Fwd: some question about side output

[Marvin777]

Hi, all:

Using Flink’s side output feature we can get a stream of the data that was discarded as late.But when i use the getSideOutput() method, i have the following error message:

this is the link address of document:

https://ci.apache.org/projects/flink/flink-docs-release-1.3/dev/windows.html#getting-late-data-as-a-side-output

Note: the code is as follows:

Thanks & Regards

Qingxiang Ma

[Biplob Biswas]

Change the type of the mainstream from DataStream to
SingleOutputStreamOperator

The getSideOutput() function is not part of the base class DataStream rather
the extended Class SingleOutputStreamOperator



--
Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/

[Chen Qin]

Hi Qingxiang,

getSideOuput is only available in SingleOutputOperator class. You might consider update your DataStream<...> window to SingleOutputOperator and it should works fine.

Thanks,

Chen

Code sample attached handy.

import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.TimeCharacteristic;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.AssignerWithPunctuatedWatermarks;
import org.apache.flink.streaming.api.functions.source.SourceFunction;
import org.apache.flink.streaming.api.functions.windowing.AllWindowFunction;
import org.apache.flink.streaming.api.watermark.Watermark;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.streaming.api.windowing.windows.TimeWindow;
import org.apache.flink.util.Collector;
import org.apache.flink.util.OutputTag;

import javax.annotation.Nullable;

public class SideOutputExample {

    public static void main(String argv[]) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);

        final OutputTag<Tuple2<String, Long>> lateTag = new OutputTag<Tuple2<String, Long>>("tag"){};

        SingleOutputStreamOperator output = env.addSource(new SourceFunction<Tuple2<String, Long>>() {
            public void run(SourceContext<Tuple2<String, Long>> sourceContext) throws Exception {
                // emit three events
                synchronized (sourceContext.getCheckpointLock()) {
                    sourceContext.collect(new Tuple2<String, Long>("a", 0l));
                    sourceContext.collect(new Tuple2<String, Long>("c", 2l));
                    sourceContext.collect(new Tuple2<String, Long>("b", 1l));
                }
            }

            public void cancel() {
                //SKIP
            }
        }).assignTimestampsAndWatermarks(new AssignerWithPunctuatedWatermarks<Tuple2<String, Long>>() {
            @Nullable
            public Watermark checkAndGetNextWatermark(Tuple2<String, Long> stringLongTuple2, long l) {
                return new Watermark(stringLongTuple2.f1);
            }

            public long extractTimestamp(Tuple2<String, Long> stringLongTuple2, long l) {
                return stringLongTuple2.f1;
            }
        }).timeWindowAll(Time.milliseconds(1)).sideOutputLateData(lateTag)

                .apply(new AllWindowFunction<Tuple2<String,Long>, String, TimeWindow>() {
            public void apply(TimeWindow timeWindow, Iterable<Tuple2<String, Long>> iterable, Collector<String> collector) throws Exception {
                for(Tuple2<String, Long> it : iterable) {
                    collector.collect(it.f0);
                }
            }
        });

        //print on time event
        output.print();

        // print late arriving event
        output.getSideOutput(lateTag).print();

        env.execute();
    }
}

On Wed, Sep 6, 2017 at 6:41 AM, 马庆祥 <[hidden email]> wrote:

Hi, all:

Using Flink’s side output feature we can get a stream of the data that was discarded as late.But when i use the getSideOutput() method, i have the following error message:

this is the link address of document:

https://ci.apache.org/projects/flink/flink-docs-release-1.3/dev/windows.html#getting-late-data-as-a-side-output

Note: the code is as follows:

Thanks & Regards

Qingxiang Ma