Description
system development approach
1
CHAPTER 2: APPROACHES TO SYSTEM DEVELOPMENT
Learning Objectives
2
Explain the purpose and various phases of the systems development life cycle (SDLC) Explain the differences between predictive SDLC and adaptive SDLC Explain the differences between a model, a tool, a technique, and a methodology Describe the two overall approaches used to develop information systems: the traditional method and the objectoriented method
The Systems Development Lifecycle
3
SDLC provides overall framework for managing systems development process. Two main approaches to SDLC
Predictive approach ² assumes project can be planned out in advance ? Adaptive approach ² more flexible, assumes project cannot be planned out in advance
?
All projects use some variation of SDLC
Choosing the Predictive vs. Adaptive Approach to the SDLC
4
Traditional Predictive Approach to the SDLC
5
Project planning ² initiate, ensure feasibility, plan schedule, obtain approval for project Analysis ² understand business needs and processing requirements Design ² define solution system based on requirements and analysis decisions Implementation ² construct, test, train users, and install new system Support ² keep system running and improve
Information System Development Phases
6
SDLC and Problem Solving
7
Organization recognizes problem (project planning) Project team investigates, understands problem and solution requirements (analysis) Solution is specified in detail (design) System that solves problem is built and installed (implementation) System used, maintained, and enhanced to continue to provide intended benefits (support)
Waterfall Model
8
Waterfall model is an SDLC approach that assumes the various phases of a project can be completed sequentially ² one phase leads into the next phase.
´Waterfallµ Approach to the SDLC
9
Modified Waterfall Approach with Overlapping Phases
10
Newer Adaptive Approaches to the SDLC
11
Based on spiral model
? ? ?
Project cycles through development activities over and over until project is complete Prototype created by end of each cycle Focuses on mitigating risk
Iteration ² Work activities are repeated
? ? ?
Each iteration refines previous result Approach assumes no one gets it right the first time There are a series of mini projects for each iteration
The Spiral Life Cycle Model
12
Activities of Each SDLC Phase
13
Predictive or adaptive approach use SDLC Activities of each ´phaseµ are similar Phases are not always sequential Phases can overlap
Activities of Planning Phase of SDLC
14
Define business problem and scope Produce detailed project schedule Confirm project feasibility
?
Economic, organizational, technical, resource, and schedule
Staff the project (resource management) Launch project official announcement
Activities of Analysis Phase of SDLC
15
Gather information to learn problem domain Define system requirements Build prototypes for discovery of requirements Prioritize requirements Generate and evaluate alternatives Review recommendations with management
Activities of Design Phase of SDLC
16
Design and integrate the network Design the application architecture Design the user interfaces Design the system interfaces Design and integrate the database Prototype for design details Design and integrate system controls
Activities of Implementation Phase of SDLC
17
Construct software components Verify and test Convert data Train users and document the system Install the system
Activities of Support Phase of SDLC
18
Maintain system
?
Small patches, repairs, and updates
Enhance system
Small upgrades or enhancements to expand system capabilities ? Larger enhancements may require separate development project
?
Support users
?
Help desk and/or support team
What are Methodologies?
19
Comprehensive guidelines to follow for completing every SDLC activity Collection of models, tools, and techniques
Relationships Among Components of a Methodology
20
What Are Models?
21
Representation of an important aspect of real world, but not the same as real thing Abstraction used to separate out aspect Diagrams and charts Project planning and budgeting aids
Some Models Used in System Development
22
What Are Tools?
23
Software support that helps create models or other required project components Range from simple drawing programs to complex CASE tools to project management software
Some Tools Used in System Development
http://www.sparxsystems.com/products/ea /index.html
24
What Are Techniques?
25
Collection of guidelines that help analysts complete a system development activity or task Can be step-by-step instructions or just general advice
Some Techniques Used in System Development
26
Two Approaches to System Development
27
Traditional approach
Also called structured system development ? Structured analysis and design technique (SADT) ? Includes information engineering (IE)
?
Object-oriented approach
Also called OOA, OOD, and OOP ? Views information system as collection of interacting objects that work together to accomplish tasks
?
