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System Analysis Overview


While the purpose of the requirements analysis is to understand the problem to be solved and the requirements this puts on the system, the purpose of the system analysis is to understand the architecture of the system itself. Essentially the issue of the system analysis is to find out what objects are needed to implement the requirements on the system. This means that the system analysis to a large extent is an analysis of the information that is needed to be represented in the system and the structure of the system itself. Information is here used in a broad sense which includes not only the data to be manipulated in the system but also the containers for algorithms and interfaces.

The system analysis in SOMT is very similar to corresponding activities in other object-oriented analysis methods and the major input and outputs of this activity are illustrated in Figure 644.

Figure 644 : The major inputs and outputs of the system analysis activity

The main input to the system analysis is the requirements object model and use cases developed during the requirements analysis and the main output is another object model, the analysis object model that describes the logical architecture of the system. In addition to this model a use case model is also created in the system analysis to describe the dynamic aspects of the architecture and textual analysis documentation is used to document analysis results not suitable to be express as use cases or object models. The different models will be discussed in detail in the following sections, the analysis object model in Analysis Object Model and the use cases in Analysis Use Case Model.

The tasks to perform in the system analysis activity are thus essentially the following:

  1. Start defining an initial version of the analysis object model, in particular concentrating on creating an overall architecture of the application.
  2. Then start refining some of the most important requirements use cases to check that the architecture defined in the analysis object model will work.
  3. Continue by iterating between modifying/refining the analysis object model and creating more analysis use cases, either by refining requirements use cases or by describing particular mechanisms in the application.

In parallel with the tasks above it may also be necessary to study various aspects of the chosen architecture, e.g. with respect to non-functional requirements. These results can be documented in the textual analysis documentation.


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