.. _restartlow:

===============
Restart
===============

1. TMC SDP Leaf node provides API for **Restart workflow**.

2. The TMC SDP Leaf node **accepts the command** if:

   a. Operational **state** of the TMC SDP Leaf node is **ON, OFF, INIT, STANDBY**, or **ALARM**.

3. The TMC SDP Leaf node **rejects the command** if:

   a. Operational **state** of the TMC SDP Leaf node is **FAULT** or **UNKNOWN**.

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

   a. SDP Subarray is in any of the observation states: **FAULT, ABORTED, RESOURCING, CONFIGURING, IDLE, READY,** or **SCANNING**.

   b. SDP Subarray node is :term:`available`.

5. The **command execution** involves the following **key operations**:

   a. SDP Subarray ObsState is checked.

      i. If the ObsState is **RESOURCING, IDLE, CONFIGURING, SCANNING, or READY**:

         - Abort command is sent to the SDP Subarray.

         - Once the SDP Subarray transitions to **ABORTED** ObsState, Restart command is sent to the SDP Subarray.

      ii. If the ObsState is **FAULT** or **ABORTED**:

         - Restart command is sent to the SDP Subarray.

   b. When Restart is invoked on the SDP Subarray:

      i. If the SDP Subarray reports **rejection or failure**, command failure is reported as **RESULT_CODE - FAILED** on the **Long Running Command Result** attribute of the TMC SDP Leaf node.

      ii. If the SDP Subarray **accepts** the command, the TMC TMC SDP Leaf node will wait for command completion.

6. The TMC SDP Leaf node **monitors the progress** of the command via the SDP Subarray node **ObsState transitions** and the **Long Running Command Results**.

   a. Command is **successful** when the SDP Subarray Node transitions to **EMPTY** ObsState. This is reported as **RESULT_CODE - OK** on the **Long Running Command Result** attribute of the TMC SDP Subarray Leaf Node.

   b. Command **failure** is reported in any of the following cases as **RESULT_CODE - FAILED** on the **Long Running Command Result** attribute of the TMC SDP Subarray Leaf Node:

      i. The SDP Subarray reports an **error event** when the command is invoked.

      ii. The command **times out** if the SDP Subarray Node **does not transition** to **EMPTY** within the timeout period specified by the CommandTimeOutDefault property in the Helm chart of the TMC SDP Leaf node.