Architecture and Design

Question 1

What is software architecture?

Answer 1

Definds how the system is organized

Breaks the entire system into a set of communicating modules.

Question 2

What is the small level or architecture?

Answer 2

At the “signle” system level

defines how a large system is broken down into subsystems.

Question 3

What is the large level of architecture?

Answer 3

at the “collection of systems” level.
Defines how a system is broken down into individual systems.

Question 4

Why do we need an architecture?

Answer 4

Stakeholder communication:
- Aid for system-level design

System analysis:
- If not discussed, implicit architecture may be suboptimal.

Large-scale resuse:
- systems with similar requirements can resuse architecture components.

Question 5

Can we specify all system characteristics in one architecture model?

Answer 5

This is impractical, because too many perspective will cause the diagram to become a mess.
Instead, we need multiple views.

Question 6

What are the 4 view models of software architecture?

Answer 6

Logical view:
Process view:
Development view:
Physical view:

Question 7

What is logical view?

Answer 7

Shows the key abstractions in the system as objects or object classes.

Question 8

What is process view?

Answer 8

Shows how, at run-time, the system is composed of interactive processes.

Question 9

What is developmet view?

Answer 9

Shows how the software is decomposed for development.

Question 10

What is physical view?

Answer 10

Shows the system hardware and how software components are distributed across the processors in the system.

Question 11

What are the purposes of architecture models?

Answer 11

Aiding discussion of system-level design

Documenting system architecture

Question 12

How to maximize performance?

Answer 12

Maximized b creating a small number of large subsystems.

Question 13

How to maximize security?

Answer 13

Maximized by layering systems with critical assets protected in the innermost layer

Question 14

How to maximize safety?

Answer 14

Maximized by placing safety-related operations in a small number of subsystems.

Question 15

How to maximize availability>

Answer 15

Maximized through redundant subsystems to allow hot-swapping for updates.

Question 16

How to maximize maintainability?

Answer 16

Maximized by creating a large number of small, independent subsystems.

Question 17

What is an architectural pattern

Answer 17

• Abstract descriptions of tried-and-tested solutions to common application problems.
• Should describe when it’s a good idea to use and when it should be avoided.

Question 18

Tradeoffs of lightweight vs. formal architectural models

Answer 18

Lightweight (block):
Valuable discussion aid
Easy to produce
Lacks the rigour needed for formal docs

Heavyweight (formal):
Valuable for documentation purposes
Expensive to produce
Difficult for people to understand