In Is CEP a Service or a Process? Paul Vincent of TIBCO blogs that any classification of CEP depends on the application, concluding that CEP is both a process and a service. 

Well (sorry Paul!), I disagree.  CEP is neither a process nor a service; CEP is a concept architecture for processing complex events.   (I have advocated a CEP functional reference architecture, as most readers know.)

To illustrated this point, let’s take a quick look at another functional reference architecture (or, if you perfer, a conceptual architecture), distributed computing.

Is distributed computing a service or a process?

Of course, it is neither a process nor a service, distributed computing is a generic architectural pattern (or style) for processing distributed data, generally across a network.

The same question can be asked of SOA. 

Is SOA a process or a service?

Again, the answer is almost identical. 

SOA is an architectural style (subclass) of distributed computing.

Now, is CEP a product or a service?

CEP is an architectural style (or pattern) for processing complex events.

CEP is neither a process nor a service. 

On the other hand, there are component of a CEP solution that can be represented as a stand alone process or a service.   The same can be said of EAI, SOA, and other subclasses of distributed computing architectural styles and patterns.