Use Case: GetOnLineObservation


The Use Case describes how the Caibration Pipeline gets the data and metadata of an Observtion to be processed. The Control system sends an Event at the beginning of the data taking, and the System starts listening to streams containing metadata (provided by the Control System, and data (provided by the Correlator System).

If the observation is canceled, and data not actually taken for the current observation, the Control System provides a specific event, with information of what is to be done.

Role(s)/Actor(s):
Primary: Control System
Secondary: Quick Look Pipeline, Archive, Executive, Operator.

Priority: Major

Performance: from seconds (such as pointing/focus measurements) to minutes for array calibrations (baseline, pointing model).

Frequency: minutes

Preconditions:

  1. A Calibration observation is started by the Control System, using a Subarray of ALMA antennas.

Basic Course:

  1. Whenever the Observation is started, the Control System creates an ObservationStarted event. Associated to that event are a few metadata, that will enable identifying the associated metadata and data, and determine data processing to be performed:
    • Scan Id
    • Observation Id
    • SubArray Id
    • ObservationIntent

    Alternate Course:The ObservationFailed event is sent by the Control System. That event has associated with it an ObservationFailedIntent.
    • Any further metadata related to that observation is ignored;
    • Further processing follows ObservationFailedIntent:
      • Either the observation will be repeated, and nothing is to be done.
      • Or the scan is terminated, with or without processing to be done.
      • Or the whole calibration is canceled.

    Exception Course:The ObservationIntent is not regognized by the System: the observation is ignored and the problem is logged.
  2. The System then starts listening to the metadata input stream provided by the Control System. Metadata associated to each observation is filtered according to its specified Observation Intent, and saved in memory.
    Exception Course:The Observation is canceled. See above.
  3. The System also starts listening to the data input stream provided by the Correlator System. Data associated to each observation is filtered according to its specified Observation Intent, and saved in memory.
    Exception Course:The Observation is canceled. See above.


Postconditions:

  1. Metatadata and data relevant to the observation are saved in memory according the relevant ObservationIntent


Issues to be Determined or Resolved:

Notes:

Owner: Robert Lucas
Last modified by $Author: telcal $ on $Date: 2002/10/22 11:53:18 $