Chapter 6 Essentials of Design and the Design Activities
Chapter 6 Overview
Focuses on Systems Analysis and Design in a Changing World.
Covers key concepts in systems design, contrasting it with systems analysis.
Highlights design activities and the importance of systems controls and security.
What Is Systems Design?
Systems Design defines how the system will be configured and constructed.
Contrasts with systems analysis, which identifies 'what' is required.
Design acts as a bridge between requirements and implementation.
Design Activities and Documentation
Key components include:
Documents and models as inputs/outputs in systems design.
Documentation of both analysis and design activities to coordinate work.
Major Design Activities
Define, organize, and structure components of the final solution as a blueprint.
Key design activities:
Understand requirements from previous chapters (Chapters 2-5).
Build models that represent system components and user interfaces.
Importance of Design in System Development
Design is critical to develop an efficient system and prevent rework.
Analysis provides starting points for design, leading to efficient implementation.
Various projects (e.g., Agile) dictate types, complexities, and depth of models created.
Components of Design Activities
Correspond to new system components, focusing on:
Environment
Application components
User interface
Database
Software classes and methods
Environmental Considerations
Key aspects:
Communications with external systems.
Use of message formats and protocols.
Security methods for data protection and recovery.
Adherence to existing technology architecture.
Application Component Design
Defined units of software performing functions.
Key considerations:
Scope and size (functions, boundaries).
Programming language selection.
Decision to build or buy component.
User Interface Design
Considered as the system by the user, impacting productivity significantly.
Requires deep user involvement in both analysis and design.
Necessitates adaptable interfaces across various devices and environments.
Database Design Specifications
Information systems require data, typically managed in a relational database.
Design must consider:
Conversion of data models to relational formats.
Throughput, response time, and security measures.
Detailed Design and Models
Detailed design activities include:
Design Class Diagrams.
Sequence Diagrams.
State-Machine Diagrams.
System Controls and Security
Integrity Controls
Maintain integrity of inputs, outputs, data, and programs.
Security Controls
Protect assets against internal and external threats.
Objectives include:
Safeguarding business transactions and data integrity.
Implementing access and authorization measures.
Specific Control Measures
Value Limit Controls: Check input ranges for reasonableness.
Completeness Controls: Ensures all data is entered accurately.
Data Validation Controls: Validate specific data values.
Field Combination Controls: Ensure correctness based on inter-field relationships.
Recovery and Protection Strategies
Backup strategies to ensure quick recovery from data loss.
Internal fraud prevention strategies: Understanding the fraud triangle (Opportunity, Motive, Rationalization).
Protection against external threats to maintain a stable operating environment.
Access and Authentication Measures
Access controls to limit data access based on user roles.
Authentication mechanisms, including multi-factor authentication.
Authorization procedures to define user permissions.
Data Security Measures
Encryption for safe data transmission and storage.
Digital signatures for document verification.
Certificates for secure transactions and authentication.
Final Thoughts on Systems Design
Systems design is crucial as it defines implementation strategies based on analysis results.
Recognizes that systems development requires continuous adaptation to changes in technology and user requirements.