# Temporal Commands reference

> Discover the range of Commands Workers can issue to the Temporal Service after Workflow Task Execution, from Completing Workflow Execution to Start Timer and Signal External Workflow Execution.

A [Command](/workflow-execution#command) is a requested action issued by a [Worker](/workers#worker) to the [Temporal Service](/temporal-service) after a [Workflow Task Execution](/tasks#workflow-task-execution) completes.

The following is a complete list of possible Commands.

### CompleteWorkflowExecution

This Command is triggered when the Workflow Function Execution returns.
It indicates to the Temporal Service that the [Workflow Execution](/workflow-execution) is complete.
The corresponding [Event](/workflow-execution/event#event) for this Command is one of the few Events that will be the last in a Workflow Execution [Event History](/workflow-execution/event#event-history).

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [WorkflowExecutionCompleted](/references/events#workflowexecutioncompleted)

### ContinueAsNewWorkflowExecution

This Command is triggered when there is a call to [Continue-As-New](/workflow-execution/continue-as-new) from within the [Workflow](/workflows).
The corresponding Event for this Command is one of the few Events that will be the last in a Workflow Execution Event History.

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [WorkflowExecutionContinuedAsNew](/references/events#workflowexecutioncontinuedasnew)

### FailWorkflowExecution

This Command is triggered when the Workflow Execution returns an error or an exception is thrown.

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [WorkflowExecutionFailed](/references/events#workflowexecutionfailed)

### CancelWorkflowExecution

This Command is triggered when the Workflow has successfully cleaned up after receiving a Cancellation Request (which will be present as [WorkflowExecutionCancelRequestedEvent](/references/events#workflowexecutioncancelrequested) in the Event History).
The Corresponding Event for this Command is one of the few Events that will be the last in a Workflow Execution Event History.

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [WorkflowExecutionCanceled](/references/events#workflowexecutioncanceled)

### StartChildWorkflowExecution

This Command is triggered by a call to spawn a [Child Workflow Execution](/child-workflows).

- Awaitable: Yes, a Workflow Execution can await on the action resulting from this Command.
- Corresponding Event: [ChildWorkflowExecutionStarted](/references/events#childworkflowexecutionstarted)

By default, you cannot have more than 2,000 pending Child Workflows.

### SignalExternalWorkflowExecution

This Command is triggered by a call to [Signal](/sending-messages#sending-signals) another Workflow Execution.

- Awaitable: Yes, a Workflow Execution can await on the action resulting from this Command.
- Corresponding Event: [SignalExternalWorkflowExecutionInitiated](/references/events#signalexternalworkflowexecutioninitiated)

By default, you cannot have more than 2,000 pending Signals to other Workflows.

### RequestCancelExternalWorkflowExecution

This Command is triggered by a call to request cancellation of another Workflow Execution.

- Awaitable: Yes, a Workflow Execution can await on the action resulting from this Command.
- Corresponding Event: [RequestCancelExternalWorkflowExecutionInitiated](/references/events#requestcancelexternalworkflowexecutioninitiated)

By default, you cannot have more than 2,000 pending Signals to other Workflows.

### ScheduleActivityTask

This Command is triggered by a call to execute an [Activity](/activities).

- Awaitable: Yes, a Workflow Execution can await on the action resulting from this Command.
- Corresponding Event: [ActivityTaskScheduled](/references/events#activitytaskscheduled)

By default, you cannot schedule more than 2,000 Activities concurrently.

### RequestCancelActivityTask

This Command is triggered by a call to request the cancellation of an [Activity Task](/tasks#activity-task).

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [ActivityTaskCancelRequested](/references/events#activitytaskcancelrequested)

### StartTimer

This Command is triggered by a call to start a Timer.

- Awaitable: Yes, a Workflow Execution can await on the action resulting from this Command.
- Corresponding Event: [TimerStarted](/references/events#timerstarted)

### CancelTimer

This Command is triggered by a call to cancel a Timer.

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [TimerCanceled](/references/events#timercanceled)

### RecordMarker

This Command is triggered by the SDK.

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [MarkerRecorded](/references/events#markerrecorded)

### UpsertWorkflowSearchAttributes

This Command is triggered by a call to "upsert" Workflow [Search Attributes](/search-attribute).

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [UpsertWorkflowSearchAttributes](/references/events#upsertworkflowsearchattributes)

### ProtocolMessageCommand

This Command helps guarantee ordering constraints for features such as Updates.

This Command points at the message from which the Event is created.
Therefore, just from the Command, you can't predict the resulting Event type.

### ScheduleNexusOperation

This Command is triggered by a call to execute a Nexus Operation in the caller Workflow.

- Awaitable: Yes, a Workflow Execution can await on the action resulting from this Command.
- Corresponding Event: [NexusOperationScheduled](/references/events#nexusoperationscheduled)

By default, you can't schedule more than 30 Nexus Operations concurrently, see [Limits](/workflow-execution/limits#workflow-execution-nexus-operation-limits) for details.

### CancelNexusOperation

This Command is triggered by a call to request the cancellation of a Nexus Operation.

- Awaitable: No, a Workflow Execution can not await on the action resulting from this Command.
- Corresponding Event: [NexusOperationCancelRequested](/references/events#nexusoperationcancelrequested)