context aware paradigm for pervasive computing environment

November 18th, 2006November 18th, 2006 CAPP by Umar MahmudCAPP by Umar Mahmud 11


Context-Aware Paradigm for Pervasive Computing Environment (CAPP)

Context-Aware Smart Service Discovery in Pervasive Context-Aware Smart Service Discovery in Pervasive EnvironmentsEnvironments


GEC Members

Dr. Farrukh Kamran, CASE IslamabadDr. Farrukh Kamran, CASE Islamabad Dr. Muhammad Akbar, CI(E Div), MCSDr. Muhammad Akbar, CI(E Div), MCS Dr. Amir Qayyum, CASE IslamabadDr. Amir Qayyum, CASE Islamabad Lt. Col Naveed Sarfraz, HoD, CS Dept, MCSLt. Col Naveed Sarfraz, HoD, CS Dept, MCS


Sequence of Presentation IntroductionIntroduction System DesignSystem Design

Context CongregatorContext Congregator Context InterpreterContext Interpreter Decision Making ModuleDecision Making Module

Evaluation & AnalysisEvaluation & Analysis EpitomeEpitome


Introduction


Pervasive Environment Pervasive computing is a term for the strongly Pervasive computing is a term for the strongly

emerging trend towardsemerging trend towards Numerous, casually accessible, often invisible Numerous, casually accessible, often invisible

computing devicescomputing devices Frequently mobile or embedded in the environmentFrequently mobile or embedded in the environment Connected to an increasingly ubiquitous network Connected to an increasingly ubiquitous network

infrastructure composed of a wired core and wireless infrastructure composed of a wired core and wireless edgesedges

Examples Examples HospitalsHospitals AirportsAirports Educational InstitutesEducational Institutes


Issues in Pervasive Computing

Context-AwarenessContext-Awareness Trust, Security and PrivacyTrust, Security and Privacy Seamless CommunicationSeamless Communication Low Powered DevicesLow Powered Devices Self ConfigurationSelf Configuration Information OverloadInformation Overload Social IssuesSocial Issues Business ModelsBusiness Models


Problem Statement

Smart service discovery & its subsequent Smart service discovery & its subsequent delivery to the mobile users by interpreting delivery to the mobile users by interpreting the users’ as well as the services’ contextthe users’ as well as the services’ context Interpretation of the contextual information Interpretation of the contextual information Resource arbitrationResource arbitration

Delivery of the best service available, among a pool of Delivery of the best service available, among a pool of similar services, to the usersimilar services, to the user


Context-Awareness

First coined by Schilit in 1994First coined by Schilit in 1994 Refers to the devices that have information about Refers to the devices that have information about

the circumstances under which they operate and can the circumstances under which they operate and can react accordinglyreact accordingly

““Context is any information that can be used to Context is any information that can be used to characterize the situation of an entity. An entity is characterize the situation of an entity. An entity is

a person, place, or object that is considered a person, place, or object that is considered relevant to the interaction between a user and an relevant to the interaction between a user and an application, including the user and applications application, including the user and applications

themselves.” themselves.”

-- Anind Key Dev, GA Tech-- Anind Key Dev, GA Tech


Feature Comparison of Existing Systems

Rich Rich ContextContext

Decentralized Decentralized ArchitectureArchitecture

OWL based OWL based OntologyOntology

Resource Resource DiscoveryDiscovery

Reasoning Reasoning SupportSupport

Active Badge (1992)Active Badge (1992)

Xerox PARC(1992)Xerox PARC(1992)

Classroom & GUIDEClassroom & GUIDE

Context Toolkit(1999)Context Toolkit(1999)

TEATEA

CAPEUSCAPEUS

GAIA OS (2002)GAIA OS (2002)

CMF (2003)CMF (2003)

CoBrA (2003)CoBrA (2003)

Hydrogen (2002)Hydrogen (2002)

SOCAM (2004)SOCAM (2004)

CASS (2004)CASS (2004)

CAMUS (2005)CAMUS (2005)


