Chapter 13:

Systems Design, Implementation, Maintenance,

and Review

Agenda Systems Design Systems Implementation Systems Maintenance Systems Review Systems Performance Measurement

Systems DesignA phase in the development of an IS system that answers the question “How will the information system do what it must do to obtain a solution to a problem?”

Logical Systems Design describes the functional requirements of a systems.

Physical Systems Design specifies the characteristics of the system components necessary to put the logical design into action.

Logical Design Elements Output design describes types, format, content and

frequency of all outputs from the system Input design specifies the types, format, content and

frequency of input data Processing design defines the manipulation required for

processing File and database design specifies files and databases (i.e.,

ER diagrams) Telecommunications design (i.e., topologies) Procedures design to operate the system Controls and security design (i.e., disaster recovery) Personnel and job design (i.e., job titles, positions)

Physical Design Elements Hardware design specifies all computer equipment Software design specifies all software capabilities Database design specifies the type, structure, and function

of the database Telecommunications design includes the characteristics of

the communications software, media, and devices Personnel design specifies the background and experience

of individuals Procedures and control design specifies how each

application is to run and what has to be done to minimize the potential for crime and fraud

Design of Procedures for Signing On Sign-on Procedures are safeguards needed for an

individual to gain access to computer resources– Systems Sign-on allows user to gain access to the computer

system

– Application Sign-on permits the user to start and use a particular application

Design for Interactive ProcessingPeople interact directly with the processing component of the

system In menu-driven systems, users pick what they want to do

from a list of alternatives Help Facility is a tool that aids a user who is having

difficulty understanding what is happening or what type of response is expected

Restart Procedures are procedures that make it very simple for an individual to restart an application from where one left off

Lookup Tables are tables within an application that simplifies and shortens data entry

Design for Interactive Dialogue Dialogue is the series of messages and prompts

communicated between the system and the user. These design elements should be considered during systems design:– Clarity

– Response time

– Consistency

– Format

– Jargon

Design for Preventing, Detecting, and Correcting Errors

Best time to deal with potential errors is at the beginning of design rather than in the late part of design, or during implementation.

Design for Emergency Alternative Procedures and Disaster RecoveryDisaster Recovery is the implementation of the disaster plan. Hardware Backup

– Hot Site is a duplicate computer system that is operational and ready for use

– Cold Site (Shell) is a computer environment that includes rooms, electrical service, telecommunications links, data storage devices

Software and database backup– Selective backup copies of only certain files– Incremental backup copies all files changed during the last few

days or the last week– Image Log is a separate file that contains only changes to

applications Telecommunications backup Personnel backup Security, fraud, and the invasion of privacy

Systems Controls System controls are procedures to maintain data security

and can help prevent: – Computer misuse

– Crime

– Fraud

Deterrence Controls are rules that prevent problems before they occur (input, output, processing, telecommunication, personal controls)

Information system departments are closed shops when only authorized operators can run the computers

In open shops, non-operators, such as programmers and systems analysts, are authorized to run the computers

Evaluation Techniques In Group Consensus, a decision-making group is appointed

and given the responsibility of making the final evaluation and selection

Cost/Benefit Analysis lists the costs and benefits of each proposed system

Benchmark Test is an examination that compares computer systems operating under the same conditions

In Point Evaluation, each evaluation factor is assigned a weight, in percentage points, based on importance; the system with the greatest total score is selected.

Design Report The Design Report reflects the decisions made for system design and prepares the way for systems implementation.

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The Value of Investment in Design

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Systems Implementation Systems Implementation includes:

Hardware/Software acquisition or development User preparation Hiring and training of personnel Site and data preparation Installation Testing Start-up User acceptance.

