Software Engineering

are:   The cascade model,   Iterative incremental model   The evolutionary model  

Spiral Model. Unplanned model or "coding - fix" is the most simple model of software life cycle. The principle of the model (Figure 6.1) is to write the code of the program without any serious pre-requirements analysis and design, launch programs to test its performance and the subsequent correction of errors and / or adding functionality to obtain version of the program that satisfies the user.

or waterfall model created by analogy with the methods of

the other engineering fields, where the practice of product creation phase of preparing specifications prior to delivery to the customer. The principle of the model (Figure 6.2) is a single execution of processes in the form of pre-ordered and clearly limited in time steps, as it were implemented in their natural boundaries. All the processes, activities, tasks are performed consistently well, is not allowed any overlap, duplication and return it. This hard limit does such a model is not practicable, as the already completed steps are not allowed any errors that require the utmost quality artifacts.

these constraints. Modified cascade model or whirlpool is a simple case

of such models. The principle of the model (Figure 6.3) is the ability to return to a previous stage in the case of finding errors in this stage and the revision or clarification of previous decisions.

solve the problems in the design under uncertainty of initial

requirements through the development of prototypes of the desired product. Model requires a set of quick construction of prototypes, and therefore the implementation of this model is only possible with appropriate instrumentation automation. The classical model uses prototyping prototyping to gradually identify the requirements. The principle of the model (Figure 6.4) is in the early development of a highly simplified prototype, which in accordance with the wishes of the user cycle improves and becomes more complicated as long as the requirements for the software does not become apparent. After that, the formalization of the identified requirements (itemize) and maintains its own product development for any model. Prototyping and product treated as a separate iteration of software life cycle.