Software Architecture in Practice

3. General Software Abstractions & Relations

• Encapsulation - helps decrease the amount of coupling between each component by information hiding 
• Polymorphism - helps increase the cohesion of communication and relationship between objects 
• Dependencies - dependent libraries and packages

 

Types of Coupling 

• Afferent coupling - number of responsibilities; incoming 
• Efferent coupling - number of dependencies; outgoing

 

Code Quality Measurements 

• Instability - ratio of efferent coupling to afferent and efferent coupling 
• Cyclomatic complexity - number of branches that a method may have, measures the complexity of methods

 

Cyclomatic Complexity 

E - N + 2 * P 

where 

- E is the number of edges 

- N is the number of nodes 

- P is the number of nodes with exit paths