Systems Analysis and Design Alan Dennis and Barbara Haley Wixom John Wiley & Sons, Inc. Slides by Fred Niederman PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

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Architecture Design Chapter 9 PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Key Definitions The architecture design consists of plans for the hardware, software, communications, security , and global support for the new application The designers must decide if processing will occur in the server (server-based), at the personal computer (client-based), or in some combination of these (client-server based). PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Key Definitions The network model shows major components of the system, where they are located and how they will be connected to one another. The hardware and software specifications describe these components in detail and aid those responsible for purchase and acquisition of these products. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Computing Architectures PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Functions of the Application System Data storage Data access logic Application logic Presentation logic PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Architectures Server based Client based Client-server based PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Alternative Servers Mainframe Minicomputer Microcomputer (personal computer) PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Alternative Clients Terminals Microcomputer (personal computer) Special purpose terminals (ATMs, kiosks, Palm Pilots, and many others) PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Server-Based Computing PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Client-Based Computing PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Client-Server-Based Computing PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Client-Server Attributes Typical Pros Compatible with web-based system design Scaleable Work with multiple vendors/products No central point of failure Typical Cons/Limits Complexity New programming languages and techniques (stress for personnel) More complex to update PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Client-Server -- Three Tiers PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Client-Server -- Four Tiers PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

N-Tiered Client-Server Attributes Typical Pros Separates processing to better balance load More scaleable Typical Cons/Limits Greater load on the network More difficult to program and test PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Your Turn Consider the course registration system at your university: What computing architecture does it use? What computing architecture would you use if you were replacing it today? PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Infrastructure Design PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Realities of Infrastructure Design Most often the infrastructure will be in place Coordination of infrastructure components is very complex The application developer will need to coordinate with infrastructure specialists PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

The Network Model No standard format Conveys complexity of the system and how components fit together Components are clients equipment connection to external systems or networks PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Top-Level Network Model PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Hardware and Software Specification Used if new hardware or software must be purchased Actual acquisition of hardware and software usually left to a purchasing department -- especially in larger firms PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Steps in Hardware and Software Specification Note hardware in low-level network model to create list of needed hardware Describe equipment in as much detail as possible Consider whether increased processing and traffic will absorb unused hardware capacity Note all software running on each hardware component PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Global Issues PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Global Requirements Multilingual requirements Concurrent multilingual systems Discrete multilingual systems Local versus centralized control Unstated norms (e.g. dates, currency) 24-7 Support Communications infrastructure PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Security PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Identifying Threats to the System A threat is any potential adverse occurrence that can do harm to the application or its data Threats come from internal as well as external sources Categories of threats Disruptions, destruction and disaster Unauthorized access PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Most Common Threats PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Assessing the Risk of Each Threat PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Creating Controls A control is something that mitigates or stops a threat Controls include redundancy fault tolerant servers disaster recovery plans anti-virus software PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Additional Controls Include A security policy Passwords and encryption Firewalls PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Explain your preference. CD Selections What sort of computer architecture would you recommend for CD Solutions? Explain your preference. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Summary The three fundamental computing architectures are server-based, client-based, and client-server based. The network model shows technical components of the system and their geographic location throughout the organization. Hardware and software must be specified for acquisition in the project The systems analyst needs to also account for global issues and security measures. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.