Temporal Events reference

Events are created by the Temporal Service in response to external occurrences and Commands generated by a Workflow Execution. All possible Events that could appear in a Workflow Execution Event History are listed below.

WorkflowExecutionStarted

This is always the first Event in a Workflow Execution Event History. It indicates that the Temporal Service received a request to spawn the Workflow Execution.

Field	Description
workflow_type	The Name of Workflow that was initiated.
parent_workflow_namespace	The Namespace of the Parent Workflow Execution, if applicable.
parent_workflow_execution	Identifies the parent Workflow and the execution run.
parent_initiated_event_id	Id of the StartWorkflowExecutionInitiated Event this Event corresponds to.
task_queue	The Task Queue that this Workflow Task was enqueued in.
input	Information that is deserialized by the SDK to provide arguments to the Workflow.
workflow_execution_timeout	The total timeout period for a Workflow Execution, including retries and continue-as-new.
workflow_run_timeout	Timeout of a single Workflow run.
workflow_task_timeout	Timeout of a single Workflow Task.
continued_execution_run_id	Run Id of the previous Workflow which continued-as-new, retried or was executed by Cron into this Workflow.
initiator	Allows the Workflow to continue as a new Workflow Execution.
continued_failure	Serialized result of a failure.
last_completion_result	Information from the previously completed Task, if applicable.
original_execution_run_id	The Run Id of the original Workflow started.
identity	The Id of the Client or parent Workflow Worker that requested the start of this Workflow.
first_execution_run_id	The first Run Id, along the chain of Continue-As-New Runs and Reset.
retry_policy	The amount of retries as determined by the service's dynamic configuration. Retries will happen until 'schedule_to_close_timeout' is reached.
attempt	The number of attempts that have been made to complete this Task.
workflow_execution_expiration_time	The absolute time at which the Workflow Execution will time out.
cron_schedule	Displays the Workflow's Cron Schedule, if applicable.
first_workflow_task_backoff	Contains the amount of time between when this iteration of the Workflow was scheduled, and when it should run next. Applies to Cron Scheduling.
memo	Non-indexed information to show in the Workflow.
search_attributes	Provides data for setting up a Workflow's Search Attributes.
prev_auto_reset_points
header	Information passed by the sender of the Signal that is copied into the Workflow Task.

WorkflowExecutionCompleted

This indicates that the Workflow Execution has successfully completed. The Event contains Workflow Execution results.

Field	Description
result	Serialized result of completed Workflow.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
new_execution_run_id	The Run Id of the new Workflow Execution started as a result of a Cron Schedule.

WorkflowExecutionFailed

This Event indicates that the Workflow Execution has unsuccessfully completed and contains the Workflow Execution error.

Field	Description
failure	Serialized result of a Workflow failure.
retry_state	The reason provided for whether the Task should or shouldn't be retried.
workflow_task_completed_event_id	The Run Id of the WorkflowTaskCompleted that the Event was reported with.
new_execution_run_id	The Run Id of the new Workflow started by Cron or Retry.

WorkflowExecutionTimedOut

This Event type indicates that the Workflow Execution has timed out by the Temporal Server due to the Workflow having not been completed within timeout settings.

Field	Description
retry_state	The reason provided for whether the Task should or shouldn't be retried.
new_execution_run_id	The Run Id of the new Workflow started by Cron or Retry.

WorkflowExecutionCancelRequested

This Event type indicates that a request has been made to cancel the Workflow Execution.

Field	Description
cause	The user-provided reason for the cancelation request.
external_initiated_event_id	The Run Id of the Event in the Workflow that requested cancelation, if applicable.
external_workflow_execution	Identifies the external Workflow and the run of the its execution.
identity	Id of the Worker that requested cancelation.

WorkflowExecutionCanceled

This Event type indicates that the client has confirmed the cancelation request and the Workflow Execution has been canceled.

Field	Description
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
details	Additional information reported by the Workflow upon cancelation.

WorkflowExecutionSignaled

This Event type indicates the Workflow has received a Signal Event. The Event type contains the Signal name, as well as a Signal payload.

Field	Description
signal_name	The name/type of Signal to be fired.
input	Information that is deserialized by the SDK to provide arguments to the Workflow function.
identity	Identifies the Worker that signaled to the Workflow.
header	Information passed by the sender of the Signal that is copied into the Workflow Task.

WorkflowExecutionTerminated

This Event type indicates that the Workflow Execution has been forcefully terminated and that likely the terminate Workflow API was called.

