mobile, context-aware databases and database systems introduction

MOBILE, CONTEXT-AWAREDATABASES AND

DATABASE SYSTEMSINTRODUCTION

Proff. C. Bolchini, E. Quintarelli, F. A. Schreiber, L. Tanca

Politecnico di Milano

© Bolchini, Quintarelli, Schreiber, Tanca Mobile, context-aware DB... Introduction 1

INFORMATION MANAGEMENT TECHNOLOGIES

EMBEDDED SISTEMS

INFORMATION SYSTEMS ANALYSIS

DATA INTEGRATION

DISTRIBUTED ETHEROGENEOUS

DATA MANAGEMENT

DATA WAREHOUSE

DATAMINING

WEB INFORMATION SYSTEMS

INFORMATION RETRIEVAL

SISTEMS

DECISION SUPPORT SYSTEMS

NON STRUCTUREDSEMISTRUCTUREDAND MULTIMEDIAL

INFORMATION

MOBILE AND CONTEXT-

AWARE COMPONENTS

•REAL-TIME•MAIN MEMORY•TEMPORALDATABASES


HELP!

MOBILE, CONTEXT- AWARE COMPUTING


THE ARCHITECTURE OF A MODERN INFORMATION SYSTEM

NARROW BAND

ANALOGICAL NETWORKS

LOCAL NETWORK

LOCAL NETWORK

INTERNAL NETWORK

WIDE BAND

DIGITAL NETWORKS

WIRELESS NETWORKS

REST

OF THE

WORLDFIREWALL

FRONT END

SERVER

SERVER


THE NEW TECHNOLOGICAL ENVIRONMENT

SMALL DEVICES

EMBEDDED SYSTEMS

CONTEXT AWARENESS

MOBILITY


EMBEDDED DATABASE

FULL-FEATURED DATABASE THAT IS:INTEGRATED DIRECTLY INTO

OR PACKAGED WITH

AN APPLICATION


EMBEDDED DBMS FEATURES

REAL TIME

ACTIVE

TEMPORAL

EDBMSMAIN

MEMORY


EMBEDDED DATABASE APPLICATIONS• PROCESS CONTROL (SOFT OR HARD RT)

MANUFACTURING AUTOMATIONAVIONICSTELECOMMUNICATIONS………..

• INFORMATION MANAGEMENT (NON RT OR SOFT RT)ENTERPRISE APPLICATIONS ON MOBILE POCKET OR HANDHELD PC AND CELL PHONESSMART CARD INFORMATION SYSTEMSSALESMAN ORDER ACQUISITION AND PROCESSINGINTERNET APPLICATIONS (LOCATION DEPENDENT QUERIES, ON LINE CHOICE OF QoS, … )


EMBEDDED DATABASE APPLICATIONS

MANUFACTURING AUTOMATIONDEVICES• PROGRAMMABLE LOGICAL CONTROLLERS (PLC)• REMOTE TELEMETRY UNITS, WIRELESS SENSOR

NETWORKS• RFID (RADIO FREQUENCY IDENTIFICATION)

