Hi,
If you subscribe as a client application to some sort of statistics related to some particular object (queues, agent group, etc..) on a Stat Server then you will get notification events about object changes, its state and other statistical events.
Note that you can receive data using one of the two main notification types, solicited or unsolicited.
For more details please clarify the SDK product which the question relates to? Is it Platform SDK or GIS (Statistics SDK Web Services) or Enterprise SDK?
Also please clarify what do you mean by "eServer" instance? Did you mean eServices component - Interaction Server?
Roman Tereschenko