Self-IntroductionWho am I ?

Christian 　Hoareauクリスチャン　ワロー

Sokendai (1st-year PhD student)

Prof. Ichiro Satoh

Ubiquitous Computing

Supervisor

Affiliation

Research

Country

Homepage web.mac.com/christianhoareau

Self-IntroductionWho am I ?

Christian 　　Hoareauクリスチャン　ワロー

B.Sc. in CS

2003 2005 2006

System Engineer (IBM)

PhD studentM.Sc. in CSDistributed Systems

Saint-Denis Paris Tokyo

• One of the four overseas départements of France• The outermost region of European Union• Volcanic island• Population : 800, 000+ • ....

Réunionなに？

RéunionJust a glance

Ubiquitous Computing, Location-Awareness andQuery Processing

Christian Hoareau

Ubiquitous Computing

Context and Location-Awareness

Location-Based Services

Query Processing

OverviewPyramidal Presentation

-- Oxford English Dictionnary

ubiquitous |yoōˈbikwətəs|

present, appearing, or found everywhere.

A little of Lexical SemanticsWhat does it mean ?

The computation has become ubiquitous or .... • pervasive• ambient • sentient• everyware• ...

?

1960~1970s 1980~1990s 2000 ~

?

1960~1970s 1980~1990s 2000 ~

one computer for

many people

one computer for

everyone

many computing devices for everyone

size

number

• Embedded processors• smaller, cheaper and faster• lightweight• more energy efficient

• Wireless communications• ad/hoc• low power• high bandwidth

• Storage• bigger and faster

• Sensors

Ubiquitous computingInformation Processing Capabilities

⇒ Context-Awareness

Ubiquitous Computing

Context and Location-Awareness

Location-Based Services

Query Processing

OverviewPyramidal Presentation

ContextSome Definitions

• Location and identity of nearby people and object [Schilit and Theimer, 1994]

• Location, identity, environment and time [Ryan et al., 1994]

• Any information that can be used to characterize the situation of entities [Dey et al., 1996]

• Context encompasses more than just the user’s location, because other things of interest are also mobile and changing. Context includes lighting, noise level, network connectivity, communication costs, communication bandwidth, and even the social situation; e.g., whether you are with your manager or with a co-worker [Schilit, 1998]

• Context Value Chain [Hegering et al., 2003]

Context-Aware Services

Ubiquitous Computing

Context and Location-Awareness

Location-Based Services

Query Processing

OverviewPyramidal Presentation

Location-Based Services (LBS)Overview

... but :• tend to be application-specific• usually rely on centralized, and inadequate, database systems

Prominent applications of Ubiquitous Computing...• Location provides relevant information on users’ context• Numerous location tracking systems now widely available (GPS, RFID-tags, WiFi-based positioning, etc.)• Many application domains (e.g., maps & way finding, tracking, social mobile apps, location-specific content)

[Becker et al. , 2005]• simple position queries, e.g. ”where is the conference room ?”• nearest neighbor queries, e.g. ”where is the closest sushi restaurant ?”• naviguation queries, e.g. ”how to reach the bus terminal ?”• range queries, e.g. ”what are the conbinis located in my neighboorhood ?”

LBSQuery Processing

⇒ Goal : Provide a query framework for LBS, by exploring the connection between decentralized location model and query processing

Query Processing for LBSWhy ?

Query Processing for LBSWhy ?

⇒ Goal : Provide a query framework for indoor LBS, by exploring the connection between decentralized location model and query processing

indoor query processing

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Query Processing for LBSLocation Modeling

Hospital

Floor 1 Roof

Helicopter

Pilot Victim First aider

Elevator Surgery

Nurse

........

PDA-1 PDA-2

.....

place

entity

device

⇒ Query Processing as Dynamic graph search

1. From Model Checking to Query Processing

2. Hybrid Logic-Based Query Language

Query Processing for LBSApproach

Model CheckingComputer-Aided Verification

⇒ Sucessfully applied in both hardware and software verification • Industrial standard tool for hardware design • Communication & security protocols “Bug-Fixer” • ......• Foundations for a location query language ?

