Structured Design Tools Dr Merle P Martin CSU

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Structured Design Tools Dr. Merle P. Martin CSU Sacramento

Structured Design Tools Dr. Merle P. Martin CSU Sacramento

Agenda Design approaches t Structured approach t Hierarchical Chart t Data Flow Diagram t

Agenda Design approaches t Structured approach t Hierarchical Chart t Data Flow Diagram t

Design Approaches Traditional (bottom-up) t Structured (top-down) t Radical Top-down t Prototyping t

Design Approaches Traditional (bottom-up) t Structured (top-down) t Radical Top-down t Prototyping t

Traditional Design Approach t Bottom-up Narrative, technical specs t User had to read them

Traditional Design Approach t Bottom-up Narrative, technical specs t User had to read them t Merely signed off t Resulting system unot expected by user uflaws t

Structured Design Approach t Top-down First derived at general level t Successive refinement of

Structured Design Approach t Top-down First derived at general level t Successive refinement of detail t Primitive level (coding) t Computer Assisted System Engineering (CASE) t

Radical Top-down Approach t Used in this course uand in MIS 108, 119 t

Radical Top-down Approach t Used in this course uand in MIS 108, 119 t Partial system development ustubbing out of primitive level modules uprioritization of modules utop priority modules developed first t Lends itself to Prototyping

Structured Approach Advantages Reduces complexity (modularity) t Focuses on ideal (logical) system t Standardizes

Structured Approach Advantages Reduces complexity (modularity) t Focuses on ideal (logical) system t Standardizes (team design) t Provides a future orientation ue. g. . , future file t Relies less on artistry uengineering approach t

Structured Approach Sequence t Hierarchical Chart Physical DFD current system (WHAT/HOW) t Logical DFD

Structured Approach Sequence t Hierarchical Chart Physical DFD current system (WHAT/HOW) t Logical DFD current system (WHAT only) t Logical DFD proposed system (revised WHAT) t Physical DFD proposed system (revised WHAT/HOW) t

Structured Approach Sequence Figure 6. 1 -1, pg. . 184)

Structured Approach Sequence Figure 6. 1 -1, pg. . 184)

Hierarchical Chart Terms: uparent, child, sibling ufunctional primitive ucontrol module t How long should

Hierarchical Chart Terms: uparent, child, sibling ufunctional primitive ucontrol module t How long should chart be? t

Hierarchical Chart Colonial Heights Figure 6 -6, pg. . 164

Hierarchical Chart Colonial Heights Figure 6 -6, pg. . 164

Data Flow Diagram (DFD) Purpose: communication with user t Components: uexternal entities (sources, sinks)

Data Flow Diagram (DFD) Purpose: communication with user t Components: uexternal entities (sources, sinks) uprocesses (subprograms) udata stores (files) udata flows (forms) t Symbols - Figure 6 -7, pg. 166 t

Data Flow Diagram (DFD) Figure 6 -9, pg. 169 Hierarchical Chart t Figure 6

Data Flow Diagram (DFD) Figure 6 -9, pg. 169 Hierarchical Chart t Figure 6 -10, pg. 170 Context Level Diagram t Figure 6 -11, pg. 170 First Level Explosion t

What You Should Remember t Different design approaches Why Radical Top-down approach? t Structured

What You Should Remember t Different design approaches Why Radical Top-down approach? t Structured Design sequence t Hierarchical Chart t DFD components and levels t Study Megavideo case (Case 6. 1) t