Presentation by Ben Knoechel during the Sensor Web System and Visualization paper session of the Sensor Web Enablement workshop (held during the 2011 Cybera Summit).

1. Design
and
implementa.on
of
a
system
for
the
improved
searching
and
accessing
of
real-­‐world
SOS
services
Ben
Knoechel
(bcknoech@ucalgary.ca)
Chih-­‐Yuan
Huang
(huangcy@ucalgary.ca)
Steve
Liang
(steve.liang@ucalgary.ca)
University
of
Calgary

2. Outline
• Introduc.on
• Methodology
• Experimental
Results
• Conclusions
2

3. Introduc.on
3

4. Introduc.on
• The
Open
Geospa.al
Consor.um
(OGC)
has
developed
the
Sensor
Web
Enablement
(SWE)
• SWE
is
a
set
of
standards
to
allow
people
to
share
and
interact
with
sensor
data
over
the
Internet
• The
Sensor
Observa.on
Service
(SOS)
is
a
standard
for
sharing
data
collected
by
sensors
– SOS
will
refer
to
version
1.0.0
4

5. Sensor
Observa.on
Service
• SOS
defines
three
core
opera.ons
– GetCapabili.es
– DescribeSensor
– GetObserva.on
• A
GetObserva.on
request
must
define
an
observa.on
offering
and
at
least
one
observed
property
• Addi.onal
filters
include
spa.al-­‐temporal
bounding
box,
feature
of
interest
5

6. Phenomenon
Layer
• A
SOS
service
may
provide
varied
data
• We
define
a
phenomenon
layer
to
refer
to
data
specific
to
a
single
observa.on
offering
and
observed
property
• A
phenomenon
layer
can
be
used
to
generate
more
specific
data
requests
to
a
SOS
service
• This
defini.on
is
specific
to
our
group
6

7. Enhancing
SOS
• SOS
accomplishes
the
goal
of
transferring
sensor
data
• We
can
extend
the
u.lity
of
SOS
by
designing
a
system
to
collect
data
from
mul.ple
SOS
services
• Our
team’s
use
case:
– To
display
all
the
sensors
measuring
the
same
phenomenon
from
all
SOS
services
7

8. Problems
• A
number
of
problems
were
encountered
when
developing
a
system
for
our
use
case
1. Large
variety
of
the
observed
property
URI
represen.ng
the
same
phenomenon
2. Sensor-­‐centric
SOS
services
3. Non-­‐compliant
SOS
services
8

9. Different
Observed
Property
URIs
For
Wind
Speed
urn:x-­‐ogc:def:property:OGC::WindSpeed
urn:ogc:def:property:universityofsaskatchewan:ip3:windspeed
urn:ogc:def:phenomenon:OGC:1.0.30:windspeed
urn:ogc:def:phenomenon:OGC:1.0.30:WindSpeeds
urn:ogc:def:phenomenon:OGC:windspeed
urn:ogc:def:property:geocens:geocensv01:windspeed
urn:ogc:def:property:noaa:ndbc:Wind
Speed
urn:ogc:def:property:OGC::WindSpeed
urn:ogc:def:property:ucberkeley:odm:Wind
Speed
Avg
MS
urn:ogc:def:property:ucberkeley:odm:Wind
Speed
Max
MS
hdp://ws.sensordatabus.org/Ows/Swe.svc/?
service=SOS&request=GetResourceByID&ResourceID=urn:renci:sdb:property:1.0.0:Wind
%20Speed
hdp://marinemetadata.org/cf#wind_speed
9

10. An
Example
of
a
Sensor-­‐Centric
SOS
Service
Observation Offering Observed Property
http://ws.sensordatabus.org/Ows/Swe.svc/?
offering_44040 service=SOS&request=GetResourceByID&ResourceID=urn:renci:sdb:property:1.0.0:Wind%20Speed
http://ws.sensordatabus.org/Ows/Swe.svc/?
offering_nos.8411250.WL service=SOS&request=GetResourceByID&ResourceID=urn:renci:sdb:property:1.0.0:Wind%20Speed
http://ws.sensordatabus.org/Ows/Swe.svc/?
offering_pwaw3 service=SOS&request=GetResourceByID&ResourceID=urn:renci:sdb:property:1.0.0:Wind%20Speed
http://ws.sensordatabus.org/Ows/Swe.svc/?
offering_mqtt2 service=SOS&request=GetResourceByID&ResourceID=urn:renci:sdb:property:1.0.0:Wind%20Speed
http://ws.sensordatabus.org/Ows/Swe.svc/?
offering_nws.SBCP.metar service=SOS&request=GetResourceByID&ResourceID=urn:renci:sdb:property:1.0.0:Wind%20Speed
10

11. Proposed
Solu.on
• We
propose
a
logical
layer
service
to
manage
heterogeneous
observed
property
URIs
• We
propose
a
transla8on
engine
to
provide
efficient
communica.on
with
SOS
services
11

