Esper is a component for CEP and ESP applications, available for Java as Esper, and for .NET as NEsper.
Esper and NEsper enable rapid development of applications that process large volumes of incoming messages or events. Esper and NEsper filter and analyze events in various ways, and respond to conditions of interest in real-time.
Esper and NEsper were designed to make it easier to build CEP and ESP applications. Esper and NEsper are open-source software available under the GNU General Public License (GPL) license.