“广播状态”解除了Flink的CEP库的“动态模式”功能的实现，这意味着什么？

Question

public static void ConnectBroadToKeyedStream() throws Exception {
    StreamExecutionEnvironment env =
            StreamExecutionEnvironment.getExecutionEnvironment().setParallelism(3);

    List<Tuple1<String>>
            controlData = new ArrayList<Tuple1<String>>();
    controlData.add(new Tuple1<String>("DROP"));
    controlData.add(new Tuple1<String>("IGNORE"));
    DataStream<Tuple1<String>> control = env.fromCollection(controlData);//.keyBy(0);

    List<Tuple1<String>>
            dataStreamData = new ArrayList<Tuple1<String>>();
    dataStreamData.add(new Tuple1<String>("data"));
    dataStreamData.add(new Tuple1<String>("DROP"));
    dataStreamData.add(new Tuple1<String>("artisans"));
    dataStreamData.add(new Tuple1<String>("IGNORE"));
    dataStreamData.add(new Tuple1<String>("IGNORE"));
    dataStreamData.add(new Tuple1<String>("IGNORE"));
    dataStreamData.add(new Tuple1<String>("IGNORE"));

    // DataStream<String> data2 = env.fromElements("data", "DROP", "artisans", "IGNORE");
    DataStream<Tuple1<String>> keyedDataStream = env.fromCollection(dataStreamData).keyBy(0);

    DataStream<String> result = control
            .broadcast()
            .connect(keyedDataStream)
            .flatMap(new MyCoFlatMap());
    result.print();
    env.execute();
}

private static final class MyCoFlatMap
        implements CoFlatMapFunction<Tuple1<String>, Tuple1<String>, String> {
    HashSet blacklist = new HashSet();

    @Override
    public void flatMap1(Tuple1<String> control_value, Collector<String> out) {
        blacklist.add(control_value);
        out.collect("listed " + control_value);
    }

    @Override
    public void flatMap2(Tuple1<String> data_value, Collector<String> out) {

        if (blacklist.contains(data_value)) {
            out.collect("skipped " + data_value);
        } else {
            out.collect("passed " + data_value);
        }
    }
}

1> passed (data)
1> passed (DROP)
3> passed (artisans)
3> passed (IGNORE)
3> passed (IGNORE)
3> passed (IGNORE)
3> passed (IGNORE)
3> listed (DROP)
3> listed (IGNORE)
1> listed (DROP)
1> listed (IGNORE)
2> listed (DROP)
2> listed (IGNORE)

Answer 1

在没有广播状态的情况下，两个Flink数据流不能以有状态的方式一起处理，除非它们以完全相同的方式进行键控。广播流可以连接到键控流，但如果您随后尝试在RichCoFlatMap中使用键控状态，则会失败。

经常需要的是能够使一个流具有动态的“规则”，这些规则将应用于另一个流上的每个事件，而不管关键字是什么。需要有一种新的托管Flink状态，可以在其中存储这些规则。对于广播状态，现在可以用一种简单的方式来完成。

有了这个特性，就可以开始支持CEP中的动态模式了。