Model-Based System Architecture

Chapter 8Requirements and Use Case Analysis

The requirements and use case analysis are not part of the system architect's activities. However, the architect has close interfaces to that discipline, for instance, when working with functional architectures (Chapter 14). In this section, we give a brief description of the requirements and use case analysis. We follow the “Systems Modeling Toolbox” (SYSMOD) for SysML [145]. The methodology uses common methods of requirements and use case analysis and is not specific for a modeling tool. The core tasks are as follows:

1. Identify and define requirements
2. Specify the system context
3. Identify use cases
4. Describe use case flows
5. Model the domain knowledge.

Hereinafter, we briefly describe each task with a focus on the interface to the system architecture discipline. The architecture tasks of SYSMOD are not covered in this chapter.

The interface between requirements engineering and system architecture is often underestimated in system development. Typically in focus is the derivation of the architecture from the requirements. That requires a close communication between the architect and the requirements engineer to resolve unclear and conflicting requirements.

In addition, as shown in the zigzag pattern (Section 7.1), the technical decisions of the architect lead to new requirements. Altogether the requirements engineers and system architects must closely collaborate and should not just communicate via documents and models.

Since requirements ...