Esper (software)


Esper is an open-source Java-based software product for Complex event processing and Event stream processing, that analyzes series of events for deriving conclusions from them.
Esper extends the SQL-92 standard for its engine and enterprise framework, providing Aggregate function, Pattern matching, event windowing and joining. Esper implements Event-driven programming and event-driven architecture.
Esper was created in 2006 by EsperTech Inc. It offers a Domain-specific language for processing events called Event Processing Language. EPL is a Declarative programming language for analyzing time-based event data and detecting situations as they occur.
Esper is a Java-based application but has been ported to the C# programming language and is available for the.NET Framework under the name NEsper.
EsperTech Inc. provides Esper Enterprise Edition with enterprise-ability features.

Example

This example illustrates a simple EPL query that outputs a row immediately when within a sliding window of 3 minutes the number of order events reaches 5 or more events.

select count from OrderEvent.win:time having count >= 5

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