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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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