users@jersey.java.net

[Jersey] Re: Async client and Response.readEntity

From: Marek Potociar <marek.potociar_at_oracle.com>
Date: Thu, 22 Jan 2015 13:42:37 +0100

Hi Mikael,

Please see inline.

> On 12 Jan 2015, at 11:29, Mikael Ståldal <mikael.staldal_at_appearnetworks.com> wrote:
>
> No, I did not get any answer to this. And neither to the JIRA issues I have filed:
>
> https://java.net/jira/browse/JERSEY-2682 <https://java.net/jira/browse/JERSEY-2682>
C&Ping my comment from the issue:

I have looked at the issue and I’m not sure I understand the problem you are pointing out:

1. InvocationCallback<Order> is run from some other thread (i.e. asynchronously) that has issued the request
2. The callback is only invoked AFTER the Response.readEntity(Order.class) has completed. So having an InvocationCallback<Response> and invoking Response.readEntity(..) inside is not making things worse.

Perhaps you are looking for a non-blocking I/O API support, which is planned for the next release of JAX-RS <https://jcp.org/en/jsr/detail?id=370>? Something like Response.readEntity(Order.class, order -> { … }) ?
Btw. do you know that you can easily check the response code from a JAX-RS ClientResponseFilter <https://jax-rs-spec.java.net/nonav/2.0-rev-a/apidocs/javax/ws/rs/client/ClientResponseFilter.html> ?

>
> To me, it seems like the async part of the JAX-RS 2.0 client API is flawed (not to mention the default implementation in Jeresy: https://java.net/jira/browse/JERSEY-2058 <https://java.net/jira/browse/JERSEY-2058>).

The primary problem is in lack of NIO support in the current JAX-RS API. We’re looking into fixing it for the next JAX-RS release, as noted above. Obviously, we will first try to make it work in Jersey, so Jersey users should have a working solution long before JAX-RS.next is released. I do not have any ETA at this point though.

>
> It's a pity, since the synchronous client API in JAX-RS 2.0 (and its implementation in Jersey) is really nice.
>
> I am considering using something else for async REST client, such as https://github.com/AsyncHttpClient/async-http-client <https://github.com/AsyncHttpClient/async-http-client> or Jetty client.

FWIW, our grizzly connector is actually wrapped into async HTTP client API. But again, current lack of NIO support in JAX-RS APIs is making it difficult to come up with a good async client solution. That said, we’re already trying, stay tuned.

Marek

>
> On Wed, Dec 31, 2014 at 9:06 PM, Robert DiFalco <robert.difalco_at_gmail.com <mailto:robert.difalco_at_gmail.com>> wrote:
> Did you ever get an answer to this?
>
> On Mon, Oct 6, 2014 at 7:45 AM, Mikael Ståldal <mikael.staldal_at_appearnetworks.com <mailto:mikael.staldal_at_appearnetworks.com>> wrote:
> Consider using Jersey client in async mode with an InvocationCallback<Response>, and then use readEntity() on the Response. Order is a custom domain object for which we have a MessageBodyReader available.
>
> Invocation invocation = client.target(someURL).request().buildGet();
> invocation.submit(new InvocationCallback<Response> {
> public void completed(Response response) {
> int status = response.getStatus();
> if (status == 200) {
> Order order = response.readEntity(Order.class); // blocking ?
> process(order);
> } else {
> error();
> }
> }
> public void failed(Throwable throwable) {
> error();
> }
> });
>
> Is the response.readEntity() call blocking? Is it I/O bound if the response is large? Or is the whole response read from network before the completed() callback is invoked?
>
> Will the asynchronicity be improved if I do InvocationCallback<Order> instead? What if I want to get other information from the Response?
>
> --
> Mikael Ståldal
> Chief Software Architect
> Appear
> Phone: +46 8 545 91 572 <>
> Email: mikael.staldal_at_appearnetworks.com <mailto:mikael.staldal_at_appearnetworks.com>
>
>
>
> --
> Mikael Ståldal
> Chief Software Architect
> Appear
> Phone: +46 8 545 91 572 <>
> Email: mikael.staldal_at_appearnetworks.com <mailto:mikael.staldal_at_appearnetworks.com>