Giles Nelson joined the debate about CEP versus EDA. I am very happy with that because he is deeply involved in the evolvement of Apama, which is a state-of-the-art complex event processor marketed by Progress Software.
Giles expressed his view in 7 clear statements. I agree with him to a certain extend, however I have one major remark with regard to his point 7 where he states:
If you are using CEP then you have at least the beginnings of an EDA because you will have been focussing on event-types.
This is a dangerous statement that could create confusion. The events in CEP are merely technical events, messages entering the system, which not necessarily represent business events or any other real-life events as meant in an EDA approach. In CEP data from incoming message streams are correlated within time-frame constraints. This data may represent "anything", e.g. arbitrary spawned clouds of arbitrary mathematical figures which are written to arbitrary ordered messages, without any functional or time-based relationship. The time-frames CEP uses to constrain the correlations between the messages could be the time-frames in which the messages are received by the CEP-engine and not content based on when the event - represented by the data in the message - actually occurred (in this example when the figures were spawned or generated).
One should be aware of the misconception that publishing the message is the event of interest. It's right that from a system point of view publishing a message is an event that triggers an endpoint's software-component. However, from an EDA point of view the message represents a different event. The message does not represent the event of its own publishing, but it represents a real-life business event. That is a different type of event that occurred at an earlier moment in time; ideal slightly earlier (near real-time) but possibly a longer time ago.
So I would rather claim using CEP-technology as being the finishing implementation of EDA. But indeed, using CEP could make you aware of the beginnings of EDA.