CPSA Designing Building Blocks 5 — Questions and Answers
Question 1: Which iSAQB arc42 view is PRIMARILY used to document building blocks and their static relationships?
- Runtime view
- Deployment view
- Building block view (Correct answer)
- Context view
Correct answer: Building block view
The arc42 building block view documents the system's static decomposition into building blocks and their inter-relationships.
Question 2: When applying the Dependency Inversion Principle to building blocks, high-level modules should:
- Directly instantiate low-level module implementations
- Depend on abstractions rather than concrete low-level implementations (Correct answer)
- Avoid using interfaces to minimize complexity
- Always be placed in the lowest architectural layer
Correct answer: Depend on abstractions rather than concrete low-level implementations
DIP requires that high-level modules depend on abstractions (interfaces), with low-level modules implementing those abstractions, inverting the traditional dependency direction.
Question 3: A team notices that every change to the 'Payment' building block also requires changes to 'Reporting' and 'Audit'. This MOST likely indicates:
- Correct use of the Single Responsibility Principle
- Inappropriate coupling or shared responsibility across blocks (Correct answer)
- Optimal cohesion within each block
- A well-designed event-driven architecture
Correct answer: Inappropriate coupling or shared responsibility across blocks
When unrelated blocks must change in lockstep, it signals excessive coupling or incorrectly distributed responsibilities.
Question 4: Which pattern allows a building block to adapt an incompatible interface to one expected by its client?
- Decorator
- Observer
- Adapter (Correct answer)
- Proxy
Correct answer: Adapter
The Adapter pattern wraps an incompatible interface and exposes the interface expected by the client building block.
Question 5: In building block design, 'cohesion' and 'coupling' are considered opposing forces because:
- High cohesion always causes high coupling
- Increasing a block's internal cohesion tends to reduce its external coupling (Correct answer)
- Low coupling requires low cohesion
- They measure the same property from different perspectives
Correct answer: Increasing a block's internal cohesion tends to reduce its external coupling
Focusing a block's responsibilities internally (high cohesion) naturally limits what it needs from other blocks, reducing external coupling.
Question 6: Which of the following is an example of 'logical' versus 'physical' building blocks?
- A class versus an interface
- An architectural component versus its deployment artifact (JAR, DLL) (Correct answer)
- A service versus a database
- A module versus a package
Correct answer: An architectural component versus its deployment artifact (JAR, DLL)
Logical building blocks represent design-time abstractions, while physical building blocks are the actual deployment artifacts that implement them.
Question 7: Why is documenting the rationale for building block decomposition decisions considered important in arc42?
- It satisfies compliance auditing requirements automatically
- It allows future architects to understand trade-offs and avoid re-litigating settled decisions (Correct answer)
- It replaces the need for interface documentation
- It is required by all agile methodologies
Correct answer: It allows future architects to understand trade-offs and avoid re-litigating settled decisions
Recording rationale preserves the reasoning behind decomposition choices so future teams understand constraints and avoid repeating past analysis.
CPSA Designing Building Blocks 5
Which iSAQB arc42 view is PRIMARILY used to document building blocks and their static relationships?