[infinispan-dev] Integration between HotRod and OGM

Emmanuel Bernard emmanuel at hibernate.org
Wed Jan 22 08:33:58 EST 2014 

BTW query support on groups (by entry of each group) is an interesting non covered use case today.

On 22 Jan 2014, at 14:26, Emmanuel Bernard <emmanuel at hibernate.org> wrote:

> Conceptually I like the grouping API better than AtomicMap as I don’t have to rely on a specific Infinispan type.
> 
> We do use FineGrainedAtomicMap both for the entity and the association persistence (not AtomicMap). It is particularly critical for how we store the association navigation information. I don’t want one update to literally prevent the whole association from being updated. This is the same semantic a RDBMS has and that’s why Manik and I designed the FGAM requirements.
> 
> So my question is what are the differences between the grouping API and the FGAM in particular for:
> 
> - the amount of data sent back and forth (seems like grouping is sending the data naturally per key as “delta compared to the group"
> - the locking level when a new entry is added to the FGAM / Grouping API
> - the locking level when a new entry is removed to the FGAM / Grouping API
> - the locking level when a new entry is updated to the FGAM / Grouping API
> - the overall network verbosity
> - does grouping offer the same repeatable read protection that AtomicMap offers within a transaction?
> 
> I think retrying as a transaction workaround is quite fragile. We can offer it as a solution but supporting or encouraging it is another story. Unless each OGM nodes do behave like a transaction but that would be wrong. I am also concerned about reading data form a group that are inconsistent.
> 
> Emmanuel
> 
> On 21 Jan 2014, at 16:07, Mircea Markus <mmarkus at redhat.com> wrote:
> 
>> Hi Emmanuel,
>> 
>> Just had a good chat with Davide on this and one solution to overcome the shortcoming you mentioned in the above email would be to enhance the hotrod client to support grouping:
>> 
>> RemoteClient.put(G g, K k, V v); //first param is the group
>> RemoteClinet.getGroup(G g) : Map<K,V>;
>> 
>> It requires an enhancement on our local grouping API: EmbeddedCache.getGroup(G). This is something useful for us in a broader context, as it is the step needed to be able to deprecated AtomicMaps and get suggest them being replaced with Grouping. 
>> 
>> This approach still has some limitations compared to the current embedded integration: 
>> - performance caused by the lack of transactions: this means increased TCP chattiness between the Hot Rod client and the server. 
>> - you'd have to handle atomicity, potentially by retrying an operation
>> 
>> What do you think?
>> 
>> 
>> On Dec 3, 2013, at 3:10 AM, Mircea Markus <mmarkus at redhat.com> wrote:
>> 
>>> 
>>> On Nov 19, 2013, at 10:22 AM, Emmanuel Bernard <emmanuel at hibernate.org> wrote:
>>> 
>>>> 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.
>>> 
>>> The Java Hotrod client is both multithreaded and exposes an Async API.
>>> 
>>>> 
>>>> 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.
>>> 
>>> I think so too :-)
>>> 
>>>> 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
>>>>>>>> 
>>>>>>>>> _______________________________________________
>>>>>>>>> infinispan-dev mailing list
>>>>>>>>> infinispan-dev at lists.jboss.org
>>>>>>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>>>>> 
>>>>>>>> _______________________________________________
>>>>>>>> infinispan-dev mailing list
>>>>>>>> infinispan-dev at lists.jboss.org
>>>>>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>>>> _______________________________________________
>>>>>>> infinispan-dev mailing list
>>>>>>> infinispan-dev at lists.jboss.org
>>>>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>>> _______________________________________________
>>>>>> infinispan-dev mailing list
>>>>>> infinispan-dev at lists.jboss.org
>>>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>> 
>>>>> Cheers,
>>>>> -- 
>>>>> Mircea Markus
>>>>> Infinispan lead (www.infinispan.org)
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> _______________________________________________
>>>>> infinispan-dev mailing list
>>>>> infinispan-dev at lists.jboss.org
>>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>> _______________________________________________
>>>> infinispan-dev mailing list
>>>> infinispan-dev at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>> 
>>> Cheers,
>>> -- 
>>> Mircea Markus
>>> Infinispan lead (www.infinispan.org)
>>> 
>>> 
>>> 
>>> 
>> 
>> Cheers,
>> -- 
>> Mircea Markus
>> Infinispan lead (www.infinispan.org)
>> 
>> 
>> 
>> 
>> 
>> _______________________________________________
>> infinispan-dev mailing list
>> infinispan-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
> 
> 
> _______________________________________________
> infinispan-dev mailing list
> infinispan-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/infinispan-dev

More information about the infinispan-dev mailing list