Design Process and Concepts

Saranya.VAP/CSE,

Sri Vidya College of Engineering & Technology,Virudhunagar

Design Specification Modules

• Data Design• Architectural Design• Interface Design• Procedural Design

Design Languages

• O-O Paradigm– Use Case Diagram

• Functional Requirements of the system• Actors

– Class Diagram• Static structure of the system and relationships and

association between the classes.

– State Diagram• Show the permissible states and the transitions.

– Sequence Diagram• Show the temporal dependencies between different

actions and objects.

Fundamental software Design concepts

• Abstraction– Procedural– Data abstraction

• Refinement (improve the design component)• Modularity• Software Architecture• Control Hierarchy or Program Structure • Structure Partitioning• Data Structure• Software Procedure• Information Hiding

Modular Design

Modular Design Method Evaluation Criteria

• Modular Decomposability (problem to sub problem)

• Modular composability (reuse of existing modules)

• Modular Understandability• Modular Protection (minimize the process

errors)• Modular Continuity (module changes

minimized)

Control Terminology

• Span of control : (number of levels control within the product)

• Depth (distance between top and bottom modules)

• Fan-Out or Width: Number of modules controlled by particular module.

• Fan-in: Number of modules control the particular module.

• Visibility• Connectivity

Effective Modular Design

• Functional dependency– Should have high cohesion and low coupling

• Cohesion– Module focus on just one thing

• Coupling– Module is connected to other modules and to the

outside world.

Design Heuristic

Design heuristic for effective modularity

• Evaluate the first iteration (reduce coupling and increase cohesion)

• Minimize the structure with high fan out• Keep the scope of the effect• Reduce complexity• Predictable functions

Ten Heuristic for User Interface Design

• Visibility of system status• Match between the system and the real world• User control and freedom• Consistency and standards• Error prevention• Recognition rather than recall• Flexibility and efficiency of use• Aesthetic (artistic) and minimalist design• Help users recognize, diagnose and recover from errors.• Help and documentation.