[jax-rs-spec users] Re: Suggestion to refactor rx invoker API

From: Pavel Bucek <>
Date: Sun, 15 Jan 2017 19:15:57 +0100


thanks for the proposal. I will look into it later, now I just want to
react to some things which are already being discussed here..

Sergey, Markus, thanks for evaluating Ondrejs proposal.

Please see inline.

On 15/01/2017 17:20, Sergey Beryozkin wrote:
> IMHO rx() needs to remain in order to get the default, this is as
> simple as it can get. Doing more than rx() in order to get
> CompletionStage would be bad.
> But I'm warming to something similar to what you are suggesting.
> .unwrap() is redundant IMHO.
> either rx() for the default
> or, example,
> RxInvoker<Observable> rxInvoker = rx(Observable.class)
> The reason it works better than the prototype suggested by Pavel is
> that this code is *portable*.
> Clearly, in most cases, it won't be the users who will create
> RxInvoker<Observable>, etc but Jersey, CXF, RestEasy will have
> dedicated modules with META-INF linking, in this case, Observable to a
> specific RxInvoker. This will be documented and users willing to work
> with non-default rx() will add a given module to the classpath...
Ideally, RxInvoker<Observable> is not created by Jersey nor CXF nor
RestEasy, but by 3rd party library, which works on ALL JAX-RS
implementations. Ideally RxJava itself could provide RxInvokerFactory
(or however that will end up named).

That would allow the real portability, since you won't need to care
about which implementation is underneath and which features does it
provide. It will just work everywhere.

Thanks and regards,

> Sergey
> On 14/01/17 14:28, Markus KARG wrote:
>> Sounds good for me, but actually I think it would be even simpler if
>> we name it "unwrap()", and do not fill in any parameters. As I said,
>> I think applications will typically use only one technology at the
>> time. So "unwrap()" simply can check if there is a @Provider
>> registered having a method with the same parameters as your proposed
>> "conver()", we finally have the requested plugability, no additonal
>> complexity, follow existing JAX-RS patterns, and get rid of repeating
>> lots of "rx(Class)". :-)
>> -Markus
>> *From:*Ondrej Mihályi []
>> *Sent:* Samstag, 14. Januar 2017 12:54
>> *To:*
>> *Subject:* Suggestion to refactor rx invoker API
>> I was thinking about an alternative to current rx API, to simplify it
>> in context of supporting extensibility.
>> My idea is to modify the CompletionStageRxInvoker, so that it returns
>> an extension to CompletionStage, which would contain additional
>> method to convert the interface to any other reactive interface:
>> public interface RxCompletionStage<T> extends CompletionStage<T> {
>> <NEW> NEW convert(Function<CompletionStage<T>, NEW> converter);
>> }
>> With this, we would move all the complexity to this new interface,
>> which still can be used as a usual CompletionStage, but with the
>> additional convert method, it provides an extension point to other
>> interfaces. And it's based on standard CompletionStage, therefore we
>> don't need additional rx invokers.
>> We could remove RxInvokerProvider, the 2 rx() methods from the
>> Builder, which accept RxInvokerProvider, and even remove the
>> RxInvoker interface, as CompletionStageRxInvoker would be the only
>> required implementation.
>> Here is an example of what I mean, with RxJava2 as an example:
>> *client*.request().rx().get(). // we get the RxCompletionStage
>> here, which extends CompletionStage
>> .convert(this::flowableFromStage) // accepts a function that
>> converts the CompletionStage to another interface .subscribe(s ->
>> testResult = s, Throwable::printStackTrace);
>> An example of a working code here
>> <>
>> (although not using JAX-RS, just wrapping a method that returns a
>> CompletionStage).
>> Ondrej