FEATURES• HISTORICAL AND STATE INFORMATION

MANAGEMENT UNDER TIMING CONSTRAINTS• SMALL/MEDIUM DATA VOLUMES• HIGH RESPONSIVENESS



ON BOARD AVIONICS SYSTEMS

KEEP TRACK OF 3000 OBJECTS

TEMPORAL COHERENCE WITH THE ACTUAL SITUATION WITHIN 200 msec

ACCEPTABLE READ/WRITE RESPONSE TIME: 1 msec



AIR TRAFFIC CONTROL

KEEP TRACK OF 20000 OBJECTS

TEMPORAL COHERENCE WITH THE ACTUAL SITUATION WITHIN 3÷6 sec

ACCEPTABLE READ/WRITE RESPONSE TIME: 5 msec



TELECOMMUNICATIONS

800-NUMBERS TRANSLATION REQUIRES LESS THAN 50 msec TURNAROUND TIME

AVAILABILITY REQUIRED: LESS THAN 1 CALL IN 106 MAY BE LOST

KEEPING INFORMATION IN MAIN MEMORY CAN REDUCE ACCESS TIME AS LOW AS 10 msec

LOGGING OVERHEAD MUST STAY LOW


EMBEDDED DBMS FUNCTIONALITY

REAL TIME ACTIVE MAIN MEMORY

PROCESS / DEVICECONTROL

MOBILE / INTERNETAPPLICATIONS

SMART CARDAPPLICATIONS

YES

HARD / FIRMYES

YES POSSIBLY

YESNO / SOFT NO

YES

FIRM / SOFT

POSSIBLY

FEATURES

APPLICATION


PORTABLE VSDBMS TECHNOLOGICAL CONSTRAINTS

• COMPUTATIONAL POWERSMALL FOOTPRINT DBMS

• ENERGY CONSUMPTIONLOW POWER BATTERIES

• PERSISTENT DATA STORAGEFLASH MEMORY TECHNOLOGIES

• BIT/BYTE ACCESS GRANULARITY• BLOCK EREASE/UPDATE GRANULARITY• UPPER LIMIT TO ERASURE NUMBER

}


EXAMPLES OF COMMERCIAL SYSTEMS (1)

SYSTEM NAME APPLICATIONAREA

ARCHITECTURE / DATA MODEL

PLATFORMSUPPORT

RECOVERYMANAGEMENT

CONCURRENCYCONTROL ACCESS PATH

Centura RDM(Mbrane Touchpoint EC)www.centurasoft.com

AT&T Bell Labs Dalì(DataBlitz)www.bell-labs.com/project/dali/

Informix Cloudscapewww.cloudscape.com

Polyhedrawww.polyhedra.com

Sleepycat SwBerkeley DBwww.sleepycat.com

Windows 9x/NT,UNIX, Linux

Windows 9x/00/NT,UNIX, Embedix, QNX, VxWorks

a variety ofRTOS

EMPRESSwww.empress.com

Windows 9x/NT,UNIX, Solaris, Linux, Lynx, ...

FastDBwww.ispras.ru/~knizhnik/fastdb.html

POET FastObjectsNavajowww.poet.com/fastobjects

Windows 9x/00/NT,UNIX, Linux,pSOS, VxWorks

Windows 98/NTWinCE, Solaris, UNIX, Linux,EPOC, RTOS, ...

Windows NT,UNIX, Linux,Solaris

Windows 9x/NT,UNIX, Solaris

e-business,web+mobile solutions

telecommunications

general applications with dominated read access pattern

RT process controlnetwork applicationsmedical systems

portable/palm mobileweb solutions

general RT and telecom applications

complex RT applica-tions

MM storage mngrdirect access to datavia shared memoryrelational APIRT DBMS library of C routinesrelational and network

distributed DBMS relational

MM DBMSdirect data access object oriented

distributed DBMSlibrary of Java clas-sesobject-relational

MM RT Active DBMSclient/serverobject-relational

RT DBMSdynamically loadable Java modulesobject oriented

small footprint transactions library of modified UNIX modules

multi-granularitylockings, x,, i, mode locking

•multi-level recovery•fuzzy checkpoints ofdirty pages

•T-trees indexing•extensible hash tables

Linked lists (one-to-manyDBTG sets)

•T-trees indexing•extensible hash tables•inverse references

shadow objects •shadow indexes•linked lists

B-trees indexing

•snapshots to disk•write-behind logging•duplicated DB (opt)

variable granule size locking

•indexes•direct pointers (?)

platform’s native file system

•write-ahead logging•checkpointing

row- or table-levellocking

SPECIALLY SUITED FOR MOBILE APPLICATIONS


EXAMPLES OF COMMERCIAL SYSTEMS (2)

SYSTEM NAME APPLICATIONAREA

ARCHITECTURE/ DATA MODEL

PLATFORMSUPPORT

RECOVERYMANAGEMENT

CONCURRENCYCONTROL ACCESS PATH

Solid Embedded enginewww.solidtech.com

Windows 9x/00/NT,UNIX, Linux, Solaris,VxWorks, ...

