Esper (software)

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Esper is an open-source Java-based software product for complex event processing (CEP) and event stream processing (ESP), 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). 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.

This example^[1] 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#time(3 min) having count(*) >= 5

• Rapide (Stanford)
• StreamSQL: StreamSQL is a query language that extends SQL with the ability to process real-time data streams.

• Complex event processing (CEP) - A related technology for building and managing event-driven information systems.
• Data Stream Management System (DSMS) - A type of software system for managing and querying data streams
• Event correlation
• Event-driven architecture — (EDA) is a software architecture pattern promoting the production, detection, consumption of, and reaction to events.
• Event stream processing — (ESP) is a related technology that focuses on processing streams of related data.
• Operational intelligence — Both CEP and ESP are technologies that underpin operational intelligence.
• Pattern matching
• Real-time business intelligence — Business Intelligence is the application of knowledge derived from CEP systems
• Real-time computing — CEP systems are typically real-time systems
• Real time enterprise

• Research Papers referencing Esper, by Google Scholar
• Analysis of Complex Event Processing with Esper by Eric Miller, a book on Esper and CEP.
• Event Processing in Action by Opher Etzion and Peter Niblett, Manning Publications (ISBN 9781935182214), a book that provides Esper examples
• Open Source SOA by Jeff Davis, Manning Publications (ISBN 1933988541), a book that provides examples of Esper for monitoring web services
• OSWorkflow: A guide for Java developers and architects to integrating open-source Business Process Management, by Diego Adrian Naya Lazo, PACKT (ISBN 978-1847191526 ), a book with a chapter on Esper
• Fraunhofer CEP Market Overview, by Fraunhofer, year 2010