diff --git a/src/repositories/GetterRepository.ts b/src/repositories/GetterRepository.ts
index 4c6a3b0..c9f473c 100644
--- a/src/repositories/GetterRepository.ts
+++ b/src/repositories/GetterRepository.ts
@@ -16,8 +16,9 @@ export interface GetterRepository {
 
   getEtasForShuttleId(shuttleId: string): Promise<IEta[]>;
   getEtasForStopId(stopId: string): Promise<IEta[]>;
-
   getEtaForShuttleAndStopId(shuttleId: string, stopId: string): Promise<IEta | null>;
+  subscribeToEtaChanges(listener: (eta: IEta) => void): Promise<void>;
+  unsubscribeFromEtaChanges(listener: (eta: IEta) => void): Promise<void>;
 
   getOrderedStopByRouteAndStopId(routeId: string, stopId: string): Promise<IOrderedStop | null>;
 
@@ -34,4 +35,4 @@ export interface GetterRepository {
    * @param routeId
    */
   getOrderedStopsByRouteId(routeId: string): Promise<IOrderedStop[]>;
-}
\ No newline at end of file
+}