Data serialization and deserialization in Apache Beam Java SDK

25 Sep 2023

In Apache Beam Java SDK, there are several options available for serialization and deserialization, depending on the requirements of your application. Let’s explore some of the common approaches:

Java Serialization: Java provides built-in serialization and deserialization mechanisms through the Serializable interface. You can implement this interface in your custom data classes and Java will handle the serialization and deserialization automatically. However, Java serialization can be slow and produce larger serialized payloads compared to other alternatives.
Avro: Apache Avro is a popular data serialization framework that provides a compact binary format and a schema for data interchange. Avro allows you to define schemas in JSON format and automatically generates Java classes from those schemas. You can use Avro serialization and deserialization in Apache Beam Java SDK by using the AvroCoder class and registering the coder with the pipeline.

import org.apache.avro.specific.SpecificRecord;
import org.apache.beam.sdk.coders.AvroCoder;

// Define your Avro schema and generate Java classes
AvroCoder.register(MyAvroClass.class);

PipelineOptions options = PipelineOptionsFactory.create();
Pipeline pipeline = Pipeline.create(options);

PCollection<MyAvroClass> data = pipeline.apply(...);

// Serialize data using AvroCoder
data.apply(ParDo.of(new DoFn<MyAvroClass, byte[]>() {
    @ProcessElement
    public void processElement(ProcessContext c) {
        MyAvroClass record = c.element();

        byte[] serializedData = AvroCoder.of(MyAvroClass.class).encode(record);
        c.output(serializedData);
    }
}));

// Deserialize data using AvroCoder
PCollection<MyAvroClass> deserializedData = serializedData.apply(ParDo.of(new DoFn<byte[], MyAvroClass>() {
    @ProcessElement
    public void processElement(ProcessContext c) {
        byte[] serializedData = c.element();

        MyAvroClass record = AvroCoder.of(MyAvroClass.class).decode(serializedData);
        c.output(record);
    }
}));

JSON or XML: If you prefer human-readable formats, you can use JSON or XML for serialization and deserialization. Apache Beam Java SDK provides built-in coders for handling JSON and XML data. You can use the JsonCoder or XmlCoder classes, respectively, to serialize and deserialize data.

import org.apache.beam.sdk.coders.CoderRegistry;
import org.apache.beam.sdk.coders.JsonCoder;
import org.apache.beam.sdk.coders.StringUtf8Coder;

PipelineOptions options = PipelineOptionsFactory.create();
Pipeline pipeline = Pipeline.create(options);

PCollection<String> data = pipeline.apply(...);

// Serialize data using JsonCoder
data.apply(ParDo.of(new DoFn<String, byte[]>() {
    @ProcessElement
    public void processElement(ProcessContext c) {
        String json = c.element();

        byte[] serializedData = JsonCoder.of(String.class).encode(json);
        c.output(serializedData);
    }
}));

// Deserialize data using JsonCoder
PCollection<String> deserializedData = serializedData.apply(ParDo.of(new DoFn<byte[], String>() {
    @ProcessElement
    public void processElement(ProcessContext c) {
        byte[] serializedData = c.element();
        
        String json = JsonCoder.of(String.class).decode(serializedData);
        c.output(json);
    }
}));

These are just a few examples of data serialization and deserialization methods available in Apache Beam Java SDK. The choice of serialization approach depends on factors such as performance, payload size, and compatibility with other systems. Choose the method that best suits your specific use case and requirements.

#ApacheBeam #JavaSDK