.. _scanmid:

============
Scan
============

    1. SDP Leaf Node provides API for **Scan workflow**.
    2. The SDP Leaf Node **accepts the command** if :-

        A. Operational **state** of the SDP Leaf node is **ON/OFF/INIT/STANDBY/ALARM**

    3. The SDP Leaf Node **rejects the command** if :-

        A. Operational **state** of SDP Leaf node is **FAULT/UNKNOWN** .

    4. The following **state requirements** are applied for the **command execution** :-

        A. SDP Subarray is in 'observation state' **READY** .
        B. SDP Subarray node is :term:`available` .

    5. The **command execution** involves below **key operations** :-

        A. Interface version is added to input json.
        B. The command is then invoked on the SDP Subarray.

            - If SDP Subarray **raises exception** , command **failure** is reported as **'RESULT_CODE - FAILED'** on Long Running Command Result attribute of the SDP leaf node.
            - If SDP Subarray **accept command** , the TMC SDP leaf node will wait for command completion.

    6. The SDP leaf node **monitors the progress** of command via the SDP sub-array node **ObsState transitions** .

        A. Command is **successful** when the SDP Subarray Node transitions to **SCANNING** ObsState. This is reported as **'RESULT_CODE - OK'** on Long Running Command Result attribute of the TMC SDP Subarray leaf node.
        B. Command **failure** is reported in any of the below cases as **'RESULT_CODE - FAILED'** on Long Running Command Result attribute of the TMC SDP Subarray leaf node.
    
            - The SDP Subarray reports **error event** when command is invoked .
            - The command **times out** if SDP SubarrayNode **does not transition** to **SCANNING** within the timeout period specified by `CommandTimeOutDefault` property specified in helm chart of the SDP Leaf Node .
    
    7. Input JSON to SDP Subarray is as per schema detailed at -  https://developer.skao.int/projects/ska-telmodel/en/latest/schemas/sdp/ska-sdp-scan.html