Which principle should guide how a modernised mainframe application is decomposed comes up in today's design review. What is the right answer?
Select an answer to reveal the explanation.
Short Explanation
Modularity is a tool, not a target. You use it where the boundaries in the business logic actually support it, not everywhere at once.
Full Explanation
The right answer is to apply modular services, APIs and hybrid-cloud patterns where they genuinely fit the business and technical constraints, not as a rule applied uniformly. Modernisation decisions should be driven by where a modular service, an API or a hybrid-cloud pattern actually reduces coupling or improves flexibility for a given piece of the application, weighed against the cost and risk of making that change.
The paragraph-per-microservice approach is incorrect because decomposing at paragraph granularity ignores cohesion entirely and produces a sprawl of services with no independent business meaning, which is harder to operate than the monolith it replaced.
The cosmetic-only refresh is incorrect because changing screen colours and fonts changes nothing about the architecture, the technical debt, or the integration risk the modernisation effort was meant to address.
The lift-and-shift without changing integration boundaries is incorrect because leaving integration boundaries untouched carries the legacy coupling into the new environment, so none of the benefits of the target platform are actually realised.
For the exam, expect 'apply where it fits the constraints' to be the correct framing over any blanket architectural rule.