draft-ietf-geopriv-loc-filters-06.txt   draft-ietf-geopriv-loc-filters-07.txt 
GEOPRIV R. Mahy GEOPRIV R. Mahy
Internet-Draft Plantronics Internet-Draft Individual
Intended status: Standards Track B. Rosen, Ed. Intended status: Standards Track B. Rosen
Expires: March 19, 2010 NeuStar Expires: April 29, 2010 NeuStar
H. Tschofenig H. Tschofenig
Nokia Siemens Networks Nokia Siemens Networks
September 15, 2009 October 26, 2009
A Document Format for Filtering and Reporting Location Notications in Filtering Location Notifications in the Session Initiation Protocol
the Presence Information Document Format Location Object (PIDF-LO) (SIP)
draft-ietf-geopriv-loc-filters-06.txt draft-ietf-geopriv-loc-filters-07.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
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Abstract Abstract
This document describes filters that limit asynchronous location This document describes filters that limit asynchronous location
notifications to compelling events, designed as an extension to RFC notifications to compelling events, designed as an extension to RFC
4661 "An XML-Based Format for Event Notification Filtering". The 4661, an XML-based format for event notification filtering, and based
resulting location information is conveyed in existing location on RFC 3856, the SIP presence event package. The resulting location
formats wrapped in the Presence Information Document Format information is conveyed in existing location formats wrapped in the
(PIDF-LO). Presence Information Data Format Location Object (PIDF-LO).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Filter Definitions . . . . . . . . . . . . . . . . . . . . . . 5 3. Filter Definitions . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Movement . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Movement . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Speed Changes . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Speed Changes . . . . . . . . . . . . . . . . . . . . . . 5
3.3. Element Value Changes . . . . . . . . . . . . . . . . . . 6 3.3. Element Value Changes . . . . . . . . . . . . . . . . . . 6
3.4. Entering or Exiting a Region . . . . . . . . . . . . . . . 6 3.4. Entering or Exiting a Region . . . . . . . . . . . . . . . 7
3.5. Location Type . . . . . . . . . . . . . . . . . . . . . . 8 3.5. Location Type . . . . . . . . . . . . . . . . . . . . . . 9
3.6. Rate Control . . . . . . . . . . . . . . . . . . . . . . . 10 3.6. Rate Control . . . . . . . . . . . . . . . . . . . . . . . 11
4. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
6.1. URN Sub-Namespace Registration for 6.1. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:location-filter . . . . . . . . . . 15 urn:ietf:params:xml:ns:location-filter . . . . . . . . . . 16
6.2. Schema Registration For location-filter . . . . . . . . . 15 6.2. Schema Registration For location-filter . . . . . . . . . 16
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 17 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 18
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . . 19 9.1. Normative References . . . . . . . . . . . . . . . . . . . 20
9.2. Informational References . . . . . . . . . . . . . . . . . 20 9.2. Informational References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
Conveying location information encapsulated with a PIDF-LO [RFC4119] Conveying location information encapsulated with a PIDF-LO [RFC4119]
document within SIP is described in document within SIP is described in
[I-D.ietf-sipcore-location-conveyance]. An alternative signaling [I-D.ietf-sipcore-location-conveyance]. An alternative signaling
approach, which uses asynchronous communication, is available with approach, which uses asynchronous communication, is available with
the SIP event notification mechanisms (see RFC 3265 [RFC3265]) and is the SIP event notification mechanisms (see RFC 3265 [RFC3265]) and is
used by this document. Unfortunately, it is more complex since many used by this document. Unfortunately, it is more complex since many
forms of location are measured as a continuous gradient. Unlike forms of location are measured as a continuous gradient. Unlike
notifications using discret quantities, it is difficult to know when notifications using discret quantities, it is difficult to know when
a change in location is large enough to warrant a notification. RFC a change in location is large enough to warrant a notification. SIP
3265 can be used with so-called 'filters' (see RFC 4661 [RFC4661]) events [RFC3265] can be used with filters (see RFC 4661 [RFC4661])
that allow the number of notifications to be reduced. The mechanism that allows the number of notifications to be reduced. The mechanism
described in this document defines an extension to RFC 4661 described in this document defines an extension to RFC 4661
[RFC4661], which limits location notification to events that are of [RFC4661], which limits location notification to events that are of
relevance to the subscriber. These filters persist until they are relevance to the subscriber. These filters persist until they are
changed with a replacement filter. changed with a replacement filter.
