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Title: Systems%20Analysis%20and%20Design%209th%20Edition

Systems Analysis and Design 9th Edition
  • Chapter 10
  • System Architecture

Chapter Objectives
  • Provide a checklist of issues to consider when
    selecting a system architecture
  • Describe servers, server-based processing,
    clients, and client-based processing
  • Explain client/server architecture, including
    tiers, cost-benefit issues, and performance
  • Compare in-house e-commerce development with
    packaged solutions

Chapter Objectives
  • Discuss the potential impact of cloud computing
    and Web 2.0
  • Explain the difference between online and batch
  • Define network topology, including hierarchical,
    bus, ring, and star models

Chapter Objectives
  • Explain network protocols and licensing issues
  • Describe wireless networking, including wireless
    standards, topologies, and trends
  • Describe the system design specification

  • An effective system combines elements into an
    architecture, or design, that is flexible,
    cost-effective, technically sound, and able to
    support the information needs of the business
  • System architecture translates the logical design
    of an information system into a physical
    structure that includes hardware, software,
    network support, and processing methods

System Architecture Checklist
  • Enterprise Resource Planning (ERP)
  • The objective of ERP is to establish a
    company-wide strategy for using IT resources
  • Supply chain management (SCM)
  • Initial Cost and TCO
  • During the final design stage, you make decisions
    that will have a major impact on the initial
    costs and TCO for the new system
  • You should review all previous cost estimates

System Architecture Checklist
  • Scalability
  • Scalability, also called extensibility, refers to
    a systems ability to expand, change or downsize
    easily to meet the changing need of a business
  • Especially important in implementing systems that
    are volume-rated, such as transaction processing

System Architecture Checklist
  • Web Integration
  • An information system includes applications
  • Web-centric architecture
  • Avoids many of the connectivity and compatibility
    problems that typically arise
  • E-marketplaces

System Architecture Checklist
  • Legacy System Interface Requirements
  • The new system might have to interface with one
    or more legacy systems
  • Interfacing a new system with a legacy system
    involves analysis of data formats and
  • The analyst must know if the new application
    eventually will replace the legacy system

System Architecture Checklist
  • Processing Options
  • In planning the architecture, designers also must
    consider how the system will process data -
    online or in batches
  • Provision must be made for backup and speedy
    recovery in the event of system failure

System Architecture Checklist
  • Security Issues
  • Security threats and defenses are a major concern
    to a systems analyst
  • The analyst must consider security issues that
    relate to system design specifications
  • Web-based systems introduce additional security

Planning the Architecture
  • Servers
  • Server
  • Clients
  • Mainframe architecture
  • Server-based processing

Planning the Architecture
  • Clients
  • As PC technology exploded in the mid-1980s and
    1990s, powerful microcomputers quickly appeared
    on corporate desktops
  • Users found that they could run their own word
    processing, spreadsheet, and database
  • Companies linked the stand-alone computers into

Planning the Architecture
  • Clients
  • Stand-Alone Computing
  • Local and wide area networks
  • Client-based processing

Client/Server Architecture
  • Overview

Client/Server Architecture
  • Client/Server Design Styles

Client/Server Architecture
  • Fat and Thin Clients

Client/Server Architecture
  • Client/Server Tiers
  • Two-tier design
  • Three-tier design
  • Middleware
  • Enables the tiers to communicate and pass data
    back and forth
  • Provides a transparent interface
  • Can integrate legacy systems and Web-based

Client/Server Architecture
  • Cost-Benefit Issues
  • Client/server systems enable the firm to scale
    the system in a rapidly changing environment
  • Client/server computing also allows companies to
    transfer applications from expensive mainframes
    to less expensive client platforms
  • Client/server systems reduce network load and
    improve response times

Client/Server Architecture
  • Client/Server Performance Issues
  • In contrast to the centralized system, a
    client/server design separates applications and
  • Distributed database management system (DDBMS)
  • The system is scalable, so new data sites can be
    added without reworking the system design
  • The system is less likely to experience
    catastrophic failure

Internet-Based Architecture
  • Developing E-Commerce Solutions In-House

Internet-Based Architecture
  • Packaged Solutions and E-commerce Service
  • Many vendors offer turnkey systems for companies
  • Another alternative is to use an application
    service provider (ASP)
  • Another option is managed hosting
  • Consider the experience of other companies in the
    same industry

Internet-Based Architecture
  • Corporate Portals
  • A corporate portal can provide access for
    customers, employees, suppliers, and the public
  • Cloud Computing
  • Effectively eliminates compatibility issues
  • Scaling on demand
  • Requires significantly more bandwidth

Internet-Based Architecture
  • Web 2.0
  • Envisions a second generation of the web that
    will enable people to collaborate, interact, and
    share information more dynamically
  • Wiki
  • Internet operating system

