Demo of Protobuff integration within Avro

pb-avro-test_pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.avro.is.great</groupId>
  <artifactId>protobuff-avro-demo</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>Demo of protobuff integration with Avro</name>
  <build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>build-helper-maven-plugin</artifactId>
            <executions>
                <execution>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>add-source</goal>
                    </goals>
                    <configuration>
                        <sources>
                            <source>${project.build.directory}/generated-sources</source>
                        </sources>
                    </configuration>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <artifactId>maven-antrun-plugin</artifactId>
            <executions>
              <execution>
                <id>generate-sources</id>
                <phase>generate-sources</phase>
                <configuration>
                  <tasks>
                    <echo>**** protoc need to be in the path ****</echo>
                    <mkdir dir="target/generated-sources"/>
                    <exec executable="protoc">
                      <arg value="--java_out=target/generated-sources" />
                      <arg value="--proto_path=src/main/resources/protobuf" />
                      <arg value="src/main/resources/protobuf/todo_provider.proto" />
                    </exec>
                  </tasks>
                  <sourceRoot>>${project.build.directory}/generated-sources</sourceRoot>
                </configuration>
                <goals>
                  <goal>run</goal>
                </goals>
              </execution>
            </executions>
        </plugin>

    </plugins>
</build>
  <dependencies>
    <dependency>
      <groupId>com.google.protobuf</groupId>
      <artifactId>protobuf-java</artifactId>
      <version>2.6.1</version>
    </dependency>
    <dependency>
          <groupId>org.apache.avro</groupId>
          <artifactId>avro</artifactId>
          <version>1.7.7</version>
    </dependency>
      <dependency>
          <groupId>org.apache.avro</groupId>
          <artifactId>avro-protobuf</artifactId>
          <version>1.7.7</version>
      </dependency>
  </dependencies>
</project>

pb-avro-test_src_main_java_com_demo_Proto2Avro.java

package com.demo;

import com.avro.is.great.TodoProvider;
import org.apache.avro.protobuf.ProtobufDatumReader;

import java.io.IOException;

public class Proto2Avro {


    public static void main(String[] args) throws IOException {
        System.out.println("******************************************************************************");
        System.out.println("******** How to convert a proto schema to avro with 2 lines of code **********");
        System.out.println("******************************************************************************");

        System.out.println("protobuff schema description:");
        System.out.println(TodoProvider.Todo.getDescriptor().toProto());
        System.out.println("----------");
        System.out.println("Avro schema:");
        ProtobufDatumReader<TodoProvider.Todo> datumReader = new ProtobufDatumReader<TodoProvider.Todo>(TodoProvider.Todo.class);
        System.out.println(datumReader.getSchema().toString(true));



    }
}

pb-avro-test_src_main_java_com_demo_ProtoWithAvro.java

package com.demo;

import com.avro.is.great.TodoProvider;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.io.Encoder;
import org.apache.avro.io.EncoderFactory;
import org.apache.avro.protobuf.ProtobufDatumReader;
import org.apache.avro.protobuf.ProtobufDatumWriter;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

public class ProtoWithAvro {


    public static void main(String[] args) throws IOException {
        System.out.println("******************************************************************************");
        System.out.println("******** DTO classes generated by Protobuff protoc can be used with Avro *****");
        System.out.println("******************************************************************************");

        // build a protobuff dto
        TodoProvider.Todo.Builder builder = TodoProvider.Todo.newBuilder();
        builder.setTitle("coucou !");
        TodoProvider.Todo todo = builder.build();

        // serialize with avro this dto
        ProtobufDatumWriter<TodoProvider.Todo> datumWriter = new ProtobufDatumWriter<TodoProvider.Todo>(TodoProvider.Todo.class);
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        Encoder e = EncoderFactory.get().binaryEncoder(os, null);
        datumWriter.write(todo, e);
        e.flush();

        // deserialize with avro the former dto
        ProtobufDatumReader<TodoProvider.Todo> datumReader = new ProtobufDatumReader<TodoProvider.Todo>(TodoProvider.Todo.class);
        Object o = datumReader.read
                (null,
                        DecoderFactory.get().binaryDecoder(new ByteArrayInputStream(os.toByteArray()), null));

        System.out.println("Protobuff DTO deserialized by avro " + o);

        // deserialize with avro, without using the protobuff dto
        GenericDatumReader<GenericRecord> genericDatumReader = new GenericDatumReader<GenericRecord>(datumReader.getSchema());
        GenericRecord record = genericDatumReader.read(null, DecoderFactory.get().binaryDecoder(new ByteArrayInputStream(os.toByteArray()), null));
        System.out.println("Avro Record deserialized " + record);



    }
}

pb-avro-test_src_main_resources_protobuf_todo_provider.proto

package examples;
 
option java_package = "com.avro.is.great";
option java_outer_classname = "TodoProvider";
 
message Todo {
	required string title = 1;
	enum Priority {
		NORMAL = 1;
		MEDIUM = 2;
		HIGH = 3;
	}
 
	optional Priority priority = 2;
}
 
message Todos {
	repeated Todo todos = 1;
}