Principles of Information Systems, Seventh Edition2 Designing new systems or modifying existing ones...

Principles of Information Systems, Seventh Edition 2

• Designing new systems or modifying existing ones should always be aimed at helping an organization achieve its goals

• State the purpose of systems design and discuss the differences between logical and physical systems design

• Describe some considerations in design modeling and the diagrams used during object-oriented design

• Outline key considerations in interface design and control and system security and control.

• Define the term RFP and discuss how this document is used to drive the acquisition of hardware and software.

• Describe the techniques used to make systems selection evaluations


• The primary emphasis of systems implementation is to make sure that the right information is delivered to the right person in the right format at the right time

• State the purpose of systems implementation and discuss the various activities associated with this phase of systems development

• List the advantages and disadvantages of purchasing versus developing software

• Discuss the software development process and some of the tools used in this process, including object-oriented program development tools


• Maintenance and review add to the useful life of a system but can consume large amounts of resources. These activities can benefit from the same rigorous methods and project management techniques applied to systems development.

• State the importance of systems and software maintenance and discuss the activities involved

• Describe the systems review process


Systems Design

• Answers the question “How will the information system do what it must do to solve a problem?”

• Has two dimensions: logical and physical

• Logical design: description of the functional requirements of a system

• Physical design: specification of the characteristics of the system components necessary to put the logical design into action


Logical Design

• Output requirements

• Input requirements

• Process requirements

• File and database requirements


Logical Design (continued)

• Telecommunications requirements

• Procedure requirements

• Controls and security requirements

• Personnel and job requirements


Physical Design

• Hardware specifications

• Software specifications

• Database specifications


Physical Design (continued)

• Telecommunications specifications

• Personnel specifications

• Procedure and control specifications


Object-Oriented Design

• Design key objects and classes of objects in the new or updated system

• Consideration of the problem domain, the operating environment, and the user interface

• Consideration of the sequence of events that must happen for the system to function correctly

• A sequence of events is often called a scenario

• A scenario can be diagrammed in a sequence diagram


Figure 13.4: The Levels of the Sign-On Procedure


Interface Design and Controls (continued)

• Interactive processing

• Menu-driven systems

• Help commands

• Table lookup facilities

• Restart procedures


Table 13.1: The Elements of Good Interactive Dialogue


Design of System Security and Controls

• Preventing, detecting, and correcting errors

• Disaster planning and recovery

• Disaster planning: the process of anticipating and providing for disasters

• Disaster recovery: the implementation of the disaster plan

• Hardware backup


Design of System Security and Controls (continued)

• Disaster planning and recovery (continued)

• Software and database backup

• Telecommunications backup

• Personnel backup

• Systems controls: rules and procedures to maintain data security


Generating Systems Design Alternatives

• Request for proposal (RFP): a document that specifies in detail required resources such as hardware and software

• Financial options


Evaluating and Selecting a Systems Design

• Preliminary evaluation

• To dismiss the unwanted proposals

• Begins after all proposals have been submitted

• Final evaluation

• A detailed investigation of the proposals offered by the vendors remaining after the preliminary evaluation


Figure 13.7: The Stages in Preliminary and Final Evaluations


Evaluation Techniques

• Group consensus

• Cost/benefit analysis

• Benchmark tests

• Point evaluation


Figure 13.8: An Illustration of the Point Evaluation System


Figure 13.9: Freezing Design Specifications


The Design Report

• Primary result of systems design

• Reflects the decisions made and prepares the way for systems implementation


Figure 13.11: Typical Steps in Systems Implementation


Acquiring Hardware from an IS Vendor

• An IS vendor is a company that offers hardware, software, telecommunications systems, databases, IS personnel, and/or other computer-related resources

• Buying computer hardware

• Leasing computer hardware

• Renting computer hardware

• “Pay-as-you-go,” “on-demand,” or “utility” computing


Acquiring Software: Make or Buy?

