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The Architecture of Distributed Systems

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Title: The Architecture of Distributed Systems


1
The Architecture of Distributed Systems
  • Enterprise wide computing, networking and the
    desktop revolution

2
IT Architecture
  • Hardware and software
  • Tools to access, package, deliver, communicate
    information
  • Standards, models, control framework
  • Configuration integrating components
  • What is the difference between an IT Architecture
    and an IT Infrastructure?

3
IT Architecture and Infrastructure
  • Architecture is overall blue print of how systems
    fit together
  • IS community has lost credibility b/c of failure
    in this area.
  • Infrastructure is a particular implementation of
    IT architecture with basic capabilities shared
    across business units.
  • ??Why is an overall IT architecture important?

4
Views of IT Infrastructure
  • Utility
  • necessary and unavoidable service, often viewed
    as administrative expense.
  • Firms with this view tend to offer fewest
    infrastructure services
  • focus on lowering costs and not reengineering
    processes.

5
Views of IT Infrastructure
  • Dependent
  • Tied to specific business programs in plan (ex.
    Improve service quality)
  • infrastructure planning included in current
    business plan
  • measured in short-term benefits
  • minimum requirement for implementing BPR

6
Views of IT Infrastructure
  • Enabling
  • continuous re-alignment of IT infrastructure with
    firm strategy.
  • Long term strategy
  • infrastructure provides basis for flexibility,
    rapid adaptation of future strategies
  • costs viewed as business investments
  • networks used extensively in business processes
  • increased up front costs

7
Focus on IT Infrastructure
  • Corp. IS departments moving from hw/sw to
    application/infrastructure focus
  • IS depts. in business of maintaining IT
    infrastructure
  • s/w development reduced to modifying packages
    for/by end users
  • CIOs starting to prefer CTO title
  • Why is IS dept. focus on infrastr. a recipe for
    obsolescence or extinction of IS depts.?

8
IT Architecture
  • Applications
  • IT-enabled process redesign
  • Productivity applications
  • Competitive advantage
  • Structure controls
  • Standards, policies and procedures
  • Information models
  • System development methodologies

9
IT Architecture
  • User interface
  • GUI
  • IO devices
  • Tools packages
  • Presentation reporting
  • Analysis modeling
  • Groupware
  • Personal productivity
  • DSS

10
IT Architecture
  • Information Management
  • Hardware
  • OS
  • DBMS
  • Document management systems
  • Information retrieval
  • Communication management
  • Networks
  • Gateways
  • Email file transfer

11
IT Architecture Evolution
  • Mainframes with dumb terminals
  • download/upload data
  • run mainframe programs (usu. batch)
  • little local processing
  • Micros moved it to desktop
  • Network computing model
  • centralized model with network replacing m/f

12
The Computer System Concept
13
Changes in Computer Architecture
1930
1950
1957
1965
1975
firstgeneration
secondgeneration
thirdgeneration
fourthgeneration
prototype
vacuumtube
transistor
integratedcircut
mechanicalrelay
microprocessor
14
Pentium Chip
15
A Microprocessor
control unit
arithmeticlogic unit
128K temporary memory
input/outputcircuitry
systemclock
16
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17
Performance vs. Price
18
Computer Classifications
Mainframes
Midrange Computers
Microcomputers
19
Networked Computer Systems
Host Systems/ Superservers
20
How distributed are your systems?
  • Where is the processing of data done?
  • Distributed processing
  • How are the processors and other devices
    interconnected?
  • Processor connectivity
  • Where is the information stored?
  • Distributed databases
  • What rules or standards are used?
  • Protocols, transmission standards, etc.

21
Distributed System Frameworks
  • Organizational View
  • Corporate HQ
  • Regional HQ
  • Plant or Site
  • Department
  • Work Group
  • Individual

22
Types of Distributed Systems
  • Host-based hierarchical systems

23
Host-based Hierarchy
24
Types of Distributed Systems
  • Host-based hierarchical systems
  • Decentralized Stand-Alone Systems

25
Decentralized Stand-alone System
26
Types of Distributed Systems
  • Host-based hierarchical systems
  • Decentralized Stand-Alone Systems
  • Peer-Peer LAN-Based Systems

27
Peer-to-Peer LAN-based System
28
Types of Distributed Systems
  • Host-based hierarchical systems
  • Decentralized Stand-Alone Systems
  • Peer-Peer LAN-Based Systems
  • Hybrid Enterprise-Wide Systems

29
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30
Types of Distributed Systems
  • Host-based hierarchical systems
  • Decentralized Stand-Alone Systems
  • Peer-Peer LAN-Based Systems
  • Hybrid Enterprise-Wide Systems
  • Client/Server Systems

31
Some Common Client/Server Definitions
  • A network that uses smart nodes instead of dumb
    terminals
  • Ability to distribute the workload
  • Client manages the human interface server
    manages the files

32
Client/Server Basic Architecture
Request Sent
Request Answered
Client
Server
33
Client/Server Basic Architecture
Server
Client
Server Becomes
Client
Mainframe
34
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35
Types of Servers
  • Database Servers
  • Resource Servers
  • Application Servers
  • Computation Servers

36
Client/Server Computing (from Gartner Group 5)
37
Benefits of Client/Server Computing
  • Easy Database Access
  • Downsizing Computer Resources
  • Shared Hardware Software Resources
  • Increased Management Control
  • Remove Islands of Automation
  • Scalable Architecture

38
Benefits of Client/Server Computing
  • Faster Application Development
  • Reduced Application Development Backlog
  • Increased Application Performance

39
Barriers to Client/Server Computing
  • Implementation Costs
  • Equipment
  • Systems Integration
  • Retraining IS Personnel
  • MIS Culture
  • Immature Technology
  • Lack of Management Tools

40
Barriers to Client/Server Computing
  • Threat to Stable Operations
  • Data Security
  • Complexity
  • Investment Payback

41
Types of Distributed Systems
  • Host-based hierarchical systems
  • Decentralized Stand-Alone Systems
  • Peer-Peer LAN-Based Systems
  • Hybrid Enterprise-Wide Systems
  • Client/Server Systems
  • Network-Centric Systems
  • NC machines (see table 6-3 for summary costs)

42
Network-Centric System
43
Enterprise IT Architecture
  • Enterprise architecture framework
  • Account for different roles in complex projects
  • planner, owner, designer, builder, sub, user
  • Account for components of complex systems
  • data models, functional models, network models,
    people, time frames, underlying goals/motivations
  • usually requires huge investment and corporate
    wide initiative

44
Assimilating New IT
  • Phased Assimilation Model
  • Technology Identification
  • Learning and Adaptation
  • Rationalization/Management Control
  • Maturity/Technology Transfer

45
Types of IT Investments
  • strategic system investments
  • Informational system investments
  • EIS, DSS, management control, etc.
  • Transactional system investments
  • support repetitive, operational processes
  • Infrastructure investments
  • provide the base foundation of IT capabilities

46
Types of IT Investments
47
Conclusions
  • Distributed systems have dominated IT development
    of 1990s architectures
  • C/S type may be moving to hybrid NC type
  • No one predicted the rise of the Internet
  • Internet2?
  • Complexity and speed of distributed systems will
    increase
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