[Clarke et al. , 2000]Goal : to verify that a system satisfies its specification by

(1) representing the system as a graph (i.e. Kripke structure)(2) writing the specification in a suitable modal logic formula (3) algorithmically check that the graph is a model of the specification formula

Database

Evaluating Logic Formulas (SQL queries)

↓Finite Structures (Relational Databases)

Model Checking-Based Query LanguageComputer-Aided Verification

Model Checking

Evaluating Logic Formulas (specification)

↓Finite Structures (Kripke structures)

[Negri et al. , 1991]

We propose :(1) Kripke-like Structure, as an extension of the location model itself(2) A Modal Logic-based Query Language

Query Processing for LBSLocation Modeling

Hospital

Floor 1 Roof

Helicopter

Pilot Victim First aider

Elevator Surgery

Nurse

........

PDA-1 PDA-2

.....

place

entity

device

Data ModelHierarchal Space Graph

! PDA-2

! Pilot! Victim! First Aider

! PDA-1

! Nurse

! Elevator! Surgery

! Helicopter

! Floor 1! Roof

Hospital

Floor 1 Roof

Helicopter

Pilot Victim First aider

Elevator Surgery

Nurse

PDA-1 PDA-2

Place

Label

R" transition

R# transition

! child 1

! child n

...

Query ProcessingHybrid Logics

• Nominals : propositional variables that are true at exactly one node in the state graph

• Access operator : it gives random access to a node of the state graph

• Downarrow binder : it creates a brand new name n and assigns it to the current node.

user's location location model

location query

q"here"

q

......

Query languageDefinition

Meaning of a formula = a satisfaction relation connecting the hierarchical graph with the formula.

Context Query

Query languageSemantics

p!x p

x

G, b, hospital |= E!surgery

Query languageExample 1

! PDA-2

! Pilot! Victim! First Aider

! PDA-1

! Nurse

! Elevator! Surgery

! Helicopter

! Floor 1! Roof

Hospital

Floor 1 Roof

Helicopter

Pilot Victim First aider

Elevator Surgery

Nurse

PDA-1 PDA-2

Place

Label

R" transition

R# transition

! child 1

! child n

...

Query languageExample 2

! PDA-2

! Pilot! Victim! First Aider

! PDA-1

! Nurse

! Elevator! Surgery

! Helicopter

! Floor 1! Roof

Hospital

Floor 1 Roof

Helicopter

Pilot Victim First aider

Elevator Surgery

Nurse

PDA-1 PDA-2

Place

Label

R" transition

R# transition

! child 1

! child n

...

ImplementationPrototype Architecture

OCAML Runtime

Interaction Shell

Model

Builder

Query

Parsing

HL Model

Checker

Checkery

Core System

Location

Query

Current Location

Tree Graph

Binders

Context

Query

EvaluationNetworked-Files Tree Structure

ConclusionRoadmap

• Experiments in a real environment (museum)

• From static to dynamic locations

• Security policy• Access control mechanisms• Privacy

• Human-readable query language encapsulation

• GUI for mobile search

[Negri et al. , 1991] M. Negri, G. Pelagatti and L. Sbattella, Formal Semantics of SQL Queries, ACM Trans. on Database Systems, vol.16, no.3, pp.513-534, ACM Press, 1991.

[Clarke et al. , 2000] E. Clarke O. Grumberg, D. Andpeled, Model Checking, MIT Press, 2000.

[Franceschet et al. , 2004] M. Franceschet, A. Montanari and M. de Rijke, Model Checking for Combined Logics with an Application to Mobile Systems, Automated Software Engineering, vol.11, no.3, pp.289-321, Kluwer Academic Publishers, 2004.

[Becker et al. , 2005] M. Bauer, C. Becker and K. Rothermel, Location Models from the Perspective of Context-Aware Applications and Mobile Ad Hoc Networks, Personal and Ubiquitous Computing, vol.6, no.5-6, pp.322-328, Springer-Verlag, 2002.

[Areces et al., 2005] C. Areces and B. ten Cate, Hybrid Logics, Handbook of Modal Logic, P. Blackburn, F. Wolter and J. van Benthem, ed., 2005.

References“Stand on the shoulders of giants”

Questions

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Ubiquitous Computing

Context and Location-Awareness

Location Modeling

Query Processing

OverviewPyramidal Presentation

Thank You !