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System Analysis Phase


The system analysis phase takes over where the requirements analysis stopped. Where the requirements analysis focussed on external requirements the system analysis focuses on the internal architecture of the system. The analysis object model is the major medium used to describe the architecture. The architecture is defined in terms of the objects and object structures defined in this model. To establish the responsibilities of the different classes and verify that the proposed architecture is sufficient the use cases from the requirements analysis are in this phase refined in the analysis use case model.

It is not uncommon in practise that there is an overlap in time between the different phases and this is also true for the requirements analysis phase and the system analyses phase. It makes sense to start sketching the architecture of the system before the requirements analysis is brought to completion to capture ideas about the architecture whenever they emerge. It is however important to view this as a side activity and not forget to force the requirements analysis to a completion before digging into the details of the architecture.

The system analysis is finished when there is a consistent and well understood definition of the major objects needed in the system, including a clear definition of the responsibilities for the different objects, and the architecture is validated using the analysis use cases. It is beneficial if the system analysis can be performed by a small team consisting of the best people available including an experienced architect and some more developers.


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