SignalR Reference: Event Hub

Event Hub: server to client callbacks (signals, order/position updates, job completion) + history/replay APIs

• Hub URL: /hubs/event/v1

Client to server

These methods return an API envelope (MesoLiveApiResponse<T>).

Envelope fields: MesoLiveApiResponse

SubscribeToStrategies

Subscribe this connection to server→client event callbacks for the specified strategies.

Args model: SubscribeToStrategiesArgs

Field	Type	Required	Nullable	Default	Description
Strategies	list[int]	No	Yes		Strategies to subscribe to. null = subscribe to all user strategies, empty = no-op.

Returns (payload): SubscribeToStrategiesResult

Field	Type	Required	Nullable	Default	Description
SuccessfulStrategies	list[int]	Yes	No		Strategy ids that were successfully subscribed to.
FailedStrategies	list[int]	Yes	No		Strategy ids that failed to subscribe to.

UnsubscribeFromStrategies

Unsubscribe this connection from server→client event callbacks for the specified strategies.

Args model: UnsubscribeFromStrategiesArgs

Field	Type	Required	Nullable	Default	Description
Strategies	list[int]	No	Yes		Strategies to unsubscribe from. null = unsubscribe from all, empty = no-op.

Returns (payload): UnsubscribeFromStrategiesResult

Field	Type	Required	Nullable	Default	Description
SuccessfulStrategies	list[int]	Yes	No		Strategy ids that were successfully unsubscribed from.
FailedStrategies	list[int]	Yes	No		Strategy ids that failed to unsubscribe from.

GetLatestEventSeqId

Get the latest event sequence id available for the authenticated user.

Args model: GetLatestEventSeqIdArgs

No fields.

Returns (payload): GetLatestEventSeqIdResult

Field	Type	Required	Nullable	Default	Description
LatestEventSeqId	int	Yes	No		Latest event sequence id currently available for the authenticated user.
SnapshotTime	datetime	Yes	No		UTC time when this snapshot was taken.

GetEventsSince

Retrieve historical events since a given event sequence id (supports pagination).

Args model: GetEventsSinceArgs

Field	Type	Required	Nullable	Default	Description
SinceEventSeqId	int	Yes	No		Fetch events strictly after this sequence id.
Limit	int	Yes	No		Maximum number of events to return. Must be less than or equal to MaxEventsLimit.
ContinuationToken	str	No	Yes		Pagination token returned by a previous GetEventsSince call.

Returns (payload): GetEventsSinceResult

Field	Type	Required	Nullable	Default	Description
Events	list[MesoLiveEventEnvelope]	Yes	No		Event envelopes returned by this page.
ContinuationToken	str	No	Yes		Pagination token for the next page. null/empty when no more events are available.

Server to client callbacks

These callbacks are invoked by the server on your connection. The callback parameter is the event payload model.

note

On connect, the server may immediately send active signals/errors to the caller.

OnEntrySignal

Called when an entry signal is evaluated and/or changes state for a strategy.

Args model: EntrySignalEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
State	SignalState	Yes	No		Entry signal state (On/Off).
StrategyId	int	Yes	No		Live strategy id this signal belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
BrokerAccountId	str	Yes	No		Broker account id this signal is associated with.
EntrySignalResult	EntrySignalsResult	No	Yes		Optional detailed evaluation results for entry checks (may be null if not included).

Returns: None

OnExitSignal

Called when an exit signal is evaluated and/or changes state for a position.

Args model: ExitSignalEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
State	SignalState	Yes	No		Exit signal state (On/Off).
StrategyId	int	Yes	No		Live strategy id this position belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
PositionId	int	Yes	No		Live position id this exit signal applies to.
PositionName	str	Yes	No		Position name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id this position belongs to (may be null in some contexts).
ExitSignalResult	ExitSignalsResult	No	Yes		Optional detailed evaluation results for exit checks (may be null if not included).

Returns: None

OnAdjustmentSignal

Called when an adjustment signal is evaluated and/or changes state for a position.