Sybase SQL Anywhere UltraLite (50 KB)www.sybase.comTimes Tenwww.timesten.com

Windows 2000/NT,UNIX, Linux, Lynx

Windows NT/XPWinCE, UNIX, Linux,EPOC, VxWorks, ...

smart telecom networks

mobile businessapplications

Internet applicationservers, mobile business applications

distributed active DBMSrelational

MM DBMSrelational

MM (RT) DBMSapplications linkablelibrariesrelational

•multiversionoptimistic

•row-level lockingroll forward log •modified B-trees

•bonsai-trees

B+-treescheckpoints and logs

•checkpoints and logs•data replication

row-, table-, db-level locking

•T-trees indexing•hash tables

VTT Inform. TechnologyRapidBasewww.vtt.fi/tte/projects/rapid

Windows 95/98/NT,UNIX, Linux

Storage/retrieval of time series data forindustrial process measurement

MM, active DBMSclient/serverC++, Java librariesrelational

checkpoints and logs

IBM DB2 Everyplacewww-106.ibm.com/developerworks/library/wi-everyplace

Oracle9i Litewww.oracle.com/ip/deploy/ias/mobile/

Windows 32, Windows CE, Palm OS, EPOC 5

General purposemobile and location-aware applications

Lightweightrelational dabase

Two-way synchronizationbetween the server and the mobile devices

Relational database (reduced functions, 137k footprint)

Advanced indexingWindows 32 /CE, PalmOS, EPOC 5, Linux, QNX Neutrino

Mobile and embeddeddevices, special purpose applications

Synchronizationserver amongdifferent platforms

centralized conflictresolution

SPECIALLY SUITED FOR MOBILE APPLICATIONS


MOBILITY ISSUESWHICH IS THE APPLICATION WORKING

MODE– WITH RESPECT TO SPACE

– LOCATION DEPENDENT DATA– LOCATION AWARE TRANSACTIONS

– WITH RESPECT TO SPACE-TIME• SENSIBLE OF EXTERNAL EVENTS (ACTIVE)• NOMADIC ROAMING (QUASI STATIC)• FULL-FEATURED MOBILE (REAL-TIME)

– QUERY ANSWERING SEMANTICS (????)^ AS OF WHERE ISSUED^ AS OF WHERE PROCESSED^ AS OF WHERE RECEIVED


WHAT IS MOBILE

• SPATIO/TEMPORAL DATABASES FOR MOBILE OBJECTS

• TRADITIONAL DATABASES FOR MOBILE DEVICES

• BOTH


MOBILE OBJECTS DATABASES a very, very short introduction

MOVING OBJECTS

– HIGH UPDATE RATE

• ACTIVE (FAST) OBJECTS– STORED IN MAIN MEMORY (HARD RT)

• INACTIVE (SLOW) OBJECTS– STORED ON DISK (FIRM/SOFT RT)


MOBILE OBJECTS DATABASES

EXAMPLE APPLICATIONS

– CELLULAR PHONE NETWORKS• UPDATE THE USER POSITION (CELL)• LOCATE A USER (CELL) TO FORWARD A

CALL

– AIR TRAFFIC CONTROL DATA• CONTINUOUSLY TRACK THE POSITION OF

EACH OBJECT IN A GIVEN AREA



COORDINATE-BASED QUERIES– SPATIO/TEMPORAL

Find all objects within a given area duringa given time interval

– TIMESLICEFind all objects’ locations within a givenarea at a certain time instant

– NEAREST NEIGHBOURFind the nearest moving object to a givenobject during a given time interval



historicaL continuouspoint nearest neighbour

t

y

x

timeslice point nearestneighbour

trajectory nearestneighbour

range

Q3

Q1 Q2Q4

Q5

t1

t2

t3

t4

t5

t6


TRAJECTORY-BASED QUERIES– TOPOLOGICAL QUERIES

• ENTER, LEAVE … A GIVEN AREA– NAVIGATIONAL QUERIES

• AVERAGE OBJECT SPEED, COVERED DISTANCE …

COMBINED QUERIES– Which trajectories followed, in the nexthour, the objects leaving via Ponzio 34 between 5 p.m. and 8 p.m. today

– Which is the nearest gas station at eachinstant during my whole trip



MOBILE OBJECTS DATABASESINDEXES

– COMPRESSION AND INDEXING TECHNIQUES FOR EFFICIENT TRACKABILITY

• IN THE PAST (TRAJECTORIES HISTORY)• IN THE FUTURE (ACTUAL POSITION AND MOTION

VECTOR)

A WHOLE AMAZONIA FOREST OF DIFFERENT TREE STRUCTURES HAS BEEN PROPOSED IN THE LITERATURE


MOBILE DEVICESFEATURES OF MOBILE DEVICES

– TYPE AND POWER OF THE DEVICE (smart cards, cell phones, PDAs, portable PC, ...)

