[javaee-spec users] Re: [cdi-dev] Fwd: Re: CompletableFuture Usage in the Platfom vs CDI

From: Romain Manni-Bucau <>
Date: Tue, 8 Mar 2016 14:06:54 +0100

@Reza: can you clarify the behavior of this snippet please:

CompletionFuture<AnEvent> cf = asyncEvent.fireAsync(...);
cf.complete(new AnEvent()); // not deterministic even if the container will
likely get false calling complete, should it be ignored? throw an
exception? other?

That's one point where CompletionStage sounds wiser than CompletionFuture
for CDI async events. The javadoc makes the goal clear: "@return a {_at_link
CompletionStage} allowing further pipeline composition on the asynchronous
operation.". Using CompletionFuture opens the door to the state
manipulation which is not intended (or you have a plan for that?) and which
is easily misleading IMHO.

CompletionFuture would however make a lot of sense for some parts of EE and
to replace @Asynchronous AsyncResult hack cause there you need to handle
the state yourself. Both being compatible I see it as a consistent usage of
each API.

Romain Manni-Bucau
@rmannibucau <> | Blog
<> | Github <> |
LinkedIn <> | Tomitriber

2016-03-08 13:53 GMT+01:00 Reza Rahman <>:

> FYI - more feedback from just another developer that happens to care a
> great deal about EE.
> Begin forwarded message:
> *From:* Josh Juneau <>
> *Date:* March 8, 2016 at 7:41:56 AM EST
> *To:* "" <>
> *Subject:* *[javaee-spec users] Re: CompletableFuture Usage in the
> Platfom vs CDI*
> *Reply-To:*
> Reza-
> I am in agreement with you. I agree that CompleteableFuture seems to make
> more sense for asynchronous events than CompletionStage. Given that it is
> widely acceptable throughout the platform, and the naming aligns more
> closely with asynchronous activity...I think CompleteableFuture would be a
> more consistent and standardized choice.
> Thanks
> Josh Juneau
> On Mon, Mar 7, 2016 at 6:40 PM, Reza Rahman <> wrote:
>> The CDI EG is incorporating the concept of CompletableFuture into
>> asynchronous events. Unfortunately for reasons I really don't see as good
>> they are using it's superinterface CompletionStage instead of
>> CompletableFuture.
>> I think this is a big ease-of-use mistake as CompletableFuture is
>> designed to be the end user high level gateway API while CompletionStage is
>> mostly as SPI intended for framework writers.
>> Given that the CompletableFuture concept is pretty widely applicable
>> throughout the platform I think there is a need for consistency, oversight
>> and guidance from the platform expert group. Otherwise I fear less than
>> ideal ad-hoc decisions might be made in this case for CDI and possibly
>> others down the line.
>> What do you think?
> _______________________________________________
> cdi-dev mailing list
> Note that for all code provided on this list, the provider licenses the
> code under the Apache License, Version 2 (
> For all other ideas
> provided on this list, the provider waives all patent and other
> intellectual property rights inherent in such information.