1.2 Principles

Dezyne aims to support known software engineering principles:

• clarity and ease of discovery
  • visual overview of architecture (layers of decomposition)
  • visual overiew of behaviour (event trace scenarios)
• rigor and formality
  • Dezyne allows enforcing completeness and correctness
  • implementations consistent with specifications
  • specification consistency

• separation of concerns (divide and conquer, low coupling – high cohesion)
  • data is separated from control
  • components allow for functional decomposition
  • interfaces specify the conversations between each peer in a point to point relation

• composition is separated from behaviour

• modularity (low coupling, high cohesion; dependency inversion)
  • at the file level, Dezyne allows separating type, interface, component and system definitions
  • a component only depends on its interfaces
  • a system only depends on it components
  • a system is a component
• abstraction (Liskov substitution)
  • data independence
  • an event represents the transition from one (system) state to another
  • its name and place in the system structure strongly indicates its meaning
  • an interface is the complete abstraction of an implementation from the perspective of any client
  • and interfaces completely isolate the implementation from its environment
• anticipation of change (open closed)
  • modularity and composition allows changing implementations whithout changing interfaces, dependencies and dependents
  • a system in Dezyne is inherently protected from changes propagating²
• generality
  • Dezyne allows trivially substituting components offering a port of a compatible interface type
  • Dezyne’s data independence³ allows components to be more general
• incremental development
  • increments in Dezyne can obviously follow component scope
  • Dezyne supports use case driven development or cross-cutting features equally well
• testability
  • trace generation allows for 100% test coverage of code paths