Structured System Development
28
Structure Programming Top-down Programming Structured Design Structured Analysis
Structured Programming
29
Improves computer program quality Allows other programmers to easily read and modify code Each program module has one beginning and one ending Three programming constructs (sequence, decision, repetition)
Three Structured Programming Constructs
30
Top-Down Programming
31
Divides complex programs into hierarchy of modules The module at top controls execution by ´callingµ lower level modules Modular programming
?
Similar to top-down programming
One program calls other programs to work together as single system
Top-Down or Modular Programming
32
Structured Design
33
What the set of programs should be What each program should accomplish How the programs should be organized into a hierarchy
Main Principles of Structured Design
34
Loosely coupled ² module is independent of other modules Highly cohesive ² module has one clear task
Structure Chart Created Using Structured Design Technique
35
Structured Analysis
36
Define what system needs to do (processing requirements) Define data system needs to store and use (data requirements) Define inputs and outputs Define how functions work together to accomplish tasks Data flow diagrams (DFD) and entity relationship diagrams (ERD) show results of structured analysis
Data Flow Diagram (DFD)
37
Entity-Relationship Diagram (ERD)
38
Framework of Structured Development
39
Information Engineering (IE)
40
Refinement to structured development Methodology with strategic planning, data modeling, automated tools focus More rigorous and complete than SADT Industry merged key concepts from structured development and information engineering approaches into traditional approach
Object-Oriented Approach
41
Completely different approach to information systems Views information system as collection of interacting objects that work together to accomplish tasks
Objects ² things in computer system that can respond to messages ? Conceptually, no processes, programs, data entities, or files are defined ² just objects
?
OO languages: Java, C++, C# .NET, VB .NET
Terminologies of O-O Approach
42
Object-oriented analysis (OOA) Object-oriented design (OOD) Object-oriented programming (OOP)
Object-oriented analysis (OOA)
43
Defines types of objects users deal with Shows use cases are required to complete tasks
Object-oriented design (OOD)
44
Defines object types needed to communicate with people and devices in system Shows how objects interact to complete tasks Refines each type of object for implementation with specific language of environment
45
Object-oriented programming (OOP)
Writing statements in programming language to define what each type of object does
Class Diagram Created During OO Analysis
46
Current Trends in Development
47
More adaptive approaches
? The
Unified Process (UP) ? Extreme Programming (XP) ? Agile Modeling ? Scrum
Details on each in Chapter 17
The Unified Process (UP)
48
Object-oriented development approach Offered by IBM / Rational
?
Booch, Rumbaugh, Jacobson
Unified Modeling Language (UML) used primarily for modeling UML can be used with any OO methodology UP defines four life cycle phases
?
Inception, elaboration, construction, transition
49
UP Reinforces Six Best Practices
50
Develop iteratively Define and manage system requirements Use component architectures Create visual models Verify quality Control changes
Extreme Programming (XP)
51
Recent, lightweight, development approach to keep process simple and efficient Describes system support needed and required system functionality through informal user stories Has users describe acceptance tests to demonstrate defined outcomes Relies on continuous testing and integration, heavy user involvement, programming done by small teams
52
Scrum
53
For highly adaptive project needs Respond to situation as rapidly as possible Scrum refers to rugby·s game
? Both
are quick, agile, and self-organizing
Team retains control over project Values individuals over processes
54
55
Tools to Support System Development
Case Tools Drawing Tool
? Microsoft
Visio
CASE Tool Repository Contains All System Information
56
Summary
57
System development projects are organized around the systems development life cycle (SDLC) Some projects use a predictive approach to the SDLC, and others use a more adaptive approach to the SDLC SDLC phases include project planning, analysis, design, implementation, and support
Summary (continued)
58
In practice, phases overlap, and projects contain many iterations of analysis, design, and implementation Models, techniques, and tools make up a system development methodology System development methodology provides guidelines to complete every activity in the SDLC
Summary (continued)
59
System development methodologies are based on traditional approach or object-oriented approach Current trends include: Extreme Programming (XP), Unified Process (UP), and Scrum CASE tools are designed to help analysts complete system development tasks
doc_693931993.ppt
system development approach
1
CHAPTER 2: APPROACHES TO SYSTEM DEVELOPMENT
Learning Objectives
2
Explain the purpose and various phases of the systems development life cycle (SDLC) Explain the differences between predictive SDLC and adaptive SDLC Explain the differences between a model, a tool, a technique, and a methodology Describe the two overall approaches used to develop information systems: the traditional method and the objectoriented method
The Systems Development Lifecycle
3
SDLC provides overall framework for managing systems development process. Two main approaches to SDLC
Predictive approach ² assumes project can be planned out in advance ? Adaptive approach ² more flexible, assumes project cannot be planned out in advance
?
