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Chapter 10 Systems Development © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke.
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Transcript of Chapter 10 Systems Development © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke.
Chapter 10
Systems Development
© 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
10-2 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
This Could Happen to You
Dee wanted to develop a blog for communication– Focused goal– Short time frame– Was successful because system was simple
Single contributor No user training
RFID at DSI more sophisticated– Vendors would need to place RFID chips– Computer program would be needed to process data
10-3 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Study Questions
What is systems development? Why is systems development difficult and risky? What are the five phases of the systems development life
cycle? How is systems definition accomplished? What is the user’s role in the requirements phase? How are the five components designed? How is an information system implemented? What are the tasks for systems maintenance? What are the problems with SDLC? How does the knowledge from this chapter help DSI?
10-4 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Systems Development
Systems analysis and design Process of creating and maintaining information
systems– Development involves all five components– Requires more than programming or technical expertise
Human relation skills Business knowledge Understanding of group dynamics
Information systems are never off-the-shelf– Must be adapted to fit needs of business and people
10-5 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
MIS in Use: Thinking Big about Systems Development
Large scale corporate information systems are more complex
– Need to ensure all employees are working toward same goals
– Must develop system that will function consistently in different languages
– May need to store information on worldwide use of product and the relevant laws
Most information systems are process-design oriented
Must be carefully planned and executed
10-6 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Major Development Challenges
Difficulty of determining requirements Requirements change as system develops Scheduling and budgeting difficult to estimate
– Change as scope changes Technology changes Diseconomies of scale
– Brook’s Law
10-7 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Systems Development Processes
Methodologies:– Systems development life cycle (SDLC)– Rapid application development (RAD)– Object-oriented systems development (OOD)– Extreme programming (XP)
No single process works in all situations– Different requirements– Some systems wholly automated, others not
Use augmentation system to fill gaps
10-8 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
SDLC
Classical process with five phases:– Systems definition
Management’s statement defines new system– Requirements analysis
Identify features and functions– Component design
Based on approved user requirements– Implementation
Implement, test, and install new system– System maintenance
Repair, add new features, maintain
10-9 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Phases in SDLC
Figure 10-2
10-10 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Systems Definition
Define goals and purpose for new system– Must facilitate organization’s competitive strategy– Supports business processes – Improves decision making
Determine project’s scope– May be delineated by users, processes, or facilities
Assess feasibility of project– Cost– Schedule– Technical– Organizational feasibility
10-11 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Systems Definition, continued
If deemed feasible, project team created from IT personnel and users– Managers– Systems analysts– Programmers and software testers– Users
10-12 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Ethics Guide: Estimation Ethics
Buy-ins – Companies agree to produce products for less
than it knows will be required “Time and materials” contracts Fixed-cost contracts
– In-house projects are often started with buy-ins Projects started with hopes of more money later Team members may disagree about costs Not all costs may have been included in estimate
– Also may have buy-in on schedule
10-13 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Requirements Analysis Phase
Determine and document features and functions– Interview users – Document requirements
Examine existing system Review reports, forms, queries, application features Security and controls
Approve requirements Less expensive to change system in this phase
10-14 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Designing Components
Develop and evaluate alternatives– Accurate requirements critical
Hardware design determined by project team Software design depends on source
– Off-the-shelf– Off-the-shelf with alterations– Custom-developed programs
Data model converted to database design Procedures designed for BI system Job descriptions created for users and operations
personnel
10-15 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Information System Implementation
System must be built – Components constructed independently– Document and review
System testing– Individual components tested – System integrated and tested
Users must be converted to new system
10-16 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Systems Testing
Test plan– Sequences of actions that users take when employing
system– Both normal and incorrect actions should be considered– Labor intensive
Product quality assurance (PQA)– Testing specialists
Beta testing– Future system users try out system on their own
10-17 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
System Conversion
Converting business activity from old system to new– Pilot
Organization implements entire system on single, limited unit If systems fails, it only affects limited boundary Reduces exposure
– Phased New system installed in phases Tested after each phase Continues until installed at entire organization Can’t be used in tightly integrated systems
10-18 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
System Conversion, continued
– Parallel New system runs in parallel with old system during
testing Expensive and time consuming Data must be entered twice Provides easy fallback position
– Plunge Direct installation Install new system and discontinue old There is no backup position
10-19 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Systems Maintenance
Fixing or adapting system– Need method to track system failures and
enhancements– Corrections usually prioritized based on severity– Enhancements usually prioritized based on
business decision Must generate reasonable rate of return Decision to restart systems development process
10-20 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Problems With SDLC
SDLC waterfall– Phases are not supposed to be repeated– Often teams have need to repeat requirements and/or
design phases
Difficulty in documenting requirements– Analysis paralysis or uncertain requirements
Scheduling and budget difficulties– Multiyear projects difficult to properly schedule– Estimations on labor often produce insufficient budgets
10-21 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Guide: The Real Estimation Process
Estimating is just theory Project managers sum up estimates and take
to management Management then negotiates the schedule
and budget– Every change will negatively impact the project
Start with optimistic schedules and end up with late projects
10-22 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
How Does the Knowledge from This Chapter Help You at DSI?
You can now give a summary of the phases of SDLC– Describe tasks more specifically– Create a realistic schedule
10-23 © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Active Review
What is systems development? Why is systems development difficult and risky? What are the five phases of the systems development life
cycle? How is systems definition accomplished? What is the user’s role in the requirements phase? How are the five components designed? How is an information system implemented? What are the tasks for systems maintenance? What are the problems with SDLC? How does the knowledge from this chapter help DSI?
