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From Николай Ижиков <nizhikov....@gmail.com>
Subject Re: ContinuousQueryWithTransformer implementation questions - 2
Date Mon, 18 Sep 2017 15:33:02 GMT
So, resuming:

1) My solution reduces network communication.
As far as I know, a lot of people want to have this feature at Ignite 2.x.
It's impossible to gain perfect API right now, it will take months to gain
it.
My solution ready right now!, let's merge it and refactor whole Continuous
Query API at 3.0.

2) Current API is bad, and, yes, my changes make it a little bit
complicated.
But, complication minimized as possible and profit much bigger that
complication.

2017-09-18 17:39 GMT+03:00 Николай Ижиков <nizhikov.dev@gmail.com>:

> Vladimir,
>
> Here is a short summary what is wrong with continuous query....
>
>
> OK.
> I agree - this is problems of current API.
>
> How we can fix it by not merging ContinuousQueryWIthTransformer?
> How we can quickly design, discuss and implement new API?
> Because at the moment there is no any ticket to start working at.
> Moreover we can't throw ContinuousQuery away until 3.0 version.
>
> > What is worse, this interface is inconsistent with JCache event
> listeners, which distinguish between create, update and delete events.
>
> Can't agree with you.
>
> 1. As far as I know jcache doesn't have any Transformer conception.
> 2. We can distinguish create, update and delete events in transformer and
> we can push that knowledge to listener.
>
>
>> What I see in your PR is that we add one more confusing concept - in
>> addition to wrongly named "local listener" now we will also have
>> "TransformedEventListener".
>>
>
> I think usage of jcache API in some Ignite-specific classes is one more
> issue of existing ContinuousQuery.
> I think we must use Ignite only API for Ignite only features and use some
> wrappers to provide external API support.
>
> For these reasons I would still prefer to think of better continuous
>> queries design first instead of making current API even more complicated.
>>
>
> I think the main reason for some feature is to provide value to the user.
> Transformers adds value to a product because usage of transformer can lead
> to significant performance win.
>
>
>> Vladimir.
>>
>> On Mon, Sep 18, 2017 at 4:04 PM, Николай Ижиков <nizhikov.dev@gmail.com>
>> wrote:
>>
>> > Igniters,
>> >
>> > I discussed API of ContinuousQuery and ContinuousQueryWithTransformer
>> with
>> > Anton Vinogradov one more time.
>> >
>> > Since users who use regular ContinuousQuery already knows pros. and
>> cons of
>> > using initialQuery and to not to complicate API more and more until 3.0
>> we
>> > agreed that best choice is to stay with existing initialQuery that
>> return
>> > Cache.Entry<K, V> for ContinuousQueryWithTransformer.
>> >
>> > Notice that initialQuery is not required and can be null.
>> >
>> > Thoughts?
>> >
>> > 2017-09-15 1:45 GMT+03:00 Denis Magda <dmagda@apache.org>:
>> >
>> > > Vladimir,
>> > >
>> > > If the API is so bad then it might take much more time to make up and
>> > roll
>> > > out the new. Plus, there should be a community member who is ready to
>> > take
>> > > it over. My suggestion would be to accept this contribution and
>> initiate
>> > an
>> > > activity towards the new API if you like.
>> > >
>> > > Personally, I considered this API as one of the most vivid we have
>> basing
>> > > on my practical usage experience. I was aware of initial query’s
>> pitfalls
>> > > but isn’t it something we can put on paper?
>> > >
>> > > —
>> > > Denis
>> > >
>> > > > On Sep 12, 2017, at 6:04 AM, Vladimir Ozerov <vozerov@gridgain.com>
>> > > wrote:
>> > > >
>> > > > My opinion is that our query API is big piece of ... you know,
>> > especially
>> > > > ContinuousQuery. A lot of concepts and features are mixed in a
>> single
>> > > > entity, what makes it hard to understand and use. Let's finally
>> > deprecate
>> > > > ContinuousQuery and design nice and consistent API. E.g.:
>> > > >
>> > > > interface IgniteCache {
>> > > >    UUID addListener(CacheEntryListener listener)
>> > > >    void removeListener(UUID listenerId);
>> > > > }
>> > > >
>> > > > This method set's a listener on all nodes which will process event
>> > > locally,
>> > > > no network communication. Now if you want semantics similar to
>> existing
>> > > > continuous queries, you use special entry listener type:
>> > > >
>> > > > class ContinuousQueryCacheEntryListener implements
>> CacheEntryListener
>> > {
>> > > >    ContinuousQueryRemoteFilter rmtFilter;
>> > > >    ContinuousQueryRemoteTransformer rmtTransformer;
>> > > >    ContinuousQueryLocalCallback locCb;
>> > > > }
>> > > >
>> > > > Last, "initial query" concept should be dropped from "continuous
>> query"
>> > > > feature completely. It doesn't guarantee any kind of atomicity or
>> > > > visibility wrt to cache events, so it adds no value. The same
>> behavior
>> > > > could be achieved as follows:
>> > > >
>> > > > cache.addListener(...)
>> > > > QueryCursor cursor = cache.query(initialQuery);
>> > > >
>> > > > Vladimir.
>> > > >
>> > > >
>> > > > On Tue, Sep 12, 2017 at 3:35 PM, Yakov Zhdanov <yzhdanov@apache.org
>> >
>> > > wrote:
>> > > >
>> > > >> Dmitry, can you please take a look at public API change.
>> > > >>
>> > > >> Ticket - https://issues.apache.org/jira/browse/IGNITE-425
>> > > >> PR - https://github.com/apache/ignite/pull/2372
>> > > >>
>> > > >> Issues:
>> > > >> 1. Do you see any other option other than creating separate class?
>> As
>> > > for
>> > > >> me I don't.
>> > > >> 2. In a new class we still have initial query which uses <K,
V>
>> types
>> > > which
>> > > >> is questionable.
>> > > >>
>> > > >> Igniters, please share your thoughts as well. Public API is the
>> face
>> > of
>> > > our
>> > > >> product we need to make it as convenient and consistent as we
can.
>> > > >>
>> > > >> --Yakov
>> > > >>
>> > >
>> > >
>> >
>> >
>> > --
>> > Nikolay Izhikov
>> > NIzhikov.dev@gmail.com
>> >
>>
>
>
>
> --
> Nikolay Izhikov
> NIzhikov.dev@gmail.com
>



-- 
Nikolay Izhikov
NIzhikov.dev@gmail.com

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