Spiral model

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Boehm spiral model

The spiral model is a process model in software development that was described by Barry W. Boehm in 1986 . It is a generic process model and therefore open to already existing process models. The management may again intervene again, as you spiral develops ahead.


The spiral model sees the development process in software engineering as an iterative process, with each cycle containing the following activities in the individual quadrants :

  1. Definition of goals , identification of alternatives and description of framework conditions
  2. Evaluation of the alternatives and the recognition, assessment and reduction of risks , e.g. B. through analyzes, simulations or prototyping
  3. Realization and verification of the intermediate product
  4. Planning the next cycle of project continuation.

The risk assessment is the essential aspect that distinguishes the spiral model from other previously developed procedural models. First, all risks that threaten the project are identified and then assessed. Then you look for a way to remove the greatest risk. The project is considered to have failed if the elimination fails. If, however, there are no longer any risks, the project has been successfully completed.

The spiral model is one of the incremental or iterative process models. It is a further development of the waterfall model , in which the phases are spiraled through several times.

The incremental and iterative process model therefore provides for a cyclical repetition of the individual phases. The project slowly approaches the goals, even if the goals change as the project progresses. According to Boehm, the spiral model significantly reduces the risk of failure in large software projects .

See also


  • Helmut Balzert : Textbook of software technology. Software management, software quality assurance, business modeling. Spektrum Akademischer Verlag, Berlin et al. 1998, ISBN 3-8274-0065-1 , pp. 129-133.

Web links

Individual evidence

  1. ^ Jochen Ludewig, Horst Lichter: Software Engineering. Basics, people, processes, techniques. dpunkt, Heidelberg 2007, ISBN 978-3-89864-268-2 , pp. 168-170.