RELATIONSHIP BETWEEN PROJECT LIFE CYCLE AND PRODUCT/SYSTEM LIFE CYCLE

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Product life cycle Spiral Model
Product life cycle spiral model is the most generic of the models. Most life cycle models can be derived as special cases of the spiral model. The spiral uses a risk management approach to software development. Some advantages of the spiral model are:
· defers elaboration of low risk software elements
· incorporates prototyping as a risk reduction strategy
· gives an early focus to reusable software
· accommodates life-cycle evolution, growth, and requirement changes
· incorporates software quality objectives into the product
· focus on early error detection and design flaws
· sets completion criteria for each project activity to answer the question: "How much is enough?"
· uses identical approaches for development and maintenance
· can be used for hardware-software system development
The spiral is a risk-reduction oriented model that breaks a software project up into mini-projects, each addressing one or more major risks. After major risks have been addressed, the spiral model terminates as a waterfall model. Spiral iterations involve six steps:
· Determine objectives, alternatives and constraints. For example there can be time constraints for completing the project. . Please remember that this corresponds to the discovery and requirements stage of the project life cycle.
· Identify and resolve risk for example there can be risks related to time or cost overruns. This stage corresponds to the functionality and design stage of the project life cycle.
· Evaluate alternatives.
· Develop the deliverables for that iteration and verify that they are correct.
· Plan the next iteration. For example the next iteration may have increased costs or new technological requirements.
· Commit to an approach for the next iteration.
The advantage of using the spiral model is that early iterations of the project are the cheapest, enabling the highest risks to be addressed at the lowest total cost. This ensures that as costs increase, risks decrease. For example, the hiring costs in the earlier part of the project are likely to be lower than those that have to be paid later. In addition, Each iteration of the spiral can be tailored to suit the needs of the project. The difficulty with the spiral model is that it is complicated and requires attentive and knowledgeable management to pull it off.

For projects with risky elements, for example computer architecture projects where the company has little experience, it's beneficial to run a series of risk-reduction iterations that can be followed by a waterfall or other non-risk-based lifecycle.
The steps in the spiral model can be generalized as follows:
1. The new system requirements are defined in as much detail as possible. Please remember that this corresponds to the requirements stage of the project life cycle. This usually involves interviewing a number of users representing all the external or internal users and other aspects of the existing system.
2. A preliminary ...