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n Sensor Web Architecture: Integration of Sensor Networks and Gr
- Rajkumar Buyya, Xingchen Chu and Jiye Lin
The Open Sensor Web Architecture (OSWA) proposed by NICTA,
at University of Melbourne extends the Sensor Web Enablement
(SWE) and further integrates the Sensor Web and Grid Computing
as well as providing middleware support of Sensor Web. The
Sensor Collection & Registry Services have been implemented and
deployed on Tomcat and Apache AXIS. Clients can enquiry the
Sensor Registry Service about available Collection Service
according to their requirements and send data query via SOAP
messages to obtain the observation data conformed to the XML
schema defined by Observation & Measurement. Different type of
connectors have been designed to fit into different kind of resources
including sensor networks running on top of TinyOS, TinyDB
application and remote observation data archives.
Figure 1- Layered Architecture
A temperature monitoring application written by NesC has been
developed and deployed onto Mica2 Sensor Motes provided by
Crossbow’s sensor development Kit. The Collection Service
collects the sensor data, converts them into O&M XML format
and then stores the data into the repository using JDO persistent
mechanism. Also a simple GUI client has been used to send
queries to the Collection Service via web services calls.
Evaluation of Performance on both auto-sending and query-
based mode have been conducted on real-sensors as well as the
simulation environment TOSSIM that runs TinyDB application.
e
Response Ti m f or col l ect i ng Ti nyDB quer y dat a
Figure 2 Sensor Web Collection Service Architecture
600
1 r ecor d
Second
400
10 r ecor ds
200 20 r ecor ds
0
1 5
1 r ecor d 34. 2635 164. 31775
10 r ecor ds 76. 5 395. 272525
20 r ecor ds 96. 05 492. 21
Num ber of Cl i ent s
Figure 4 Performance of collecting auto-sending and query data
e e
Response Ti m f or col l ect i ng r eal - t i m dat a
400
300
Second
1 r ecor d
200 10 r ecor ds
100 20 r ecor ds
0
1 5 50 500
1 r ecor d 2. 047 2. 097 3. 569 22. 904
Figure 3 GUI Client for Collecting Sensor Data 10 r ecor ds 12. 14 16. 29 27. 032 173. 48
20 r ecor ds 24. 52 32. 904 54. 602 354. 86
Number of Cl i ent s
The performance for the auto-sending mode application is quite moderate when the number of clients who request the observation
simultaneity is quite small. Even the number of clients reaches 500, the response time for small number of records is also acceptable. In
contrast, the performance of query-based model is fairly unacceptable even just one client requesting one observation takes 34 second. The
response time increases near linearly when the number of clients and the number of records go up.