Args model: AdjustmentSignalEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
State	SignalState	Yes	No		Adjustment signal state (On/Off).
StrategyId	int	Yes	No		Live strategy id this position belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
PositionId	int	Yes	No		Live position id this adjustment signal applies to.
PositionName	str	Yes	No		Position name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id this position belongs to (may be null in some contexts).
AdjustmentTimeOk	bool	Yes	No		Whether the adjustment timing window is satisfied.
Condition	ConditionEvaluation	Yes	No		Condition evaluation that triggered/represents this adjustment signal.

Returns: None

OnOrderUpdate

Called when a live order changes state (submitted, filled, rejected, etc.).

Args model: OrderUpdateEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
OrderId	int	Yes	No		Live order id.
BrokerAccountId	str	No	Yes		Broker account id the order belongs to (may be null in some contexts).
ExecPlanId	int	No	Yes		Live execution plan id this order belongs to (if known).
LegGroupId	int	No	Yes		Leg group id within the execution plan (if known).
StrategyId	int	Yes	No		Live strategy id this order is associated with.
StrategyName	str	Yes	No		Strategy name at the time of the event.
State	OrderState	Yes	No		Current order state.
FilledQty	Decimal	Yes	Yes		Quantity filled so far (if available).
RemainingQty	Decimal	Yes	Yes		Remaining quantity (if available).
FillPrice	Decimal	Yes	Yes		Last fill price (if available).
AvgFillPrice	Decimal	Yes	Yes		Average fill price across all fills (if available).
Rejection	OrderRejectionInfo	No	Yes		Rejection details when the order is rejected.

Returns: None

OnPositionUpdate

Called when a live position changes state (created, closed, adjusted, etc.).

Args model: PositionUpdateEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
PositionId	int	Yes	No		Live position id.
StrategyId	int	Yes	No		Live strategy id this position belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
PositionName	str	Yes	No		Position name at the time of the event.
BrokerAccountId	str	Yes	No		Broker account id this position belongs to.
Status	PositionStatus	Yes	No		Position status.
RealizedPnL	Decimal	No	No		Realized PnL at the time of the event.

Returns: None

OnLegUpdate

Called when a live leg changes state (created, closed, quantity changed, etc.).

Args model: LegUpdateEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
BrokerAccountId	str	Yes	No		Broker account id this leg belongs to.
PositionId	int	Yes	No		Live position id this leg belongs to.
PositionName	str	Yes	No		Position name at the time of the event.
StrategyId	int	Yes	No		Live strategy id this position belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
LegId	int	Yes	No		Live leg id.
LegName	str	Yes	No		Leg name at the time of the event.
Contract	LiveContract	Yes	No		Contract for this leg.
Status	LegStatus	Yes	No		Leg status.
Qty	Decimal	No	No		Current leg quantity.
RealizedPnL	Decimal	No	No		Realized PnL attributed to this leg at the time of the event.

Returns: None

OnAgentStatusChange

Called when an agent/connector status changes (connected, disconnected, error).

Args model: AgentStatusEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
Status	AgentStatus	Yes	No		Agent status.
Message	str	Yes	No		Human-readable status message.
Connector	AgentConnector	No	Yes		Optional hint which connector raised the event.

Returns: None

OnError

Called when an error event is emitted or updated for a strategy/position.

Args model: ErrorEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
State	ErrorState	Yes	No		Error state transition.
ErrorId	UUID	Yes	No		Stable unique identifier for this error instance.
StrategyId	int	No	Yes		Live strategy id associated with the error (if applicable).
StrategyName	str	No	Yes		Strategy name associated with the error (if applicable).
PositionId	int	No	Yes		Live position id associated with the error (if applicable).
PositionName	str	No	Yes		Position name associated with the error (if applicable).
BrokerAccountId	str	No	Yes		Broker account id associated with the error (if applicable).
Message	str	No	Yes		Human-readable error message (if available).
ConditionType	ConditionType	No	Yes		Condition type associated with the error (if applicable).
Statement	str	No	Yes		Expression/statement associated with the error (if applicable).

Returns: None

OnPositionEntryPreparationCompleted

Called when an asynchronous "prepare entry" job completes successfully.

Args model: PositionEntryPreparationCompletedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id returned by StartPreparePositionEntry.
StrategyId	int	Yes	No		Live strategy id the entry preparation belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the job (if available).
Result	PreparePositionEntryResult	Yes	No		Successful prepare-entry result payload.

