Lecture 6 Design Concepts and principles
Lecture 6 Design Concepts and Principles
Analysis to Design Data PSPEC component (procedural) Description de ERD DFD resign Data interface Dictionary de sign architectural design TD data CSPEC design THE ANALYSIS MODEL THE DESIGN MODEL
Analysis to Design Data Dictionary THE ANALYSIS MODEL interface design architectural design data design THE DESIGN MODEL PSPEC CSPEC ERD DFD STD Data Object Description component (procedural) design
Where do We begin? modelling Prototype Spec D esign
Where Do We Begin? Spec Prototype Design modelling
Design Principles / Dav957 The design process should not suffer from tunnel vision The design should be traceable to the analysis model The design should not reinvent the wheel The design should"minimize the intellectual distance between the software and the problem as it exists in the real world The design should exhibit uniformity and integration
Design Principles [Dav95] ◼ The design process should not suffer from ‘tunnel vision.’ ◼ The design should be traceable to the analysis model. ◼ The design should not reinvent the wheel. ◼ The design should “minimize the intellectual distance” between the software and the problem as it exists in the real world. ◼ The design should exhibit uniformity and integration
Design Principles /Dav957 The design should be structured to accommodate change The design should be structured to degrade gently, even when aberrant data, events, or operating conditions are encountered Design is not coding coding is not design The design should be assessed for quality as it is being created, not after the fact The design should be reviewed to minimize conceptual(semantic)errors
Design Principles [Dav95] ◼ The design should be structured to accommodate change. ◼ The design should be structured to degrade gently, even when aberrant data, events, or operating conditions are encountered. ◼ Design is not coding, coding is not design. ◼ The design should be assessed for quality as it is being created, not after the fact. ◼ The design should be reviewed to minimize conceptual (semantic) errors