To define a custom service entry point in Dynatrace, which can be used?

Defining a custom service entry point in Dynatrace involves utilizing methods, classes, or interfaces. This flexibility allows users to tailor monitoring based on specific use cases or requirements of their applications. By specifying methods and classes as entry points, it becomes possible to capture detailed performance metrics and trace data that correspond to the application's architecture and design.

Using methods allows for pinpointing where actual business logic is executed, while defining classes can provide a broader context of the services that the application offers. Meanwhile, interfaces can also serve as effective entry points, especially in object-oriented programming where multiple classes might implement the same interface, helping to consolidate monitoring strategies across those implementations.

Other options like databases or APIs may have their specific monitoring capabilities, but they are not suitable as entry points for custom service definitions in the sense that this question implies. The focus on methods, classes, and interfaces highlights the ability to adapt monitoring to the application's code structure and logical flow, which is central to effective observability in Dynatrace.