Apache Flink CEP，模式不匹配

Question

我是 Flink CEP 的新手，正在尝试测试基本的东西 - 在下面的代码中，我的期望是所有输入都应该在模式中匹配并且应该打印为匹配的结果。 但不知何故，没有什么是匹配的 ('matechedStream.print()') 关于原因的任何想法？

任何建议/帮助将不胜感激。

package com.o9.flink;
import com.o9.flink.asyncio.DemandSupply;
import org.apache.flink.cep.CEP;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.flink.cep.PatternStream;
import org.apache.flink.cep.functions.PatternProcessFunction;
import org.apache.flink.cep.pattern.Pattern;
import org.apache.flink.cep.pattern.conditions.SimpleCondition;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.util.Collector;


public class DemandSupplyPattern {

    public static void main(String[] args) throws Exception {

        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(1);
        DataStream<String> keyedInputStream = env.fromElements("AAA","BBB","CCC");

        Pattern<String, ?> dspattern = Pattern.<String>begin("start");

        PatternStream<String> patternStream = CEP.pattern(keyedInputStream, dspattern);
        DataStream<String> matechedStream =  patternStream.process(new PatternProcessFunction<String, String>() {
            @Override
            public void processMatch(Map<String, List<String>> map, Context context, Collector<String> collector) throws Exception {
                collector.collect(map.get("start").toString());
            }
        });

        matechedStream.print();

        env.execute("DemandSupply-CEP");
    }
}

Maven 依赖关系：

<dependencies>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-runtime</artifactId>
        <version>${flink.version}</version>
        <!--<scope>test</scope>-->
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-core</artifactId>
        <version>${flink.version}</version>
        <!--<scope>provided</scope>-->
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-java</artifactId>
        <version>${flink.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-avro</artifactId>
        <version>${flink.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-streaming-java</artifactId>
        <version>${flink.version}</version>
        <!--<scope>provided</scope>-->
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-clients</artifactId>
        <version>${flink.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-connector-kafka</artifactId>
        <version>${flink.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-statebackend-rocksdb</artifactId>
        <version>${flink.version}</version>
        <!--<scope>test</scope>-->
    </dependency>
    <dependency>
        <groupId>org.asynchttpclient</groupId>
        <artifactId>async-http-client</artifactId>
        <version>2.2.0</version>
    </dependency>

    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-cep</artifactId>
        <version>${flink.version}</version>
        <!--<scope>provided</scope>-->
    </dependency>


</dependencies>

谢谢马亨德拉

Answer 1

FlinkCEP 默认使用 EventTime，它依赖于 WaterMark 来帮助这些事件继续进行。 如果您将其切换到 ProcessingTime，它可能会有所帮助。

PatternStream<String> patternStream = CEP.pattern(keyedInputStream, dspattern).inProcessingTime();

如果您不知道差异以及时间语义，您可以查看Flink Notion of Time 的官方文档