dbb606011111111111">
<displayName xml:lang="en">New York City Police Department
</displayName>
<service>urn:service:sos.police</service>
<serviceBoundary profile="geodetic-2d">
<gml:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
<gml:exterior>
<gml:LinearRing>
<gml:pos>37.775 -122.4194</gml:pos>
<gml:pos>37.555 -122.4194</gml:pos>
<gml:pos>37.555 -122.4264</gml:pos>
<gml:pos>37.775 -122.4264</gml:pos>
<gml:pos>37.775 -122.4194</gml:pos>
</gml:LinearRing>
</gml:exterior>
</gml:Polygon>
</serviceBoundary>
<uri>sip:nypd@example.com</uri>
<uri>xmpp:nypd@example.com</uri>
<serviceNumber>911</serviceNumber>
</mapping>
</sync:getMappingsResponse>
]]></artwork>
</figure>
</t>
</section>
</section>
<!-- ******************************************************************************** -->
<section anchor="push"
title="Pushing Mappings via <pushMappings> and
<pushMappingsResponse>">
<section title="Behavior of the LoST Sync Source">
<t>When a LoST Sync source obtains new information that is of interest to its peers,
it may push the new mappings to its peers. Configuration settings at both peers
decide whether this functionality is used and what mappings are pushed to which
other peers. New mappings may arrive through various means, such as a manual
addition to the local mapping database, or through the interaction with other
entities. Deleting mappings may also trigger a protocol interaction.</t>
<t>The LoST Sync source SHOULD keep track of which LoST Sync destination it has
pushed mapping elements. If it does not keep state information then it always
has to push the complete data set. As discussed in Section 5.1 of <xref
target="RFC5222"/>, mapping elements are identified by the 'source',
'sourceID' and 'lastUpdated' attributes. A mapping is considered the same if
these three attributes match. <!-- It is RECOMMENDED not to push the same information
to the same peer more than once.--> </t>
<t>A <pushMappings> request sent by a LoST Sync source MUST containing one or
more <mapping> elements. </t>
<t>
To delete a mapping, the content of the mapping is left empty, i.e. the <mapping>
element only contains the 'source', 'sourceID', 'lastUpdated', and 'expires" attribute. <xref target="pushMappings"/> shows an example request where the mapping with the source="nj.us.example", sourceId="123", lastUpdated="2008-11-01T01:00:00Z", expires="2008-11-01T01:00:00Z" is requested to be deleted. Note that the 'expires' attribute is required per schema definition but will be ignored in processing the request on the receiving side. A sync source may want to delete the mapping from its internal mapping database, but has to remember which peers it has distributed this update to unless it has other ways to ensure that databases do not get out of sync.</t>
</section>
<section title="Behavior of the LoST Sync Destination">
<t>When a LoST Sync destination receives a <pushMappingsRequest> message then
the cache with the existing mappings is inspected to determine whether
the received mapping should lead to an update of an already existing mapping,
should create a new mapping in the cache, or should be discarded.</t>
<t>If a newly received mapping has a more
recent time in its 'lastUpdated' attribute, it MUST update an existing mapping
that has matching 'source' and 'sourceID' attributes.</t>
<t>If the received mapping does not match with any existing mapping based on the 'source' and 'sourceId'
then it MUST be added to the local cache as an independent mapping.</t>
<t>
If a <pushMappingsRequest> message with an empty <mapping>
element is received then a corresponding mapping has to be determined based on
the 'source', and the 'sourceID'.</t>
<t>
If no mapping can be identified then an
<errors> response MUST be returned that contains the <notDeleted>
child element. The <notDeleted> element MAY contain a
'message' attribute with an error description used for debugging purposes.
