public class ServiceManager {

	public void addService(String service) {
		// todo
	}

	public void addServiceCall(String service, long time, String payload) {
		// todo
	}

	public List<String> getAllServiceCallsBetweenTimes(long time1, long time2) {
		// todo
	}
}

ServiceManager m = new ServiceManager();
m.addService("A");
m.addService("B");
m.addServiceCall("A", 1, "abc");
m.addServiceCall("A", 5, "abec");
m.addServiceCall("B", 3, "ac");
m.getAllServiceCallsBetweenTimes(1, 4); // ["abc", "ac"]