Figure – Chapter 6

Architectural design decisions

• Architectural design is a creative process , where you design a system organization that will satisfy the functional and non functional requirements.
• So the process differs depending on the type of system being developed.
• Think of architectural design as a series of decisions to be made rather than a sequence of activities.
• However, a number of common decisions span all design processes and these decisions affect the non-functional characteristics of the system.

Architectural design decisions

Based on their experience and knowledge , system architects have to consider these fundamental questions:

• Is there a generic application architecture that can be used?
• How will the system be distributed?
• What architectural styles are appropriate?
• What approach will be used to structure the system?
• How will the system be decomposed into modules?
• What control strategy should be used?
• How will the architectural design be evaluated?
• How should the architecture be documented?

Architecture reuse

• Systems in the same domain often have similar architectures that reflect domain concepts.
• Application product lines are application that are built around a core architecture with variants that satisfy particular customer requirements. So when designing an architecture , you have to decide what your system and broader application classes have in common, then decide how much knowledge can be reused.
• The architecture of a system may be designed around one of more architectural patterns or ‘styles’.
• These capture the essence of an architecture and can be instantiated in different ways.
• Discussed later in this lecture.

Architecture and system characteristics

For distributed systems across many different computers, the choice of distribution architecture is a key decision that affects :

• Performance
• Security
• Safety
• Availability
• Maintainability