The frequency of notifications necessary for various geographic The frequency of notifications necessary for various geographic
location applications varies dramatically. The subscriber should be location applications varies dramatically. The subscriber should be
able to get asynchronous notifications with appropriate frequency and able to get asynchronous notifications with appropriate frequency and
granularity, without having to issue a large number of notifications granularity, without having to issue a large number of notifications
that are not important to the application. that are not important to the application.
This document defines the following list of events that may be This document defines a few new event filters and describes others
relevant to a subscriber: using existing mechanisms that may be relevant to a subscriber in the
context of location filtering:
1. the Device moves more than a specified distance since the last 1. the Device moves more than a specified distance since the last
notification notification
2. the Device exceeds a specified speed 2. the Device exceeds a specified speed
3. the Device enters or exits a region (described by a circle or a 3. the Device enters or exits a region (described by a circle or a
polygon) polygon)
4. one or more of the values of the specified address labels have 4. one or more of the values of the specified address labels have
changed for the location of the Device. For example, the value changed for the location of the Device. For example, the value
of the <A1> civic address element has changed from 'California' of the <A1> civic address element has changed from 'California'
to 'Nevada'. to 'Nevada'.
5. the type of location information being requested. 5. the type of location information being requested.
6. the rate at which location information delivery is desired. 6. the rate at which location information delivery is desired.
This document builds on the presence event package' [RFC3856], i.e. This document builds on the presence event package [RFC3856], i.e. an
an existing event package for communicating location information existing event package for communicating location information inside
inside the PIDF-LO. the PIDF-LO.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
This document reuses terminology from [I-D.ietf-geopriv-arch]. This document reuses terminology from [I-D.ietf-geopriv-arch].
3. Filter Definitions 3. Filter Definitions
This specification builds on top of a number of other specifications,
as noted in Section 1. In order to reduce the number of options (and
thereby increase the chance of interoperability problems), only the
functionality described in this document MUST be implemented. Only
the functionality of [RFC4661] listed in the sub-sections below MUST
be implemented, namely the <ns-bindings> (see Section 3.3 of
[RFC4661]), the <filter> (Section 3.4 of [RFC4661]), and the
<trigger> (Section 3.6 of [RFC4661] excluding the functionality of
the <added> and <removed> element).
3.1. Movement 3.1. Movement
The <moved> element with a value in meters indicates the minimum The <moved> element with a value in meters indicates the minimum
distance that the resource must have moved from the location of the distance that the resource must have moved from the location of the
resource when the last notification was sent in order to trigger this resource when the last notification was sent in order to trigger this
event. The distance is measured in meters absolutely from the point event. The distance is measured in meters absolutely from the point
of last notification rather than in terms of cumulative motion. The of last notification rather than in terms of cumulative motion. The
<moved> element MUST only appear once as a child element of <filter>. <moved> element MUST only appear once as a child element of <filter>.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<filter-set <filter-set
xmlns="urn:ietf:params:xml:ns:simple-filter" xmlns="urn:ietf:params:xml:ns:simple-filter"
xmlns:ext="urn:ietf:params:xml:ns:location-filter"> xmlns:lf="urn:ietf:params:xml:ns:location-filter">
<filter id="123" uri="sip:presentity@example.com"> <filter id="123" uri="sip:presentity@example.com">
<ext:moved>300</ext:moved> <lf:moved>300</lf:moved>
</filter> </filter>
</filter-set> </filter-set>
Figure 1: Movement Filter Example Figure 1: Movement Filter Example
3.2. Speed Changes 3.2. Speed Changes
Speed changes can be filtered with the help of RFC 4661 and the Speed changes can be filtered with the help of RFC 4661 and the
functionality provided in [I-D.singh-geopriv-pidf-lo-dynamic], which functionality provided in [I-D.singh-geopriv-pidf-lo-dynamic], which
extends the PIDF-LO with support for spatial orientation, speed, extends the PIDF-LO with support for spatial orientation, speed,
heading, and acceleration. heading, and acceleration. The value of <speed> in
[I-D.singh-geopriv-pidf-lo-dynamic] is defined in meters per second.
