scis.regis.edu ● scis@regis.edu

CIS-425: Systems Analysis and Design

Week 6

Dr. Jesús BorregoLead Faculty, COSRegis University

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Class Outline•Questions on material covered•Key Terms•Chapter 10: System Architecture•Activity 1•Project Updates•Questions?

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Homework Questions

•Questions on homework or assignments?

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Questions on material covered?•How to create a web page?•How to create schedules with Project?•How to create diagrams with Visio?

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Key Terms

• See p. 491

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scis.regis.edu ● scis@regis.edu

Systems Analysis and Design 9th EditionChapter 10System 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

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Chapter Objectives

•Discuss the potential impact of cloud computing and Web 2.0

•Explain the difference between online and batch processing

•Define network topology, including hierarchical, bus, ring, and star models

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Chapter Objectives

•Explain network protocols and licensing issues

•Describe wireless networking, including wireless standards, topologies, and trends

•Describe the system design specification

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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, and processing methods

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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

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System Architecture Checklist

•Scalability▫Scalability, also called extensibility, refers

to a system’s ability to expand, change or downsize easily to meet the changing need of a business enterprise

▫Especially important in implementing systems that are volume-rated, such as transaction processing systems

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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

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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 compatibility

▫The analyst must know if the new application eventually will replace the legacy system

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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

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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 concerns

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Planning the Architecture• Servers

▫ Server▫ Clients▫ Mainframe architecture▫ Server-based processing

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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 applications

▫Companies linked the stand-alone computers into networks

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Planning the Architecture• Clients

▫ Stand-Alone Computing▫ Local and wide area

networks▫ Client-based processing

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Client/Server Architecture•Overview

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Client/Server Architecture

•Client/Server Design Styles

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Client/Server Architecture•Fat and Thin Clients

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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 applications

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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

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Client/Server Architecture

• Client/Server Performance Issues– In contrast to the centralized system, a

client/server design separates applications and data

–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

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Activity 1• 1 hour video: Take notes• Anatomy of a Design Decision (65:29 min.):

http://video.esri.com/watch/2228/keynote-address-anatomy-of-a-design-decision

• Write the top 3 topics/ideas (3 good, 3 bad) that stuck in your mind

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

House

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Internet-Based Architecture

•Packaged Solutions and E-commerce Service Providers▫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

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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

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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

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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

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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

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Processing Methods•Combined Online and Batch Processing

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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

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Network Models

•Network Protocols▫In all cases, the network must use a

protocol▫Transmission Control Protocol/Internet

Protocol (TCP/IP)▫File Transfer Protocol (FTP)

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Network Models

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• Network Topology▫ Hierarchical network

it mirrors the actual operational flow in the organization

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

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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)

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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

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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

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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

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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

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Wireless Networks

•A wireless local area network, or WLAN•Wireless Network Standards

▫802.11▫Institute of Electrical and Electronics

Engineers (IEEE)▫Amendments▫Mbps (megabits per second)

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Wireless Networks

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

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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

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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

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Systems Design Completion

•System Design Specification▫A typical system design specification uses a

structure similar to the following:1. Management summary2. System components3. System environment4. Implementation requirements5. Time and cost estimates6. Additional material

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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 management

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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

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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

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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 processing51

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

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Activity 2• 3 Web Design Tips (5:19 min.):

http://www.youtube.com/watch?v=Kkg0Jx72M48

• What Makes Good Web Design? (2:05 min.): http://www.youtube.com/watch?v=UHpyES6Jbx0

• Web Design Mock-Up Walk-Through (9:43 min.): http://www.youtube.com/watch?v=kBTx7VP66Go

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Activity 3• Top Level Design Activities:

▫ Process Design▫ Network Design▫ Database Design▫ Web Design▫ Form Design▫ Report Design

• Detailed Design Activities:▫ Next level for each

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Project tasks

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Class Phase Description Activity

1 Introduction Problem StatementPrepare interview questions

2 Project Scope Determine projectConduct Customer Interview

3 Requirements Project Specification Present project scope to customer

4Top Level Design Determine design

Specification to customer

5 Detailed DesignDevelop components Top level design6 Architecture Final Proposal Detailed design7 Management Complete project Final Project design

8 ImplementationFinal Project Presentation

Final Project presentation

Questions?

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