StreamBase has just, amidst much fanfare, announced that it is pushing for the establishment of a standard development language for event processing applications. While the company does not necessarily expect that its StreamSQL will be adopted for this purpose, it does contend that SQL should be the starting point for such a …
SQL is Declarative
I think an important consideration is that it is far easier to make mistakes in event-based logic using a non-declarative language, especially when you consider some of the likely authors ;-)
Thus, an extension of SQL as the only declarative language people are likely to know makes more sense than basing on Java, Python or C++.