• Externally developed software: lower cost, lower risk, ease of installation

• In-house developed software

• Meeting user and organizational requirements

• More features and increased flexibility in terms of customization and changes


Acquiring Software: Make or Buy? (continued)

• In-house developed software (continued)

• Greater potential for providing a competitive advantage

• Chief programmer teams

• The programming life cycle

• Tools and techniques for software development


Figure 13.13: Steps in the Programming Life Cycle


Tools and Techniques for Software Development

• Structured programming

• Improving the logical program flow by breaking the program into groups of statements, called structures

• CASE tools: used during software development to automate some of the techniques

• Object-oriented implementation

• A collection of existing modules of code, or objects, can be used across a number of applications


Tools and Techniques for Software Development (continued)

• Cross-platform development: allows programmers to develop programs that can run on computer systems having different hardware and operating systems, or platforms

• Integrated development environment: combines the tools needed for programming with a programming language into one integrated package

• Structured walkthrough: a planned and preannounced review of the progress of a program module, a structure chart, or a human procedure


Acquiring Database and Telecommunications Systems

• Relational databases

• Object-oriented database systems

• Databases are a blend of hardware and software

• Telecommunications systems require a blend of hardware and software


User Preparation

• Readying managers, decision makers, employees, other users, and stakeholders for new systems

• Training users


IS Personnel: Hiring and Training

• IS manager

• Systems analysts

• Computer programmers

• Data-entry operators


Site Preparation

• Preparation of the location of a new system

• Making room for a computer in an office

• Special wiring and air conditioning

• Special floor

• Additional power circuits


Data Preparation

• Also called data conversion

• Ensuring all files and databases are ready to be used with new computer software and systems


Installation

• The process of physically placing the computer equipment on the site and making it operational

• Normally the manufacturer is responsible for installing computer equipment

• Someone from the organization (usually the IS manager) should oversee the process


Testing

• Unit testing: testing of individual programs

• System testing: testing the entire system of programs

• Volume testing: testing the application with a large amount of data

• Integration testing: testing all related systems together

• Acceptance testing: conducting any tests required by the user


Start-Up

• The process of making the final tested information system fully operational

• Direct conversion (also called plunge or direct cutover)

• Phase-in approach

• Pilot start-up

• Parallel start-up


User Acceptance

• User acceptance document: formal agreement signed by the user that states that a phase of the installation or the complete system is approved


Systems Operation and Maintenance

• Systems operation: use of a new or modified system

• Systems maintenance: checking, changing, and enhancing the system to make it more useful in achieving user and organizational goals


Types of Maintenance

• Slipstream upgrade

• Patch

• Release

• Version


Figure 13.19: Maintenance Costs as a Function of Age


Figure 13.20: The Value of Investment in Design


Systems Review

• Process of analyzing systems to make sure that they are operating as intended

• Often compares the performance and benefits of the system as it was designed with the actual performance and benefits of the system in operation

• Event-driven review: review triggered by a problem or opportunity such as an error, a corporate merger, or a new market for products

• Time-driven review: review performed after a specified amount of time


Factors to Consider During Systems Review

• Mission

• Organizational goals

• Hardware and software

• Database

• Telecommunications


Factors to Consider During Systems Review (continued)

• Information systems personnel

• Control

• Training

• Costs

• Complexity


Factors to Consider During Systems Review (continued)

• Reliability

• Efficiency

• Response time

• Documentation


Summary

• Systems design answers the question “How will the information system do what it must do to solve a problem?”

• Systems design has two dimensions: logical and physical

• Logical design is description of the functional requirements of a system

• Physical design is specification of the characteristics of the system components necessary to put the logical design into action


Summary (continued)

• Steps of systems implementation: hardware acquisition, software acquisition, user preparation, personnel: hiring and training, site preparation, data preparation, installation, testing, start-up, and user acceptance

• Systems operation is the use of a new or modified system

• Systems maintenance involves checking, changing, and enhancing the system to make it more useful in achieving user and organizational goals


Summary (continued)

• Systems review is the process of analyzing systems to make sure that they are operating as intended

• Event-driven review is triggered by a problem or opportunity such as an error, a corporate merger, or a new market for products

• Time-driven review is performed after a specified amount of time

Principles of Information Systems, Seventh Edition2 Designing new systems or modifying existing ones...

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