Limitations of Present Systems

Early context aware systems were only Early context aware systems were only location basedlocation based Need of a comprehensive and rich context data Need of a comprehensive and rich context data

representation representation OWL based ontologyOWL based ontology

Existing context-aware systems are problem Existing context-aware systems are problem specific specific Context-aware applicationsContext-aware applications Custom reasoning enginesCustom reasoning engines


Research Objectives

Design of a Context-Aware SystemDesign of a Context-Aware System Organization of contextual informationOrganization of contextual information Representation of the contextual informationRepresentation of the contextual information Interpretation of the contextual informationInterpretation of the contextual information Best service selection for the userBest service selection for the user


System Design


Architectural Foundation Design Principles of Distributed SystemsDesign Principles of Distributed Systems

Service-Oriented Architecture (SOA)Service-Oriented Architecture (SOA)

Context AcquisitionContext Acquisition Context Server ApproachContext Server Approach

Context ManagementContext Management Networked Services ApproachNetworked Services Approach

Context RepresentationContext Representation Ontology Based Models Ontology Based Models

OWL (Web Ontology Language)OWL (Web Ontology Language)


Design of CAPP

CAPP

DispatcherModule

Context CongregatorModule

ContextInterpreter

ModuleRepresentation Rules

Decision MakerModule

User ID,User Request

BestService

GatheredContext

InterpretedContext

User ID,User Request

Session Manager

BestService

User


Design of CAPP (contd.)DispatcherModule

Function Receives request and dispatches it to the context congregator module. Returns the result to the requester

Description This module listens to incoming requests and forwards them to the congregator for context gathering.

ContextCongregator

Function Gather context data on the basis of client’s info and request and represent the gathered information in the form enforced by the rule Repository

Description This module gathers context data.

ContextInterpreter

Function To interpret the gathered context as Who, What, When & Where contexts of both the user and the services

Description This module interprets the gathered context by and identifying Who, What, Where & When contexts

Decision MakingModule

Function Makes decision on which service is to be delivered to the client on the basis of interpreted context and weighted averages of the interpreted contexts

Description Receives interpreted context and decides as which is the best available service that should be delivered to the client or returns a list of probable services to the client


Context Congregator


Context Space in CAPP

Context

User Context Service Context

SpatialInformation

(Location,orientation, speed,

direction)

TemporalInformation(Time, date)

AdvancedInformation

(Mood, gesture,feelings, user

device state, role)

EnvironmentalInformation(Temperature,

humidity, light,noise)

CommunityInformation

(Peers information)

ActivityInformation

(state)

AdvancedInformation(Availability,battery power,

bandwidth)


(Nearby services )

ActivityInformation(Status, load)

Spatial Information(Location,

orientation, speed,direction)

TemporalInformation

(Time, date, season)

EnvironmentalInformation(Temperature,

humidity, light,noise)

Identification(User ID, name)

Identification(Service name, ID

type)

HealthInformation

(BP, sugar level,temperature)


Representation Scheme in CAPP

OWL (Web Ontology Language)OWL (Web Ontology Language) OWL Full for rich context representationOWL Full for rich context representation

Controlled VocabularyControlled Vocabulary Set of keywords or phrases that are used to tag units of Set of keywords or phrases that are used to tag units of

information for smart and efficient retrieval by a searchinformation for smart and efficient retrieval by a search Services may have names or aliases Services may have names or aliases For example, a user asking for a For example, a user asking for a temperature servicetemperature service

could be replied by locating a could be replied by locating a weather serviceweather service that is that is registered with the systemregistered with the system


Vital Context

It is inefficient to gather all the data at all times or It is inefficient to gather all the data at all times or when a user has requested for an interactionwhen a user has requested for an interaction Some of the data is necessary for a particular interaction Some of the data is necessary for a particular interaction

while the rest has no effect on the interactionwhile the rest has no effect on the interaction Gather only data that is critical to the interactionGather only data that is critical to the interaction

A list of necessary data for each type of interaction has A list of necessary data for each type of interaction has been identified and is maintained in the context been identified and is maintained in the context congregator congregator


