Interface Summary Interface Description IBpmSignalHistoryQuery sent signals. IBpmSignalReceivers IBpmSignalServiceA service for sending and querying signals. ISignaledTaskA task that has been started by a signal. ISignalEventA signal event that was sent. IStartSignalEventElementA Signal Start element that is waiting for a signal pattern. ITaskBoundarySignalEventReceiverA task with an attached Signal Boundary Event element that is waiting for a signal pattern.