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Dana Popovici (PhD student), Mikael Desertot (co-adviser), Sylvain Lecomte (adviser)

LAMIHL

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A B O R A T O I R E

D’ UTOMATIQUE

DE ECANIQUE ET

D’ NFORMATIQUE

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E T U M A I N E S

+Plan

!  Introduction !  Circumstances of our work

!  Domain & goal

!  The proposed framework – for transportation applications

!  Context of execution – what is context?

!  Architecture – on top of OSGi

!  VESPA – example of a transportation application

!  Conclusion & perspectives

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+Circumstances of our work

!  Nowadays: important technological advancements !  PDA; Smartphones (with GPS, Wi-Fi, …)

!  Information & services available everywhere

!  Existing applications that make use of such technology !  Location based services (using GPS): itinerary; POI; traffic information; …

!  Cooperation applications between users: guided museum visits; file sharing; …

!  Limits of the applications !  isolated applications – no cooperation between applications

!  lack of flexibility – example: GPS navigation in a tunnel

!  diversity of architectures

! lack of an unified framework to model and manage applications

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+ Domain

!  Transportation applications for mobile devices (Smartphone, tablet, …)

!  Assist users traveling from one place to another

!  GPS navigation + accidents notification + POI + parking + …

!  React to context changes

!  Easy to install and use

City POI

Gas

Shop

accident

Shop

City

What about in a city?

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Highway

accident

ignored ! Gas

Brake !!

What is interesting on the highway?

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+ Constraints & challenges

!  Constraints

!  Limited device resources

!  small screen; little memory; …

!  Need for communication – infrastructure access is not ensured

!  in-car devices (no GSM); area without 3G coverage

!  The user can't manage the device at all time

!  especially drivers

!  Challenges

!  Users are highly mobile & distributed

!  both the user and her/his neighbors move

!  The context evolves

!  city/highway; indoor/outdoor; new neighbor; GPS signal lost;…

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+Scenario of use

!  A driver using an application on the mobile phone

!  navigation + parking place service (with simple broadcast protocol)

!  the underground parking uses a dedicated parking place service

!  the server & a user have the service

!  Problems

1.  how to download a service?

2.  how to choose which one?

3.  how to connect it to the existing application?

!  Currently: not possible

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+ Context-Aware Transportation Services (CATS) Framework

!  A framework on mobile devices (Smartphone, in-car device,…) for transportation specific applications:

1.  Context-Aware: applications react to context changes by reconfiguring or replacing services

2.  Transportation: specific context elements

3.  Services: modular applications built of services

4.  Framework: simultaneous management of the applications

Framework

Service Aa

Application 1

Service Ca

Service Ba

Application 2

Service Da

Service Ea

Ser

vice

Bb

Execution manager

Trader

Context manager

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+CATS Framework

1.   Taking into account the context

2.  Modular architecture

3.  Service research and installation

Framework

Service Aa

Application 1

Service Ca

Service Ba

Application 2

Service Da

Service Ea

Execution manager

Trader

Context manager

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+The context

!  Context is all information that can be used to characterize the situation of an entity [Dey and Abowd, 1999] !  a system is context-aware if it uses context to provide relevant services &

information with respect to the user's task

!  Who uses context and which elements? !  all mobile applications that are in frequently changing environments

!  elements: sensor data (temperature, sound, …); personal context (user's schedule, preferences, …); services available in proximity; etc.

! impossible to model all the context !!

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+Context in transportation

!  Our applications assist users on the move !  Goal: don't stop working & adapt to the context

!  How do we adapt? !  replace services (they don't work / they're not suited)

!  download & install new services

!  What are the domain characteristics? !  high mobility of the users

pedestrians, passengers (bus, train, …), drivers (city, highway)

!  unstable communication network

infrastructure connection loss, changing neighbors

!  need to function in ad-hoc

(example: notification of an accident or emergency breaking)

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+Context elements

Context

DeviceCtx ExecutionCtx EnvironmentCtx UserCtx

Software Hardware Services Data Position Network Use External Time Profile Prefers

!  The device – services may be specific for a device or need certain resources (important at download!)

!  The execution framework – services have dependencies which must be resolved (important at download!)

