External or internal services in the diagram?

In system analysis diagrams, external services are usually represented as external actors or external systems — they are outside the boundary of the system being analyzed and interact with it through interfaces. Internal services are components of the system itself that implement business logic or technical functions.

If the diagram describes the system boundaries and interactions with the external world (for example, a context diagram), external services are shown as external actors. If the diagram is more detailed (for example, a component or service diagram), internal services are displayed within the system.

Thus:

• External services are shown outside the system boundary on the diagram.
• Internal services are inside the system.

This helps clearly delineate responsibilities and understand which parts of the system are controlled and which are external dependencies.