This is the only supported measure and hence the value in the 'by'
attribute MUST be expressed in meters per second.
Figure 2 shows an example for a trigger that fires when the speed of Figure 2 shows an example for a trigger that fires when the speed of
the Target changes by 3 meters per second. the Target changes by 3 meters per second.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter"> <filter-set xmlns="urn:ietf:params:xml:ns:simple-filter">
<ns-bindings> <ns-bindings>
<ns-binding prefix="dyn" <ns-binding prefix="dyn"
urn="urn:ietf:params:xml:schema:pidf:dynamic"/> urn="urn:ietf:params:xml:schema:pidf:dynamic"/>
</ns-bindings> </ns-bindings>
skipping to change at page 6, line 22 skipping to change at page 6, line 22
<trigger> <trigger>
<changed by="3"> <changed by="3">
//dyn:speed //dyn:speed
</changed> </changed>
</trigger> </trigger>
</filter> </filter>
</filter-set> </filter-set>
Figure 2: Speed Change Example Figure 2: Speed Change Example
An implementation MUST support the functionality as shown in Figure 2
with <ns-bindings> replacing the prefix. No other variant is
supported. The <changed> element comes with a few attributes but
only the 'by' attribute MUST be implemented by this specification.
3.3. Element Value Changes 3.3. Element Value Changes
Changes in values, for example related to civic location information, Changes in values, for example related to civic location information,
can be provided by the base functionality offered with RFC 4661. is provided by the base functionality offered with RFC 4661 utilizing
the <changed> element.
Figure 3 shows an example where a notification is sent when the civic Figure 3 shows an example where a notification is sent when the civic
address tokens A1, A2, A3, or PC change. address tokens A1, A2, A3, or PC change (all 4 must change in order
to let the <trigger> element evaluate to TRUE).
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter"> <filter-set xmlns="urn:ietf:params:xml:ns:simple-filter">
<ns-bindings> <ns-bindings>
<ns-binding prefix="ca" <ns-binding prefix="ca"
urn="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"/> urn="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"/>
</ns-bindings> </ns-bindings>
<filter id="123" uri="sip:presentity@example.com"> <filter id="123" uri="sip:presentity@example.com">
<trigger> <trigger>
<changed>//ca:A1</changed> <changed>//ca:A1</changed>
<changed>//ca:A2</changed> <changed>//ca:A2</changed>
<changed>//ca:A3</changed> <changed>//ca:A3</changed>
<changed>//ca:PC</changed> <changed>//ca:PC</changed>
</trigger> </trigger>
</filter> </filter>
</filter-set> </filter-set>
Figure 3: Speed Change Example Figure 3: Speed Change Example
The following example illustrates a filter that triggers when the
Target's location changes from 'FR' (France) to some other country.
<?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter">
<ns-bindings>
<ns-binding prefix="ca"
urn="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"/>
</ns-bindings>
<filter id="123" uri="sip:presentity@example.com">
<trigger>
<changed from="FR">//ca:country</changed>
</trigger>
</filter>
</filter-set>
Figure 4: Speed Change Example (Country Change)
An implementation MUST support the functionality as shown in Figure 3
with <ns-bindings> replacing the prefix. No other variant is
supported. The <changed> element comes with a few attributes and the
'by', 'to' and 'from' attribute MUST be implemented by this
specification.
3.4. Entering or Exiting a Region 3.4. Entering or Exiting a Region
The <enterOrExit> condition is satisfied when the Target enters or The <enterOrExit> condition is satisfied when the Target enters or
exits a named 2-dimensional region described by a polygon (as defined exits a named 2-dimensional region described by a polygon (as defined
in Section 5.2.2 of [RFC5491]), or a circle (as defined in Section in Section 5.2.2 of [RFC5491]), or a circle (as defined in Section
5.2.3 of [RFC5491]). 5.2.3 of [RFC5491]). The <enterOrExit> element MUST have contain
either a polygon or a circle as a child element. More than one a
polygon and/or a circle as a child element of <enterOrExit> MUST NOT
occur.
