About subscriptions handling
Parameter notifications are sent from the server application (the EK80 program) to the client through a separate UDP connection where the data are packed in dynamic binary structures. This ensures an efficient distribution of parameter notifications.
The communication protocol used for parameter notification shall ensure that all notifications are delivered in the same chronological order as they occurred in the server. The following messages are part of the parameter subscription management:
•  Value and attribute update messages
•  Server alive message
•  Request re-transmit message
The basic principles of operation are that the server sends value and attribute update messages periodically when there are parameter value/attribute changes, or a server alive message if no parameter value/attribute has changed. The client can send a request re-transmit message if it detects that is has lost any messages.
Related topics
Handling parameter subscriptions