All projects use some variation of SDLC
Choosing the Predictive vs. Adaptive Approach to the SDLC
4
Traditional Predictive Approach to the SDLC
5
Project planning ² initiate, ensure feasibility, plan schedule, obtain approval for project Analysis ² understand business needs and processing requirements Design ² define solution system based on requirements and analysis decisions Implementation ² construct, test, train users, and install new system Support ² keep system running and improve
Information System Development Phases
6
SDLC and Problem Solving
7
Organization recognizes problem (project planning) Project team investigates, understands problem and solution requirements (analysis) Solution is specified in detail (design) System that solves problem is built and installed (implementation) System used, maintained, and enhanced to continue to provide intended benefits (support)
Waterfall Model
8
Waterfall model is an SDLC approach that assumes the various phases of a project can be completed sequentially ² one phase leads into the next phase.
´Waterfallµ Approach to the SDLC
9
Modified Waterfall Approach with Overlapping Phases
10
Newer Adaptive Approaches to the SDLC
11
Based on spiral model
? ? ?
Project cycles through development activities over and over until project is complete Prototype created by end of each cycle Focuses on mitigating risk
Iteration ² Work activities are repeated
? ? ?
Each iteration refines previous result Approach assumes no one gets it right the first time There are a series of mini projects for each iteration
The Spiral Life Cycle Model
12
Activities of Each SDLC Phase
13
Predictive or adaptive approach use SDLC Activities of each ´phaseµ are similar Phases are not always sequential Phases can overlap
Activities of Planning Phase of SDLC
14
Define business problem and scope Produce detailed project schedule Confirm project feasibility
?
Economic, organizational, technical, resource, and schedule
Staff the project (resource management) Launch project official announcement
Activities of Analysis Phase of SDLC
15
Gather information to learn problem domain Define system requirements Build prototypes for discovery of requirements Prioritize requirements Generate and evaluate alternatives Review recommendations with management
Activities of Design Phase of SDLC
16
Design and integrate the network Design the application architecture Design the user interfaces Design the system interfaces Design and integrate the database Prototype for design details Design and integrate system controls
Activities of Implementation Phase of SDLC
17
Construct software components Verify and test Convert data Train users and document the system Install the system
Activities of Support Phase of SDLC
18
Maintain system
?
Small patches, repairs, and updates
Enhance system
Small upgrades or enhancements to expand system capabilities ? Larger enhancements may require separate development project
?
Support users
?
Help desk and/or support team
What are Methodologies?
19
Comprehensive guidelines to follow for completing every SDLC activity Collection of models, tools, and techniques
Relationships Among Components of a Methodology
20
What Are Models?
21
Representation of an important aspect of real world, but not the same as real thing Abstraction used to separate out aspect Diagrams and charts Project planning and budgeting aids
Some Models Used in System Development
22
What Are Tools?
23
Software support that helps create models or other required project components Range from simple drawing programs to complex CASE tools to project management software
Some Tools Used in System Development
http://www.sparxsystems.com/products/ea /index.html
24
What Are Techniques?
25
Collection of guidelines that help analysts complete a system development activity or task Can be step-by-step instructions or just general advice
Some Techniques Used in System Development
26
Two Approaches to System Development
27
Traditional approach
Also called structured system development ? Structured analysis and design technique (SADT) ? Includes information engineering (IE)
?
Object-oriented approach
Also called OOA, OOD, and OOP ? Views information system as collection of interacting objects that work together to accomplish tasks
?
