Database Architectures and the Web
Transcript of Database Architectures and the Web
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COMP1711 Database Modelling and Knowledge Engineering
Database Architecturesand the Web
Chapter 3
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Chapter 3 - Objectives
• Components of a DMBS
• Multi-user DBMS Architectures
• Web services
• Distributed DBMSs
• Data Warehousing
• Oracle Architecture
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Chapter 3 - Objectives
• Components of a DMBS
• Multi-user DBMS Architectures
• Web services
• Distributed DBMSs
• Data Warehousing
• Oracle Architecture
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Components of a DBMS
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Components of a DBMS
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Components of a DBMS
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Components of Database Manager
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Chapter 3 - Objectives
• Components of a DMBS
• Multi-user DBMS Architectures
• Web services
• Distributed DBMSs
• Data Warehousing
• Oracle Architecture
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Multi-User DBMS Architectures
• Teleprocessing
• File-server
• Client-server
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Teleprocessing
• Traditional architecture.
• Single mainframe with a number of terminals attached.
• Trend is now towards downsizing.
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File-Server Architecture
DBMS on
each workstation
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File-Server
• File-server is connected to several workstations across a network.
• Database resides on file-server.
• DBMS and applications run on each workstation.
• Disadvantages include:• Significant network traffic.
• Copy of DBMS on each workstation.
• Concurrency, recovery and integrity control more complex.
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Traditional Two-Tier Client-Server
Applications
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Traditional Two-Tier Client-Server
• Client (tier 1) manages user interface and runs applications.
• Server (tier 2) holds database and DBMS.
• Advantages include:• wider access to existing databases;
• increased performance;
• possible reduction in hardware costs;
• reduction in communication costs;
• increased consistency.
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Traditional Two-Tier Client-Server
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Three-Tier Client-Server
• Client side presented two problems preventing true scalability:• ‘Fat’ client, requiring considerable resources on client’s computer to run
effectively.
• Significant client side administration overhead.
• By 1995, three layers proposed, each potentially running on a different platform.
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Three-Tier Client-Server
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Three-Tier Client-Server
• Advantages:• ‘Thin’ client, requiring less expensive hardware.
• Application maintenance centralized.
• Easier to modify or replace one tier without affecting others.
• Separating business logic from database functions makes it easier toimplement load balancing.
• Maps quite naturally to Web environment.
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Multi-user DBMS Architectures
• N-tier architectures• Three-tier architecture can be expanded to n tiers
• Application servers• Hosts an application programming interface (API) to expose business
logic and business processes for use by other applications
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Chapter 3 - Objectives
• Components of a DMBS
• Multi-user DBMS Architectures
• Web services
• Distributed DBMSs
• Data Warehousing
• Oracle Architecture
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Distributed DBMS
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Distributed DBMSs
• Distributed database• Logically interrelated collection of shared data physically distributed
over a computer network
• Distributed DBMS• Software system that permits the management of the distributed
database
Makes the distribution transparent to users
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Distributed DBMSs
• Characteristics of DDBMS• Collection of logically related shared data
• Data split into fragments
• Fragments may be replicated
• Fragments/replicas are allocated to sites
• Sites are linked by a communications network
• Data at each site is controlled by DBMS
• DMBS handles local apps autonomously
• Each DBMS in one or more global app
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Distributed Processing
A centralized database that can be accessed over acomputer network.
NOT a distribute
database!
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Chapter 3 - Objectives
• Components of a DMBS
• Multi-user DBMS Architectures
• Web services
• Distributed DBMSs
• Data Warehousing
• Oracle Architecture
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Architecture of a Data Warehouse
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Data Warehousing
• Data warehouse• Consolidated view of corporate data
• Drawn from disparate operational data sources
• Range of end-user access tools capable of supporting simple to highly complex queries to support decision making
• Subject-oriented, integrated, time-variant, and nonvolatile
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Chapter 3 - Objectives
• Components of a DMBS
• Multi-user DBMS Architectures
• Web services
• Distributed DBMSs
• Data Warehousing
• Oracle Architecture
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