Field	Description
reason	Information provided by the user or client for Workflow termination.
details	Additional information reported by the Workflow upon termination.
identity	Identifies the Worker that requested termination.

WorkflowExecutionContinuedAsNew

This Event type indicates that the Workflow has successfully completed, and a new Workflow has been started within the same transaction. This Event type contains last Workflow Execution results as well as new Workflow Execution inputs.

Field	Description
new_execution_run_id	The Run Id of the new Workflow started by this Continue-As-New Event.
workflow_type	The name/type of Workflow that was started by this Event.
task_queue	The Task Queue that this Workflow Task was enqueued in.
input	Information that is deserialized by the SDK to provide arguments to the Workflow.
workflow_run_timeout	Timeout of a single Workflow run.
workflow_task_timeout	Timeout of a single Workflow Task.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event command was reported with.
backoff_start_interval	The amount of time to delay the beginning of the ContinuedAsNew Workflow.
initiator	Allows the Workflow to continue as a new execution.
last_completion_result	Information passed by the previously completed Task to the ongoing execution.
header	Information passed by the sender of the Signal that is copied into the Workflow Task.
memo	Non-indexed information to show in the Workflow.
search_attributes	Provides data for setting up a Workflow's Search Attributes.

WorkflowTaskScheduled

This Event type indicates that the Workflow Task has been scheduled. The SDK client should now be able to process any new history events.

Field	Description
task_queue	The Task Queue that this Workflow Task was enqueued in.
start_to_close_timeout	The time that the Worker takes to process this Task once it's received.
attempt	The number of attempts that have been made to complete this Task.

WorkflowTaskStarted

This Event type indicates that the Workflow Task has started. The SDK client has picked up the Workflow Task and is processing new history events.

Field	Description
scheduled_event_id	The Id of the WorkflowTaskScheduled Event that this Workflow Task corresponds to.
identity	Identifies the Worker that started this Task.
request_id	Identifies the Workflow Task request.

WorkflowTaskCompleted

This Event type indicates that the Workflow Task completed.

Field	Description
scheduled_event_id	The Id of the WorkflowTaskScheduled Event that this Workflow Task corresponds to.
started_event_id	The Id of the WorkflowTaskStarted Event that this Task corresponds to.
identity	Identity of the Worker that completed this Task.
binary_checksum	Binary Id of the Worker that completed this Task.

The SDK client picked up the Workflow Task, processed new history events, and may or may not ask the Temporal Server to do additional work. It is possible for the following events to still occur:

• ActivityTaskScheduled
• TimerStarted
• UpsertWorkflowSearchAttributes
• MarkerRecorded
• StartChildWorkflowExecutionInitiated
• RequestCancelExternalWorkflowExecutionInitiated
• SignalExternalWorkflowExecutionInitiated
• WorkflowExecutionCompleted
• WorkflowExecutionFailed
• WorkflowExecutionCanceled
• WorkflowExecutionContinuedAsNew

WorkflowTaskTimedOut

This Event type indicates that the Workflow Task encountered a timeout. Either an SDK client with a local cache was not available at the time, or it took too long for the SDK client to process the Task.

Field	Description
scheduled_event_id	The Id of the WorkflowTaskScheduled Event that this Workflow Task corresponds to.
started_event_id	The Id of the WorkflowTaskStarted Event that this Task corresponds to.
timeout_type	The type of timeout that has occurred.

WorkflowTaskFailed

This Event type indicates that the Workflow Task encountered a failure. Usually this means that the Workflow was non-deterministic. However, the Workflow reset functionality also uses this Event.

Field	Description
scheduled_event_id	The Id of the WorkflowTaskScheduled Event that this Workflow Task corresponds to.
started_event_id	The Id of the WorkflowTaskStarted Event that this Workflow Task corresponds to.
failure	Details for the Workflow Task's failure.
identity	The identity of the Worker that failed this Task. The Worker must be explicitly defined to return a value for this field.
base_run_id	The original Run Id of the Workflow.
new_run_id	The Run Id of the reset Workflow.
fork_event_version	Identifies the Event version that was forked off to the reset Workflow.
binary_checksum	The Binary Id of the Worker that failed this Task. The Worker must be explicitly defined to return a value for this field.

ActivityTaskScheduled

This Event type indicates that an Activity Task was scheduled. The SDK client should pick up this Activity Task and execute. This Event type contains Activity inputs, as well as Activity Timeout configurations.