!  The environment – changes constantly and influences the performance of the services; it determines the reconfiguration or replacement of services

!  The user – can influence the behavior of some services

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+Approach

!  A context element can determine the stopping of a service !  an equivalent service must be found, independent of that element

!  example: positioning with GPS / Wi-Fi

!  Some services are context-dependent !  they need to know the value of an element to configure parameters – example:

traffic event notification on the highway / in the city

!  equivalent services based on the context

!  Context monitoring with a publish & subscribe mechanism for the context elements

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+CATS Framework

1.   Taking into account the context !  Context Manager – takes snapshots of the context elements

2.  Modular architecture

3.  Service research and installation

Framework

Service Aa

Application 1

Service Ca

Service Ba

Application 2

Service Da

Service Ea

Execution manager

Trader

Context manager

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+CATS Framework

1.  Taking into account the context

2.   Modular architecture – service based !  OSGi framework

3.  Service research and installation

Framework

Service Aa

Application 1

Service Ca

Service Ba

Application 2

Service Da

Service Ea

Execution manager

Trader

Context manager

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+Execution Manager

!  Needed for extra functionality on top of OSGi

!  Manages services with respect to the context !  stops services which are no longer conform with the conditions

!  starts an equivalent service which is suited

!  handles the situation when no equivalent is present on the device

!  launches a search for the service on neighboring devices

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+CATS Framework

1.  Taking into account the context

2.  Modular architecture

3.   Service research and installation !  service description; discovery

Framework

Service Aa

Application 1

Service Ca

Service Ba

Application 2

Service Da

Service Ea

Execution manager

Trader

Context manager

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+ Service discovery (in the transportation domain)

!  Infrastructure access is not always available – search near by !  ideally: have a maximum of services on the device (when possible)

!  Constraints: !  download before the devices are too far apart – choose "best" device

!  services should be of small size

service?

too far

too fast ok

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+The Trader

!  Goal: retrieve as fast as possible a suitable service

!  Criteria: !  service functionality – does it do what we want?

!  context dependency – is it suited for the current context of the device?

!  relative movement of the devices – is there enough time to download?

!  Functioning of the Trader [work in progress] !  the device sends a request for a service to neighboring devices

!  the neighbors having an implementation of the service answer

!  the device chooses the "best" service

!  the device downloads & installs the service

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+So… the CATS framework

!  is based on OSGi – allows to install & deploy services on the fly

!  has bundles to manage the framework and the applications !  Context Manager; Execution Manager; Trader

!  uses equivalent services based on context situations and encourages a maximum of local services !  3G/Internet is not always available

! Which applications run on CATS ?

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+ VESPA !  uses V2V communication to share information about events on the road

!  information dissemination => dissemination protocol

!  estimation of event relevancy => based on GPS coordinates

!  user notification => information display on screen

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+ VESPA on CATS !  Several map services (for event notification):

!  no map – display distance & direction to the event

!  google – needs 3G or Internet

!  local – simplified map to download (example: user made map of a village)

!  Several parking place protocols: !  dissemination – risk of competition

!  reservation protocol – increased number of messages

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Framework

EP

VESPA

Positioning

Dissemination

Application 2

Service Da

Service Ea

Execution manager

Trader

Context manager

+ Evaluations – service exchange

!  Prototype on Android 2.2 with Felix 3.0.3

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!  Comparison between HTC Hero and Samsung Galaxy

!  complete change

!  download

!  Download time with respect to

!  distance

!  file size

+Conclusion

!  Despite the large amount of research in the domain of mobile applications, few works consider the creation of a dynamic framework with services installed on the fly

!  Our goal is to propose a framework suitable for the transportation domain, hosting flexible applications !  easy context adaptation through services exchange

!  continuous functioning in all environments, with minimal user intervention

!  The OSGi framework enables us to achieve these goals

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+Work in progress & future work

!  The evaluations were done on devices with very limited mobility !  the influence of mobility must be evaluated further

!  The distributed trader is not finalized !  a query language must be developed, to allow a fine description of the

needed service based on context elements

!  Improvement of the service reconfiguration for a better adaptation to the context changes

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+ LAMIHL

A

M

I

H

A B O R A T O I R E

D’ UTOMATIQUE

DE ECANIQUE ET

D’ NFORMATIQUE

INDUSTRIELLES

E T U M A I N E S

Merci pour votre attention!

Dana Popovici (doctorante), Mikael Desertot (encadrant), Sylvain Lecomte (directeur de thèse)