The <notDeleted> element MUST contain the <mapping>
element(s) that caused the error.</t>
<t>The response to a <pushMappingsRequest> request is a
<pushMappingsResponse> message. With this specification, a successful
response message returns no additional elements, whereas an <errors>
response is returned in the response message, if the request failed. Only the
<badRequest>, <forbidden>, <internalError> or
<serverTimeout> errors defined in Section 13.1 of <xref target="RFC5222"
/>, are used. The <redirect> and <warnings> messages are not used
for this query/response.</t>
<t>If the set of nodes that are synchronizing their data does not form a tree, it is
possible that the same information arrives through several other nodes. This is
unavoidable, but generally only imposes a modest overhead. (It would be possible
to create a spanning tree in the same fashion as IP multicast, but the
complexity does not seem warranted, given the relatively low volume of
data.)</t>
</section>
<section title="Example">
<t> An example is shown in <xref target="pushMappings"/>. Imagine a LoST node that
obtained two new mappings identified as follows: <list style="symbols">
<t>
<figure>
<artwork><![CDATA[
source="authoritative.example"
sourceId="7e3f40b098c711dbb6060800200c9a66"
lastUpdated="2008-11-26T01:00:00Z"
]]></artwork>
</figure>
</t>
<t>
<figure>
<artwork><![CDATA[
source="authoritative.example"
sourceId="7e3f40b098c711dbb606011111111111"
lastUpdated="2008-11-01T01:00:00Z"
]]></artwork>
</figure></t>
</list>
</t>
<t> These two mappings have to be added to the peer's mapping database. </t>
<t> Additionally, the following mapping has to be deleted: <list style="symbols">
<t> source="nj.us.example" sourceId="123" lastUpdated="2008-11-01T01:00:00Z"
</t>
</list>
</t>
<t>
<figure anchor="pushMappings"
title="Example <pushMappingsRequest> Message">
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<sync:pushMappings
xmlns:sync="urn:ietf:params:xml:ns:lostsync1"
xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:gml="http://www.opengis.net/gml">
<mapping source="authoritative.example"
sourceId="7e3f40b098c711dbb6060800200c9a66"
lastUpdated="2008-11-26T01:00:00Z"
expires="2009-12-26T01:00:00Z">
<displayName xml:lang="en">Leonia Police Department
</displayName>
<service>urn:service:sos.police</service>
<serviceBoundary
profile="urn:ietf:params:lost:location-profile:basic-civic">
<civicAddress
xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>US</country>
<A1>NJ</A1>
<A3>Leonia</A3>
<PC>07605</PC>
</civicAddress>
</serviceBoundary>
<uri>sip:police@leonianj.example.org</uri>
<serviceNumber>911</serviceNumber>
</mapping>
<mapping expires="2009-01-01T01:44:33Z"
lastUpdated="2008-11-01T01:00:00Z"
source="authoritative.example"
sourceId="7e3f40b098c711dbb606011111111111">
<displayName xml:lang="en">New York City Police Department
</displayName>
<service>urn:service:sos.police</service>
<serviceBoundary profile="geodetic-2d">
<gml:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
<gml:exterior>
<gml:LinearRing>
<gml:pos>37.775 -122.4194</gml:pos>
<gml:pos>37.555 -122.4194</gml:pos>
<gml:pos>37.555 -122.4264</gml:pos>
<gml:pos>37.775 -122.4264</gml:pos>
<gml:pos>37.775 -122.4194</gml:pos>
</gml:LinearRing>
</gml:exterior>
</gml:Polygon>
</serviceBoundary>
<uri>sip:nypd@example.com</uri>
<uri>xmpp:nypd@example.com</uri>
<serviceNumber>911</serviceNumber>
</mapping>
<mapping source="nj.us.example"
sourceId="123"
lastUpdated="2008-11-01T01:00:00Z"
expires="2008-11-01T01:00:00Z"/>
</sync:pushMappings>
]]></artwork>
</figure>
</t>
<t>In response, the peer performs the necessary operation and updates its mapping
database. In particular, it will check whether the other peer is authorized to
perform the update and whether the elements and attributes contain values that
it understands. In our example, a positive response is returned as shown in
<xref target="pushMappingsResponse"/>.</t>
<t>
<figure anchor="pushMappingsResponse"
title="Example <pushMappingsResponse>">
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<pushMappingsResponse xmlns="urn:ietf:params:xml:ns:lostsync1" />
]]></artwork>
</figure>
</t>
<t>In case that a mapping could not be deleted as requested the following error
response might be returned instead. <figure anchor="error"
title="Example <errors> Message">
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<errors xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:sync="urn:ietf:params:xml:ns:lostsync1"
source="nodeA.example.com">
<sync:notDeleted
message="Could not delete the indicated mapping."
xml:lang="en">
<mapping source="nj.us.example"
sourceId="123"
lastUpdated="2008-11-01T01:00:00Z"
expires="2008-11-01T01:00:00Z"/>
</sync:notDeleted>
</errors>
]]></artwork>
</figure>
</t>
</section>
</section>
<!-- ******************************************************************************** -->
<section anchor="transport" title="Transport">
<t> LoST Sync needs an underlying protocol transport mechanism to carry requests and
responses. This document uses HTTPS as a transport to exchange XML documents.
No fallback to HTTP is provided.