Figure 4 shows filter examples whereby a notification is sent when If the Target was previously outside the region, the notifier sends a
the Target enters or exits an area described by a circle and Figure 5 notification when the Target's location is within the region with at
least 50% confidence. Similarly, when a Target starts within the
region, a notification is sent when the Target's location moves
outside the region with at least 50% confidence.
Note that having 50% confidence that the Target is inside the area
does not correspond to 50% outside. Confidence that the location is
within the region, plus confidence that the location is outside the
region cannot be 100%. The total confidence depends on the
confidence in the original location, which is always less than 100%
(95% is recommended in [RFC5491]). The benefit of this is that
notifications are naturally limited: small movements at the borders
of the region do not trigger notifications.
Figure 5 shows filter examples whereby a notification is sent when
the Target enters or exits an area described by a circle and Figure 6
describes an area using a polygon. describes an area using a polygon.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<filter-set <filter-set
xmlns="urn:ietf:params:xml:ns:simple-filter" xmlns="urn:ietf:params:xml:ns:simple-filter"
xmlns:ext="urn:ietf:params:xml:ns:location-filter" xmlns:lf="urn:ietf:params:xml:ns:location-filter"
xmlns:gml="http://www.opengis.net/gml" xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"> xmlns:gs="http://www.opengis.net/pidflo/1.0">
<filter id="123" uri="sip:presentity@example.com"> <filter id="123" uri="sip:presentity@example.com">
<ext:enterOrExit> <lf:enterOrExit>
<gs:Circle srsName="urn:ogc:def:crs:EPSG::4326"> <gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
<gml:pos>42.5463 -73.2512</gml:pos> <gml:pos>42.5463 -73.2512</gml:pos>
<gs:radius uom="urn:ogc:def:uom:EPSG::9001"> <gs:radius uom="urn:ogc:def:uom:EPSG::9001">
850.24 850.24
</gs:radius> </gs:radius>
</gs:Circle> </gs:Circle>
</ext:enterOrExit> </lf:enterOrExit>
</filter> </filter>
</filter-set> </filter-set>
Figure 4: <enterOrExit> Circle Filter Example Figure 5: <enterOrExit> Circle Filter Example
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter" <filter-set xmlns="urn:ietf:params:xml:ns:simple-filter"
xmlns:ext="urn:ietf:params:xml:ns:location-filter" xmlns:lf="urn:ietf:params:xml:ns:location-filter"
xmlns:gml="http://www.opengis.net/gml"> xmlns:gml="http://www.opengis.net/gml">
<filter id="123" uri="sip:presentity@example.com"> <filter id="123" uri="sip:presentity@example.com">
<ext:enterOrExit> <lf:enterOrExit>
<gml:Polygon srsName="urn:ogc:def:crs:EPSG::4326"> <gml:Polygon srsName="urn:ogc:def:crs:EPSG::4326">
<gml:exterior> <gml:lferior>
<gml:LinearRing> <gml:LinearRing>
<gml:posList> <gml:posList>
43.311 -73.422 43.111 -73.322 43.311 -73.422 43.111 -73.322
43.111 -73.222 43.311 -73.122 43.111 -73.222 43.311 -73.122
43.411 -73.222 43.411 -73.322 43.411 -73.222 43.411 -73.322
43.311 -73.422 43.311 -73.422
</gml:posList> </gml:posList>
</gml:LinearRing> </gml:LinearRing>
</gml:exterior> </gml:exterior>
</gml:Polygon> </gml:Polygon>
</ext:enterOrExit> </lf:enterOrExit>
</filter> </filter>
</filter-set> </filter-set>
Figure 5: <enterOrExit> Polygon Filter Example Figure 6: <enterOrExit> Polygon Filter Example
3.5. Location Type 3.5. Location Type
The <locationType> element MAY be included as a child element of the The <locationType> element MAY be included as a child element of the
<filter> element and it contains a list of location information types <filter> element and it contains a list of location information types
that are requested by the subscriber. The following list describes that are requested by the subscriber. The following list describes
the possible values: the possible values:
any: The Notifier SHOULD attempt to provide LI in all forms any: The Notifier SHOULD attempt to provide LI in all forms
available to it. available to it.
