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Chapter 8. PHASE 3: SYSTEMS DESIGN. 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

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chapter 8

Chapter 8

PHASE 3: SYSTEMS DESIGN

System Architecture

chapter objectives
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 considerations
  • Describe the impact of the Internet on system architecture
chapter objectives1
Chapter Objectives
  • Explain the difference between online and batch processing
  • Define network topology, and provide examples of hierarchical, star, bus, and ring network models
  • Explain network protocols and licensing issues
chapter objectives2
Chapter Objectives
  • Explain system management tools and techniques, including performance measurement, fault management, backup, and disaster recovery
  • Describe the systems design specification and explain the contents of each section
introduction
Introduction
  • 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, processing methods, and security
system architecture checklist
System Architecture Checklist
  • A systems analyst must approach system architecture with an overall checklist
    • Enterprise resource planning (ERP)
    • Initial and total cost of ownership (TCO)
    • Scalability
    • Web integration
    • Legacy system interface requirements
    • System security
    • Processing options
system architecture checklist1
System Architecture Checklist
  • Enterprise Resource Planning (ERP)
    • The objective of ERP is to establish a company-wide strategy for using IT resources
    • Describes environment – platform
    • Supply chain management
  • 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 checklist2
System Architecture Checklist
  • Initial Cost and TCO
    • Ask questions like the following
      • Is in-house development still best choice?
      • Is specific package still best choice?
      • New outsourcing available?
      • New technology available?
    • Answers might affect the initial cost and TCO for the proposed system
system architecture checklist3
System Architecture Checklist
  • Scalability
    • Scalability, also called extensibility
    • Especially important in implementing systems that are volume-related, such as transaction processing systems
  • Web Integration
    • An information system includes application programs, also called applications
    • Web-centric
system architecture checklist4
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 legacy systems involves analysis of data formats and compatibility
    • The analyst must know if the new application eventually will replace the legacy system
system architecture checklist5
System Architecture Checklist
  • Processing Options
    • Online or Batch
    • 24/7
    • Backup and Recovery
system architecture checklist6
System Architecture Checklist
  • Security Issues
    • Security is a concern at every stage of system development
    • The systems analyst must consider security issues that relate to system design specifications and determine how the company will address them
    • Web-based systems introduce additional security concerns
planning the architecture
Planning the Architecture

Every information system involves 3 main functions:

  • Data Storage and Access Methods
  • Application Programs
  • Interface

The 3 functions may be performed on a …

  • Server OR
  • Client OR
  • Divided between Server and Client
client server architecture
Client/Server Architecture
  • Today’s interconnected world requires an information architecture that spans the entire enterprise
  • Whether you are dealing with a departmental network or a multinational corporation, as a systems analyst you will work with a distributed computing strategy called client/server architecture
client server architecture1
Client/Server Architecture

Overview

  • Client/server architecture
client server architecture2
Client/Server Architecture

Client/Server Design Styles

  • Many forms
  • Database Server
  • Transaction Server
  • Web Server
client server architecture3
Client/Server Architecture

Types of Clients: Fat and Thin

  • Fat client - Thick client
  • Thin client

Comparison:

Thin  better performance

Thick  more processing

client server architecture4
Client/Server Architecture

Client/Server Tiers

  • Two-tier design
  • Three-tier design
  • Middle layer
client server architecture5
Client/Server Architecture

Middleware -Cost-Benefit Issues

  • Scale the system

http://www.centene.com/investors/annual_reports

  • Transfer applications
  • Improve response times
client server architecture6
Client/Server Architecture

Client/Server Performance Issues

  • Separation of server-based data and networked clients
  • Separates applications and data
  • Client contacts server only when necessary
  • Distributed Database Management System (DDBMS)
internet based architecture
Internet-Based Architecture
  • The Internet has had an enormous impact on system architecture
  • To support this trend, systems analysts must suggest e-commerce strategies that apply available technology and meet their company’s business requirements
internet based architecture1
Internet-Based Architecture
  • Developing E-Commerce Solutions In-House
    • If you decide to proceed with an in-house solution, you must have an overall plan to help achieve your goals
    • An in-house solution usually requires a greater initial investment, but provides more flexibility for a company that must adapt quickly in a dynamic e-commerce environment
internet based architecture2
Internet-Based Architecture
  • Packaged Solutions and E-Commerce Service Providers
    • Turnkey systems
    • Application service provider (ASP)
    • Does lower initial cost outweigh disadvantage of reduced flexibility?
internet based architecture3
Internet-Based Architecture
  • Corporate Portals
    • A portal is an entrance to a multifunction Web site
    • A corporate portal can provide access for customers, employees, suppliers, and the public
network models
Network Models

The OSI Reference Model – consists of 7 layers

  • Application layer
  • Presentation layer
  • Session layer
  • Transport layer
  • Network layer
  • Data link layer
  • Physical layer
network models1
Network Models

Network Topology

  • Hierarchical network
network models2
Network Models

Network Topology

  • Star network
network models3
Network Models

Network Topology

  • Bus network
network models4
Network Models

Network Topology

  • Ring network
network models5
Network Models

Network Topology

  • Other topologies

http://compnetworking.about.com/od/networkdesign/a/topologies.htm

network models6
Network Models

Network Protocols and Licensing Issues

  • The network must use a protocol
  • A popular network protocol is Transmission Control Protocol/Internet Protocol (TCP/IP)
  • A familiar example of a TCP/IP protocol is the file transfer protocol (FTP)
systems design completion
Systems Design Completion

System Design Specification

  • Baseline
  • Contents vary depending on company standards
  • You do not have to turn this in
systems design completion1
Systems Design Completion

User Approval of …

  • Interface design
  • Report and menu designs
  • Data entry screens
  • Source documents
  • Other
systems design completion2
Systems Design Completion

Presentations

  • Systems analysts, programmers, technical staff
  • Department managers and users
  • Company management
  • Objective: Obtain management’s approval/support
chapter summary
Chapter Summary
  • The analyst must consider enterprise resource planning, initial cost and TCO, scalability, Web integration, legacy interface requirements, security, and processing options
  • System security is an important concern
  • An architecture requires servers and clients
  • Compared to file server designs, client/server systems are more scalable and flexible
chapter summary1
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

Any questions?

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