Traditional Systems Development

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Traditional Systems Development

• Details on the Systems Development Life Cycle
  approach to design.

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• Planning
• Priority
• Feasibility

Business
Analysis
Technical
Design
Imple-mentation
Mainten-ance
Operations
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SDLC Project Management

• Manage development schedule and cost
• Make average contributors more effective
• Prevent genius members from creating a system
  that cannot be maintained

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Initial Investigation

• What is the system supposed to do and what
  priority should we give it?
• On IS budget
• Memo or oral
• Define users general expectations
• Business justification
• Rough cost
• Assign priority

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How do we find problems?

• Dictated by business projects
• Competitive initiative
• Surveillance
• Reaction
• Opportunistic
• Frameworks
• Competitive strategy
• Value Chain

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Initial Investigation

• State the business problem.
• Summarize the proposed IT solution.
• Show how the proposed solution contributes to the
  fundamental business goals.
• Strategic model
• Estimate net benefits.

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Response Strategies

• Low Cost Provider
• Differentiation
• Excellence
• Customer Service
• Niche Market

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Feasibility Study

• How Should we do it?

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Feasibility Study

• Formal report
• On user budget
• What should we do?
• How should we do it?
• What should it cost?
• How will we use it?

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Feasibility TELOS

• Technical how can we do it?
• Economic is it cost justifiable?
• Legal are there legal issues?
• Operational does this fit the way we want to do
  business?
• Schedule can we get it done on time?

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FormatInclude these sections

• Title page
• Table of contents
• Executive summary
• Problem statement
• Analysis of alternatives
• Cost and benefits
• Recommendation
• Request for authorization
• Appendix

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Business Decomposition

• What are the business components of the system?

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Babysitter Service

• The AITP Service Club wants to run a babysitting
  service. Customers call to request a sitter and
  the Club Coordinator assigns an employee to sit
  for the customer from a list of employees
  available for the particular day requested.

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Functional Decomposition

• Determine Employee Availability
• Assign Employees to Job
• Accept Call
• Record Customer
• Record Job
• Assign Employee
• Confirm Assignment

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Data Decomposition

• Employees
• Customers
• Jobs

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Function/Data Interaction Matrix
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Location

• Reach Where should it be available
• Range What functions should it support
• Response How quickly must it respond

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General Analysis

• Specify logical system requirements

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TOP DOWN DATA ANALYSIS

• Computer systems are extremely complicated and
  cannot be developed without careful planning.
  The first step is generally to build a model of
  the information system based on the general
  objectives and goals it must meet. This is
  called top down modeling.

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E-R Diagram
Employee
Customer
Job
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Data-Flow Model

• A logical representation of the processes and
  data transformation of a system or organization
  in graphical form

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Context Diagram
Request
Customer
Confirirm- ation
Babysitter Information System
Availability
Assignment
Employee
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Level 1 DFD
Request
Assignment
Availability
Confirirm- ation
1. Assign Employee
2. Offer Availa- bility
Avail Times
New
Current
Avail Times
Job Assign
D1 Customer
D2 Employee
D3 Jobs
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Communications Model

• A representation of the location at which data is
  stored and processed and the communications links
  that connect them.

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General Systems Analysis

• Understand the current system
• Be sure you dont omit essential features
• Obtain detailed specifications of expected
  functions
• Operations level requirements
• Provide specifications for IT developers to
  design from

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General Analysis

• Is this an information system or a reengineering
  project?
• Reengineering requires a mandate to change the
  way you do business, and requires a major
  commitment from all participants. Most
  information systems are written to support
  existing processes.

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Detailed Conceptual and Physical Design

• Computer system structure and module specification

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• Input/Output design
• Logical data structures and views
• Data dictionaries
• System logic definitions
• System flow
• Network design charts
• Documentation

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System Implementation

• Build it

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Development

• Structured Code
• CASE tools
• Code generators
• Rapid Application Development
• Object Oriented development
• Prototypes

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Testing

• Walkthroughs and code inspection
• Application test
• Unit test - each program
• System test - whole system together
• Processes and user acceptance

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Installation

• Conversion
• Direct
• Phased
• Pilot
• Parallel
• Training
• Operations acceptance

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Maintenance

• Everything after acceptance

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