Structured System Development
28
Structure Programming Top-down Programming Structured Design Structured Analysis
Structured Programming
29
Improves computer program quality Allows other programmers to easily read and modify code Each program module has one beginning and one ending Three programming constructs (sequence, decision, repetition)
Three Structured Programming Constructs
30
Top-Down Programming
31
Divides complex programs into hierarchy of modules The module at top controls execution by ´callingµ lower level modules Modular programming
?
Similar to top-down programming
One program calls other programs to work together as single system
Top-Down or Modular Programming
32
Structured Design
33
What the set of programs should be What each program should accomplish How the programs should be organized into a hierarchy
Main Principles of Structured Design
34
Loosely coupled ² module is independent of other modules Highly cohesive ² module has one clear task
Structure Chart Created Using Structured Design Technique
35
Structured Analysis
36
Define what system needs to do (processing requirements) Define data system needs to store and use (data requirements) Define inputs and outputs Define how functions work together to accomplish tasks Data flow diagrams (DFD) and entity relationship diagrams (ERD) show results of structured analysis
Data Flow Diagram (DFD)
37
Entity-Relationship Diagram (ERD)
38
Framework of Structured Development
39
Information Engineering (IE)
40
Refinement to structured development Methodology with strategic planning, data modeling, automated tools focus More rigorous and complete than SADT Industry merged key concepts from structured development and information engineering approaches into traditional approach
Object-Oriented Approach
41
Completely different approach to information systems Views information system as collection of interacting objects that work together to accomplish tasks
Objects ² things in computer system that can respond to messages ? Conceptually, no processes, programs, data entities, or files are defined ² just objects
?
OO languages: Java, C++, C# .NET, VB .NET
Terminologies of O-O Approach
42
Object-oriented analysis (OOA) Object-oriented design (OOD) Object-oriented programming (OOP)
Object-oriented analysis (OOA)
43
Defines types of objects users deal with Shows use cases are required to complete tasks
Object-oriented design (OOD)
44
Defines object types needed to communicate with people and devices in system Shows how objects interact to complete tasks Refines each type of object for implementation with specific language of environment
45
Object-oriented programming (OOP)
Writing statements in programming language to define what each type of object does
Class Diagram Created During OO Analysis
46
Current Trends in Development
47
More adaptive approaches
? The
Unified Process (UP) ? Extreme Programming (XP) ? Agile Modeling ? Scrum
Details on each in Chapter 17
The Unified Process (UP)
48
Object-oriented development approach Offered by IBM / Rational
?
Booch, Rumbaugh, Jacobson
Unified Modeling Language (UML) used primarily for modeling UML can be used with any OO methodology UP defines four life cycle phases
?
Inception, elaboration, construction, transition
49
UP Reinforces Six Best Practices
50
Develop iteratively Define and manage system requirements Use component architectures Create visual models Verify quality Control changes
Extreme Programming (XP)
51
Recent, lightweight, development approach to keep process simple and efficient Describes system support needed and required system functionality through informal user stories Has users describe acceptance tests to demonstrate defined outcomes Relies on continuous testing and integration, heavy user involvement, programming done by small teams
52
Scrum
53
For highly adaptive project needs Respond to situation as rapidly as possible Scrum refers to rugby·s game
? Both
are quick, agile, and self-organizing
Team retains control over project Values individuals over processes
54
55
Tools to Support System Development
Case Tools Drawing Tool
? Microsoft
Visio
CASE Tool Repository Contains All System Information
56
Summary
57
System development projects are organized around the systems development life cycle (SDLC) Some projects use a predictive approach to the SDLC, and others use a more adaptive approach to the SDLC SDLC phases include project planning, analysis, design, implementation, and support
Summary (continued)
58
In practice, phases overlap, and projects contain many iterations of analysis, design, and implementation Models, techniques, and tools make up a system development methodology System development methodology provides guidelines to complete every activity in the SDLC
Summary (continued)
59
System development methodologies are based on traditional approach or object-oriented approach Current trends include: Extreme Programming (XP), Unified Process (UP), and Scrum CASE tools are designed to help analysts complete system development tasks
doc_693931993.ppt