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Financial Options to Acquire SystemsAdvantages Disadvantages

Buying Cheaper than leasing or rentingAbility to change systemTax advantagesFull control

High initial costRisk of obsolescenceRisk of being stuck if choice is wrongFull responsibility

Leasing No capital is tied upNo financing requiredLeasing is cheaper than rental

Do not own systemHeavy penalty for terminating leaseMore expensive than buying

Renting No capital is tied upNo financing requiredEasy to change systemsMaintenance and insurance usually included

Do not own systemCost is high

The Make-or-Buy Software Decision Building Own Software

– IS educated staff

Buying Software – Review needs of requirements

– Acquire software

– Modify or customize software

– Acquire software interfaces

– Test and accept the software

– Maintain the software and make necessary modifications

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Programming Life Cycle Programming Life Cycle is a series of steps and planned activities developed to maximize the likelihood of developing good software:– Language selection

– Program coding

– Testing and debugging

– Developing documentation

– Implementation or conversion

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Documentation Technical Documentation

– Used by computer operators to execute the program and by analysts and programmers in case there are problems with the program or if the program needs modification.

User Documentation– Developed for the individuals who use the program. This type of

documentation shows users, in easy-to-understand terms, how the program can and should be used.

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Tools and Techniques for Software Development

Structured design breaks a large, difficult problem into smaller problems, each simple enough to manage and solve independently

Structured Programming a way of developing code that provides structure within the program so that testing and maintenance tasks are facilitated.

Object-Oriented Development is the development of a collection of existing modules of code or objects than can be used across any number of applications without being rewritten.

Computer Aided Software Engineering (CASE) Cross-Platform Development allows programmers to develop programs

that can run on computer systems having different hardware and operating systems

Integrated Development Environments (IDEs) are software packages that combine the tools needed for programming with a programming language into one integrated package

A Structured Walkthrough is a planned and pre-announced review of the progress of a program module, a structure chart, or a human procedure

Types of Testing

Testing of individual programs.

Testing the entire system of programs.

Testing the application with a large amount of data.

Testing all related systems together.

Conducting any tests required by the user.

Start-Up Approaches

Start-Up Approach Procedures that begin with the final tested information system; when start-up is finished, the system will be fully operational.

Reasons for MaintenanceSystems Maintenance involves checking, changing, and enhancing the system to make it more useful in achieving user and organizational goals.

Changes in business processes New requests from stakeholders, users, and managers Bugs or errors in the program Technical and hardware problems Corporate mergers and acquisitions Government regulations Change in operating system or hardware on which the

application runs

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Type of Maintenance Slipstream Upgrade is a minor upgrade not worth

announcing. A Patch is a minor change to correct a problem or make a

small enhancement. A Release is a significant program change that often

requires changes in the documentation. A Version is a major program change, typically

encompassing many new features.

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Maintenance Costs as a Function of Age

Systems Review Systems Review is the process of analyzing systems to

make sure they are operating as intended. An Event-Driven Review is triggered by a problem or

opportunity such as an error, a corporate merger, or a new market for products

A Time-Driven Review is a review of all systems that is performed after a specified amount of time.

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Systems Performance Measurement Systems Performance Measurement is a systems review

that involves monitoring the system -- the number of errors encountered, the amount of memory required, the amount of processing or CPU time needed, and other problems.

System Performance Products are products developed to measure all components of the computer-based information system, including hardware, software, database, telecommunications, and network systems.

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Systems Development Alternatives Request for proposal Vendor evaluation

– Reliability

– Financial stability

– Service

– Maintenance

– Training

Points to Remember Systems Design Systems Implementation Systems Maintenance Systems Review Systems Performance Measurement

Pop Quiz Name the design to describe the functional requirements of a systems. Name the design to specify the characteristics of the system

components. Name the design to specify the characteristics of the communications

software, media, and devices. Name the procedures to safeguard the access to computer resources. Name two backup methods for hardware equipments. Name three backup methods for software programs and database. Name the evaluation technique using a evaluation factor based on the

importance. Name three financial options to acquire systems. Name the review triggered by a problem or opportunity. Name the systems review to monitor the system.

Pop Quiz Answer Name the design to describe the functional requirements of a systems.

Logical Name the design to specify the characteristics of the system

components. Physical Name the design to specify the characteristics of the communications

software, media, and devices. Telecommunication Name the procedures to safeguard the access to computer resources.

Sign on Name two backup methods for hardware equipments. Hot site, cold

site Name three backup methods for software programs and database.

Selective, incremental, image Name the evaluation technique using a evaluation factor based on the

importance. Point evaluation Name three financial options to acquire systems. Buy, lease, rent Name the review triggered by a problem or opportunity. Event driven Name the systems review to monitor the system. System performance

measurement