Field	Description
activity_id	The identifier assigned to this Activity by a Worker or user.
activity_type	The type of Activity that was scheduled.
namespace	Namespace of the Workflow that the Activity resides in.
task_queue	The Task Queue that this Activity Task was enqueued in.
header	Information passed by the sender of the Signal that is copied into the Workflow Task.
input	Information that is deserialized by the SDK to provide arguments to the Workflow function.
schedule_to_close_timeout	The amount of time that a caller will wait for Activity completion. Limits the amount of time that retries will be attempted for this Activity.
schedule_to_start_timeout	Limits the time that an Activity Task can stay in a Task Queue. This timeout cannot be retried.
start_to_close_timeout	Maximum amount of execution time that an Activity is allowed after being picked up by a Worker. This timeout is retryable.
heartbeat_timeout	Maximum amount of time allowed between successful Worker heartbeats.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
retry_policy	The amount of retries as determined by the service's dynamic configuration. Retries will happen until schedule_to_close_timeout is reached.

ActivityTaskStarted

This Event type indicates that an Activity Task Execution was started. The SDK Worker picked up the Activity Task and started processing the Activity invocation. Note, however, that this Event is not written to History until the terminal Event (like ActivityTaskCompleted or ActivityTaskFailed) occurs.

Field	Description
scheduled_event_id	The Id of the ActivityTaskScheduled Event that this Task corresponds to.
identity	Identifies the Worker that started the Task.
request_id	Identifies the Activity Task request.
attempt	The number of attempts that have been made to complete this Task.
last_failure	Details from the most recent failure Event. Only assigned values if the Task has previously failed and been retried.

ActivityTaskCompleted

This Event type indicates that the Activity Task has completed. The SDK client has picked up and successfully completed the Activity Task. This Event type contains Activity Execution results.

Field	Description
result	Serialized result of a completed Activity.
scheduled_event_id	The Id of the ActivityTaskScheduled Event that this completion Event corresponds to.
started_event_id	The Id of the ActivityTaskStarted Event that this Task corresponds to.
identity	Identity of the Worker that completed this Task.

ActivityTaskFailed

This Event type indicates that the Activity Task has failed. The SDK client picked up the Activity Task but unsuccessfully completed it. This Event type contains Activity Execution errors.

Field	Description
failure	Serialized result of a Workflow failure.
scheduled_event_id	The Id of the ActivityTaskScheduled Event that this failure Event corresponds to.
started_event_id	The Id of the ActivityTaskStarted Event that this failure corresponds to.
retry_state	The reason provided for whether the Task should or shouldn't be retried.

ActivityTaskTimedOut

This Event type indicates that the Activity has timed out according to the Temporal Server, due to one of these Activity timeouts: Schedule-to-Close Timeout and Schedule-to-Start Timeout.

Field	Description
failure	Serialized result of a Workflow failure.
scheduled_event_id	The Id of the ActivityTaskScheduled Event that this timeout Event corresponds to.
started_event_id	The Id of the ActivityTaskStarted Event that this timeout corresponds to.
retry_state	The reason provided for whether the Task should or shouldn't be retried.
timeout_type	The type of timeout that led to this Event, e.g., Start-to-Close, Schedule-to-Close, Schedule-to-Start.

You can run a Workflow containing an Activity Execution that takes longer than the Start-to-Close Timeout you set and use a RetryPolicy that sets MaxAttempts to 1 so it does not retry indefinitely. When the Activity times out, you will observe that the ActivityTaskTimedOut Event contains other attributes missing from the documentation, including the type of timeout that led to the Event.

ActivityTaskCancelRequested

This Event type indicates that a request to cancel the Activity has occurred.

Field	Description
scheduled_event_id	The Id of the ActivityTaskScheduled Event that this cancel Event corresponds to.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.

ActivityTaskCanceled

This Event type indicates that the Activity has been canceled.

Field	Description
details	Additional information reported by the Activity upon confirming cancelation.
latest_cancel_requested_event_id	Id of the most recent ActivityTaskCancelRequested Event which refers to the same Activity.
scheduled_event_id	The Id of the ActivityTaskScheduled Event that this cancelation corresponds to.
started_event_id	The Id of the ActivityTaskStarted Event that this cancelation corresponds to.
identity	Identifies the Worker that requested cancelation.

TimerStarted

This Event type indicates a timer has started.

