What protocol was used for interaction with [system/service]?

Interaction with a system or service in Java typically occurs via HTTP/HTTPS protocols, especially when it comes to web services (REST, SOAP). TCP or UDP protocols may also be used for low-level data exchange, RMI for remote method invocation, JMS for message exchange, or gRPC for high-performance communication.

The choice of protocol depends on the requirements for performance, reliability, and system architecture. For example, REST over HTTP is widely used due to its simplicity and support in browsers and mobile clients.