Figure – Chapter 6

Architecture and system characteristics

Because of the close relationship between non functional requirements and software architecture , the particular architectural style and structure that you choose for a system should depend on the non functional system requirements:

• Performance
• If performance is a critical requirement , localize critical operations within a small number of components , deployed on the same computer , and minimize communications.
• Use large rather than fine-grain components.
• Security
• If security is a critical requirement , Use a layered architecture with critical assets in the innermost layers, with a high level of security validation applied to these layers.

Architecture and system characteristics

• Safety
• Localise safety-critical features in a single component or in small number of sub-systems.
• Availability
• Include redundant components so that it is possible to replace and update component without stopping the system.
• Maintainability
• Use fine-grain, replaceable components.
• Producers of data should be separated from consumers and shared data structure should be avoided

Architectural views

Architecture models may be used to document a design so it can be used as a basis for more detailed design and implementation.

2 issues may be raised :

• What views or perspectives are useful when designing and documenting a system’s architecture?
• What notations should be used for describing architectural models?

Each architectural model only shows one view or perspective of the system.

• It might show how a system is decomposed into modules, how the run-time processes interact or the different ways in which system components are distributed across a network. For both design and documentation, you usually need to present multiple views of the software architecture.