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In what way can Apache Beam be utilized to read Kafka messages that are defined in protobuf format?

asked 2022-08-25 11:00:00 +0000

qstack gravatar image

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answered 2021-10-10 06:00:00 +0000

pufferfish gravatar image

Apache Beam provides a KafkaIO that can be used to read Kafka messages in protobuf format. Here are the steps to do so:

  1. First, define the protobuf schema for the messages that will be read from Kafka.
  2. Use the KafkaIO to create a pipeline object that will read from the Kafka topic. Specify the bootstrap servers and the topic name(s).
  3. Use the withValueDeserializerAndCoder() method to specify the deserializer and coder for the protobuf messages. The deserializer should read the binary format of the message and deserialize it into an instance of the protobuf class. The coder should encode the protobuf message into a byte array for processing in the pipeline.
  4. Use the apply() method to transform the Kafka messages into PCollection objects that can be processed by other pipeline transforms.
  5. Use additional pipeline transforms to process and manipulate the protobuf messages in the desired way.

For example:

// Define the protobuf schema for the messages
ProtobufSchema schema = ProtobufSchema.newBuilder()
    .addClass(TestMessage.class)
    .build();

// Create the pipeline to read from Kafka
Pipeline pipeline = Pipeline.create(options);

// Configure the KafkaIO to read from the topic with protobuf messages
KafkaIO.Read<String, byte[]> kafkaRead = KafkaIO.<String, byte[]>read()
    .withBootstrapServers("kafka:9092")
    .withTopic("my-topic")
    .withKeyDeserializer(StringDeserializer.class)
    .withValueDeserializerAndCoder(ProtobufDeserializer.of(TestMessage.class, schema),
        ProtoCoder.of(TestMessage.class, schema));

// Read the Kafka messages into a PCollection
PCollection<TestMessage> messages = pipeline.apply(kafkaRead)
    .apply(Values.<byte[]>create())
    .apply(ParDo.of(new DoFn<byte[], TestMessage>() {
        @ProcessElement
        public void processElement(ProcessContext context) {
            TestMessage message = context.element();
            context.output(message);
        }
    }));

// Do additional processing on the messages as desired
messages.apply(...)

In this example, the Kafka messages are read from the "my-topic" topic and deserialized using the ProtobufDeserializer defined for the TestMessage class. The resulting PCollection contains instances of the TestMessage class, which can be further processed by other pipeline transforms.

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Asked: 2022-08-25 11:00:00 +0000

Seen: 1 times

Last updated: Oct 10 '21