users@jax-rs-spec.java.net

[jax-rs-spec users] Re: JAX-RS Client Reactive API review

From: Sergey Beryozkin <sberyozkin_at_talend.com>
Date: Mon, 16 Jan 2017 18:10:49 +0000

Hi Pavel

I'm not sure at the moment.
In CXF, say, a CompletionStage invoker, only works on the async HTTP transport. So we do supply a Supplier and the async thread will wait inside this Supplier till the result is avail from the async transport thread.
Expecting RxInvoker implementations will work with the SyncInvoker alone to support them may not always work...
I glanced earlier at JerseyCompletionStageRxInvoker and looks like an HTTP invocation over the sync transport is .supplyAsync-ed.
But as I said we do it over the async transport only - may be it is not needed, but may be it is ?
I wonder if some new abstraction may need to be introduced.

Cheers, Sergey


On 16/01/17 17:27, Pavel Bucek wrote:

Hi Sergey,

good catch!

Would it be enough to change the param to SyncInvoker? (Invocation.Builder already extends that, so it would be very simple change).

Thanks,
Pavel

On 16/01/2017 17:55, Sergey Beryozkin wrote:
Hi Pavel

Looks like Invocation.Builder.rx() methods which accept
RxInvokerProvider are visible to these RxInvokerProviders.

This is problematic. I see Jersey RxInvokerProviders delegate back to Invocation.Builder so I can appreciate why Invocation.Builder is passed on,

but it just does not look right to me that rx() and similarly, async() bridges, are still visible to the providers.

Cheers, Sergey

On 13/01/17 20:36, Pavel Bucek wrote:

Dear experts,

please review following wiki and APIs:

https://java.net/projects/jax-rs-spec/pages/RxClient

All added classes related to Reactive Client APIs are linked from that page, but let me allow a short recap.

JAX-RS Client is being extended by the ability to provide a way how to process responses in reactive fashion. The change consists of:

- adding rx(...) methods to Invocation.Builder
- defining RxInvoker
- allowing users to extend this API by providing RxInvokerProvider

Specification will mandate implementation for CompletionStage from Java SE 8.

Client code examples:

- basic use

CompletionStage<List<String>> cs =
        client.target("remote/forecast/{destination}")
                .resolveTemplate("destination", "mars")
                .request()
                .header("Rx-User", "Java8")
                .rx() // gets CompletionStageRxInvoker
                .get(new GenericType<List<String>>() {
                });

cs.thenAccept(System.out::println);



- using custom RxInvokerFactory (this is little artificial, since the factory just returns CompletionStageRxInvoker, but support for Observable from RxJava or ListenableFuture from Guava can be done in the exact same manner)

CompletionStage<List<String>> cs =
        client.target("remote/forecast/{destination}")
                .resolveTemplate("destination", "mars")
                .request()
                .header("Rx-User", "Java8")
                .rx(CompletionStageRxInvokerProvider.class)
                .get(new GenericType<List<String>>() {
                });

cs.thenAccept(System.out::println);


Source links:

- https://github.com/jax-rs/api/blob/2.1-m02/jaxrs-api/src/main/java/javax/ws/rs/client/Invocation.java#L298

jax-rs/api<https://github.com/jax-rs/api/blob/2.1-m02/jaxrs-api/src/main/java/javax/ws/rs/client/Invocation.java#L298>
github.com
api - JAX-RS API Source Code


- https://github.com/jax-rs/api/blob/2.1-m02/jaxrs-api/src/main/java/javax/ws/rs/client/RxInvoker.java
- https://github.com/jax-rs/api/blob/2.1-m02/jaxrs-api/src/main/java/javax/ws/rs/client/RxInvokerProvider.java

Examples & tests:

- https://github.com/jax-rs/api/blob/2.1-m02/jaxrs-api/src/test/java/javax/ws/rs/core/RxClientTest.java
- https://github.com/jersey/jersey/blob/2.x/core-client/src/test/java/org/glassfish/jersey/client/ClientRxTest.java#L86

The last link is to the Jersey repository. Jersey version 2.26 will be JAX-RS 2.1 RI and branch 2.x is where the development will happen. Jersey 2.26-b01 (which is being released right now) implements all rx(...) methods; feel free to test/evaluate it there.

Looking forward to your feedback!

Thanks and regards,
Pavel