2016-03-08 14:22 GMT+01:00 Reza Rahman <reza_rahman(a)lycos.com>:
I think the JDK team made the right usability call by including
everything
into CompletableFuture as a one stop shop. That's why the API will probably
prove more usable in the end.
This is also about choosing the right level of exposed API.
Can a developer erroneously call complete()? Sure, but it's
pretty
unlikely since it just doesn't fit the client usage pattern for a promise.
And they can make this unlikely error either for @Asynchronous, CDI
asynchronous events and pretty much just about anywhere CompletableFuture
is used as an API.
In previous sample I would agree it is a programming error but in a real
application you can pass the future through several layers and then it is
less obvious (this async event opens a nice and fluent way to trigger an
event which is actually your returned data as well: return
asyncEvent.fireAsync(myResult);).
That said, I've also reached out to the JDK team on this. I hope
they will
have the time to explain their design motivations themselves and clarify
what they would expect from EE or just about anyone else needing to use
their APIs.
Thanks
On Mar 8, 2016, at 8:06 AM, Romain Manni-Bucau
<rmannibucau(a)gmail.com>
wrote:
@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 {@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 <
https://twitter.com/rmannibucau> | Blog
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http://rmannibucau.wordpress.com> | Github
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https://github.com/rmannibucau> | LinkedIn
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https://www.linkedin.com/in/rmannibucau> | Tomitriber
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2016-03-08 13:53 GMT+01:00 Reza Rahman <reza_rahman(a)lycos.com>:
> FYI - more feedback from just another developer that happens to care a
> great deal about EE.
>
> Begin forwarded message:
>
> *From:* Josh Juneau <juneau001(a)gmail.com>
> *Date:* March 8, 2016 at 7:41:56 AM EST
> *To:* "users(a)javaee-spec.java.net" <users(a)javaee-spec.java.net>
> *Subject:* *[javaee-spec users] Re: CompletableFuture Usage in the
> Platfom vs CDI*
> *Reply-To:* users(a)javaee-spec.java.net
>
> 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
> juneau001(a)gmail.com
>
http://jj-blogger.blogspot.com
>
https://www.apress.com/index.php/author/author/view/id/1866
>
>
> On Mon, Mar 7, 2016 at 6:40 PM, Reza Rahman <reza_rahman(a)lycos.com>
> 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?
>
>
>
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