Returns: None

OnPositionEntryPreparationFailed

Called when an asynchronous "prepare entry" job fails.

Args model: PositionEntryPreparationFailedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id returned by StartPreparePositionEntry.
StrategyId	int	Yes	No		Live strategy id the entry preparation belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the job (if available).
Error	str	Yes	No		Error message describing why the job failed.

Returns: None

OnPositionExitPreparationCompleted

Called when an asynchronous "prepare exit" job completes successfully.

Args model: PositionExitPreparationCompletedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id returned by StartPreparePositionExit.
StrategyId	int	Yes	No		Live strategy id the exit preparation belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the job (if available).
Result	PreparePositionExitResult	Yes	No		Successful prepare-exit result payload.

Returns: None

OnPositionExitPreparationFailed

Called when an asynchronous "prepare exit" job fails.

Args model: PositionExitPreparationFailedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id returned by StartPreparePositionExit.
StrategyId	int	Yes	No		Live strategy id the exit preparation belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the job (if available).
Error	str	Yes	No		Error message describing why the job failed.

Returns: None

OnPositionAdjustmentPreparationCompleted

Called when an asynchronous "prepare adjustment" job completes successfully.

Args model: PositionAdjustmentPreparationCompletedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id returned by StartPreparePositionAdjustment.
StrategyId	int	Yes	No		Live strategy id the adjustment preparation belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the job (if available).
Result	PreparePositionAdjustmentResult	Yes	No		Successful prepare-adjustment result payload.

Returns: None

OnPositionAdjustmentPreparationFailed

Called when an asynchronous "prepare adjustment" job fails.

Args model: PositionAdjustmentPreparationFailedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id returned by StartPreparePositionAdjustment.
StrategyId	int	Yes	No		Live strategy id the adjustment preparation belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the job (if available).
Error	str	Yes	No		Error message describing why the job failed.

Returns: None

OnAutoUpdateVarsAdjustmentStarted

Called when an auto-update-vars adjustment workflow starts.

Args model: AutoUpdateVarsAdjustmentStartedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id for the adjustment workflow.
StrategyId	int	Yes	No		Live strategy id the workflow belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
PositionId	int	Yes	No		Live position id the workflow applies to.
PositionName	str	Yes	No		Position name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the workflow (if available).
Condition	str	Yes	No		Condition identifier/expression used for selecting and validating the adjustment.

Returns: None

OnAutoUpdateVarsAdjustmentCompleted

Called when an auto-update-vars adjustment workflow completes successfully.

Args model: AutoUpdateVarsAdjustmentCompletedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id for the adjustment workflow.
StrategyId	int	Yes	No		Live strategy id the workflow belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
PositionId	int	Yes	No		Live position id the workflow applies to.
PositionName	str	Yes	No		Position name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the workflow (if available).
Condition	str	Yes	No		Condition identifier/expression used for selecting and validating the adjustment.
UpdatedVars	dict[str, Decimal]	Yes	No		Variables updated by the workflow (var name → new value).

Returns: None

OnAutoUpdateVarsAdjustmentFailed

Called when an auto-update-vars adjustment workflow fails.

Args model: AutoUpdateVarsAdjustmentFailedEvent

Field	Type	Required	Nullable	Default	Description
EventId	UUID	No	No		Stable unique identifier for this event instance.
EventSeqId	int	No	No		Server-assigned event sequence id used for ordering and replay/history APIs.
EventTime	datetime	Yes	No		UTC timestamp when the event occurred on the server.
JobId	str	Yes	No		Job id for the adjustment workflow.
StrategyId	int	Yes	No		Live strategy id the workflow belongs to.
StrategyName	str	Yes	No		Strategy name at the time of the event.
PositionId	int	Yes	No		Live position id the workflow applies to.
PositionName	str	Yes	No		Position name at the time of the event.
BrokerAccountId	str	No	Yes		Broker account id associated with the workflow (if available).
Condition	str	Yes	No		Condition identifier/expression used for selecting and validating the adjustment.
Error	str	Yes	No		Error message describing why the workflow failed.

Returns: None