Self-Introduction Who am I ?
Country Affiliation
Sokendai (1st-year PhD student)
Supervisor
Prof. Ichiro Satoh
Research
Ubiquitous Computing
Homepage
web.mac.com/christianhoareau
クリスチャン ワロー
Christian Hoareau
Self-Introduction Who am I ?
クリスチャン ワロー
Christian Hoareau Paris
Saint-Denis
2006
2005
2003 B.Sc. in CS
Tokyo
M.Sc. in CS Distributed Systems
System Engineer (IBM)
PhD student
Réunion なに?
• One of the four overseas départements of France • The outermost region of European Union • Volcanic island • Population : 800, 000+ • ....
Réunion Just a glance
Ubiquitous Computing, Location-Awareness and Query Processing Christian Hoareau
Overview
Pyramidal Presentation
Query Processing Location-Based Services Context and Location-Awareness Ubiquitous Computing
A little of Lexical Semantics What does it mean ?
ubiquitous ¦yoō bikwətəs¦ present, appearing, or found everywhere. -- Oxford English Dictionnary
The computation has become ubiquitous or .... • pervasive • ambient • sentient • everyware • ...
?
1960~1970s
1980~1990s
2000 ~
size
one computer for many people
one computer for everyone many computing devices for everyone
?
number 1960~1970s
1980~1990s
2000 ~
Ubiquitous computing
Information Processing Capabilities
• Embedded processors • smaller, cheaper and faster • lightweight • more energy efficient • Wireless communications • ad/hoc • low power • high bandwidth • Storage • bigger and faster • Sensors
Context-Awareness
Overview
Pyramidal Presentation
Query Processing Location-Based Services Context and Location-Awareness Ubiquitous Computing
Context Some 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 coworker [Schilit, 1998]
Context-Aware Services • Context Value Chain [Hegering et al., 2003]
Overview
Pyramidal Presentation
Query Processing Location-Based Services Context and Location-Awareness Ubiquitous Computing
Location-Based Services (LBS) Overview 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) ... but : • tend to be application-specific • usually rely on centralized, and inadequate, database systems
LBS Query Processing [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 ?”
Goal : Provide a query framework for LBS, by exploring the connection between decentralized location model and query processing
Query Processing for LBS Why ?
Query Processing for LBS Why ?
indoor query processing
? Goal : Provide a query framework for indoor LBS, by exploring the connection between decentralized location model and query processing
Query Processing for LBS Location Modeling
Hospital
place entity
Floor 1
Elevator
Nurse
PDA-1
.....
........
Surgery
Roof
device
Helicopter Pilot
Victim
First aider
PDA-2
Query Processing as Dynamic graph search
Query Processing for LBS Approach
1. From Model Checking to Query Processing 2. Hybrid Logic-Based Query Language
Model Checking
Computer-Aided Verification [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
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 ?
Model Checking-Based Query Language Computer-Aided Verification
Model Checking
Database
Evaluating Logic Formulas (specification)
Evaluating Logic Formulas (SQL queries)
Finite Structures (Kripke structures)
Finite Structures (Relational Databases) [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 LBS Location Modeling
Hospital
place entity
Floor 1
Elevator
Nurse
PDA-1
.....
........
Surgery
Roof
device
Helicopter Pilot
Victim
First aider
PDA-2
Data Model Hierarchal Space Graph
Hospital
Place
Floor 1
Roof
! Nurse
Elevator
! child 1
! Helicopter
...
! Elevator ! Surgery
! Floor 1 ! Roof
Surgery
Helicopter
! child n ! Pilot ! Victim ! First Aider
R# transition R" transition
! PDA-2
! PDA-1
Nurse
PDA-1
Pilot
Victim
Label
First aider
PDA-2
Query Processing Hybrid 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. q location query q
user's location
...... "here"
location model
Query language Definition
Context
Query
Meaning of a formula = a satisfaction relation connecting the hierarchical graph with the formula.
Query language Semantics
!x
p
p x
Query language Example 1 G, b, hospital |= E↓ surgery
Hospital
Place
Floor 1
Roof
! Nurse
Elevator
! child 1
! Helicopter
...
! Elevator ! Surgery
! Floor 1 ! Roof
Surgery
Helicopter
! child n ! Pilot ! Victim ! First Aider
R# transition R" transition
! PDA-2
! PDA-1
Nurse
PDA-1
Pilot
Victim
Label
First aider
PDA-2
Query language Example 2
Hospital
Place
Floor 1
Roof
! Nurse
Elevator
! child 1
! Helicopter
...
! Elevator ! Surgery
! Floor 1 ! Roof
Surgery
Helicopter
! child n ! Pilot ! Victim ! First Aider
R# transition R" transition
! PDA-2
! PDA-1
Nurse
PDA-1
Pilot
Victim
Label
First aider
PDA-2
Implementation Prototype Architecture
Interaction Shell Context
Query Evaluation
Location Query
Current Location
Tree Graph Networked-Files Tree Structure
Binders
Checkery Core System
HL Model Checker
Query Parsing
OCAML Runtime
Model Builder
Conclusion Roadmap
• 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
References
“Stand on the shoulders of giants” [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.
Questions
?
Overview
Pyramidal Presentation
Thank You ! Query Processing Location Modeling Context and Location-Awareness Ubiquitous Computing