SDOEmergency Services Coordination Workshop ESW06

1
A Location-to-Service Translation Protocol
(LoST) Mapping Protocol Architecture

• Ted Hardie
• Andrew Newton
• Henning Schulzrinne
• Hannes Tschofenig

2
Overview

• LoST is a simple XML-based query and response
  protocol running on top of HTTP
• either naked HTTP or SOAP
• Main Purpose Return URIs for given location
  information and service identifier
• i.e., service URN location ? URIs
• Status Work in progress
• Expected WGLC in Nov. 2006

3
Finding the correct PSAP

• Which PSAP should the e-call go to?
• Usually to the PSAP that serves the geographic
  area
• Sometimes to a backup PSAP
• If no location, then default PSAP

4
LoST Functionality

• Satisfies the requirements (draft-ietf-ecrit-requi
  rements) for mapping protocols
• Civic as well as geospatial queries
• civic address validation
• Recursive and iterative resolution
• Fully distributed and hierarchical deployment
• can be split by any geographic or civic boundary
• same civic region can span multiple LoST servers
• Indicates errors in civic location data ?
  debugging
• but provides best-effort resolution
• Supports overlapping service regions

5
LoST Properties

• Minimizes round trips
• caching individual mappings
• returns coverage regions (hinting)
• civic (all of CUS, A1NY) or geo (polygon)
• Facilitates reuse of Transport Layer Security
  (TLS)
• Returns emergency service numbers for a region
• Query for supported Service URN types

6
Protocol request (mapping)
eByLocation xmlns"urnietfparamsxmlnslost1" v
alidate"false" operation"recursive" fo US
New York New York
Broadway Suite 75
10027-0401 nfo urnservicesos.police indServiceByLocation
details likely to change
7
Protocol response (mapping)


xmllang"en" timeToLive"10000"
New York
City Police Department
unknown

US New
York New York

sipnypd_at_example.com
xmppnypd_at_example.com
911

8
Validation

• Determine if civic location is (partially) valid
• Returns XML tag names of components
• validated and used for mapping
• no attempt to validate (and not used)
• e.g., house number
• known to be invalid
• Return (default) PSAP based on validated elements
• May return list of guesses for correct addresses,
  if requested

9
Geo support

• Which geo types should be supported?
• Point (3D) ?
• Polygon? ? may yield ambiguous answers
• more complicated shapes?
• Current proposal
• always include 3D-point
• may include other shapes

10
LoST Location-to-URL Mapping
VSP1
cluster serving VSP1
replicate root information
cluster serves VSP2
123 Broad Ave Leonia Bergen County NJ US
LoST
root nodes
NY US
NJ US
sippsap_at_leonianj.gov
search referral
Bergen County NJ US
Leonia NJ US
11
LoST Architecture
G
tree guide
G
G
G
broadcast (gossip)
T1 .us T2 .de
G
resolver
T2 (.de)
seeker 313 Westview Leonia, NJ US
T3 (.dk)
T1 (.us)
Leonia, NJ ? sippsap_at_leonianj.gov
12
Conclusion

• Mapping is core component of emergency calling
  problem
• LoST fully international and distributed
• tries to avoid who runs the root problem
• optimized for efficient use in mobile end systems

13
References and Contact Info

• IETF ECRIT Working Grouphttp//www.ietf.org/html.
  charters/ecrit-charter.html
• LoST draft
• http//tools.ietf.org/wg/ecrit/draft-ietf-ecrit-l
  ost/
• Mapping architecture draft
• http//tools.ietf.org/wg/ecrit/draft-ietf-ecrit-m
  apping-arch
• Prototype implementation work in progress (see
  demo)
• First interoperability tests planned for early
  2006 / beginning 2007.