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The Star Life Cycle

Today we will talk about one of the very early methodologies of system development, the star life cycle. The star model was developed in the late 1980s by Hartson and Hix, in contrast with the other methods at that time, the star model takes the idea of prototyping and evaluation much further than any other approach. The star life cycle also emphasizes the important distinction between conceptual design and physical design. Let's go and have a deeper look!


Evaluation is central in this method. All aspects of systems development are subject to constant evaluation by users and experts. The star model also promotes an "alternating waves" approach to system development, being more synthetic, stressing rapid prototyping and incremental development of the final product. In the star life cycle approach, system development may begin at any stage and may be followed by any of the other stages. This may seem a strange notion, but in reality, is quite common. The requirements, design, and the product gradually evolve, becoming increasingly well defined. The provision of good software tools is vital in order to underpin this approach.

The star model (adapted from Hartson and Hix, 1989, 1993.



As said at the beginning of the article, the star life cycle also emphasizes the important distinction between conceptual design and physical design. Conceptual design concerns itself with questions of what is required; what the system should do, what data is required, what users will need to know, and so on. Physical design is concerned with questions of how these things can be achieved. The conceptual/physical distinction is fundamental to the provision of good systems because it defers decisions as to who or what will ultimately perform which functions or provide which data until late in the design process.


The star life cycle is primarily oriented to the particular demands of developing interactive systems that will be usable by people. The emphasis on rapid prototyping, alternating waves of analytic and synthetic approaches, and evaluation are both realistic and user-centered. The principle that development may commence from any point in the star overcomes many of the limitations of the traditional model. Just as important as the processes of design are the representation of the system that is employed. For some purposes, informal models such as sketches, scenarios, and prototypes will be most apt, whereas for other purposes formal notations will be more appropriate. checklists, design rules, and guidelines are also used to assist the designer at various stages.









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