1 introduction chapter 1. 2 key ideas many failed systems were abandoned because analysts tried to...
TRANSCRIPT
1
Introduction
Chapter 1
2
Key Ideas
Many failed systems were abandoned because analysts tried to build wonderful systems without understanding the organization.
The primarily goal is to create value for the organization.
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Key Ideas
The systems analyst is a key person analyzing the business, identifying opportunities for improvement, and designing information systems to implement these ideas.
It is important to understand and develop through practice the skills needed to successfully design and implement new information systems.
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THE SYSTEMS DEVELOPMENT LIFE
CYCLE
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Major Attributes of the Lifecycle
The projectMoves systematically through phases where each phase has a standard set of outputsProduces project deliverablesUses deliverables in implementationResults in actual information systemUses gradual refinement
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Project Phases
PlanningWhy build the system?
AnalysisWho, what, when, where will the system be?
DesignHow will the system work?
ImplementationSystem delivery
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A “Simple” Process for Making Lunch
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Identifying business value
Analyze feasibilityTechnical feasibility (Can we do?)
Economic feasibility (Can it provides value?)
Organizational feasibility (Will it be used?)
Develop work plan
Staff the project
Control and direct project
Planning
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Analysis
Information gathering
Process modeling
Data modeling
Analysis
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Physical design
Architectural design
Interface design
Database and file design
Program design
Design
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Construction
Installation
Implementation
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Processes and Deliverables
Process Product
Planning
Analysis
Design
Implementation
Project Plan
System Proposal
System Specification
New System and Maintenance
Plan
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THE EVOLUTION OF SYSTEM DEVELOPMENT
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What Is a Methodology?
A formalized approach or series of steps
Writing code without a well-thought-out system request may work for small programs, but rarely works for large ones.
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Structured Design
Projects move methodically from one to the next step
Generally, a step is finished before the next one begins
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Waterfall Development Method
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Pros and Cons of the Waterfall Method
Pros Cons
Identifies systems requirements long before programming begins
Design must be specified on paper before programming begins
Long time between system proposal and delivery of new system
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Alternatives to the SDLC
Rapid Application Development (RAD)
Phased Development
Prototyping
Throw-Away Prototyping
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Rapid Application Development
Critical elementsCASE tools
JAD sessions
Fourth generation/visualization programming languages
Code generators
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Rapid Application Development Categories
Phased developmentA series of versions
PrototypingSystem prototyping
Throw-away prototypingDesign prototyping
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How Prototyping Works
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Throwaway Prototyping
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Object-Oriented Analysis and Design
Attempts to balance emphasis on data and process
Uses Unified Modeling Language (UML) for diagramming
Use-case Driven
Architecture Centric
Iterative and Incremental
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BASIC CHARACTERISTICS OF OBJECT-ORIENTED
SYSTEMS
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Key Elements
Classes -- template to define objects
Instances -- specific examples of class members
Objects -- building block of the system
Attributes -- describe data aspects of the object
Methods -- the processes the object can perform
Messages -- instructions sent to or received from other objects
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A Class and Its Objects
PATIENT
-Name-Birthdate-Phone Number+Insert ()()+Delete ()()
PATIENT 1: TOP PACKAGE: PATIENT
-Name = Teresa Marks-Birthdate = March 16, 1975-Phone number = 314-997-3456
PATIENT 2: TOP PACKAGE: PATIENT
-Name = Mel Bourne-Birthdate = May 11, 1965-Phone number = 314-997-3219
Attributes
Methods
Class
Instantiated Objects of the Class
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The Key to Reusability
Information hiding is the principle that only information required to use the object is available outside the object
Encapsulation is the mechanism that combines data and processes in a single object
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Class Hierarchy
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Inheritance
Abstract Class
Concrete Class
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Polymorphism
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OBJECT-ORIENTED ANALYSIS AND DESIGN
USING UML
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UML
The full UML provides 9 separate diagramming techniques
Structure Diagrams
• Class Diagram, Object Diagram
• Package Diagram, Deployment Diagram
• Component Diagram
Behavioral Diagrams
• Activity Diagram, Sequence Diagram
• Use Case Diagram, Interaction Diagram
• State Machine
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PROJECT TEAM ROLES AND SKILLS
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Information Systems Roles
Business analyst
System analyst
Infrastructure analyst
Change management analyst
Project manager