Exam S90.09 topic 1 question 23 discussion

Actual exam question from SOA's S90.09

Question #: 23
Topic #: 1

Service A. Service B. and Service C are each designed to access the same shared legacy system. The service contracts for Service A, Service B, and Service C are standardized and decoupled from the underlying service logic. Service A and Service B are agnostic services that are frequently reused by different service compositions. Service C is a non-agnostic task service that requires access to the legacy system in order to retrieve business rules required for the service to make runtime decisions that determine its service composition logic. The legacy system uses a proprietary file format that Services A, B, and C need to convert to and from.

You are told that additional services need to be created, all of which need access to the legacy system. You are also told that the legacy system may be replaced in the near future. What steps can be taken to ensure that the replacement of the legacy system has a minimal impact on Services A, B, and C and any future services that are designed to rely upon it?

A. The Legacy Wrapper pattern can be applied together with the Standardized Service Contract principle to position a standardized service contract between the legacy system and any services that require access to it. This effectively establishes a new utility service dedicated to the encapsulation of the legacy system. When the legacy system is replaced, the utility service can keep its standardized service contract. To build the utility service, the Data Format Transformation pattern is applied to convert between the proprietary legacy system file format and the XML format used in the standardized service contract.
B. The Legacy Wrapper pattern can be applied together with the Official Endpoint pattern so that the Service A service contract is positioned as the sole access point for the legacy system. The Data Format Transformation pattern is applied to enable the conversion between the proprietary legacy system file format and the XML format used in the Service A service contract. Finally, the Contract Centralization pattern is applied so that Service A is forced to only access the legacy system via its published standardized service contract.
C. The Legacy Wrapper pattern can be applied together with the Data Format Transformation pattern and the Standardized Service Contract principle in order to establish an intermediate layer of standardized transformation logic that is positioned between the legacy system and Services A, B, and C. This way, if the legacy system is replaced, the services will not be affected because of the abstraction established by the standardized transformation layer.
D. None of the above.

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Suggested Answer: A 🗳️

by tacihosi at April 6, 2025, 5:50 a.m.

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