<!--
Client and server developers are reminded that full support of RFC 2616 HTTP
facilities is expected. If clients or servers re-implement HTTP, rather than using
available servers or client code as a base, careful attention must be paid to full
interoperability.The
selection of the transport mechanism will in most cases be determined through manual
configuration although the usage of the U-NAPTR application defined in the LoST
specification is possible. In protocols that support content type indication, LoST
Sync uses the media type application/lostsync+xml.--> </t>
<t>When using HTTP-over-TLS <xref target="RFC2818"/>,
LoST Sync messages use the POST method. Request MUST use the
Cache-Control response directive "no-cache".</t>
<t>All LoST Sync 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
request itself failed or was redirected; these responses do not contain any LoST
Sync XML elements. </t>
</section>
<!-- ******************************************************************************** -->
<section anchor="schema" title="RelaxNG">
<t>
Note: In order to avoid copying pattern definitions from the LoST Relax NG schema <xref target="RFC5222"/>
to this document we include it as "lost.rng" (XML syntax) in the Relax NG schema below.
</t>
<t>
<figure>
<artwork><![CDATA[
<?xml version="1.0" encoding="utf-8"?>
<grammar ns="urn:ietf:params:xml:ns:lostsync1"
xmlns="http://relaxng.org/ns/structure/1.0"
xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0"
datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
<include href="lost.rng"/>
<start combine="choice">
<a:documentation> Location-to-Service Translation (LoST)
Synchronization Protocol</a:documentation>
<choice>
<ref name="pushMappings"/>
<ref name="pushMappingsResponse"/>
<ref name="getMappingsRequest"/>
<ref name="getMappingsResponse"/>
</choice>
</start>
<define name="pushMappings">
<element name="pushMappings">
<oneOrMore>
<ref name="mapping"/>
</oneOrMore>
<ref name="extensionPoint"/>
</element>
</define>
<define name="pushMappingsResponse">
<element name="pushMappingsResponse">
<ref name="extensionPoint"/>
</element>
</define>
<define name="getMappingsRequest">
<element name="getMappingsRequest">
<choice>
<ref name="exists"></ref>
<ref name="extensionPoint"/>
</choice>
</element>
</define>
<define name="exists">
<element name="exists">
<oneOrMore>
<element name="mapping-fingerprint">
<attribute name="source">
<data type="token"/>
</attribute>
<attribute name="sourceId">
<data type="token"/>
</attribute>
<attribute name="lastUpdated">
<data type="dateTime"/>
</attribute>
<ref name="extensionPoint"/>
</element>
</oneOrMore>
</element>
</define>
<define name="getMappingsResponse">
<element name="getMappingsResponse">
<oneOrMore>
<ref name="mapping"/>
</oneOrMore>
<ref name="extensionPoint"/>
</element>
</define>
<!-- error messages -->
<define name="notDeleted">
<element name="notDeleted">
<ref name="basicException"/>
<oneOrMore>
<ref name="mapping"/>
</oneOrMore>
</element>
</define>
</grammar>
]]></artwork>
</figure>
</t>
</section>
<!-- ******************************************************************************** -->
<section anchor="ops" title="Operational Considerations">
<t>When different LoST servers use the mechanism described in this document to
synchronize their mapping data then it is important to ensure that loops are
avoided. The example shown in <xref target="sync-problem"/> with three LoST servers
A, B and C (each of them acts as a sync source and a sync destination) illustrates
the challenge in more detail. A and B synchronize data between each other; the same
is true for A and C, and B and C, respectively. </t>
<t>
<figure anchor="sync-problem" title="Synchronization Configuration Example">
<artwork><![CDATA[
A -------- B
\ /
\ /
\ /
\ /
C
]]></artwork>
</figure>
</t>
<t>Now, imagine that server A adds a new mapping. This mapping is uniquely identified by
the combination of "source", "sourceid" and "last updated". Assume that A would push
this new mapping to B and C. When B obtained this new mapping it would find out that
it has to distribute it to its peer C. C would also want to distribute the mapping
to B. If the original mapping with the "source", "sourceid" and
"last updated" is not modified by either B or C then these two servers would
recognize that they already possess the mapping and can ignore the update.</t>
<t>It is important that implementations MUST NOT modify mappings they receive. An entity
acting maliciously would, however, intentially modify mappings or inject bogus
mappings. To avoid the possibility of an untrustworthy member claiming a coverage
region that it is not authorized for, authoritative mapping server
MUST sign mappings they distribute using an XML digital signature <xref
target="W3C.REC-xmldsig-core-20020212"/>. A recipient MUST verify that the
signing entity is indeed authorized to speak for that region. In many cases, this will require
an out-of-band agreement to be in place to agree on specific entities to take on this role.
