This chapter include objectives: To introduce architectural design and to discuss its importance; to explain the architectural design decisions that have to be made; to introduce three complementary architectural styles covering organisation, decomposition and control; to discuss reference architectures are used to communicate and compare architectures. | Architectural Design Objectives To introduce architectural design and to discuss its importance To explain the architectural design decisions that have to be made To introduce three complementary architectural styles covering organisation, decomposition and control To discuss reference architectures are used to communicate and compare architectures Topics covered Architectural design decisions System organisation Decomposition styles Control styles Reference architectures Software architecture The design process for identifying the sub-systems making up a system and the framework for sub-system control and communication is architectural design. The output of this design process is a description of the software architecture. Architectural design An early stage of the system design process. Represents the link between specification and design processes. Often carried out in parallel with some specification activities. It involves identifying major system components and their . | Architectural Design Objectives To introduce architectural design and to discuss its importance To explain the architectural design decisions that have to be made To introduce three complementary architectural styles covering organisation, decomposition and control To discuss reference architectures are used to communicate and compare architectures Topics covered Architectural design decisions System organisation Decomposition styles Control styles Reference architectures Software architecture The design process for identifying the sub-systems making up a system and the framework for sub-system control and communication is architectural design. The output of this design process is a description of the software architecture. Architectural design An early stage of the system design process. Represents the link between specification and design processes. Often carried out in parallel with some specification activities. It involves identifying major system components and their communications. Advantages of explicit architecture Stakeholder communication Architecture may be used as a focus of discussion by system stakeholders. System analysis Means that analysis of whether the system can meet its non-functional requirements is possible. Large-scale reuse The architecture may be reusable across a range of systems. Architecture and system characteristics Performance Localise critical operations and minimise communications. Use large rather than fine-grain components. Security Use a layered architecture with critical assets in the inner layers. Safety Localise safety-critical features in a small number of sub-systems. Availability Include redundant components and mechanisms for fault tolerance. Maintainability Use fine-grain, replaceable components. Architectural conflicts Using large-grain components improves performance but reduces maintainability. Introducing redundant data improves availability but makes security more difficult. Localising safety-related features .
