Registers a non-specific callback func to process any events received by client. If this function has already been called, the previous callback registration will be replaced with the new registration.

When an event is received for client, the callback function func will be invoked to process the event and will be passed client_data as a parameter. The content and use of client_data is determined by you the caller; it is not examined or used in any way by the Broker system.

Callbacks registered with this function are called non-specific callbacks because they may be invoked to handle any event. You may also use the awRegisterCallbackForSubId function, described on awRegisterCallbackForSubId, to register a specific callback function for a particular event subscription ID. Specific callback functions will take precedence over a non-specific callback function.