1 CS851 Data Services in Advanced System Applications Sang H. Son son@cs.virginia.edu.

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CS851 Data Services in Advanced

System Applications

Sang H. Sonson@cs.virginia.edu

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What is Data Service?

Need for proper functioning of applications Same/similar to queries and transactions in

database systems? A database models real-world enterprise.

– Entities (e.g., students, courses)– Relationships (e.g., Alexander is taking

CS851) What is Database Management System (DBMS)? A software system designed to store and

manage databases Queries and transactions: key aspects of DBMS

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Current Trends in Advanced Applications

Interaction with the physical world/entities Dynamic data; real-time data; temporal data Sophisticated in their data needs Raw sensor data vs aggregated or derived

data Huge volume Real-time or near real-time access Large scale Resource constraints

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Why Study Data Services?

Shift from DBMS to data services– Extensions of traditional DBMS– Advanced applications present different

requirements: application-centric and data-centric Datasets increase in diversity and volume

– Digital libraries, interactive video, sensor networks, stream data, gene/biological data, satellite images

– ... need for data services exploding DBMS is a key component in data service

system architecture

?

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Key Ideas of DBMS – Schemas/Views

Many views, single conceptual (logical) schema and physical schema.

Views describe how users see the data.

Conceptual schema defines logical structure

Physical schema describes the files and indexes used.

Physical Schema

Conceptual Schema

View 1 View 2 View 3

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Key Ideas - Data Independence

Applications insulated from how data is structured and stored.

Logical data independence: Protection from changes in logical structure of data.

Physical data independence: Protection from changes in physical structure of data.

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Key Ideas - Transactions Key concept is transaction, which is an atomic

sequence of database actions (reads/writes). Each transaction, executed completely, must

leave the DB in a consistent state if DB is consistent when the transaction begins.

Users can specify integrity constraints on the data; DBMS enforces these constraints.

Ensuring that a transaction (run alone) preserves consistency is ultimately the user’s responsibility!

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Applications to Study in CS851 Real-time systems Stream data management Wireless sensor systems Dynamic data dissemination

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Issues in Those Applications

Real-time systems– Freshness and timeliness– QoS and robustness

Stream data management – Monitoring, operator scheduling, load shedding

Wireless sensor systems– Event service, data aggregation and dissemination

Dynamic data dissemination– Coherence preservation, adaptive push and pull

Wide variety of applications – application specific issues

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Application Spectrum of WSN

HazardDetection

BiologicalMonitoring

Linear StructureProtection

SmartEnvironment

WearableComputing

ImmerseEnvironments

Earth Science &Exploration

Context-AwareComputing

Interactive VRGame

Wireless SensorNetworks

Urban WarfareMilitary Surveillance

Disaster RecoveryEnvironmental Monitoring

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Key Components in CS851 Paper selection by next Tuesday Paper presentation

– Draft slide submitted at least 2 days before the scheduled presentation date

– Presentation of main ideas/contributions– Examples and animation– Discussions and critiques

Paper reading and summary/critique submission Project proposal Project presentation and final report submission Best presentation award