Field	Description
timer_id	The Id assigned for the timer by a Worker or user.
start_to_fire_timeout	Amount of time to elapse before the timer fires.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.

TimerFired

This Event type indicates a timer has fired.

Field	Description
timer_id	The Id assigned for the timer by a Worker or user.
started_event_id	The Id of the TimerStarted Event itself.

TimerCanceled

This Event type indicates a Timer has been canceled.

Field	Description
timer_id	The Id assigned for the timer by a Worker or user.
started_event_id	The Id of the TimerStarted Event itself.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.

RequestCancelExternalWorkflowExecutionInitiated

This Event type indicates that a Workflow has requested that the Temporal Server try to cancel another Workflow.

Field	Description
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
namespace	Namespace of the Workflow that`s going to be signaled for execution.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
child_workflow_only	Set to true if this Workflow is a child of the Workflow which issued the cancelation request.
reason	Information provided by the user or client for Workflow cancelation.

RequestCancelExternalWorkflowExecutionFailed

This Event type indicates that Temporal Server could not cancel the targeted Workflow. This is usually because the target Workflow could not be found.

Field	Description
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
namespace	Namespace of the Workflow that failed to cancel.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
initiated_event_id	Id of the [RequestCancelExternalWorkflowExecutionInitiated] Event this failure corresponds to.

ExternalWorkflowExecutionCancelRequested

This Event type indicates that the Temporal Server has successfully requested the cancelation of the target Workflow.

Field	Description
initiated_event_id	Id of the RequestCancelExternalWorkflowExecutionInitiated Event that this cancelation request corresponds to.
namespace	Namespace of the Workflow that was requested to cancel.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.

ExternalWorkflowExecutionSignaled

This Event type indicates that the Temporal Server has successfully Signaled the targeted Workflow.

Field	Description
initiated_event_id	Id of the SignalExternalWorkflowExecutionInitiated Event this Event corresponds to.
namespace	Namespace of the Workflow that was signaled to.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.

MarkerRecorded

This Event type is transparent to the Temporal Server . The Server will only store it and will not try to understand it. The SDK client may use it for local activities or side effects.

Field	Description
marker_name	Identifies various markers.
details	Serialized information recorded in the marker.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
header	Information passed by the sender of the Signal that is copied into the marker.
failure	Serialized result of a Workflow failure.

StartChildWorkflowExecutionInitiated

This Event type indicates that the Temporal Server will try to start a Child Workflow.

Field	Description
namespace	Namespace of the Child Workflow.
workflow_id	Identifies the Child Workflow.
workflow_type	The name/type of Workflow that was initiated.

StartChildWorkflowExecutionFailed

This Event type indicates a Child Workflow Execution cannot be started / triggered. It is usually due to a Child Workflow Id collision.

Field	Description
namespace	Namespace of the Child Workflow.
workflow_id	Identifies the Child Workflow.
workflow_type	The name/type of Workflow that has failed.
initiated_event_id	Id of the StartChildWorkflowExecutionInitiated Event this Event corresponds to.
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.

ChildWorkflowExecutionStarted

This Event type indicates a Child Workflow Execution has successfully started / triggered. This would also cause the WorkflowExecutionStarted to be recorded for the Workflow that has started.

Field	Description
namespace	Namespace of the Child Workflow.
initiated_event_id	Id of the StartChildWorkflowExecutionInitiated Event this Event corresponds to.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
workflow_type	The name/type of Workflow that has started execution.
header	Information passed by the sender of the Signal that is copied into the Child Workflow Task.

ChildWorkflowExecutionCompleted

This Event type indicates that the Child Workflow Execution has successfully completed. This would also cause the WorkflowExecutionCompleted to be recorded for the Workflow that has completed.

Field	Description
result	Serialized result of the completed Child Workflow.
namespace	Namespace of the completed Child Workflow.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
workflow_type	The name/type of Workflow that was completed.
initiated_event_id	Id of the StartChildWorkflowExecutionInitiated Event this Event corresponds to.
started_event_id	Id of the ChildWorkflowExecutionStarted Event this Event corresponds to.

ChildWorkflowExecutionFailed

This Event type indicates that the Child Workflow Execution has unsuccessfully completed. This would also cause the WorkflowExecutionFailed to be recorded for the Workflow that has failed.

