Event classes are classifications of events. After separating information into event classes, adaptors format the information into messages that represent specific instances of event classes. Then they send the information to the event server, which processes the information, along with information received from other adapters.
Event classes can be divided into subclasses to facilitate a further breakdown of information so that more detailed rules can be applied to the event information. Essentially, event classes are an agreement between the adapter and the event server about what information the adapter sends to the event server.