skipping to change at page 8, line 50 skipping to change at page 9, line 50
geodetic: The Notifier SHOULD return a location by value in the form geodetic: The Notifier SHOULD return a location by value in the form
of a geodetic location. of a geodetic location.
civic: The Notifier SHOULD return a location by value in the form of civic: The Notifier SHOULD return a location by value in the form of
a civic address. a civic address.
The Notifier SHOULD return the requested location type or types. The The Notifier SHOULD return the requested location type or types. The
location types the LIS returns also depend on the setting of the location types the LIS returns also depend on the setting of the
optional "exact" attribute. If the 'exact' attribute is set to optional "exact" attribute. If the 'exact' attribute is set to
"true" then the Notifier MUST return either the requested location "true" then the Notifier MUST return either the requested location
type or provide an error response. The 'exact' attribute does not type or no location information. The 'exact' attribute does not
apply (is ignored) for a request for a location type of "any". apply (is ignored) for a request for a location type of "any".
In the case of a request for specific locationType(s) and the 'exact' In the case of a request for specific locationType(s) and the 'exact'
attribute is false, the Notifier MAY provide additional location attribute is false, the Notifier MAY provide additional location
types, or it MAY provide alternative types if the request cannot be types, or it MAY provide alternative types if the request cannot be
satisfied for a requested location type. The "SHOULD"-strength satisfied for a requested location type. The "SHOULD"-strength
requirements on this parameter for specific location types are requirements on this parameter for specific location types are
included to allow for soft-failover. included to allow for soft-failover.
If the <locationType> element is absent, a value of "any" MUST be If the <locationType> element is absent, a value of "any" MUST be
skipping to change at page 9, line 44 skipping to change at page 10, line 44
As stated above, the <locationType> element MAY carry the 'exact' As stated above, the <locationType> element MAY carry the 'exact'
attribute. When the 'exact' attribute is set to "true", it indicates attribute. When the 'exact' attribute is set to "true", it indicates
to the Notifier that the contents of the <locationType> element MUST to the Notifier that the contents of the <locationType> element MUST
be strictly followed. The default value of "false" allows the be strictly followed. The default value of "false" allows the
Notifier the option of returning something beyond what is specified, Notifier the option of returning something beyond what is specified,
such as a set of location URIs when only a civic location was such as a set of location URIs when only a civic location was
requested. A value of "true" indicates that the Notifier MUST requested. A value of "true" indicates that the Notifier MUST
provide a location of the requested type or types or MUST provide an provide a location of the requested type or types or MUST provide an
error. error.
An example is shown in Figure 6 that utilizes the <locationType> An example is shown in Figure 7 that utilizes the <locationType>
element with the 'exact' and the 'responseTime' attribute. element with the 'exact' and the 'responseTime' attribute.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<filter-set <filter-set
xmlns="urn:ietf:params:xml:ns:simple-filter" xmlns="urn:ietf:params:xml:ns:simple-filter"
xmlns:ext="urn:ietf:params:xml:ns:location-filter"> xmlns:lf="urn:ietf:params:xml:ns:location-filter">
<filter id="123" uri="sip:presentity@example.com"> <filter id="123" uri="sip:presentity@example.com">
<ext:locationType exact="true"> <lf:locationType exact="true">
geodetic geodetic
</ext:locationType> </lf:locationType>
</filter> </filter>
</filter-set> </filter-set>
Figure 6: <locationType> Filter Example Figure 7: <locationType> Filter Example
3.6. Rate Control 3.6. Rate Control
[I-D.ietf-sipcore-event-rate-control] defines an extension to the SIP [I-D.ietf-sipcore-event-rate-control] defines an extension to the SIP
events framework defining the following three "Event" header field events framework defining the following three "Event" header field
parameters that allow a subscriber to set a minimum, a maximum and an parameters that allow a subscriber to set a minimum, a maximum and an
average rate of event notifications generated by the notifier. This average rate of event notifications generated by the notifier. This
document makes use of two of the parameters to accomplish document makes use of two of the parameters to accomplish
functionality equivalent to the 'responseTime' attribute used in HELD functionality equivalent to the 'responseTime' attribute used in HELD
[I-D.ietf-geopriv-http-location-delivery], namely "min-interval" [I-D.ietf-geopriv-http-location-delivery], namely "min-interval"
(which specifies a minimum notification time period between two (which specifies a minimum notification time period between two
notifications, in seconds) and "max-interval" (which specifies a notifications, in seconds) and "max-interval" (which specifies a
maximum notification time period between two notifications, in maximum notification time period between two notifications, in
seconds.). Whenever the time since the most recent notification seconds.). This specification only defines the semantic for these
exceeds the value in the "max-interval" parameter, then the current two attributes and requires implementation of these two from the set
state would be sent in its entirety, just like after a subscription of attributes defined in [I-D.ietf-sipcore-event-rate-control].
