Apache AVRO with Rest

Question

I am evaluating using Apache AVRO for my Jersey REST services. I am using Springboot with Jersey REST.

Currently I am accepting JSON as input which are converted to Java Pojos using the Jackson object mapper.

I have looked in different places but I cannot find any example that is using Apache AVRO with a Jersey end point.

I have found this Github repository (https://github.com/FasterXML/jackson-dataformats-binary/) which has Apache AVRO plugin.

I still cannot find any good example as how to integrate this. Has anyone used Apache AVRO with Jersey? If yes, is there any example I can use?

Answer 1

To start , two things need to happen:

1. You need to develop a custom ObjectMapper after the fashion of the Avro schema format
2. You need to supply that custom ObjectMapper to Jersey.

That should look something like this:

@Provider
public class AvroMapperProvider implements ContextResolver<ObjectMapper> {

    final AvroMapper avroMapper = new AvroMapper();

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return avroMapper;
    }
}

Configure your application to use Jackson as the message handler:

public class MyApplication extends ResourceConfig {
    public MyApplication() {
         super(JacksonFeature.class,AvroMapperProvider.class);
    }
}

---

Alternatively, you can implement a custom MessageBodyReader and MessageBodyWriter that allows you to directly process the payloads on the way in and out:

public class AvroMessageReader implements MessageBodyReader<Person> {

    AvroSchema schema;

    final AvroMapper avroMapper = new AvroMapper();

    public AvroMessageReader(){
        schema = avroMapper.schemaFor(Person.class); //generates an Avro schema from the POJO class.
    }

    @Override
    public boolean isReadable(Class<?> type, Type type1, Annotation[] antns, MediaType mt) {
        return type == Person.class; //determines that this reader can handle the Person class.
    }

    @Override
    public Person readFrom(Class<Person> type, Type type1, Annotation[] antns, MediaType mt, MultivaluedMap<String, String> mm, InputStream in) throws IOException, WebApplicationException {
        return avroMapper.reader(schema).readValue(in);
    }

}

Here, we generate an avro schema from a hypothetical Person class. The JAX-RS runtime will select this reader based on the response from isReadable.

You can then inject the MessageBodyWorkers component into your service implementation class:

@Path("app")
public static class BodyReaderTest{

    @Context
    private MessageBodyWorkers workers;

    @POST
    @Produces("avro/binary")
    @Consumes("avro/binary")
    public String processMessage() {

        workers.getMessageBodyReader(Person.class, Person.class, new Annotation[]{}, MediaType.APPLICATION_JSON_TYPE);
    }
 }

To answer your last comment: Setting the mime type on your handler to the recommended avro/binary ought to do it.