While working on the Website of the EPIA book, we asked the language owners to provide downloadable version of the product implementing their language. I was asked by some of the language owners if instead they can provide instead a possibility to provide their software as a service and let the readers run it on their servers. My answer was positive, and we'll see couple of such examples (one already there, one is coming up).
The book's website is just a resource for readers who wish to study languages, but this brought me to a thought about event processing as a service in general.
Some of the reasons for doing it is to gain the benefits of cloud computing in terms of scalability,
I've recently came across some material about activeinsights which seems to be a new Israeli company developing open source "event stream processing" in the cloud (well - I have some terminology comments to them, but this is not the main point) that advocate the use of event processing in the cloud to cope with scalability issues. Using SAAS model for event processing can give rise to some interesting cost models, that are either related to the input (amount of input event processed) or the output (amount of situations detected by the event processing service, with some cost per situation, or amount of aggregated/transformed derived events) which ties the cost directly to the benefit. One of the barriers of using event processing as a service is lack of standards especially for interoperability, which does not enable just to connect and run, but requires substantial investment in writing adapters in a proprietary way. I assume that we'll see more of that, when the cost/benefit model will be clarified.