They are required to map between the different formats when the data flows from the service interface down to the database and back.

当数据在服务接口与数据库之间来回流动时，需要用这些操作来完成不同格式之间的映射。

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Then the selector can invoke the interface map that, in turn, calls the actual service implementation.

然后，选择器可以调用接口映射，该接口映射接着调用实际的服务实现。

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The service code implements the WSDL interface and applies business and mapping logic to call into and map results from backend systems.

服务代码实现 WSDL 接口并将业务与映射逻辑应用于调用和映射来自后端系统的结果。

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