– OPERATING ENVIRONMENT VARIABILITY (proprietary, intranet/internet, …)

– NETWORK CONNECTIVITY (guided or occasional disconnections, asymmetrical link bandwidth)

– ACCURATE AND COHERENT SPATIO/TEMPORALPERCEPTION OF SERVICE STATE AND QUALITY (QoS)

– MULTICANALITY (shape the information content for the device it is aimed at)


MOBILE SYSTEMS CONSTRAINTS

DEVICEPOWER NEEDS FOR TRANSMISSION >> POWER NEEDS FOR PROCESSING

NETWORKLOW BANDWITH AND UNRELIABLE LINKS

MATERIALIZE DATA ON THE MOBILE DEVICE


MOBILE INFORMATION SYSTEMS

INTERNET/INTRANET ENVIRONMENTACCURATE AND COHERENT SPATIO-TEMPORAL VIEW OF THE DISTRIBUTED STATE AND OF THE QoS

• WHICH IS THE NEAREST HOTEL TO MY CURRENT POSITION?

• WHICH IS THE NEAREST GAS STATION?• HOW LONG WILL IT TAKE TO DOWNLOAD A GIVEN

PICTURE AT A GIVEN RESOLUTION?


DATABASES FOR MOBILE DEVICES

• MOBILE USERS – FIXED HOST(S)– TRAVELLING EMPLOYEES CORPORATE DB– MOBILE USERS DATA SERVICE PROVIDER– PUBLIC BROADCASTED INFORMATION

• MOBILE HOST(S) – FIXED USERS– WIRELESS SENSORS BASE STATION

• BOTH MOBILE– PEER-TO- PEER NETWORKS– PORTABLE PERSONAL FOLDERS


DATABASES FOR MOBILE DEVICES

WHAT IS RESIDENT ON THE MOBILE DEVICE• LOCAL DATA ONLY

– smart cards personal data• SMALL LOCAL PERMANENT STORAGE

– old cellular phones directories• STORAGE AND TRANSACTION MANAGEMENT

CAPABILITIES– umts cellular phones– palm and portable PCs


MOBILE DB TECHNOLOGICAL ISSUES

DISCONNECTED OPERATION

• DATA SYNCHRONIZATION– FILE SYNCHRONIZERS (PRODUCTS)

• MANUAL CONFLICT RESOLUTION (e.g., MS ActiveSync)

– TRANSFORMATIONAL APPROACH (RESEARCH)

• OPERATIONS AT EACH SITE ARE BROADCASTED TO OTHER SITES WHERE THEY ARE INTEGRATED AND TRANSFORMED FOR THE LOCAL EXECUTION CONTEXT


MOBILE DB TECHNOLOGICAL ISSUES

LONG TRANSACTIONS– PESSIMISTIC APPROACHES

• TOO LONG DELAYS IN COMMITTING– OPTIMISTIC APPROACHES

• TOO LARGE DIVERGENCES AMONG LOCAL AND SERVER COPIES

• DOUBLE COMMIT (RESEARCH)– LOCAL, IN DISCONNECTED MODE– GLOBAL, AT RECONNECTION TIME

• CONTRACT AND OPERATIONAL RULES FOR GOVERNING THE REINTEGRATION OF LOCALLY MODIFIED COPIES


THE NEW APPLICATION ENVIRONMENT

• A VERY LARGE NUMBER OF LARGE DATA SOURCES

• GENERALLY HIGHLY VARIABLE AND VOLATILE DATA (ES. WEB)

• HIGHLY HETEROGENEOUS DATA SOURCES

• DIFFERENT DATA STRUCTURING LEVELS– DATABASES WITH DIFFERENT UDERLYING MODELS

(RELATIONAL, OBJECT ORIENTED, LEGACY…)– SEMI-STRUCTURED DATA (XML, HTML, OTHER

TAGGING SYSTEMS…)– NON-STRUCTURED DATA (TEXT, IMAGE, SOUND,

ETC…)

• DIFFERENT TERMINOLOGIES AND CONTEXTS


NEW APPLICATION ARCHITECTURES

PEER-TO-PEER• INFORMATION SOURCES COINCIDE WITH USER DEVICES

– PURE P2P: FLAT ARCHITECTURE, NO DIFFERENCE AMONG THE NODES (Gnutella)

