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Chapter 3. Database Architectures and the Web. Multi-User DBMS Architectures. Teleprocessing File-server Client-server. Teleprocessing. Traditional architecture Single mainframe with number of terminals attached. File-Server. File-server connected to several workstations across network

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chapter 3

Chapter 3

Database Architectures

and the Web

multi user dbms architectures
Multi-User DBMS Architectures

Teleprocessing

File-server

Client-server

teleprocessing
Teleprocessing

Traditional architecture

Single mainframe with number of terminals attached

file server
File-Server

File-server connected to several workstations across network

Database resides on file-server

DBMS and applications run on each workstation

Disadvantages:

Significant network traffic

Copy of DBMS on each workstation

Concurrency, recovery and integrity control more complex

traditional two tier client server
Traditional Two-Tier Client-Server

Client (tier 1) manages user interface and runs applications

Server (tier 2) holds database and DBMS

Advantages:

wider access to existing databases

increased performance

possible reduction in hardware costs

reduction in communication costs

increased consistency

three tier client server
Three-Tier Client-Server

Problems preventing true scalability in 2-tier:

‘Fat’ client, requiring considerable resources on client’s computer to run effectively

Significant client side administration overhead

1995 - three layers proposed

three tier client server1
Three-Tier Client-Server

Advantages:

‘Thin’ client

Requires less expensive hardware

Application maintenance centralized

Easier to modify/replace one tier without affecting others

Separation business logic from database functions → easier to implement load balancing

Maps naturally to Web environment

transaction processing monitors tpm
Transaction Processing Monitors (TPM)

Program that controls data transfer between clients and servers in order to provide a consistent environment, particularly for Online Transaction Processing (OLTP).

slide13
TPM
  • Transaction processing monitor
    • Controls data transfer between clients/servers
    • Provides a consistent environment, particularly for online transaction processing (OLTP)
    • Significant advantages
      • Transaction routing
      • Managing distributed transactions
      • Load balancing
      • Funneling
      • Increased reliability
multi user dbms architectures1
Multi-user DBMS Architectures
  • Teleprocessing
    • Traditional architecture for multi-user systems
    • One computer with a single central processing unit (CPU) and a number of terminals
    • Put a huge burden on the central computer
  • Downsizing
    • Replacing expensive mainframe computers with more cost-effective networks of personal computers
multi user dbms architectures2
Multi-user DBMS Architectures
  • File-server architecture
    • Processing distributed about network
    • Disadvantages:
      • Large amount of network traffic
      • Full copy of DBMS required on each workstation
      • Concurrency, recovery, and integrity control are complex
multi user dbms architectures3
Multi-user DBMS Architectures
  • Traditional two-tier client–server architecture
    • Client process requires some resource
    • Server provides the resource
    • Basic separation of four main components of business application
    • Typical interaction between client and server
multi user dbms architectures4
Multi-user DBMS Architectures
  • Three-tier client–server architecture
    • User interface layer
    • Business logic and data processing layer
    • DBMS
    • Many advantages over traditional two-tier or single-tier designs
multi user dbms architectures5
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
multi user dbms architectures6
Multi-user DBMS Architectures
  • Middleware
    • Software that mediates with other software
    • Communication among disparate applications
    • Six main types
      • Asynchronous Remote Procedure Call (RPC)
      • Synchronous RPC
      • Publish/Subscribe
      • Message-Oriented middleware (MOM)
      • Object-request broker (ORB)
      • SQL-oriented data access
web services and service oriented architectures
Web Services and Service-Oriented Architectures
  • Web service
    • Software system that supports interoperable machine-to-machine interaction over network
    • No user interface
    • Examples of Web services
      • Microsoft Virtual Earth Web service
    • Uses widely accepted technologies and standards
web services and service oriented architectures1
Web Services and Service-Oriented Architectures
  • Service-Oriented Architectures (SOA)
    • Architecture for building applications that implement business processes as sets of services
  • Some principles built upon:
    • Loose coupling
    • Reusability
    • Composability
distributed dbmss
Distributed DBMSs
  • Distributed database
    • Logically interrelated collection of shared data physically (single database) distributed over network
  • Distributed DBMS
    • Software system that permits management of distributed database
    • Distribution transparent to users
distributed dbmss1
Distributed DBMSs
  • Characteristics of DDBMS
    • Collection of logically related shared data
    • Data split into fragments
    • Fragments may be replicated
    • Fragments/replicas allocated to sites
    • Sites linked by communications network
    • Data at each site controlled by DBMS
    • DMBS handles local apps autonomously
    • Each DBMS in one or more global app
distributed dbmss2
Distributed DBMSs
  • Distributed processing
    • Centralized database that can be accessed over computer network
  • System consists of data physically distributed across number of sites in network
data warehousing
Data Warehousing
  • Data warehouse
    • Consolidated/integrated 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
components of a dbms
Components of a DBMS
  • Major components of a DBMS:
    • Query processor
    • Database manager (DM)
    • File manager
    • DML preprocessor
    • DDL compiler
    • Catalog manager
components of a dbms1
Components of a DBMS
  • Major software components for database manager
    • Authorization control
    • Command processor
    • Integrity checker
    • Query optimizer
  • Transaction manager
  • Scheduler
  • Recovery manager
  • Buffer manager
oracle architecture
Oracle Architecture
  • Oracle’s logical database structure
    • Tablespaces
    • Schemas
    • Data blocks
    • Extents/segments
oracle architecture1
Oracle Architecture
  • Oracle’s physical database structure
    • Datafiles
    • Redo log files
    • Control files
  • The Oracle instance
    • Oracle processes and shared memory required to access information in the database