Processing Methods
  • Online Processing
  • Because it is interactive, online processing
    avoids delays and allows a constant dialog
    between the user and the system
  • Online processing also can be used with
    file-oriented systems

Processing Methods
  • Batch Processing
  • The IT operations group can run batch programs on
    a predetermined schedule, without user
    involvement, during regular business hours, at
    night, or on weekends
  • Require significantly fewer network resources
    than online systems

Processing Methods
  • Combined Online and Batch Processing

Network Models
  • The OSI Reference Model
  • The OSI model consists of seven layers
  • Each layer performs a specific function
  • Offers a set of design standards

Network Models
  • Network Protocols
  • In all cases, the network must use a protocol
  • Transmission Control Protocol/Internet Protocol
  • File Transfer Protocol (FTP)

Network Models
  • Network Topology
  • Hierarchical network
  • it mirrors the actual operational flow in the
  • One disadvantage of a hierarchical network is
    that if a business adds additional processing
    levels, the network becomes more complex and
    expensive to operate and maintain

Network Models
  • Network Topology
  • Bus network
  • Devices can be attached or detached from the
    network at any point without disturbing the rest
    of the network
  • Overall performance declines as more users and
    devices are added
  • Today, the bus design is much less popular

Network Models
  • Network Topology
  • Ring network
  • One disadvantage of a ring network is that if a
    network device fails (such as a PC or a server),
    the devices downstream from the failed device
    cannot communicate with the network
  • Multistation Access Unit (MAU)

Network Models
  • Network Topology
  • Star network
  • Disadvantage of the star design is that the
    entire network is dependent on the switch
  • However, in most large star networks, backup
    switches are available immediately in case of
    hardware failure

Network Models
  • Network Topology
  • Mesh network
  • While this design is extremely reliable, it also
    is very expensive to install and maintain
  • Originally developed for military applications

Network Models
  • Routers
  • Routers differ from switches in that they work at
    a higher OSI level
  • Can connect to a larger, dissimilar network, such
    as the Internet
  • Gateway
  • Proxy server

Network Models
  • Network Modeling Tools
  • As you translate the OSI logical model into a
    physical model of the networked system, you can
    use software tools
  • Network Licensing Issues
  • Software licensing restrictions

Wireless Networks
  • A wireless local area network, or WLAN
  • Wireless Network Standards
  • 802.11
  • Institute of Electrical and Electronics Engineers
  • Amendments
  • Mbps (megabits per second)

Wireless Networks
  • Wireless Network Standards
  • 802.11g
  • 802.11n
  • Multiple input/multiple output (MIMO)
  • Multipath design
  • 802.11y

Wireless Networks
  • Wireless Network Topologies
  • Basic Service Set (BSS) infrastructure mode
  • Access point
  • Extended Service Set (ESS)
  • Roaming
  • Independence Service Set (ISS) peer-to-peer mode

Wireless Networks
  • Wireless Trends
  • Wi-Fi Alliance
  • Wi-Fi (wireless fidelity)
  • BlueTooth
  • On addition to 802.11 protocols for LANs, IEEE is
    working on 802.16 standards
  • MANs (metropolitan area networks)
  • WiMAX

Systems Design Completion
  • System Design Specification
  • A typical system design specification uses a
    structure similar to the following
  • Management summary
  • System components
  • System environment
  • Implementation requirements
  • Time and cost estimates
  • Additional material

Systems Design Completion
  • User Approval
  • Users must review and approve the interface
    design, report and menu designs, data entry
    screens, source documents, and other areas of the
    system that affect them
  • Other IT department members also need to review
    the system design specification
  • When the system design specification is complete,
    you distribute the document to a target group of
    users, IT department personnel, and company

Systems Design Completion
  • Presentations
  • The first presentation is to the systems
    analysts, programmers, and technical support
    staff members
  • Your next presentation is to department managers
    and users from departments affected by the system
  • The final presentation is for company management
  • Management might reach one of three decisions
    proceed with systems development, perform
    additional work on the systems design phase, or
    terminate the project

Chapter Summary
  • An information system combines hardware,
    software, data, procedures, and people into a
    system architecture
  • The analyst must consider enterprise resource
    planning, initial cost and TCO, scalability, Web
    integration, legacy interface requirements,
    processing options, and security issues
  • An architecture requires servers and clients

Chapter Summary
  • Compared to file server designs, client/server
    systems are more scalable and flexible
  • In implementing a design, an analyst should
    consider e-commerce strategies, the availability
    of packaged solutions, and corporate portals,
    which are entrances to a multifunction Web site
  • The primary processing methods are online and
    batch processing

Chapter Summary
  • Networks allow the sharing of hardware, software,
    and data resources in order to reduce expenses
    and provide more capability to users
  • The way a network is configured is called the
    network topology
  • The system design specification presents the
    complete systems design for an information system
  • Chapter 10 complete
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