The application of the Legacy Wrapper pattern typically results in:

Question

Options

• Ano coupling of the wrapper service logic to the legacy system
• Bno coupling of the wrapper service logic to the service contract
• Cno coupling of the service consumer to the legacy system encapsulated by the wrapper service
• Dno coupling of the service logic to the service contract

• A
  7% (3)
• B
  2% (1)
• C
  88% (38)
• D
  2% (1)

Explanation

Option C is correct because the Legacy Wrapper pattern's primary purpose is to encapsulate a legacy system behind a clean service interface, so consumers interact only with the wrapper's published service contract and remain completely unaware of - and therefore decoupled from - the legacy internals.

Why the distractors are wrong:

• A is wrong because the wrapper itself must be tightly coupled to the legacy system - it translates between the service contract and the legacy system's proprietary interfaces; that coupling is unavoidable and intentional.
• B is wrong because the wrapper must conform to a service contract; it implements that contract to expose itself to consumers, so it is inherently coupled to it.
• D is essentially a restatement of B and is wrong for the same reason - the wrapper's logic is explicitly designed around the service contract it must fulfill.

Memory tip: Think of the wrapper as a power adapter - the adapter is physically coupled to both the wall socket (legacy system) and the plug standard (service contract), but your device (the consumer) only sees a clean universal port and never touches the wall socket directly. The consumer's decoupling from the legacy system is the whole payoff.

No community discussion yet for this question.