[infinispan-dev] Integration between HotRod and OGM

[Emmanuel Bernard]

It's an interesting approach that would work fine-ish for entities
assuming the Hot Rod client is multi threaded and assuming the client
uses Future to parallelize the calls.

But it won't work for associations as we have them designed today.
Each association - or more precisely the query results to go from an
entity A1 to the list of entities B associated to it - is represented by
an AtomicMap.
Each entry in this map does correspond to an entry in the association.

While we can "guess" the column names and build from the metadata the
list of composed keys for entities, we cannot do the same for
associations as the key is literally the (composite) id of the
association and we cannot guess that most of the time (we can in very
pathological cases).
We could imagine that we list the association row keys in a special
entry to work around that but this approach is just as problematic and
is conceptually the same.
The only solution would be to lock the whole association for each
operation and I guess impose some versioning / optimistic lock.

That is not a pattern that scales sufficiently from my experience.
That's the problem with interconnected data :)

Emmanuel

On Mon 2013-11-18 23:05, Mircea Markus wrote:
> Neither the grouping API nor the AtomicMap work over hotrod.
> Between the grouping API and AtomicMap, I think the one that would make more sense migrating is the grouping API.
> One way or the other, I think the hotrod protocol would require an enhancement - mind raising a JIRA for that?
> For now I guess you can sacrifice performance and always sending the entire object across on every update instead of only the deltas?
> 
> On Nov 18, 2013, at 9:56 AM, Emmanuel Bernard <emmanuel at hibernate.org> wrote:
> 
> > Someone mentioned the grouping API as some sort of alternative to
> > AtomicMap. Maybe we should use that?
> > Note that if we don't have a fine-grained approach we will need to
> > make sure we *copy* the complex data structure upon reads to mimic
> > proper transaction isolation.
> > 
> > On Tue 2013-11-12 15:14, Sanne Grinovero wrote:
> >> On 12 November 2013 14:54, Emmanuel Bernard <emmanuel at hibernate.org> wrote:
> >>> On the transaction side, we can start without them.
> >> 
> >> +1 on omitting transactions for now.
> >> 
> >> And on the missing AtomicMaps, I hope the Infinispan will want to implement it?
> >> Would be good to eventually converge on similar featuresets on remote
> >> vs embedded APIs.
> >> 
> >> I know the embedded version relies on batching/transactions, but I
> >> guess we could obtain a similar effect with some ad-hoc commands in
> >> Hot Rod?
> >> 
> >> Sanne
> >> 
> >>> 
> >>> On Tue 2013-11-12 14:34, Davide D'Alto wrote:
> >>>> Hi,
> >>>> I'm working on the integration between HotRod and OGM.
> >>>> 
> >>>> We already have a dialect for Inifinispan and I'm trying to follow the same
> >>>> logic.
> >>>> At the moment I'm having two problems:
> >>>> 
> >>>> 1) In the Infinispan dialect we are using the AtomicMap and the
> >>>> AtomicMapLookup but this classes don't work with the RemoteCache. Is there
> >>>> an equivalent for HotRod?
> >>>> 
> >>>> 2) As far as I know HotRod does not support transactions. I've found a link
> >>>> to a branch on Mircea repository:
> >>>> https://github.com/mmarkus/ops_over_hotrod/wiki/Usage-guide
> >>>> Is this something I could/should use?
> >>>> 
> >>>> Any help is appreciated.
> >>>> 
> >>>> Thanks,
> >>>> Davide
> >>> 
> >>>> _______________________________________________
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> >>> 
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> 
> Cheers,
> -- 
> Mircea Markus
> Infinispan lead (www.infinispan.org)
> 
> 
> 
> 
> 
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