In Dynamics 365 for Finance and Operations, we still have custom services available to expose the system's functionality to the external world. Microsoft uses the SysOperation framework, where data contracts are decorated with standard attributes, and it automatically serializes and desterilizes data that is shared between two applications. Any service method can be exposed to the external world by using SysEntryPointAttribute and then specifying the service operation under Application Explorer | AOT | Services.
In this recipe, we will create a custom service that will be consumed in subsequent recipes to demonstrate how it could be consumed by the external world.
