Principles of Information Systems Eighth Edition

1
Principles of Information SystemsEighth Edition

• Chapter 13
• Systems Development Design, Implementation,
  Maintenance, and Review

2
SDLC
3
Systems Design

• Answers the question how will the information
  system solve a problem?
• Results in a technical design
• Details system outputs, inputs, and user
  interfaces
• Specifies hardware, software, databases,
  telecommunications, personnel, and procedures

4
Logical and Physical Design

• Logical design
• Description of functional requirements of a
  system
• Independent of a platform
• Physical design
• Specification of characteristics of system
  components necessary to put logical design into
  action
• Characteristics of hardware, software, database,
  telecommunications, and personnel

5
OOD

• Object-Oriented Design
• Designing key objects and classes of objects in
  new or updated system
• Also, interface design, etc.
• Determines sequence of events that must happen
  for the system to function correctly
• Sequence diagram
• Illustrates a scenario sequence of events

6
OOD
Figure 13.1 A Sequence Diagram to Add a New
KayakItem Scenario First, Create arrow is a
message from clerk to KayakItem object to create
a new kayak for rental KayakItem requests kayak
ID getID Then, clerk types in ID KayakItem
requests getDatePurchased Finally, datePurchased
is transferred to KayakItem object
7
Generating Systems Design Alternatives

• Consider many factors when selecting a vendor
• Reliability, stability, services, reviews, etc.
• Request for proposal (RFP)
• Document that specifies required resources such
  as hardware and software in detail
• Pick the best proposal
• Evaluation technique
• e.g. cost/benefit analysis

8
SDLC
9
SystemsImplementation
10
Hardware Software Acquisition

• Database systems (e.g. Oracle, etc.)
• Telecommunications hardware and software
• Make or buy?
• Buying
• Commercial off-the-shelf (COTS) development
  process
• Leasing/renting
• Salesforce.com rents apps
• Application service provider (ASP)
• DB and ERP

11
User Preparation

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

12
IS Personnel Hiring and Training

• Personnel that might be needed for new system
• IS manager
• Systems analysts
• Computer programmers
• Data-entry operators
• Training programs should be conducted for IS
  personnel who will be using the system

13
Site and Data Preparation

• Site preparation
• Preparation of the location of a new system
• Data Preparation
• Also called data conversion
• Ensuring all files and databases are ready to be
  used with new computer software and systems
• Avoid conversion at wrong times for a given
  industry
• Retail sales, bad time when?

14
Installation

• Process of physically placing computer equipment
  on the site and making it operational
• Normally, manufacturer is responsible for
  installing computer equipment

15
Testing

• Unit testing
• Testing of individual programs
• System testing
• Testing 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 user

16
Testing (continued)

• Alpha testing
• Testing an incomplete or early version of system
• Beta testing
• Testing a complete and stable system by end users

17
Start-Up

• Process of making the final tested information
  system fully operational
• Approaches
• Direct conversion (plunge, direct cutover)
• Phase-in approach (piecemeal)
• Pilot start-up
• Parallel start-up

18
Start-Up (continued)
Figure 13.13 Start-Up Approaches
19
Start-Up (continued)
Figure 13.13 Start-Up Approaches (continued)
20
User Acceptance

• User acceptance document
• Formal agreement signed by user
• States that the system is approved
• Legal document that removes or reduces IS
  vendors liability

21
SDLC
22
Systems Operation and Maintenance

• Systems operation
• Use of a new or modified system
• Help desk provides support
• Systems maintenance
• Checking, changing, and enhancing the system to
  make it more useful in achieving user and
  organizational goals
• Difficult and costly for legacy systems
• Autonomic computing allows computers to manage
  themselves

23
Types of Maintenance

• Slipstream upgrade
• Minor upgrade (minor bug)
• Patch
• Fix a problem or make small enhancement
• e.g. addition
• Release
• Significant program change requiring new
  documentation
• Version
• Major program change with many new features

24
The Financial Implications of Maintenance

• Total maintenance expenditures increase in time
  and money as programs age
• For older programsCost of maintenance 5x total
  cost of development
• Determining factor in decision to replace a
  system
• Costs more to fix than replace system

25
Figure 13.14 Maintenance Costs as a Function of
Age
26
The Relationship Between Maintenance and Design

• More time and money spent on design less time
  and money spent on maintenance

Figure 13.15 The Value of Investment in Design
27
Systems Review

• Analysis of systems to make sure that they are
  operating as intended
• Often compares performance and benefits of
  designed system with operational system
• Event-driven review results when
• Problem with an existing system
• Executive decision to upgrade website to stay
  competitive
• Merger
• Time-driven review
• Monthly, yearly, every 5 years, etc.