refresh. Whenever the time since the most recent notification exceeds the
value in the "max-interval" parameter, then the current state would
be sent in its entirety, just like after a subscription refresh.
If complete state is not immediately available, a NOTIFY containing If complete state is not immediately available, a NOTIFY containing
state (i.e. location) is generated some time between the time state (i.e. location) is generated some time between the time
included in 'min-interval' and the time in 'max-interval'. An included in 'min-interval' and the time in 'max-interval'. An
important use case for location based applications focuses on the important use case for location based applications focuses on the
behavior of the initial NOTIFY message(s) and the information it behavior of the initial NOTIFY message(s) and the information it
returns, for example in case of emergency call routing. When an returns, for example in case of emergency call routing. When an
initial NOTIFY is transmitted it might not include complete state. initial NOTIFY is transmitted it might not include complete state.
Subscriber Notifier Subscriber Notifier
|---SUBSCRIBE(1)--->| Request state subscription |---SUBSCRIBE(1)--->| Request state subscription
|<-------200--------| Acknowledge subscription |<-------200--------| Acknowledge subscription
|<-----NOTIFY(2)----| Return current state information |<-----NOTIFY(2)----| Return current state information
|-------200(3)----->| |-------200(3)----->|
|<-----NOTIFY(4)----| Return current state information |<-----NOTIFY(4)----| Return current state information
|--------200------->| |--------200------->|
Figure 7: SUBSCRIBE/NOTIFY with Rate Control Figure 8: SUBSCRIBE/NOTIFY with Rate Control
Figure 7 shows a SUBSCRIBE/NOTIFY exchange. The initial SUBSCRIBE Figure 8 shows a SUBSCRIBE/NOTIFY exchange. The initial SUBSCRIBE
message (1) has filters attached and contains a 'max-interval' rate message (1) has filters attached and contains a 'max-interval' rate
control parameter. In certain situations it is important to obtain control parameter. In certain situations it is important to obtain
some amount of location information within a relatively short and some amount of location information within a relatively short and
pre-defined period of time even if the obtained location information pre-defined period of time even if the obtained location information
contains a high amount of uncertainty and location information withy contains a high amount of uncertainty and location information with
less uncertainty at a later point in time. An example is emergency less uncertainty at a later point in time. An example is emergency
call routing where a emergency services routing proxy may need to call routing where a emergency services routing proxy may need to
obtain location information suitable for routing rather quickly and obtain location information suitable for routing rather quickly and
subsequently a Public Safety Answering Point requests location subsequently a Public Safety Answering Point requests location
information for dispatch. To obtain location information in a timely information for dispatch.
