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From: Niclas Hedhman <niclas@hedhman.org>
Date: Fri, 23 Jun 2017 10:15:27 +0800
Message-ID: <CADmm+KdvccivC8JKy=Pwep=AKs2j390cBLXgfk3qjBw8VEuODQ@mail.gmail.com>
Subject: Hangout on Monday 19 June
To: dev@polygene.apache.org
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archived-at: Fri, 23 Jun 2017 02:15:55 -0000

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Gang,
Should have done this earlier, but been quite busy.

First of all, remarkably the time was almost right. Tibor pointed out that
CET is the non-DST timezone name. I should probably used Europe/Berlin or
Europe/Paris.

Participants;
 - Niclas Hedhman
 - Tibor Mlynarik
 - Stanislav Muhametsin (no cam/mic)

Tibor came with a list of things, after trying to port his 2.x application
to 3.x

* @Uses disallowing Composites breaks his app. And it worked before. I
realized from his feedback that I forbade a much wider usecase than the one
that is a problem. Need to revert. Tibor, please add Jira issue. Or reopen
the one from before.

* Tibor felt a bit confused on how the State in composites really work
under the hood. And he would like documentation on that. I tried to explain
it in person, but add a Jira, and I will look into writing it up sooner or
later.

* I have a note on "UnitOfWork closed inconsistently", but can't recall
what that was about.

* ConcurrentModification checks might not work in clustered setups. Tibor
suspects that the "version" is not checked against the store, and if it is,
transaction-free stores have no chance to do a "Compare/Set" operation if
that is supported (such as MongoDb has). I find this one particularly
interesting, and would like investigate if we can improve the EntityStore
SPI to take such into consideration in some manner.

* Indexing state change notification sent before commit. Possibly having a
time window when the index has a new value, but the entity doesn't yet. I
don't think this is a priority issue, since there is also the thing about
isolation of transactions and caching on stores, which will also give a
similar result, i.e. "find entities with sales > 10000" and one of those
are in the UoW cache, with a value less than 10000. Additionally, the
indexing may be asynchronous, operate on clusters, just like the ES might
do, with unpredictable delays everywhere.
Eventual consistency should perhaps be promoted more in Polygene and make
this as transparent as possible.

If Tibor's list contained anything else, I didn't take a note of it,
perhaps he can fill it in.


Other than that, some general chitchat and non-distinct ideas.

Hope to see more people on July 17th 2017. Stan promises to arrange cam/mic
by that time. :-)


Cheers and see you all next time.
-- 
Niclas Hedhman, Software Developer
http://polygene.apache.org - New Energy for Java

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