Abstract: An electronic price label (ESL) system for performing asynchronous ESL transactions. An event notification technique allows a communication base station (CBS) manager to directly notify an ESL manager when responses from an ESL are received, without the ESL manager needing to constantly poll the CBS manager. In one aspect, an inter-process communication layer (IPC) to allow for such event notification by the CBS manager. When initially beginning operation, the ESL manager subscribes to a CBS manager's event and provides the name of a function in the ESL manager to be called when this event occurs. When the ESL manager instructs the CBS manager to send a message to an ESL, the CBS manager provides the ESL manager with a handle or unique identification number to identify the message. When a response is received from the ESL, the CBS manager “fires an event” utilizing the IPC and indicates the identification number of the response.