# Activity execution - Ruby SDK

> Shows how to perform Activity execution with the Ruby SDK

## Start Activity Execution 

Calls to spawn [Activity Executions](/activity-execution) are written within a [Workflow Definition](/workflow-definition).
The call to spawn an Activity Execution generates the [ScheduleActivityTask](/references/commands#scheduleactivitytask) Command.
This results in the set of three [Activity Task](/tasks#activity-task) related Events ([ActivityTaskScheduled](/references/events#activitytaskscheduled), [ActivityTaskStarted](/references/events#activitytaskstarted), and `ActivityTask[Closed]`)in your Workflow Execution Event History.

The values passed to Activities through invocation parameters or returned through a result value are recorded in the Execution history.
The entire Execution history is transferred from the Temporal service to Workflow Workers when a Workflow state needs to recover.
A large Execution history can thus adversely impact the performance of your Workflow.

Therefore, be mindful of the amount of data you transfer through Activity invocation parameters or Return Values.
Otherwise, no additional limitations exist on Activity implementations.

To spawn an Activity Execution, use the `execute_activity` operation from within your Workflow Definition.

```ruby
class MyWorkflow < Temporalio::Workflow::Definition
  # Customize the name
  workflow_name :MyDifferentWorkflowName

  def execute(name)
    Temporalio::Workflow.execute_activity(
      MyActivity,
      { greeting: 'Hello', name: },
      start_to_close_timeout: 100
    )
  end
end
```

Activity Execution semantics rely on several parameters.
The only required value that needs to be set is either a [Schedule-To-Close Timeout](/encyclopedia/detecting-activity-failures#schedule-to-close-timeout) or a [Start-To-Close Timeout](/encyclopedia/detecting-activity-failures#start-to-close-timeout).
These values are set as keyword parameters.

The Activity result is the returned from the `execute_activity` call.