Determining who can
speak for a particular region is inherently difficult unless there is a small set of
authorizing entities that participants in the mapping architecture can trust.
Receiving systems should be particularly suspicious if an existing coverage region
is replaced by a new one that contains a different value in the <uri> element.
When
mappings are digitially signed, they cannot be modified by
intermediate LoST servers.</t>
</section>
<!-- ******************************************************************************** -->
<section anchor="security" title="Security Considerations">
<t>This document defines a protocol for exchange of authoritative mapping information between two
entities. Hence, the protocol operations described in this document require
authentication of neighboring nodes.</t>
<t>The LoST Sync client and servers MUST implement TLS and use TLS. Which version(s)
ought to be implemented will vary over time, and depend on
the widespread deployment and known security vulnerabilities at
the time of implementation. At the time of this writing, TLS version
1.2 <xref target="RFC5246"/> is the most recent version, but has very limited
actual deployment, and might not be readily available in
implementation toolkits. TLS version 1.0 <xref target="RFC2246"/> is the
most widely deployed version, and will give the broadest
interoperability.</t>
<t>Mutual authentication between the LoST Sync source and the LoST Sync destination is not
necessarily required in all deployments unless an emergency service authority wants to enforce access control prior to the distribution of their
mapping elements. This may, for example, be the case when certain emergency services network internal mappings are not meant for public distribution.</t>
<t>An additional threat is caused by compromised or misconfigured LoST servers.
A denial of service could be the consequence of an injected mapping. If the
mapping data contains an URL that does not exist then emergency services for the
indicated area are not reachable. If all mapping data contains URLs that point to a
single PSAP (rather than a large number of PSAPs) then this PSAP is likely to experience
overload conditions. If the mapping data contains a URL that points to a server
controlled by the adversary itself then it might impersonate PSAPs.</t>
<t><xref target="ops"/>
discusses this security threat and mandates signed mappings. For unusal changes
to the mapping database approval by a system administrator of the emergency services
infrastructure (or a similar expert) may be required before any mappings are
installed. </t>
</section>
<!-- ******************************************************************************** -->
<section title="IANA Considerations">
<section title="Media Type Registration">
<t>This specification requests the registration of a new media type according to the
procedures of RFC 4288 <xref target="RFC4288"/> and guidelines in RFC 3023 <xref
target="RFC3023"/>.</t>
<t>
<list style="hanging">
<t hangText="Type name:">application <vspace blankLines="1"/>
</t>
<t hangText="Subtype name:">lostsync+xml <vspace blankLines="1"/>
</t>
<t hangText="Required parameters:">none<vspace blankLines="1"/>
</t>
<t hangText="Optional parameters:">charset<vspace blankLines="1"/>Same as charset parameter of application/xml as specified in RFC
3023 <xref target="RFC3023"/>.<vspace blankLines="1"/>
</t>
<t hangText="Encoding considerations:"> Identical to those of "application/xml" as
described in <xref
target="RFC3023"/>, Section 3.2.
<vspace blankLines="1"/></t>
<t hangText="Security considerations:"> This content type is designed to
carry LoST Synchronization protocol payloads and the security
considerations section of RFCXXXX is applicable.
In addition, as this media type uses the "+xml" convention, it
shares the same security considerations as described in <xref
target="RFC3023"/>,
Section 10.
[NOTE TO IANA/RFC-EDITOR:
Please replace XXXX with the RFC number of this specification.]