12. Contribu.on
• Our
system
has
three
contribu.ons
1. Summarizes
and
inves.gates
the
current
status
of
SOS
services
online
today
2. Highlights
issues
with
developing
a
system
to
address
a
common
use
case
3. Presents
a
system
architecture
for
handling
these
solu.ons
12

13. Related
Work
• The
OGC
Catalogue
Service
provides
informa.on
about
available
OGC
services
• Not
all
SOS
services
are
registered
in
a
Catalogue
Service
• Also,
the
system
must
also
account
for
communica.ng
with
mul.ple
SOS
services
13

14. Related
Work
• A
search
engine
is
commonly
used
for
answering
advanced
queries
• This
is
a
difficult
process
due
to
varying
URNs
of
observed
proper.es
• This
also
doesn’t
account
for
managing
communica.on
with
mul.ple
SOS
services
14

15. Methodology
15

16. Overview
16

17. Logical
Layer
Service
• Manages
and
maps
the
logical
concept
of
an
observed
property
to
corresponding
phenomenon
layers
• We
use
a
dic.onary
to
manage
our
list
of
observed
proper.es
• The
dic.onary
is
manually
created
by
a
data
processing
team
that
interprets
sensor
data
by
phenomenon
types
17

18. Logical
Layer
Service
• Dic.onary
terms
are
managed
by
hierarchies
to
facilitate
user
searches
• The
mapping
from
dic.onary
terms
to
phenomenon
layers
is
also
done
manually
• The
textual
informa.on
of
the
observa.on
offering
and
observed
property
URI
are
interpreted
manually
and
mapped
to
corresponding
dic.onary
terms
18

19. Logical
Layer
Service
Hierarchy
Dic.onary
Phenomenon
Layer
Earth
.de
level
water
temp
Atmosphere
Hydro
soil
moisture
soil
temp
air
temp
Air
Soil
1
(1)
hdp://app.geocens.ca:8171/sos,
Temperature,
urn:ogc:def:property:noaa:ndbc:Air
Temperature
19

20. Transla.on
Engine
• The
transla.on
engine
has
four
components
1. Controller
2. SOS
Connector
3. Feeder
4. Cache
Database
20

21. Transla.on
Engine
21

22. Client
• Web
based
front
end
• Users
select
a
hierarchy,
and
use
the
hierarchy
to
select
an
observed
property
• The
client
automa.cally
loads
all
data
for
that
observed
property
from
all
available
SOS
services
22

23. Client
23

24. Experimental
Results
24

25. Data
Mapping
• Data
mapping
is
performed
manually,
we
will
not
focus
on
valida.ng
correctness
of
mapping
• Instead,
we
will
summarize
the
overall
mappings
25

26. Data
Mapping
• The
dic.onary
defines
76
observed
proper.es
• The
mapping
defines
phenomenon
layers,
so
the
user
does
not
need
to
create
mul.ple
requests
to
mul.ple
SOS
services
• For
example,
there
are
369
wind
speed
phenomenon
layers,
across
7
different
SOS
services
26

27. Top
Ten
Observed
Proper.es
with
Highest
Number
of
Mappings
Observed Property URN Number of Mappings Number of Services
horizontal_wind_speed 402 2
wind_direction 369 7
wind_speed 55 12
dew_point_temperature 31 4
min_air_temperature 25 14
air_temperature 25 14
max_air_temperature 20 10
dry_bulb_temperature 19 9
mean_air_temperature 18 9
atmospheric_pressure 18 14
27

28. Number
of
instances
in
the
real-­‐world
SOS
services
and
the
logical
layer
service
28

29. Data
Access
• To
evaluate
the
performance
of
data
access,
we
used
our
system
approach
versus
the
naïve
approach
• We
downloaded
recent
observa.on
data
from
sensors
• Tes.ng
was
performed
on
Acer
Aspire
M3910
with
Intel®
Core
™
i7-­‐870
@
2.93GHz
and
4
gigabyte
DIMM
Synchronous
1333
MHz
29

30. Data
loading
latencies
by
using
naïve
solu.on
and
proposed
scheme
30

31. Conclusions
31

32. Conclusions
• A
logical
layer
service
and
transla.on
engine
are
proposed
to
solve
data
access
to
mul.ple,
heterogeneous
SOS
services
• The
data
mapping
aggregates
similar
phenomenon
layers
• The
proposed
data
access
scheme
is
efficient
when
compared
to
a
naïve
approach
32

33. Future
Work
• The
work
here
can
be
extended
by
inves.ga.ng
automa.c
and
semi-­‐automa.c
methods
of
mapping,
dic.onary
genera.on,
and
informa.on
retrieval
• We
can
leverage
recent
research
in
the
seman.c
web
and
data
mining
for
opening
the
sensor
web
to
end
users
for
data
browsing
33

34. Acknowledgements
34