fashion using the SUBSCRIBE/NOTIFY mechanism, it is RECOMMENDED that
the initial SUBSCRIBE contains a 'max-interval' rate control To obtain location information in a timely fashion using the
parameter (with a small value) that is in a later message updated to SUBSCRIBE/NOTIFY mechanism, it is RECOMMENDED that the initial
a more sensible value. The 'max-interval' for this first request is SUBSCRIBE contains a 'max-interval' rate control parameter (with a
therefore much lower than thereafter. Updating the 'max-interval' small value) that is in a later message updated to a more sensible
for the subscription can be performed in the 200 response (see value. The 'max-interval' for this first request is therefore much
message 3) to the NOTIFY that contains state. Depending on the value lower than thereafter. Updating the 'max-interval' for the
in the 'max-interval' parameter the Notifier may create a NOTIFY subscription can be performed in the 200 response (see message 3) to
message (see message 2) immediately in response to the SUBSCRIBE that the NOTIFY that contains state. Depending on the value in the 'max-
might be empty in case no location information is available at this interval' parameter the Notifier may create a NOTIFY message (see
point in time. The desired location information may then arrive in message 2) immediately in response to the SUBSCRIBE that might be
the subsequent NOTIFY message (see message 4). empty in case no location information is available at this point in
time. The desired location information may then arrive in the
subsequent NOTIFY message (see message 4).
4. XML Schema 4. XML Schema
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<xs:schema <xs:schema
targetNamespace="urn:ietf:params:xml:ns:location-filter" targetNamespace="urn:ietf:params:xml:ns:location-filter"
xmlns:filter="urn:ietf:params:xml:ns:location-filter" xmlns:filter="urn:ietf:params:xml:ns:location-filter"
xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:gml="http://www.opengis.net/gml"> xmlns:gml="http://www.opengis.net/gml">
skipping to change at page 13, line 20 skipping to change at page 14, line 20
<xs:complexType name="locationTypeType"> <xs:complexType name="locationTypeType">
<xs:simpleContent> <xs:simpleContent>
<xs:extension base="filter:locationTypeBase"> <xs:extension base="filter:locationTypeBase">
<xs:attribute name="exact" type="xs:boolean" <xs:attribute name="exact" type="xs:boolean"
use="optional" default="false"/> use="optional" default="false"/>
</xs:extension> </xs:extension>
</xs:simpleContent> </xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:schema> </xs:schema>
Figure 8: XML Schema Figure 9: XML Schema
5. Security Considerations 5. Security Considerations
This document builds on a number of specifications, namely This document builds on a number of specifications, namely
o the SIP event notification mechanism, described in RFC 3265 o the SIP event notification mechanism, described in RFC 3265
[RFC3265], defining the SUBSCRIBE/NOTIFY messages. [RFC3265], defining the SUBSCRIBE/NOTIFY messages.
o the presence event package, described in RFC 3856 [RFC3856], which o the presence event package, described in RFC 3856 [RFC3856], which
is a concrete instantiation of the general event notification is a concrete instantiation of the general event notification
framework. framework.
o PIDF-LO, described in RFC 4119 [RFC4119], as the XML container
that carries location information. PIDF payloads are exchanged
via the presence event package and the location object extension
of it provides the necessary functionality for this document.
o the filter framework, described in RFC 4661 [RFC4661], to offer o the filter framework, described in RFC 4661 [RFC4661], to offer
the ability to reduce the amount of notifications being sent. the ability to reduce the amount of notifications being sent.
Finally, this document indirectly (via the SIP presence event
package) relies on PIDF-LO, described in RFC 4119 [RFC4119], as the
XML container that carries location information.
Each of these documents listed above comes with a security Each of these documents listed above comes with a security
consideration section but the security and privacy aspects are best consideration section but the security and privacy aspects are best
covered by the SIP presence event package, see Section 9 of covered by the SIP presence event package, see Section 9 of
[RFC3856], and with the GEOPRIV architectural description found in [RFC3856], and with the GEOPRIV architectural description found in
[I-D.ietf-geopriv-arch]. The functionality for uploading [I-D.ietf-geopriv-arch]. The functionality for uploading
authorization policies and other information that limit access to authorization policies and other information that limit access to
location information are provided by other protocols, such Common location information are provided by other protocols, such Common
Policy [RFC4745], Geolocation Policy [I-D.ietf-geopriv-policy] or Policy [RFC4745], Geolocation Policy [I-D.ietf-geopriv-policy] or
more recent work around HELD context more recent work around HELD context
[I-D.winterbottom-geopriv-held-context]. The functionality described [I-D.winterbottom-geopriv-held-context]. The functionality described
in this document extends the filter framework with location specific in this document extends the filter framework with location specific
filters. Local policies might be associated with the usage of filters. Local policies might be associated with the usage of
certain filter constructs and with the amount of notifications certain filter constructs and with the amount of notifications
specific filter settings might cause. specific filter settings might cause.
