Esper: Event Stream Processing and Correlation

I mentioned about Esper before(here). Esper allows users to submit continuous queries to its engine and sends out alerts whenever conditions match user-defined queries. In this article, the authors showed code snippets to demonstrate Esper's usage.

1. Configure the engine using API or an XML file.
2. Register continuous queries.
3. Attach listeners to the queries.

For the engine to tap into event streams, according to the document, it is accomplished by sending events to the engine via the runtime interface.

Esper seems easy to use and, I think, it looks promising to gain popularity.