1
Lecture 11: System Design
and Development
K S Rajan
IIIT, Hyderabad
A Synthesis
1. WHAT are the boundary conditions and constraints imposed by the
User on a system, product, or service in terms of missions within a
prescribed OPERATING ENVIRONMENT?
2. Given the set of boundary conditions and constraints, HOW does
the User envision deploying, operating, and supporting the system,
product, or service to perform its missions within specific time
limitations, if applicable?
3. Given the deployment, operation, support, and time constraints
planned for the system, product, or service, WHAT is the set of
outcome-based behaviors and responses required of the system to
accomplish its missions?
4. Given the set of outcome-based behaviors and responses required
of the system to accomplish its mission, HOW is the deliverable
system, product, or service to be physically implemented to perform
those missions and demonstrate?
Design and Development Practices
• System Development Strategies Practices
• System Specification Practices
• System Design and Development Practices
• Decision Support Practices
• System Verification and Validation Practices
• System Deployment, Operations, and
Support Practices
System Flow – a perspective System Development Phase
2
• System Design Process Strategy
– highly iterative, topdown/bottom-up/lateral process
• Select the right Implementation approach
– Level of understanding of the problem and solution
spaces.
– The maturity of the SPS requirements.
– Level of risk.
– Critical operational or technical issues (COIs/CTIs).
– Eg: Waterfall, Incremental Development, and Spiral
Development
Engineering Design Strategy
SITE
System Integration, Test and
Evaluation (SITE) “V” Model
System Development Spiral Another Design Framework
3
System Development Models
1. The Waterfall Development Model
2. The Evolutionary Development Model
3. The Incremental Development Model
4. The Spiral Development Model
Waterfall Model
Evolutionary Developmental
Models
Dr. Boehm notes the following points:
• Fallacy 1: The Evolutionary Development Model
is difficult to delineate from the build, test, and fix
approaches “whose spaghetti code and lack of
planning were the initial motivation for the
“waterfall model.”
• Fallacy 2: The Evolutionary Development Model
stemmed from the “often unrealistic” assumption
that the system would always provide the
flexibility to accommodate unplanned evolution
paths.
Spiral Developmental Model
Incremental Development StrategySystem Specification Practices
Requirements that bound the User’s solution space subject to -
technology,
cost,
schedule,
support, and
risk constraints.
Specification requirements have to be analyzed, derived, developed, and reviewed.
4
Specification DevelopmentRequirements vs. Operational
States
System Design and Development
Practices
Need to understand -
• the operational utility, suitability, effectiveness,
and availability requirements;
• formulation of domain solutions;
• selection of a system architecture;
• configuration identification;
• system interface design;
• standards and conventions; and
• design and development documentation.
Approaches
Organizations and SEs employ a number of
approaches to development of specifications.
Typical approaches include:
1. Feature-based approach
2. Reuse-based approach
3. Performance-based approach
4. Model-based approach
Decision Support Practices
• statistical variation influences on system
design;
• system performance budgets and margins;
• system reliability, availability, and
maintainability;
• system modeling and simulation; and
• trade study analysis of alternatives
System Verification and Validation
Practices
1. Is the system being designed and
developed RIGHT—in accordance with
the contract requirements and
2. Does the system satisfy the user’s
operational needs?
• Technical reviews
• System integration, test, and evaluation
5
System Deployment, Operations, and
Support PracticesSE and System Analyst work doesn’t end with Operationalization of the System. He further needs to
1. Assess mission outcomes and performance
2. Suggest corrective actions
3. Study it for future systems and capabilities requirements
• Check How a system is deployed including site selection, development, and activation;
• Identify Key considerations for System integration into a higher level system;
• Address how system deficiencies are investigated – a basis for acquisition requirements for new systems, products, or services; and
• Investigate key engineering considerations that must be translated into specification requirements for new systems.
Top Related