– HYBRID AND MIXED P2P: FLAT ARCHITECTURE FOR DATA, CLIENT-SERVER ARCHITECTURE FOR META-DATA (Napster, eMule, BitTorrent)

– USED FOR MULTIMEDIAL INFORMATION EXCHANGE

• CONTEXT-AWARENESS: ESSENTIAL IN SOLVING PARTNERS HETEROGENEITY

• ONTOLOGY: ESSENTIAL IN – INFORMATION SEARCHING – FORMULATING QUERIES AGAINST UNKNOWN PARTIES– RECONCILING ANSWERS FROM DIFFERENT SOURCES

• MOBILITY: NOT A NECESSARY ISSUE


CONTEXT AWARENESS• CONTEXT AWARE INFORMATION SYSTEMS

• SPACE, TIME, QoS ARE BUT EXAMPLES OF ENVIRONMENTAL VARIABLES

• IN GENERAL ONE CAN SPEAK OF CONTEXT-AWARENESS OR AMBIENT INTELLIGENCE AS

THE ABILITY OF COMPUTER SYSTEMS TO RECOGNIZE A USER’S SITUATION AND RESPOND TO IT IN A WAY THAT IS USEFUL TO THE USER

• LOCATION• TASK• TIME• SOCIAL SETTING• AMBIENT NOISE LEVEL• PRIVACY REQUIREMENTS• ………………………


CONTEXT• A RATHER GENERAL CONCEPT

INTERPRETED IN DIFFERENT WAYS IN– PSYCHOLOGY– PHILOSOPHY – COMPUTER SCIENCE

• IN COMPUTER SCIENCE, INITIALLY PERCEIVED AS USER LOCATION AND PROFILE

• MOST CONTEXT-AWARE APPLICATIONS HAVE FOCUSED MAINLY ON PRESENTATIONISSUES


CONTEXT- AWARE DATABASE DESIGNDATA-CENTRIC NOTION OF CONTEXT

• CONTEXT: SET OF PERSONAL AND ENVIRONMENTAL FEATURES DETERMINING THE PORTION OF DATA THAT MUST BE STORED LOCALLY– APPLICATION– INFORMATION– ENVIRONMENT

• CONTEXT IS META-KNOWLEDGE, IT NEEDS AN APPROPRIATE CONTEXT MODEL


ContextADDICT ARCHITECTURE


INTRODUCTORY BIBLIOGRAPHY AND INTERESTING SITES

• G. Bernard et Al. – Mobile Databases: a Report on Open Issues and Research Directions - ACM SIGMOD, (2003) http://lpd.epfl.ch/site/publications/

• F. Giunchiglia, I. Zaihrayeu – Coordinating Mobile Databases -www.p2pkm.org/2004/Camera_Ready/1568938498.pdf

• M. A. Olson - Selecting and Implementing an Embedded Database System - IEEE Computer, vol. 33, n. 9, pp. 27-34, (2000)

• D. Pfoser, C.S. Jensen, Y. Theodoridis – Novel Approaches to the Indexing of Mobile Objects trajectories – Proc VLDB 2000, pp. 395-406

• O. Wolfson - Moving Objects Information Management: The Database Challenge - http://www.cs.uic.edu/%7Ewolfson/mobile_ps/ ngits02.pdf

• http://www.cs.bilkent.edu.tr/~muratk/phd/ontology.htm• http://www.mobiforum.org/mobiforum/mobi.php• http://www.cs.rutgers.edu/dataman/

http://www.cs.bilkent.edu.tr/~muratk/phd/ontology.htm

http://www.mobiforum.org/mobiforum/mobi.php

http://www.cs.rutgers.edu/dataman/


MANUFACTURERS’ SITES• www.bell-labs.com/project/dali/• www.centurasoft.com *• www.cloudscape.com• www.empress.com • www-306.ibm.com/software/data/db2/everyplace/• www.ispras.ru/~knizhnik/fastdb.html• http://otn.oracle.com/products/lite/content.html• www.poet.com/fastobjects *• www.polyhedra.com• www.sleepycat.com• www.solidtech.com• www.sybase.com• www.timesten.com• www.vtt.fi/tte/projects/rapid/

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mobile, context-aware databases and database systems introduction