Field	Description
failure	Serialized result of a Workflow failure.
namespace	Namespace of the Child Workflow that failed.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
workflow_type	The name/type of Workflow that has failed.
initiated_event_id	Id of the StartChildWorkflowExecutionInitiated Event this Event corresponds to.
started_event_id	Id of the ChildWorkflowExecutionStarted Event this failure corresponds to.
retry_state	The reason provided for whether the Task should or shouldn't be retried.

ChildWorkflowExecutionCanceled

This Event type indicates that the Child Workflow Execution has been canceled. This would also cause the WorkflowExecutionCanceled to be recorded for the Workflow that was canceled.

Field	Description
details	Additional information reported by the Child Workflow upon cancelation.
namespace	Namespace of the Child Workflow that was canceled.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
workflow_type	The name/type of Workflow that was canceled.
initiated_event_id	Id of the StartChildWorkflowExecutionInitiated Event this Event corresponds to.
started_event_id	Id of the ChildWorkflowExecutionStarted Event this cancelation corresponds to.

ChildWorkflowExecutionTimedOut

This Event type indicates that the Child Workflow Execution has timed out by the Temporal Server. This would also cause the WorkflowExecutionTimeOut to be recorded for the Workflow that timed out.

Field	Description
namespace	Namespace of the Child Workflow.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
workflow_type	The name/type of Workflow that has timed out.
initiated_event_id	Id of the StartChildWorkflowExecutionInitiated Event this Event corresponds to.
started_event_id	Id of the ChildWorkflowExecutionStarted Event that this timeout corresponds to.
retry_state	The reason provided for whether the Task should or shouldn't be retried.

ChildWorkflowExecutionTerminated

This Event type indicates that the Child Workflow Execution has been terminated. This would also cause the WorkflowExecutionTerminated to be recorded for the Workflow that was terminated.

Field	Description
namespace	Namespace of the Child Workflow.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
workflow_type	The name/type of Workflow that was terminated.
initiated_event_id	Id of the StartChildWorkflowExecutionInitiated Event this Event corresponds to.
started_event_id	Id of the ChildWorkflowExecutionStarted Event that this termination corresponds to.
retry_state	The reason provided for whether the Task should or shouldn't be retried.

SignalExternalWorkflowExecutionInitiated

This Event type indicates that the Temporal Server will try to Signal the targeted Workflow. This Event type contains the Signal name, as well as a Signal payload.

Field	Description
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
namespace	Namespace of the Workflow that's to be signaled.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
signal_name	The name/type of Signal to be fired.
input	Information that is deserialized by the SDK to provide arguments to the Workflow Function.
child_workflow_only	Set to true if this Workflow is a child of the Workflow which issued the cancelation request.
header	Information to be passed from the Signal to the targeted Workflow.

SignalExternalWorkflowExecutionFailed

This Event type indicates that the Temporal Server cannot Signal the targeted Workflow, usually because the Workflow could not be found.

Field	Description
workflow_task_completed_event_id	The Id of the WorkflowTaskCompleted that the Event was reported with.
namespace	Namespace of the Workflow that failed to execute.
workflow_execution	Identifies the Workflow and the run of the Workflow Execution.
initiated_event_id	Id of the RequestCancelExternalWorkflowExecutionInitiated Event this failure signal corresponds to.

UpsertWorkflowSearchAttributes

This Event type indicates that the Workflow Search Attributes should be updated and synchronized with the visibility store.

Field	Description
workflow_task_completed_event_id	The WorkflowTaskCompleted Event reported the Event with this Id.
search_attributes	Provides data for setting up a Workflow's Search Attributes.

WorkflowExecutionUpdateAcceptedEvent

This Event type indicates that a Workflow Execution has accepted an Update for execution. The original request input payload is both indicated and stored by this Event, as it generates no Event when initially requesting an Update.

Field	Description
protocol_instance_id	The instance of the Update protocol with this Id is executing this Update.
accepted_request_message_id	The Id of the request message sent by Temporal Server to the Worker.
accepted_request_sequencing_event_id	Execute this Update after the Event with this Id.
accepted_request	The request input and metadata initially provided by the invoker of the Update and subsequently relayed by Temporal Server to the Worker for acceptance and execution.

WorkflowExecutionUpdateCompletedEvent

This Event type indicates that a Workflow Execution has executed an Update to completion.

Field	Description
meta	The metadata associated with this Update, sourced from the initial request.
accepted_event_id	The Id of the WorkflowExecutionUpdateAcceptedEvent The Platform accepted this Update for execution.
outcome	The outcome of execution of this Update whether the execution resulted in a success or a failure.