Although [I-D.ietf-geopriv-policy] defines a standardized format for
authorization policies but it does not define specific policies for
controlling filters specifically.
6. IANA Considerations 6. IANA Considerations
6.1. URN Sub-Namespace Registration for 6.1. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:location-filter urn:ietf:params:xml:ns:location-filter
This section registers a new XML namespace, as per the guidelines in This section registers a new XML namespace, as per the guidelines in
[RFC3688]. [RFC3688].
URI: urn:ietf:params:xml:ns:location-filter URI: urn:ietf:params:xml:ns:location-filter
skipping to change at page 18, line 7 skipping to change at page 19, line 7
XML: The XML can be found as the sole content of Section 4. XML: The XML can be found as the sole content of Section 4.
7. Contributors 7. Contributors
We would like to thank Martin Thomson and James Polk for their We would like to thank Martin Thomson and James Polk for their
contributions to this document. contributions to this document.
8. Acknowledgments 8. Acknowledgments
Thanks to Richard Barnes and Alissa Cooper, Adam Roach, Allan Thanks to Richard Barnes and Alissa Cooper, Carl Reed, Adam Roach,
Thomson, James Winterbottom for their comments. Allan Thomson, James Winterbottom for their comments.
9. References 9. References
9.1. Normative References 9.1. Normative References
[GML] OpenGIS, "Open Geography Markup Language (GML) [GML] OpenGIS, "Open Geography Markup Language (GML)
Implementation Specification", OpenGIS OGC 02-023r4, Implementation Specification", OpenGIS OGC 02-023r4,
January 2003, January 2003,
<http://www.opengis.org/techno/implementation.htm>. <http://www.opengis.org/techno/implementation.htm>.
skipping to change at page 20, line 36 skipping to change at page 21, line 36
July 2009. July 2009.
[I-D.ietf-sipcore-location-conveyance] [I-D.ietf-sipcore-location-conveyance]
Polk, J. and B. Rosen, "Location Conveyance for the Polk, J. and B. Rosen, "Location Conveyance for the
Session Initiation Protocol", Session Initiation Protocol",
draft-ietf-sipcore-location-conveyance-01 (work in draft-ietf-sipcore-location-conveyance-01 (work in
progress), July 2009. progress), July 2009.
[I-D.winterbottom-geopriv-held-context] [I-D.winterbottom-geopriv-held-context]
Winterbottom, J., Tschofenig, H., and M. Thomson, Winterbottom, J., Tschofenig, H., and M. Thomson,
"Establishing Location URI Contexts using HTTP-Enabled "Location URI Contexts in HTTP-Enabled Location Delivery
Location Delivery (HELD)", (HELD)", draft-winterbottom-geopriv-held-context-05 (work
draft-winterbottom-geopriv-held-context-04 (work in in progress), October 2009.
progress), April 2009.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004. January 2004.
[RFC4745] Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J., [RFC4745] Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J.,
Polk, J., and J. Rosenberg, "Common Policy: A Document Polk, J., and J. Rosenberg, "Common Policy: A Document
Format for Expressing Privacy Preferences", RFC 4745, Format for Expressing Privacy Preferences", RFC 4745,
February 2007. February 2007.
Authors' Addresses Authors' Addresses
Rohan Mahy Rohan Mahy
Plantronics Individual
345 Encincal Street
Santa Cruz, CA
USA
Email: rohan@ekabal.com Email: rohan@ekabal.com
Brian Rosen (editor) Brian Rosen
NeuStar NeuStar
470 Conrad Dr. 470 Conrad Dr.
Mars, PA 16046 Mars, PA 16046
US US
Phone: +1 724 382 1051 Phone: +1 724 382 1051
Email: br@brianrosen.net Email: br@brianrosen.net
Hannes Tschofenig Hannes Tschofenig
Nokia Siemens Networks Nokia Siemens Networks
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