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  • On Accessing GSM-enabled Mobile Sensors Zissis K. Plitsis, Ioannis Fudos, Evaggelia Pitoura and Apostolos Zarras ISSNIP 2005 University of Ioannina, Greece The Distributed Management of Data L aboratory
  • Outline
    • Motivation and Approach
    • Technology and Services
    • System Architecture
    • Use Case: Integrating a Mobile Camera
    • Performance Evaluation
    • Conclusions
  • Motivation
    • Accessing various kinds of GSM-enabled Mobile Sensors
      • Delivering image, temperature, seismic activity, measurements and other textual or not information
      • Controlled by SMS messages and delivering information by SMS/MMS
  • Motivation
    • Our goal is to automate the process of incorporating these mobile sensors, in an ubiquitous and heterogeneous computing environment
  • Approach
    • Introduction of:
    • A middleware framework that enables uniform WEB-based access to mobile sensors
    • Mobile Sensor Control Description (MSCD), describing sensor behavior and functionality
  • Approach
    • Produce HTML-based and WAP-based interfaces
    • Instantiate a sensor-customized proxy server, serving client requests for sensor information
  • Technology and Services
    • S.M.S.: S hort M essage S ervice or S hort M essage S ending
      • Widely supported in mobile phones in most countries
      • Communication between mobile phones with short textual messages in an asynchronous way, as e-mails for mobile phones
      • Binding together the pertinent telephony and computing protocols with SMS comes “naturally”, as SMS can be used to form protocols
      • Relatively inexpensive
  • Technology and Services
    • Except from HTTP, compatibility with WAP is provided by our system
    • WAP ( W ireless A pplication P rotocol) allows low-end devices with limited CPU power, memory and storage to access the wireless WEB
      • Uses WML for publishing pages, containing cards for browsing in small screens with limited capabilities
  • Our Goal
    • The proposed middleware framework is reflective as it self-customizes its interfaces with respect to behavioral constraints of the particular mobile sensor
    • Our goal is:
    • Web-based access transparency over mobile sensors
  • System Architecture
    • Our framework consists of:
    • A mobile sensor customizer, server proxies and WEB page proxies …
  • Architecture
  • Architecture Mobile Server Customizer and MSCD
  • Mobile Sensor Customizer and MSCD
    • Unifying the communication between clients and mobile sensors by providing the WEB-based interfaces
    • Using as input an MSCD, acquire the SMS control sequence that perform the operations on the mobile sensor
    • The MSCD of a mobile sensor, provided by means of an XML file, consists of the following elements:
      • Initialization information
      • Query delivery information
    • An XML scheme describes the structure of MSCD files
  • Example of a Mobile Sensor Control Description file for a mobile sensor providing images and temperature via SMS or MMS; the GSM Camera is the use case that will present later on.
  • An example of the initialization information in the MSCD file.
  • Examples of the delivery information in the MSCD file.
  • Architecture Server Proxy and WEB page Proxy
  • Application server: Server Proxy and WEB Page Proxy
    • Proxy Server
      • Collects requests for information issued by clients and translates them into sequences of sensors-specific SMS messages
      • Receives the specified information and makes it available in client-compatible formats
    • WEB Page Proxy
      • Builds a WEB page that contains the results obtained by the sensor, when this is requested
    • The Proxy Server uses polling while waiting the page creation with the results and informs the client for the progress and the completion, in the case of HTTP, with a popup window.
  • Use Case: Integrating a Mobile Camera Mobile Camera: Nokia Observation Camera; a stand-alone remote GSM-GPRS device with imaging hardware, motion detector, thermometer and microphone, ready to operate where there is GSM coverage
  • Integrating a Mobile Camera (2/4)
    • The MSCD specification for the camera, shown in the example previously, is used for:
      • Customization of the proxy server and WEB page proxy
      • Creating the corresponding HTML and WAP based interfaces
  • Integrating a Mobile Camera (3/4)
    • The HTML interface consists of a form, by witch the client determines the context and the delivery information
    • Image and temperature may will be delivered in a result web page
    • Similarly the requested information may will be delivered as an MMS or SMS message
  • HTML Form for Selection
  • An instance of the interaction protocol
  • Result Page
  • Integrating a Mobile Camera (4/4)
    • The HTTP and WAP based interfaces:
      • http://sensor-proxy.cs.uoi.gr/index_ds.htm
      • wap:// sensor-proxy .cs.uoi.gr/index_ds.wml
      • Please, feel free to try them later!
  • Performance Evaluation
      • Performance Evaluation to measure:
      • The overhead introduced by our middleware framework in the case of accessing the GSM Camera.
  • Performance Evaluation (2/6)
    • Query experiments performed:
      • Request image and temperature, through HTML-based interface
        • with image resolution default, high and compact
        • delivering on a WEB page
      • Request temperature only, through HTML-based interface
        • delivering to a mobile phone with an SMS message
      • The above experiments submitted through the WAP-based interface
  • Performance Evaluation (3/6)
      • Measurements:
      • preparation time required by the server for sending the SMS messages to the mobile camera , in fact :
      • the middleware framework overhead
      • overall response time , from the submission until the reception of results
  • Performance Evaluation (4/6)
      • The Response time of the middleware was divided into three parts:
      • the preparation time required by the server
      • the processing time for the camera for sending the SMS/MMS messages with information, and
      • the time for message unpacking and processing at the WEB page proxy
  • Performance Evaluation fig.1
  • Performance Evaluation (5/6)
      • Important overhead of preparation at the proxy server, based on the server capabilities and the number of requests
      • This overhead is close to double in the case of many SMS control messages, when e.g. the resolution mode should change to high or compact
      • and as expected:
      • High resolution mode results in larger image files and more time for unpacking the MMS messages that contains them
  • Performance Evaluation fig.2
  • Performance Evaluation (6/6)
      • The overhead introduced by our middleware framework:
      • Almost doubles the time required by the system to deliver the results
      • Currently we work on reducing the overhead by optimizing the implementation and the capabilities of our prototype
  • Conclusions
    • “ WEB-based access transparency over different types of mobile sensors” can be achieved by:
      • XML-based control descriptions that specify the proprietary SMS/MMS-based communication protocols assumed by the sensors, leading to automated customization
      • WEB-based interfaces (HTML and WAP), based in the MCSD of the sensors
  • Conclusions
    • An instance of the proposed middleware framework was implemented and evaluated for a GSM-enabled camera
      • A MSCD file was used for this camera and the functionality that it provide
      • That file specified the servers, the user interfaces that should be used and provide some protocols of requesting information
  • On Accessing GSM-enabled Mobile Sensors Thank you ISSNIP 2005 University of Ioannina, Greece The Distributed Management of Data Laboratory
  • On Accessing GSM-enabled Mobile Sensors
    • Questions…
    • Feel free to try the following HTTP and WAP based interfaces:
      • http://sensor-proxy.cs.uoi.gr/index_ds.htm
      • wap:// sensor-proxy .cs.uoi.gr/index_ds.wml