Context Interpretation


Context Processing

Context Congregation

Context Interpretation

Raw, Low-Level Context

Interpreted, High-Level Context

(Data from Sensor Services)

(To The Decision Making Module)

Context Processing


High-Level View of ContextContext

User Context Service Context

Spatial Information

TemporalInformation

AdvancedInformation

EnvironmentalInformation


Activity Information

AdvancedInformation


ActivityInformation

Spatial Information

TemporalInformation

EnvironmentalInformation

Identification Identification

High-Level View of Context

Low-Level View of Context


Interpretation in CAPP Categorization of contextual dataCategorization of contextual data The high-level context identifies the ‘The high-level context identifies the ‘Who’, ‘What’, Who’, ‘What’,

‘Where’ ‘Where’ and ‘and ‘When’ When’ contexts of both the users’ as contexts of both the users’ as well as the services’well as the services’ ‘‘Who’ - identification and description parameters Who’ - identification and description parameters ‘‘What’ - user’s request and the services’ capabilitiesWhat’ - user’s request and the services’ capabilities ‘‘Where’ - the location and environmental parameters Where’ - the location and environmental parameters ‘‘When’ - time of request and time of deliveryWhen’ - time of request and time of delivery


Interpretation in CAPP (contd.) High-Level User ContextHigh-Level User Context

Deduced WhoDeduced Who Deduced WhenDeduced When Deduced WhereDeduced Where Deduced Health Deduced Health

High-Level Service ContextHigh-Level Service Context Deduced WhoDeduced Who Deduced WhatDeduced What Deduced WhenDeduced When Deduced WhereDeduced Where


Deduced Who (User)

STARTID, Role,

Name, Alias,SSN

IFRole != NULL

No

User Activity,Peers Activity,User Location,

UserOrientation

Deduce useractivity on thebasis of userlocation andorientation

IFUser Activity == Peers Activity

THENUser Role = Peers Role

Yes

Yes

No

Deduced Who(User ID, User Role)

Get Role fromUser

End


Deduced When (User)

IFUser State == Device (s) State

&&User State == active

Deduced Activity

Yes

No

User isengaged

User isnot engaged

START

User time, time ofday, date,

user activity,device state

IFUser Time != NULL

&&User Date != NULL

Yes

Deduced Time

End

Get time ofrequest

No

Deduced When(User Time, User Activity)


Deduced Where (User)

START

User Location, mobility,direction, speed,

orientation, surroundinginformation

End

IFUser Mobility == False

Deduced Location

Deduce expectedlocation on basis

of direction, speedand orientation

Deduced Where(User Location)

No

Yes

IFUser Location != NULL

YesDeduce userlocation on basis

of usersurroundinginformation

No


Deduced Health (User)START

Usertemperature,

bloodpressure,

pulse, sugarlevel

IFUser Temperature != Normal Temperature

||User Blood Pressure != Normal Blood Pressure

||User Pulse != Normal Pulse

||User Sugar Level != Normal

Yes

Deduced Health

End

No

User isnot normal

User isnormal


Interpreted User Context

““User User Deduced User (User) Deduced User (User) has requested a has requested a Deduced Deduced What (User)What (User) service at service at Deduced When (User)Deduced When (User) time. The time. The

user wants the service to be delivered at user wants the service to be delivered at Deduced Deduced Location (User)Location (User) while he/she is involved in activity while he/she is involved in activity Deduced Activity (User) Deduced Activity (User) and has health condition and has health condition

Deduced Health (User)”Deduced Health (User)”


Deduced Who (Service)Start

Service ID,name, alias,

owner

IFService ID != NULL

Deduce service IDon basis of name,alias and owner

information

Deduced Who(Service ID, Service

Name)

Yes

No

End


Deduced What (Service)

Start

Service type,methods names,

port, address,namespace

IFService Type != NULL

Deduce servicetype on basis of

service description

Deduced What(Primary Service Type,

Secondary ServiceType)

Yes

No

End


Deduced When (Service)Start

Service time, date, time of day,season of year, queue length,queue space, availability time,

network situation, state

IFService Activity != Offline

Inform user ofunavailability of the

service

Deduced When(Service Availability Time)

