RxJava support

[boulderwebdev]

Are there plans in motion for adding RxJava(2) support? Also, could you add to the documentation that as the project stands, it is not compatible with vertx-rx?

[vietj]

this SDK does not use Vert.x generated API, so it will not benefit from an auto generated RxJava API.

it seems to me that the only option is to use RxJava support from the AWS SDK

[vietj]

@aesteve correct me if I'm wrong

[aesteve]

You're right, there's no specific support.

In fact, we don't re-write every AWS SDK method in a Vert.x fashion, it would be a lot of work. We could eventually try to generate a layer on top of it, but I'm not even sure how.

Looks like Netflix used to provide something like that in the past: https://github.com/Netflix/rx-aws-java-sdk but gave up maintaining it at some point.

Honestly, I see no easy way to implement it at the moment. I'll keep that in mind though in case I see something that'd fit.

On Sun, Oct 25, 2020 at 7:00 PM Julien Viet [email protected] wrote:

@aesteve https://github.com/aesteve correct me if I'm wrong

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[aesteve]

What do you mean by "not compatible with vertx-rx" exactly? What did you try, what were your expecting and was the result? Thanks.

[boulderwebdev]

@aesteve Well, for starters, the compiler will complain about the following line

withVertx(builder, vertx.getOrCreateContext()).build();

with a reactivex context. I.e. if I use the imports

import io.vertx.reactivex.core.Context;
import static io.reactiverse.awssdk.VertxSdkClient.withVertx;

At the bare minimum, I want to instantiate a client upon creating a handler to put into the router. Then, I can make calls to S3 whenever I need to retrieve some data that's not cached locally.

[boulderwebdev]

Also, from my understanding of reading this codebase, it seems like the main idea is to give amazon a custom HTTP client which is compatible with Vert.x's event loop so calls to any AWS api uses this client. Is this correct? If so, (I think) an Rxified wrapper around this project could be created which is compatible with the Rxified vertx API.

Also, it seems like the single method in the test code takes you 90% of the way for handling requests to S3, but I'm not sure how well it generalizes to the other services. I modified it in some code I wrote to

public static <T> Single<T> single(CompletableFuture<T> future) {
    final SingleOnSubscribe<T> sos = emitter ->
      future.handle((result, error) -> {
        if (emitter.isDisposed()) {
          return future; // maybe should be 'return null' ?
        }
        if (error != null) {
          emitter.onError(error);
        } else {
          emitter.onSuccess(result);
        }
        return future;
      });
    return Single.create(sos);
  }

and this compiles correctly and doesn't throw any errors with various test cases.

[aesteve]

In order to fix the compilation error, I think you can use `vertx.delegate.getOrCreateContext()ˋ, let me know if this works.

As for the single method in tests, I'm happy it helps you tackle most of your use cases.

I'll update the docs to mention RxJava support is out of the scope of the lib, but indicate there are some hints in the tests.

Thanks for reporting this.

[aesteve]

it seems like the main idea is to give amazon a custom HTTP client which is compatible with Vert.x's event loop so calls to any AWS api uses this client. Is this correct?

Partially yes. As indicated in the docs, the lib also makes sure callbacks are executed in the same context that initiated the AWS API call, which is one of Vert.x guarantees.

If you think such a wrapper is needed and are ready to test it then maintain it in the long run, it's certainly a good idea.

[boulderwebdev]

@aesteve thanks for the pointers. I'll go ahead and create a test case soon to see if vertx.getDelegate() fixed my problems.