org.apache.beam.sdk.extensions.sql.meta.provider.kafka.BeamKafkaCSVTable.java Source code

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Here is the source code for org.apache.beam.sdk.extensions.sql.meta.provider.kafka.BeamKafkaCSVTable.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.beam.sdk.extensions.sql.meta.provider.kafka;

import static java.nio.charset.StandardCharsets.UTF_8;
import static org.apache.beam.sdk.extensions.sql.impl.schema.BeamTableUtils.beamRow2CsvLine;
import static org.apache.beam.sdk.extensions.sql.impl.schema.BeamTableUtils.csvLines2BeamRows;

import java.util.List;
import org.apache.beam.sdk.schemas.Schema;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.values.KV;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.Row;
import org.apache.commons.csv.CSVFormat;

/** A Kafka topic that saves records as CSV format. */
public class BeamKafkaCSVTable extends BeamKafkaTable {
    private CSVFormat csvFormat;

    public BeamKafkaCSVTable(Schema beamSchema, String bootstrapServers, List<String> topics) {
        this(beamSchema, bootstrapServers, topics, CSVFormat.DEFAULT);
    }

    public BeamKafkaCSVTable(Schema beamSchema, String bootstrapServers, List<String> topics, CSVFormat format) {
        super(beamSchema, bootstrapServers, topics);
        this.csvFormat = format;
    }

    @Override
    public PTransform<PCollection<KV<byte[], byte[]>>, PCollection<Row>> getPTransformForInput() {
        return new CsvRecorderDecoder(schema, csvFormat);
    }

    @Override
    public PTransform<PCollection<Row>, PCollection<KV<byte[], byte[]>>> getPTransformForOutput() {
        return new CsvRecorderEncoder(schema, csvFormat);
    }

    /** A PTransform to convert {@code KV<byte[], byte[]>} to {@link Row}. */
    public static class CsvRecorderDecoder extends PTransform<PCollection<KV<byte[], byte[]>>, PCollection<Row>> {
        private Schema schema;
        private CSVFormat format;

        public CsvRecorderDecoder(Schema schema, CSVFormat format) {
            this.schema = schema;
            this.format = format;
        }

        @Override
        public PCollection<Row> expand(PCollection<KV<byte[], byte[]>> input) {
            return input.apply("decodeRecord", ParDo.of(new DoFn<KV<byte[], byte[]>, Row>() {
                @ProcessElement
                public void processElement(ProcessContext c) {
                    String rowInString = new String(c.element().getValue(), UTF_8);
                    for (Row row : csvLines2BeamRows(format, rowInString, schema)) {
                        c.output(row);
                    }
                }
            })).setRowSchema(schema);
        }
    }

    /** A PTransform to convert {@link Row} to {@code KV<byte[], byte[]>}. */
    public static class CsvRecorderEncoder extends PTransform<PCollection<Row>, PCollection<KV<byte[], byte[]>>> {
        private Schema schema;
        private CSVFormat format;

        public CsvRecorderEncoder(Schema schema, CSVFormat format) {
            this.schema = schema;
            this.format = format;
        }

        @Override
        public PCollection<KV<byte[], byte[]>> expand(PCollection<Row> input) {
            return input.apply("encodeRecord", ParDo.of(new DoFn<Row, KV<byte[], byte[]>>() {
                @ProcessElement
                public void processElement(ProcessContext c) {
                    Row in = c.element();
                    c.output(KV.of(new byte[] {}, beamRow2CsvLine(in, format).getBytes(UTF_8)));
                }
            }));
        }
    }
}