Yes

No

End

IFService Activity != Idle

Deduce availability timeon basis of load and

network situation

No

Yes

Deduce service time on basisof time, date, time of day and

season of year

Service isinactive

Service isreadily available


Deduced Where (Service)Start

Service location, mobility,speed, direction,

surrounding information

IFService Location != NULL

Deduce servicelocation on basis ofservice surrounding

information

Deduced Where(Service Location)

Yes

No

End

IFService Mobility != False

Deduce expectedlocation on basis of

speed and direction ofthe service

No

Yes


Interpreted Service Context

““Service Service Deduced Service (Service)Deduced Service (Service) is of type is of type Deduced What (Service)Deduced What (Service). The service is located . The service is located

at location at location Deduced Where (Service)Deduced Where (Service) and will and will be available at time be available at time Deduced When (Service)”Deduced When (Service)”


Decision Making Module


Which Service

Decision Making Module

User Context

Service Context 2

Service Context 1

Service Context N

Service Context J

User Context

Output

Inputs

BestAssociation

WHICH


Which Service (contd.) Deduced What (User) vs. Deduced What (Service)Deduced What (User) vs. Deduced What (Service)

Primary type of the service or the secondary type of the Primary type of the service or the secondary type of the serviceservice

Deduced When (User) vs. Deduced When (Service)Deduced When (User) vs. Deduced When (Service) Service that will be available the earliest to the service Service that will be available the earliest to the service

that will be delivered at the latestthat will be delivered at the latest Deduced Where (User) vs. Deduced Where (Service)Deduced Where (User) vs. Deduced Where (Service)

Services starting from the nearest to the farthest service Services starting from the nearest to the farthest service

Deduced Health (User)Deduced Health (User) The user health imposes restrictions on the selection of The user health imposes restrictions on the selection of

the servicethe service


Which Service (contd.) The final selection process selects the best The final selection process selects the best

service for the user service for the user weighted average scheme of weighted average scheme of What, Where, When What, Where, When and and

Health Health Values for any scenario is calculated as Values for any scenario is calculated as

eHealthValusWhenValuer

WhereValueqWhatValuepServiceNWA

Where p, q, r and s are the weights


Decision ProcessStart

InterpretedUser &Service

Contexts

Deduced What (User)compared with

Deduced What (Service)

Deduced Where (User)compared with

Deduced Where (Service)

Deduced When (User)compared with

Deduced When (Service)

Calculate Weighted Averageof each service

IFNumber of Selected Service != 1

AppropriateService

No

Send ShortList to the User

Yes

End

Manually selectedservice by user


Evaluation & Analysis


Evaluation Criteria

Java based simulationJava based simulation Implementation of the flow models in interpretation and Implementation of the flow models in interpretation and

decision makingdecision making Test cases from everyday interaction in CS departmentTest cases from everyday interaction in CS department

Effectiveness of the CAPPEffectiveness of the CAPP Successful if it is able to return a single service or a short Successful if it is able to return a single service or a short

list of probable services to the user for a scenariolist of probable services to the user for a scenario Failure if it is unable to reach a conclusion either by Failure if it is unable to reach a conclusion either by

returning a single service or a short list of probable returning a single service or a short list of probable services and returns list of all servicesservices and returns list of all services

For the case when the user requests a service that is not For the case when the user requests a service that is not listed in the smart space, informing the user that the listed in the smart space, informing the user that the service is not listed is also termed as a successservice is not listed is also termed as a success

Successes should be at least 75% of the total number of Successes should be at least 75% of the total number of casescases


Assumptions Each service type has at most and at least three Each service type has at most and at least three

services and each user has at most and at least three services and each user has at most and at least three devices (mobile or traditional)devices (mobile or traditional)

The contextual data is always available to the system The contextual data is always available to the system and no ambiguous data is provided by the sensor and no ambiguous data is provided by the sensor servicesservices

Values assigned to priority levels are Values assigned to priority levels are High = 0.9High = 0.9 Medium = 0.5Medium = 0.5 Low = 0.1Low = 0.1


