on accessing gsm-enabled mobile sensors

On Accessing GSM-enabled Mobile Sensors

Zissis K. Plitsis, Ioannis Fudos, Evaggelia Pitoura and Apostolos Zarras

ISSNIP 2005ISSNIP 2005

University of Ioannina, Greece

The Distributed Management of Data Laboratory

04/19/23 On Accesing GSM-enabled Mobile Sensors

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Outline

Motivation and Approach Technology and Services System Architecture Use Case: Integrating a Mobile Camera Performance Evaluation Conclusions


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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


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Motivation

Our goal is to automate the process of incorporating these mobile sensors, in an ubiquitous and heterogeneous computing environment


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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


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Approach

Produce HTML-based and WAP-based interfaces

Instantiate a sensor-customized proxy server, serving client requests for sensor information


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Technology and Services

S.M.S.: Short Message Service or Short Message Sending

– 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


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Technology and Services

Except from HTTP, compatibility with WAP is provided by our system

WAP (Wireless Application Protocol) 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


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Our Goal

The proposed middleware framework is reflectivemiddleware 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 sensorsWeb-based access transparency over mobile sensors


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System Architecture

Our framework consists of:

A mobile sensor customizer, server proxies and WEB page proxies …


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Architecture


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ArchitectureMobile Server Customizer and MSCD


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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.


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ArchitectureServer Proxy and WEB page Proxy


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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.


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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

Use Case: Integrating a Mobile Camera


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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


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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


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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 Please, feel free to try them later!later!

http://sensor-proxy.cs.uoi.gr/index_ds.htm

http://apollonium.cs.uoi.gr/CAMERA/mms32/index.htm

http://sensor-proxy.cs.uoi.gr/index_ds.htm

http://apollonium.cs.uoi.gr/CAMERA/mms32/index.htm


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Performance Evaluation

Performance Evaluation to measure:

The overhead introduced by our middleware framework in the case of accessing the GSM Camera.


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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


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Measurements:– preparation time required by the server for

sending the SMS messages to the mobile camera, in fact :

the middleware framework overheadthe middleware framework overhead

– overall response timeoverall response time, from the submission until the reception of results


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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


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• Important overhead of preparationoverhead 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


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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


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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


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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


Thank you

ISSNIP 2005

University of Ioannina, Greece

The Distributed Management of Data Laboratory


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Questions…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

on accessing gsm-enabled mobile sensors

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