Chapter 7: Software Engineering

(1)

Computer Science: An Overview Twelfth Edition

J. Glenn Brookshear by Dennis Brylow

Chapter 7:

Software Engineering

Chapter 7: Software Engineering

• 7.1 The Software Engineering Discipline

• 7.2 The Software Life Cycle

• 7.3 Software Engineering Methodologies

• 7.4 Modularity

• 7.5 Tools of the Trade

• 7.6 Testing

• 7.7 Documentation

• 7.8 Software Ownership and Liability

The Software Engineering Discipline

• Distinct from other engineering fields – Prefabricated components

– Metrics

• Practitioners versus Theoreticians

• Professional Organizations: ACM, IEEE, etc.

Computer Aided Software Engineering (CASE) tools

• Project planning

• Project management

• Documentation

• Prototyping and simulation

• Interface design

(2)

Figure 7.1 The software life cycle

Figure 7.2 The development phase of the software life cycle

Analysis Stage

• Requirements – Application oriented

• Specifications – Technically oriented

• Software requirements document

Design Stage

• Methodologies and tools (discussed later)

• Human interface (psychology and

ergonomics)

(3)

Implementation Stage

• Create system from design – Write programs

– Create data files – Develop databases

• Role of “software analyst” versus

“programmer”

Testing Stage

• Validation testing

– Confirm that system meets specifications

• Defect testing – Find bugs

Software Engineering Methodologies

• Waterfall Model

• Incremental Model

– Prototyping (Evolutionary vs. Throwaway)

• Open-source Development

• Extreme Programming

Modularity

• Functions − Imperative paradigm – Structure charts

• Objects − Object-oriented paradigm – Collaboration diagrams

• Components − Component architecture

(4)

Figure 7.3 A simple structure chart

Figure 7.4 The structure of PlayerClass and its instances

Figure 7.5 The interaction between objects resulting from PlayerA’s serve

Figure 7.6 A structure chart

including data coupling

(5)

Coupling versus Cohesion

• Coupling

– Control coupling – Data coupling

• Cohesion

– Logical cohesion – Functional cohesion

Figure 7.7 Logical and functional cohesion within an object

Tools of the Trade

• Data Flow Diagram

• Entity-Relationship Diagram – One-to-one relation

– One-to-many relation – Many-to-many relation

Figure 7.8 A simple dataflow diagram

(6)

Figure 7.9 A simple use case diagram

Figure 7.10 A simple class diagram

Unified Modeling Language

• Use Case Diagram – Use cases

– Actors

• Class Diagram

Figure 7.11 One-to-one, one-to-many, and

many-to-many relationships between

entities of types X and Y

(7)

Figure 7.12 A class diagram depicting generalizations

Figure 7.13 A sequence diagram depicting a generic volley

Structured Walkthoughs

• “Theatrical” experiment

• Class-responsibility-collaboration cards

Design Patterns

• Well designed “templates” for solving recurring problems

• Examples:

– Adapter pattern: Used to adapter a module’s interface to current needs

– Decorator pattern: Used to control the complexity

involved when many different combinations of the

(8)

Software Testing Strategies

• Glass-box testing – Pareto principle – Basis path testing

• Black-box testing – Boundary value analysis – Redundancy testing – Beta testing

Documentation

• User Documentation

– Printed book for all customers – On-line help modules

• System Documentation – Source code

– Design documents

• Technical Documentation

– For installing, customizing, updating, etc.

Software Ownership

• Copyright

– Allow a product to be released while retaining ownership of intellectual property

– Asserted in all works:

• Specifications

• Source code

• Final product

Software Ownership (continued)

• Software License

– A legal agreement that grants the user certain permissions without transferring ownership

• Patents

– Must demonstrate that it is new, usable, and

not obvious to others with similar backgrounds

– Process is expensive and time-consuming