In the sequence diagram for the Weather Information System, arrange the object…
2019
In the sequence diagram for the Weather Information System, arrange the object lifelines in increasing order of activation length (shortest to longest). Exclude the external actor from the options.
- A.
Sat comms → Weather station → Commslink → Weather data
- B.
Sat comms → Comms link → Weather station → Weather data
- C.
Weather data → Comms link → Weather station → Sat Comms
- D.
Weather data → Weather station → Comms link → Sat Comms
Attempted by 56 students.
Show answer & explanation
Correct answer: C
Correct answer: Weather Data → Commslink → Weather Station → Sat Comms
The question asks for increasing activation/lifeline length, not simply the left-to-right order of object boxes.
Weather Data: shortest activation; it only performs the summarization and returns the result.
Commslink: starts when get(summary) is called and ends after returning the summary.
Weather Station: starts earlier than Commslink and remains active while requesting the summary and sending the report.
Sat Comms: has the longest activation among the listed objects because it receives the external request, sends/receives messages, replies, and acknowledges.