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A CEP library to run Siddhi within Apache Flink™ Streaming Application
Java Scala
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A light-weight library to run Siddhi CEP within Apache Flink streaming application.


Siddhi CEP is a lightweight and easy-to-use Open Source Complex Event Processing Engine (CEP) released as a Java Library under Apache Software License v2.0. Siddhi CEP processes events which are generated by various event sources, analyses them and notifies appropriate complex events according to the user specified queries.

This project is mainly to provide a light-weight library to easily run Siddhi CEP within flink streaming application.



  • Java (Version: 1.8)
  • Apache Maven
  • Apache Flink (Version: 1.3.2)


git clone


mvn clean install -DskipTests


mvn clean test

Usage and API

  • Add flink-siddhi in maven dependency:

  • Execute SiddhiQL with SiddhiCEP API, for example:

      StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
      SiddhiCEP cep = SiddhiCEP.getSiddhiEnvironment(env);
      cep.registerStream("inputStream1", input1, "id", "name", "price","timestamp");
      cep.registerStream("inputStream2", input2, "id", "name", "price","timestamp");
      DataStream<Tuple5<Integer,String,Integer,String,Double>> output = cep
           "from every s1 = inputStream1[id == 2] "
           + " -> s2 = inputStream2[id == 3] "
           + "select as id_1, as name_1, as id_2, as name_2 , custom:plus(s1.price,s2.price) as price"
           + "insert into outputStream")

    For more examples, please see org.apache.flink.contrib.siddhi.SiddhiCEPITCase


  • Integrate Siddhi CEP as an stream operator (i.e. TupleStreamSiddhiOperator), supporting rich CEP features like
    • Filter
    • Join
    • Aggregation
    • Group by
    • Having
    • Window
    • Conditions and Expressions
    • Pattern processing
    • Sequence processing
    • Event Tables
    • ...
  • Provide easy-to-use Siddhi CEP API to integrate Flink DataStream API (See SiddhiCEP and SiddhiStream)
    • Register Flink DataStream associating native type information with Siddhi Stream Schema, supporting POJO,Tuple, Primitive Type, etc.
    • Connect with single or multiple Flink DataStreams with Siddhi CEP Execution Plan
    • Return output stream as DataStream with type intelligently inferred from Siddhi Stream Schema
  • Integrate siddhi runtime state management with Flink state (See AbstractSiddhiOperator)
  • Support siddhi plugin management to extend CEP functions. (See SiddhiCEP#registerExtension)


Support and Contact



Welcome to make contribution to code or document by sending a pull request, or reporting issues or bugs.


Licensed under the Apache License, Version 2.0. More details, please refer to LICENSE file.

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