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Ktable Aggregate query

Pragya Keshap answered on February 28, 2023 Popularity 1/10 Helpfulness 1/10

answer Ktable Aggregate query

Ktable Aggregate query

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public class KTableAggDemo {
    private static final Logger logger = LogManager.getLogger();

    public static void main(String[] args) {

        String hostName = (args.length < 2) ? "localhost" : args[0];
        int portNumber = (args.length < 2) ? 7010 : Integer.parseInt(args[1]);

        Properties props = new Properties();
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, AppConfigs.applicationID);
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, AppConfigs.bootstrapServers);
        props.put(StreamsConfig.STATE_DIR_CONFIG, AppConfigs.stateStoreLocation);
        props.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG, 100);
        props.put(StreamsConfig.APPLICATION_SERVER_CONFIG, hostName + ":" + portNumber);
        props.put(StreamsConfig.NUM_STREAM_THREADS_CONFIG, 2);

        StreamsBuilder streamsBuilder = new StreamsBuilder();
        streamsBuilder.table(AppConfigs.topicName,
            Consumed.with(AppSerdes.String(), AppSerdes.Employee()))
            .groupBy((k, v) -> KeyValue.pair(v.getDepartment(), v), Grouped.with(AppSerdes.String(), AppSerdes.Employee()))
            .aggregate(
                //Initializer
                () -> new DepartmentAggregate()
                    .withEmployeeCount(0)
                    .withTotalSalary(0)
                    .withAvgSalary(0D),
                //Adder
                (k, v, aggV) -> new DepartmentAggregate()
                    .withEmployeeCount(aggV.getEmployeeCount() + 1)
                    .withTotalSalary(aggV.getTotalSalary() + v.getSalary())
                    .withAvgSalary((aggV.getTotalSalary() + v.getSalary()) / (aggV.getEmployeeCount() + 1D)),
                //Subtractor
                (k, v, aggV) -> new DepartmentAggregate()
                    .withEmployeeCount(aggV.getEmployeeCount() - 1)
                    .withTotalSalary(aggV.getTotalSalary() - v.getSalary())
                    .withAvgSalary((aggV.getTotalSalary() - v.getSalary()) / (aggV.getEmployeeCount() - 1D)),
                //Serializer
                Materialized.<String, DepartmentAggregate, KeyValueStore<Bytes, byte[]>>as(
                    AppConfigs.stateStoreName).withValueSerde(AppSerdes.DepartmentAggregate())
            ).toStream().print(Printed.<String, DepartmentAggregate>toSysOut().withLabel("Department Aggregate"));

        KafkaStreams streams = new KafkaStreams(streamsBuilder.build(), props);
        AppRestService queryServer = new AppRestService(streams, hostName, portNumber);
        streams.setStateListener((currentState, prevState) -> {
            logger.info("State Changing to " + currentState + " from " + prevState);
            queryServer.setActive(currentState == KafkaStreams.State.RUNNING && prevState == KafkaStreams.State.REBALANCING);
        });
        streams.start();
        queryServer.start();

        Runtime.getRuntime().addShutdownHook(new Thread(() -> {
            logger.info("Stopping Streams");
            queryServer.stop();
            streams.close();
        }));
    }
}

Popularity 1/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: aggregate java ktable

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Contributed on Feb 28 2023

Pragya Keshap

0 Answers Avg Quality 2/10

Ktable Aggregate query

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