Test Case 1 Ayesha a student of BE is sitting in BELAB and requests a Print Ayesha a student of BE is sitting in BELAB and requests a Print

serviceservice There are three print services in the department, one in MSLAB and two There are three print services in the department, one in MSLAB and two

in BELABin BELAB One of the services in BELAB is a Fax service that provides prints as a One of the services in BELAB is a Fax service that provides prints as a

secondary capabilitysecondary capability Ayesha’s health condition is Normal and has No health constraintsAyesha’s health condition is Normal and has No health constraints

3

A

AAA WhenValuer

ValueWhereqValueWhatpW

3

B

BBB WhenValuer


3

C

CCC WhenValuer


1,1,1 rqp


Test Case 1 - Vital ContextUser Context Service Contexts

Attribute Ayesha Attribute Service A Service B Service C

Role Student Queue length 65 60 50

Devices 3 Space avail 64 67 44

Type PDA, smart phone, PC

Status Busy Busy Busy

Status Active, Idle, Idle

Bandwidth 100 Mbps 100 Mbps 100 Mbps

Activity of user Busy Availability time 25 minutes 10 minutes 18 minutes

Illumination Bright Illumination Bright Bright Bright

Dust level Normal Dust level Normal Normal Normal

Temperature 16 C Temperature 16 C 16 C 16 C

Humidity Normal Humidity Normal Normal Normal

Noise Normal Noise High High High

Sistolic 80 Air quality Fit Fit Fit

Di Sistolic 110 Owner Admin Admin Admin

Pulse 71 Primary type Fax Print Print

User temp 38.2 C Secondary type Print NULL NULL

Sugar level Normal ID PRFAXBE PRINTBE02 PRINTMS


Test Case 1 - Vital Context (contd.) User Context Service Contexts

Attribute Ayesha Attribute Service A Service B Service C

ID AYESHA_BE_08_37

Name PRINTFAX PRINTBE PRINTCS

SSN 37405-0521200-6

Alias BEPRINTANDFAX NULL NULL

Name Ayesha Ahmad

IP 192.168.13.33 192.168.13.181

192.168.13.201

Alias NULL Namespace //belab023//prfaxbe //belab075//printbe02

//mslab017//printms

Orientation Sitting Port 8080 8080 8080

Mobility False Location BELAB BELAB MSLAB

Direction NULL Mobility False False False

Speed 0 Direction NULL NULL NULL

Location BELAB Speed 0 0 0

Date 18 June, 2006

Date 18 June, 2006 18 June, 2006 18 June, 2006

Time 1130 hrs Time 1130 hrs 1130 hrs 1130 hrs


Test Case 1- Results

What Value Where Value When Value Weighted Average

Service A 0.1 0.9 0.9 0.63

Service B 0.9 0.9 0.9 0.9

Service C 0.9 0.1 0.5 0.5

0

0.2

0.4

0.6

0.8

1

Valu

es

Service A Service B Service C

Services

First Scenario: Ayesha Requests a Print Service

What Value

Where Value

When Value

Weighted Average


Test Case 1 - Output


Test Case 2 Kashif a student of BE is sitting in MSLAB and requests a Scan Kashif a student of BE is sitting in MSLAB and requests a Scan

serviceservice There are three print services in the department, two are in MSLAB and There are three print services in the department, two are in MSLAB and

one is in BELABone is in BELAB Kashif’s health condition is Not Normal and has Fever as his health Kashif’s health condition is Not Normal and has Fever as his health

constraintconstraint

4

AA

AAA eHealthValusWhenValuer


4

BB

BBB eHealthValusWhenValuer


4

BC

CCC eHealthValusWhenValuer


5.1,5.0,5.0,5.0 srqp


Test Case 2 – Vital ContextUser Context Service Contexts

Attribute Kashif Attribute Service A Service B Service C

Role Student Queue length 0 0 0


Type PC, PDA, Laptop

Status Idle Idle Idle

Status Active, Active, Active

Power supply A.C. A.C. A.C.

