Passing JSON to WebService

You're setting the type correctly and making the request correctly.

The problem is you have nothing to handle the response.

A message body reader for Java class my.class.path.InputBean

...is basically saying, you're returning something that cannot be read, formatted, and ouputted to anything useful.

You're returning a Product type in your service, which is your octet-stream, but I don't see where you have a MessageBodyWriter to output this response to JSON.

You need:

 @Provider@Produces( { MediaType.APPLICATION_JSON } )public static class ProductWriter implements MessageBodyWriter<Product>{    @Override    public long getSize(Product data, Class<?> type, Type genericType, Annotation annotations[], MediaType mediaType)    {        // cannot predetermine this so return -1        return -1;    }    @Override    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType)    {        if ( mediaType.equals(MediaType.APPLICATION_JSON_TYPE) )        {            return Product.class.isAssignableFrom(type);        }        return false;    }    @Override    public void writeTo(Product data, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType,                        MultivaluedMap<String, Object> headers, OutputStream out) throws IOException, WebApplicationException    {        if ( mediaType.equals(MediaType.APPLICATION_JSON_TYPE) )        {            outputToJSON( data, out );        }    }    private void outputToJSON(Product data, OutputStream out) throws IOException    {        try (Writer w = new OutputStreamWriter(out, "UTF-8"))        {            gson.toJson( data, w );        }    }}

It seems that JSONObject cannot be serialized, because no message writer could be found. Why don't you just give the InputBean as input?

Change your client code to:

public String getProduct() {        Client client = Client.create();        WebResource webResource =       client.resource("http://localhost:8080/product/getProduct");        InputBean data = new InputBean(1,1); // make sure there's a constructor        ClientResponse response = webResource.type(MediaType.APPLICATION_JSON)                .accept(MediaType.APPLICATION_JSON)                .post(ClientResponse.class, data);        return response.getEntity(String.class);    }

Dropwizard preferes Jackson for JSON serialization & deserialization, in which case you should be able to pass InputBean directly, you can also specify the mime type manually or use the Entity wrapper, e.g.

    final Client client = new JerseyClientBuilder(environment)            .using(config.getJerseyClientConfiguration())            .build("jersey-client");    WebResource webResource = client.resource("http://localhost:8080/product/getProduct");    InputBean data = new InputBean(1,1);    String response = webResource.post(String.class, Entity.json(data));

See http://www.dropwizard.io/1.2.2/docs/manual/client.html#jersey-client for details on how to create a configured Jersey client.