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Open Sensor Web Architecture


									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.
                                                                                      Response Ti m f or col l ect i ng Ti nyDB quer y dat a
       Figure 2 Sensor Web Collection Service Architecture

                                                                                                                                               1 r ecor d

                                                                                                                                               10 r ecor ds
                                                                                             200                                               20 r ecor ds

                                                                                                               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


                                                                                                                                                                     1 r ecor d
                                                                                                                          200                                        10 r ecor ds
                                                                                                                          100                                        20 r ecor ds
                                                                                                                                   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.

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