How can developers use data contracts and service classes to build maintainable custom services in Dynamics 365 Finance and Operations?

Custom services in Dynamics 365 Finance and Operations require a clear separation between the data exchanged by the service and the business logic that processes it. Explore how data contracts define service payloads while service classes encapsulate the operations performed by the service. Understand how this structure supports integrations, maintainability, validation, and clean service design in X++. This is a valuable skill for F&O Technical Developers working on enterprise integrations and custom APIs.