Activity of user Busy Availability time 0 minutes 0 minutes 0 minutes

Illumination Bright Illumination Bright Bright Normal

Dust level Normal Dust level Normal Normal Normal

Temperature 25 C Temperature 25 C 16 C 16 C

Humidity Normal Humidity Normal Normal Normal

Noise Normal Noise Normal Normal Normal

Sistolic 82 Air quality Fit Fit Fit

Di Sistolic 120 Owner Admin Admin Admin

Pulse 71 Primary type Scan Scan Scan

User temp 102 F Secondary type NULL NULL NULL

Sugar level Normal ID SCANBE SCANMS SCANMS2


Test Case 2 – Vital Context (contd.)

User Context Service Contexts

Attribute Kashif Attribute Service A Service B Service C

ID KASH_BE_05_199

Name BESCAN MSSCAN MSSCAN2

SSN 37405-126524-9 Alias NULL NULL NULL

Name Kashif Farooq IP 192.168.13.26 192.168.13.125 192.168.13.129

Orientation Standing Namespace

//belab024//scanbe

//mslab096//scanms

//mslab065//scanms2

Location MSLAB Location BELAB MSLAB MSLAB

Date 28 July, 2006 Date 28 July, 2006 28 July, 2006 28 July, 2006

Time 1215 hrs Time 1215hrs 1215hrs 1215 hrs


Test Case 2 - ResultsWhat Value

Where Value

When Value

Health Value

Weighted Average

Service A 0.9 0.1 0.9 0.9 0.575

Service B 0.9 0.9 0.9 0.1 0.375

Service C 0.9 0.9 0.9 0.1 0.375

00.10.20.30.40.50.60.70.80.9

Valu

es


Services

Second Scenario: Kashif Requests a Scan Service

What Values

Where Values

When Values

Health values

Weighted Average


Test Case 3 Waqas a faculty member of CS Department is sitting in faculty Waqas a faculty member of CS Department is sitting in faculty

offices and requests for a Multimedia Projector serviceoffices and requests for a Multimedia Projector service There are three projector services in the department, one in There are three projector services in the department, one in

LECTUREHALL01, one in LECTUREHALL02 and one in MSLABLECTUREHALL01, one in LECTUREHALL02 and one in MSLAB Waqas’s health condition is Normal and has No health constraintsWaqas’s health condition is Normal and has No health constraints

3 AAAA WhenValuerValueWhereqValueWhatpW

3 BBBB WhenValuerValueWhereqValueWhatpW

3 CCCC WhenValuerValueWhereqValueWhatpW

1,1,1 rqp



Attribute Waqas Attribute Service A Service B Service C

Role Faculty Queue length 1 0 0


Type PC, phone, laptop

Status Busy Idle Idle

Status Idle, Active, Active

Availability time

50 minutes 0 minutes 0 minutes

Activity of user Busy Primary type Multimedia Projector

Multimedia Projector

Multimedia Projector

ID WAQ_FAC_CS_23

Secondary type

NULL NULL NULL

SSN 37405-053320-8

ID ML1 ML2 MMSLAB

Name Waqas Arshad

Name MULTIMEDIALECHALL1

MULTIMEDIALECHALL2

MULTIMEDIAMSLAB

Alias Viky Alias NULL NULL NULL

Orientation Sitting IP NULL NULL NULL

Location Faculty office Location LECHALL01 LECHALL02 MSLAB

Date July 28, 2006 Date July 28, 2006 July 28, 2006 July 28, 2006



Test Case 3 - Results

What Value Where Value When Value Weighted Average

Service A 0.9 0.1 0.1 0.366666667

Service B 0.9 0.1 0.9 0.633333333

Service C 0.9 0.1 0.9 0.633333333

00.10.20.30.40.50.60.70.80.9

Va

lue

s


Services

Third Scenario: Waqas Requests a Projector Service

What Values

Where Values

When Values

Weighted Average


Test Case 4 Maryam a faculty member is standing in the Hallway of CS Maryam a faculty member is standing in the Hallway of CS

department and requests a Telephone service as she wants to department and requests a Telephone service as she wants to make a phone callmake a phone call Maryam being new to the CS department requires the system to select Maryam being new to the CS department requires the system to select

a telephone service for hera telephone service for her There are three telephone services in the department, one is in MSLAB, There are three telephone services in the department, one is in MSLAB,

one is in BELAB and one is in the faculty officeone is in BELAB and one is in the faculty office Maryam’s health condition is Normal and has No health constraintMaryam’s health condition is Normal and has No health constraint

