Spiral model is one of the best models that may be used for risk-based projects. In this model more emphasis is given on risk analysis. The spiral model is favored for large, expensive, and complicated projects.The spiral model combines the idea of iterative development with the systematic, controlled aspects of the waterfall model.It has basically following four phases :
Planning Phase/Determine Objective: Requirements are gathered during the planning phase. Requirements like ‘BRS’ that is ‘Bussiness Requirement Specifications’ and ‘SRS’ that is ‘System Requirement specifications’. This phase starts with gathering the business requirements in the baseline spiral. In the subsequent spirals as the product matures, identification of system requirements, subsystem requirements and unit requirements are all done in this phase.This also includes understanding the system requirements by continuous communication between the customer and the system analyst. At the end of the spiral the product is deployed in the identified market.
Risk Analysis: In the risk analysis phase, a process is undertaken to identify risk and alternate solutions. Risk Analysis includes identifying, estimating, and monitoring technical feasibility and management risks, such as schedule slippage and cost overrun. A prototype is produced at the end of the risk analysis phase. If any risk is found during the risk analysis then alternate solutions are suggested and implemented.
Engineering/Design Phase: In this phase software is developed, along with testing at the end of the phase. Hence in this phase the development and testing is done. Design phase starts with the conceptual design in the baseline spiral and involves architectural design, logical design of modules, physical product design and final design in the subsequent spirals.
Evaluation phase: This phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral.after testing the build, at the end of first iteration, the customer evaluates the software and provides feedback.
These all phases keeps on rotating in spiral.After one spiral the planning includes the plans for next iterations and so on. Although this is a complex model but can be used to risk-based projects.
Advantages :
- Changing requirements can be accommodated.
- Allows for extensive use of prototypes
- Requirements can be captured more accurately.
- Users see the system early.
- Development can be divided into smaller parts and more risky parts can be developed earlier which helps better risk management.
- A highly customized product can be developed using this.
Planning Phase/Determine Objective: Requirements are gathered during the planning phase. Requirements like ‘BRS’ that is ‘Bussiness Requirement Specifications’ and ‘SRS’ that is ‘System Requirement specifications’. This phase starts with gathering the business requirements in the baseline spiral. In the subsequent spirals as the product matures, identification of system requirements, subsystem requirements and unit requirements are all done in this phase.This also includes understanding the system requirements by continuous communication between the customer and the system analyst. At the end of the spiral the product is deployed in the identified market.
Risk Analysis: In the risk analysis phase, a process is undertaken to identify risk and alternate solutions. Risk Analysis includes identifying, estimating, and monitoring technical feasibility and management risks, such as schedule slippage and cost overrun. A prototype is produced at the end of the risk analysis phase. If any risk is found during the risk analysis then alternate solutions are suggested and implemented.
Engineering/Design Phase: In this phase software is developed, along with testing at the end of the phase. Hence in this phase the development and testing is done. Design phase starts with the conceptual design in the baseline spiral and involves architectural design, logical design of modules, physical product design and final design in the subsequent spirals.
Evaluation phase: This phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral.after testing the build, at the end of first iteration, the customer evaluates the software and provides feedback.
These all phases keeps on rotating in spiral.After one spiral the planning includes the plans for next iterations and so on. Although this is a complex model but can be used to risk-based projects.
Advantages :
- Changing requirements can be accommodated.
- Allows for extensive use of prototypes
- Requirements can be captured more accurately.
- Users see the system early.
- Development can be divided into smaller parts and more risky parts can be developed earlier which helps better risk management.
- A highly customized product can be developed using this.
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