<vspace blankLines="1"/></t>
<t hangText="Interoperability considerations:">None<vspace blankLines="1"
/><vspace blankLines="1"/></t>
<t hangText="Published specification:">RFCXXXX [NOTE TO IANA/RFC-EDITOR:
Please replace XXXX with the RFC number of this specification.]<vspace
blankLines="1"/>
</t>
<t hangText="Applications which use this media type:"> Emergency and
Location-based Systems<vspace blankLines="1"/>
</t>
<t hangText="Additional information:">
<list style="hanging">
<t hangText="Magic number(s):">None<vspace blankLines="1"/>
</t>
<t hangText="File extension(s):">.lostsyncxml<vspace blankLines="1"/>
</t>
<t hangText="Macintosh file type code(s):">'TEXT'<vspace blankLines="1"
/>
</t>
</list>
</t>
<t hangText="Person & email address to contact for further information:">Hannes
Tschofenig <Hannes.Tschofenig@gmx.net><vspace blankLines="1"/>
</t>
<t hangText="Intended usage:">LIMITED USE<vspace blankLines="1"/>
</t>
<t hangText="Restrictions on usage:">None<vspace blankLines="1"/>
</t>
<t hangText="Author:">Hannes
Tschofenig <Hannes.Tschofenig@gmx.net><vspace blankLines="1"/>
</t>
<t hangText="Change controller:">
<vspace blankLines="1"/> This specification is a work item of the IETF
ECRIT working group, with mailing list address
<ecrit@ietf.org>.<vspace blankLines="1"/>
</t>
<t hangText="Change controller:">
<vspace blankLines="1"/>The IESG <iesg@ietf.org> </t>
</list>
</t>
</section>
<section title="LoST Sync Relax NG Schema Registration">
<t>Please register the schema defined in this document under the XML schema registry at http://www.iana.org/assignments/xml-registry/schema.html</t>
<t>
<list style="hanging">
<t hangText="URI:">urn:ietf:params:xml:schema:lostsync1</t>
<t hangText="Registrant Contact:">IETF ECRIT Working Group, Hannes
Tschofenig (Hannes.Tschofenig@gmx.net).</t>
<t hangText="Relax NG Schema:">The Relax NG schema to be registered is
contained in <xref target="schema"/>. </t>
</list>
</t>
</section>
<section title="LoST Synchronization Namespace Registration">
<t>Please register the namespace defined in this document under the XML namespace registry at http://www.iana.org/assignments/xml-registry/ns.html</t>
<t>
<list style="hanging">
<t hangText="URI:">urn:ietf:params:xml:ns:lostsync1</t>
<t hangText="Registrant Contact:">IETF ECRIT Working Group, Hannes
Tschofenig (Hannes.Tschofenig@gmx.net).</t>
<t hangText="XML:">
<figure>
<artwork><![CDATA[
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>LoST Synchronization Namespace</title>
</head>
<body>
<h1>Namespace for LoST server synchronization</h1>
<h2>urn:ietf:params:xml:ns:lostsync1</h2>
<p>See <a href="[URL of published RFC]">RFCXXXX
[NOTE TO IANA/RFC-EDITOR:
Please replace XXXX with the RFC number of this
specification.]</a>.</p>
</body>
</html>
END
]]></artwork>
</figure>
</t>
</list>
</t>
</section>
</section>
<!-- ******************************************************************************** -->
<section title="Acknowledgments">
<t>Robins George, Cullen Jennings, Karl Heinz Wolf, Richard Barnes, Mayutan
Arumaithurai, Alexander Mayrhofer, and Andrew Newton provided helpful input. Jari
Urpalainen assisted with the Relax NG schema. We would also like to thank our document
shepherd Roger Marshall for his help with the document.</t>
<t>We would like to particularly thank Andrew Newton for his timely and valuable review
of the XML-related content.</t>
<t>We would like to thank Robert Sparks, Barry Leiba, Stephen Farrell, Brian Haberman, Pete Resnick, and Sean Turner for their AD reviews. We would also like to thank Bjoern Hoehrmann for his media type review, Julian Reschke and Martin Duerst for their applications area reviews, and Wassim Haddad for his Gen-ART review.</t>
</section>
<!-- ******************************************************************************** -->
</middle>
<back>
<references title="Normative References"> &rfc2119; &rfc2617; &rfc5222;
&rfc5246; &RFC3023; &RFC4288; &RFC2616; &RFC2818;
&RFC2246;
<reference
anchor="W3C.REC-xmldsig-core-20020212">
<front>
<title>XML-Signature Syntax and Processing</title>
<author initials="D." surname="Eastlake" fullname="Donald Eastlake">
<organization/>
</author>
<author initials="J." surname="Reagle" fullname="Joseph Reagle">
<organization/>
</author>
<author initials="D." surname="Solo" fullname="David Solo">
<organization/>
</author>
<author initials="F." surname="Hirsch" fullname="Frederick Hirsch">
<organization/>
</author>
<author initials="T." surname="Roessler" fullname="Thomas Roessler">
<organization/>
</author>
<date month="June" day="10" year="2008"/>
</front>
<seriesInfo name="World Wide Web Consortium Second Edition"
value="REC-xmldsig-core-20020212"/>
<format type="HTML" target="http://www.w3.org/TR/xmldsig-core/."/>
</reference>
</references>
<references title="Informative References"> &RFC5582; </references>
</back>
</rfc>
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