3 AAAA WhenValuerValueWhereqValueWhatpW

3 BBBB WhenValuerValueWhereqValueWhatpW

3 CCCC WhenValuerValueWhereqValueWhatpW

1,1,1 rqp



Attribute Maryam Attribute Service A Service B Service C

Role Faculty Status Idle Idle Idle

Devices 3 Power supply A.C. A.C. A.C.

Type PDA, PDA, Laptop

Availability time 0 minutes 0 minutes 0 minutes

Status Idle, Idle, Idle

Owner Admin Admin Admin

Activity of user Idle Primary type Telephone Telephone Telephone

ID MARY_FAC_EE_057

Secondary type NULL NULL NULL

SSN 37405-056204-7

ID TELMS TELBE TELFAC

Name Maryam Ayaz

Name MSLABTELEPHONE

BELABTELEPHONE

FACULTYTELEPHONE

Orientation Standing Location MSLAB BELAB FACULTYOFFICE

Date 29 July, 2006

Date 29 July, 2006

29 July, 2006 29 July, 2006



Test Case 4 - Results

What ValueWhat Value Where ValueWhere Value When ValueWhen Value Weighted AverageWeighted Average

Service AService A 0.90.9 0.10.1 0.90.9 0.6333333330.633333333

Service BService B 0.90.9 0.10.1 0.90.9 0.6333333330.633333333

Service CService C 0.90.9 0.10.1 0.90.9 0.6333333330.633333333

0

0.2

0.4

0.6

0.8

1

Va

lue

s


Services

Fourth Scenario: Maryam Requests a Telephone Service

What Values

Where Values

When Values

Weighted Averge


Performance Success rate Success rate

In the scenarios there were three successes and one In the scenarios there were three successes and one failurefailure

Only cases where there are no health constraints and Only cases where there are no health constraints and the weights are set to 1, are consideredthe weights are set to 1, are considered

The total number of values where there are three The total number of values where there are three services and each service can have the same three services and each service can have the same three values where ‘A’ is the all possible combination when ‘V’ values where ‘A’ is the all possible combination when ‘V’ is the value levels for ‘N’ number of services is given asis the value levels for ‘N’ number of services is given as

27

33

A

A

VA N


Performance (contd.)Service A Service B Service C Outcome

1 0.9 0.9 0.9 A B C

2 0.9 0.9 0.5 A B

3 0.9 0.9 0.1 A B

4 0.9 0.5 0.9 A C

5 0.9 0.5 0.5 A

6 0.9 0.5 0.1 A

7 0.9 0.1 0.9 A C

8 0.9 0.1 0.5 A

9 0.9 0.1 0.1 A

10 0.5 0.9 0.9 B C

11 0.5 0.9 0.5 B

12 0.5 0.9 0.1 B

13 0.5 0.5 0.9 C

14 0.5 0.5 0.5 A B C

15 0.5 0.5 0.1 A B

16 0.5 0.1 0.9 C

17 0.5 0.1 0.5 A C

18 0.5 0.1 0.1 A

19 0.1 0.9 0.9 B C

20 0.1 0.9 0.5 B

21 0.1 0.9 0.1 B

22 0.1 0.5 0.9 C

23 0.1 0.5 0.5 B C

24 0.1 0.5 0.1 B

25 0.1 0.1 0.9 C

26 0.1 0.1 0.5 C

27 0.1 0.1 0.1 A B C


Performance (contd.) There are 3 failures out of a total 27 possible There are 3 failures out of a total 27 possible

combinationscombinations 15 cases resulted in selection of single service while 9 cases 15 cases resulted in selection of single service while 9 cases

provided a short list of the probable servicesprovided a short list of the probable services

