Google Protobuf Message Converter for AMQP Rabbit Based on https://github.com/gensen/spring-amqp-protobuf/blob/master/src/main/scala/com/gs/amqp/ProtobufMessageConverter.scala

BackendMessageConverter.java

public class BackendMessageConverter extends ProtobufMessageConverter {

    public BackendMessageConverter() {
        // Server object is the object generated by protoc
        super(Server.getDescriptor());
    }

}

ProtobufMessageConverter.java

package org.zenithar.mapper.protobuf.amqp;

import com.google.common.base.Preconditions;
import com.google.protobuf.Descriptors;
import com.google.protobuf.DynamicMessage;
import org.springframework.amqp.AmqpRejectAndDontRequeueException;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.support.converter.AbstractMessageConverter;
import org.springframework.amqp.support.converter.MessageConversionException;

import java.util.Map;

/**
 * Based on Scala version : https://github.com/gensen/spring-amqp-protobuf/blob/master/src/main/scala/com/gs/amqp/ProtobufMessageConverter.scala
 * @author Thibault NORMAND
 * @date 21/03/13
 */
public class ProtobufMessageConverter extends AbstractMessageConverter {

    private final static String MESSAGE_TYPE_NAME = "_msg_type_name_";
    private final static String CONTENT_TYPE_PROTOBUF = "application/x-backend-command";

    private Descriptors.FileDescriptor fileDescriptor;

    private ProtobufMessageConverter() {
        super();
    }

    public ProtobufMessageConverter(Descriptors.FileDescriptor fileDescriptor) {
        this.fileDescriptor = fileDescriptor;
    }

    @Override
    protected Message createMessage(Object object, MessageProperties messageProperties) {
        Preconditions.checkNotNull(object, "Object to send is null !");

        if (!com.google.protobuf.Message.class.isAssignableFrom(object.getClass())) {
            throw new MessageConversionException("Message wasn't a protobuf");
        } else {
            com.google.protobuf.Message protobuf = (com.google.protobuf.Message) object;
            byte[] byteArray = protobuf.toByteArray();

            messageProperties.setContentLength(byteArray.length);
            messageProperties.setContentType(ProtobufMessageConverter.CONTENT_TYPE_PROTOBUF);
            messageProperties.setHeader(ProtobufMessageConverter.MESSAGE_TYPE_NAME, protobuf.getDescriptorForType().getName());

            return new Message(byteArray, messageProperties);
        }
    }

    @Override
    public Object fromMessage(Message message) throws MessageConversionException {

        com.google.protobuf.Message parsedMessage = null;
        try {
            if(ProtobufMessageConverter.CONTENT_TYPE_PROTOBUF.equals(message.getMessageProperties().getContentType())) {
                String typeName = getMessageTypeName(message);
                Descriptors.Descriptor messageType = fileDescriptor.findMessageTypeByName(typeName);
                parsedMessage = DynamicMessage.parseFrom(messageType, message.getBody());
            }
        } catch (Exception e) {
            throw new AmqpRejectAndDontRequeueException("Cannot convert, unknown message type %s".format(getMessageTypeName(message)));
        }
        return parsedMessage;
    }

    private String getMessageTypeName(Message msg) {
        Map<String, Object> headers = msg.getMessageProperties().getHeaders();
        return Preconditions.checkNotNull(headers.get(ProtobufMessageConverter.MESSAGE_TYPE_NAME)).toString();
    }

}

spring.xml

<bean id="rabbitProtobufMessageConverter" class="org.zenithar.converters.protobuf.amqp.BackendMessageConverter" />
<rabbit:template connection-factory="rabbitConnectionFactory"
                 message-converter="rabbitProtobufMessageConverter"/>

Server.getDescriptor()

The Server class is missing from my generated files. Can I configure protoc somehow to generate it? I'm using Gradle.