Val,

The problems with CompletableFuture in public API are:
* It is a class, not an interface
* It is completable - anyone can call .complete(), which is not what we want

There seems to be no clear guidance in Java world on async API design;
however, it is often recommended to return CompletionStage instead of
CompletableFuture
from the public APIs [1] [2], and some products follow this [3].

Other products return their own future interface that extends both Future
and CompletionStage,
which seems to be a better alternative to me [4].

Thoughts?

[1]
https://stackoverflow.com/questions/47571117/what-is-the-difference-between-completionstage-and-completablefuture
[2]
https://stackoverflow.com/questions/34930840/should-i-return-completablefuture-or-future-when-defining-api
<https://stackoverflow.com/questions/34930840/should-i-return-completablefuture-or-future-when-defining-api#:~:text=by%20returning%20a%20CompletableFuture%2C%20you,API%2C%20which%20is%20not%20good.>
[3]
https://docs.hazelcast.org/docs/latest/javadoc/com/hazelcast/cache/ICache.html
[4]
https://lettuce.io/lettuce-4/release/api/com/lambdaworks/redis/RedisFuture.html

On Fri, Aug 21, 2020 at 10:28 AM Alex Plehanov <[email protected]>
wrote:

> Pavel,
>
> Thanks for the discussion, I've also faced with the necessity of having
> async calls while implementing POC for thin client data streamer [1] and
> solve it similarly (but in my case it's required only for internal
> implementation, so I've only changed the internal API).
>
> I want to note that described in IEP approach (and implemented in POC) is
> not fully async, since "send" is still used in the user's thread. To make
> it fully async we need additional sending thread (since blocking IO is used
> for communication with the server). If partition awareness is enabled there
> will be 2 threads per each server connection, perhaps we should think about
> moving to NIO and introducing some kind of communication thread pool.
>
> [1]: https://github.com/apache/ignite/pull/8175
>
> пт, 21 авг. 2020 г. в 03:35, Valentin Kulichenko <
> [email protected]>:
>
> > Sounds good. I've added this to the 3.0 roadmap:
> > https://cwiki.apache.org/confluence/display/IGNITE/Apache+Ignite+3.0
> >
> > Unless there are any objections from others, let's stick with the
> > CompletableFuture for any future development, including the thin client.
> >
> > -Val
> >
> > On Thu, Aug 20, 2020 at 9:30 AM Pavel Tupitsyn <[email protected]>
> > wrote:
> >
> > > Val, no objections from my side.
> > > As noted above, the only benefit of IgniteFuture is consistency across
> > > thin/thick APIs,
> > > which is probably not so important.
> > >
> > > On Thu, Aug 20, 2020 at 6:28 PM Valentin Kulichenko <
> > > [email protected]> wrote:
> > >
> > > > Hi Pavel,
> > > >
> > > > Are there any benefits of IgniteFuture over CompletableFuture?
> > > >
> > > > IgniteFuture was created long ago, during the time when
> > CompletableFuture
> > > > did not exist. There is a big chance that IgniteFuture actually
> became
> > > > redundant at the moment we transitioned to Java8. If that's the
> case, I
> > > > would prefer using CompletableFuture in the thin client and getting
> rid
> > > of
> > > > IgniteFuture altogether in 3.0.
> > > >
> > > > What do you think?
> > > >
> > > > -Val
> > > >
> > > > On Thu, Aug 20, 2020 at 7:19 AM Pavel Tupitsyn <[email protected]
> >
> > > > wrote:
> > > >
> > > > > Igniters,
> > > > >
> > > > > I've prepared an IEP [1], please review and let me know what you
> > think.
> > > > >
> > > > > In particular, I'd like to discuss the Future interface to be used:
> > > > > * IgniteFuture is the first candidate - Thin APIs will be
> consistent
> > > with
> > > > > Thick APIs, probably better for existing Ignite users.
> > > > > * CompletableFuture is the standard for async Java APIs. Many users
> > may
> > > > > prefer that instead of a custom IgniteFuture.
> > > > >
> > > > > [1]
> > > > >
> > > > >
> > > >
> > >
> >
> https://cwiki.apache.org/confluence/display/IGNITE/IEP-51%3A+Java+Thin+Client+Async+API
> > > > >
> > > >
> > >
> >
>

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