The success rate, where ‘F’ is the failure rate when ‘f’ is The success rate, where ‘F’ is the failure rate when ‘f’ is the number of failures among ‘A’ possible combinations the number of failures among ‘A’ possible combinations and ‘S’ is the success rate is given asand ‘S’ is the success rate is given as

%89889.0

111.027

3

S

F

F

AfF


Epitome


Limitations of CAPP

Availability of the context sensing devices or the Availability of the context sensing devices or the sensor servicessensor services

The data generated by the devices is very large The data generated by the devices is very large History provides predicted contextual data to the systemHistory provides predicted contextual data to the system

SecuritySecurity The confidentiality can be provided by encrypting and The confidentiality can be provided by encrypting and

then storing the datathen storing the data Gathering data only from the trusted sensor services Gathering data only from the trusted sensor services

present in the environmentpresent in the environment


Advantages

ModularityModularity ScalabilityScalability Service orientationService orientation Incorporating multiple sensor sourcesIncorporating multiple sensor sources Industry standardsIndustry standards Support to asynchronous as well as synchronous callsSupport to asynchronous as well as synchronous calls AtomicityAtomicity HeterogeneityHeterogeneity TransparencyTransparency


Conclusion Context-Aware Systems Context-Aware Systems

Context AcquisitionContext Acquisition Context Representation Context Representation Context InterpretationContext Interpretation Decision Making Decision Making

CAPP is a service oriented framework that provides CAPP is a service oriented framework that provides context-aware smart service discovery and deliverycontext-aware smart service discovery and delivery Robust, scalable & modularRobust, scalable & modular Loose coupling Loose coupling conforms to the object-oriented features of encapsulation conforms to the object-oriented features of encapsulation

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Latest References T.P. Moran and P. Dourish, “Context-Aware Computing,” T.P. Moran and P. Dourish, “Context-Aware Computing,”

Special Issue of Human-Computer Interaction,Special Issue of Human-Computer Interaction, vol. 16, 2001 vol. 16, 2001 A.K. Dey, “Understanding and Using Context”, A.K. Dey, “Understanding and Using Context”, Personal and Personal and

Ubiquitous ComputingUbiquitous Computing, Vol. 5, Issue 1, pp. 4 – 7, 2001., Vol. 5, Issue 1, pp. 4 – 7, 2001. M. Baldauf, S. Dustdar, and F. Rosenberg, “A Survey on M. Baldauf, S. Dustdar, and F. Rosenberg, “A Survey on

Context-Aware Systems,” Context-Aware Systems,” International Journal of Ad Hoc International Journal of Ad Hoc and Ubiquitous Computing, and Ubiquitous Computing, 2004.2004.

T. Strang, and C. Linnhoff-Popien, “A Context Modeling T. Strang, and C. Linnhoff-Popien, “A Context Modeling Survey,” Survey,” First International Workshop on Advanced Context First International Workshop on Advanced Context Modeling, Reasoning & Management,Modeling, Reasoning & Management, 2004. 2004.

T. Strang, and C. Linnhoff-Popien, “A Context Modeling T. Strang, and C. Linnhoff-Popien, “A Context Modeling Survey,” Survey,” First International Workshop on Advanced Context First International Workshop on Advanced Context Modeling, Reasoning & Management,Modeling, Reasoning & Management, 2004. 2004.

M. Riaz, S.L. Kiani, S. Lee, S. Han and Y. Lee, “Service M. Riaz, S.L. Kiani, S. Lee, S. Han and Y. Lee, “Service Delivery in Context Aware Environments: Lookup and Delivery in Context Aware Environments: Lookup and Access Control Issues,” in Access Control Issues,” in proceedings of RTSCA’05,proceedings of RTSCA’05, 2005. 2005.


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context aware paradigm for pervasive computing environment

Education

gathered context

lowlevel context

vital context

context space

context congregatormodule

contextaware paradigm

highlevel view of context

gathered information