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From Sergey Kozlov <skoz...@gridgain.com>
Subject Re: Json support in Ignite
Date Wed, 15 Jul 2015 14:43:58 GMT
I think we should to plan not only put/get operations but create/drop
caches as well since we've implemented dynamic caches. It gives to user the
full stack to interact with a grid.

On Wed, Jul 15, 2015 at 11:32 AM, Dmitriy Setrakyan <dsetrakyan@apache.org>
wrote:

> On Wed, Jul 15, 2015 at 12:00 AM, Semyon Boikov <sboikov@gridgain.com>
> wrote:
>
> > Hi all,
> >
> > As part of integration with Node.Js (IGNITE-961) we age going to add in
> > Ignite support for JSON (possibility for IgniteCache to put, get, index
> and
> > query JSON data).
> >
> > We can implement standard 'javax.json' API (JSR 353), with this API work
> > with cache will look like in this example:
> >
> >
> Are we going to implement JSON specification ourselves? Sounds a bit fishy.
> Can we just take some available implementation (assuming that the license
> fits)?
>
>
>
> > Ignite should somehow provide access to 'javax.json' API, unfortunately
> > 'javax.json' is not part of JDK so we have several options how it can be
> > added in Ignite:
> >
> > 1. Add dependency for 'javax.json-api' in core module, in this case we
> can
> > have method to get access for json API on 'org.apache.ignite.Ignite':
> >
> > * interface Ignite {*
> > *    ...*
> >
> > *    javax.json.JsonProvider json();*
> > * }*
> >
> > * JsonProvider json = ignite.json();*
> >
> > Not sure it is ok, since now we don't have 3rd party dependencies in
> ignite
> > 'core' module except 'javax.cache' API.
> >
> > 2. Added another optional module 'json', this module will have dependency
> > for 'javax.json' API, and in this module we can have factory providing
> > access to 'javax.json' API:
> >
>
> I think an optional module makes sense.
>
>
>
> >
> > 3. Create plugin for json, in this case plugin will provide access to
> > 'javax.json' API:
> >
> > * IgniteJsonPlugin jsonPlugin = ignite.plugin(IgniteJsonPlugin.NAME);*
> >
> > * javax.json.JsonProvider provider = jsonPlugin.json();*
> >
> >
> > Not sure this aproach with plugin is ok, since now we don't have 'core'
> > ignite functionality implemented as plugins.
> >
>
> Agree, this probably won't work.
>
>
>
> > Also we need following functionality for json objects
> >
> > 1. Possibility to map json cache key to affinity key. This can be
> achieved
> > with custom affinity mapper:
> >
> >     cache.setAffinityMapper(new AffinityKeyMapper() {
> >         @Override public Object affinityKey(Object key) {
> >             return ((JsonObject)key).getJsonNumber("orgId").longValue();
> >         }
> >     });
> >
>
> We can also have a special field within JSON Object, called
> ignite_affinity_field=bla
>
>
> >
> > 2. Efficient implementation for equals/hashCode for json cache keys.
> >
> > One option is just have equals/hashCode like in HashMap.
> >
> > Another option can be add special JsonConfiguration, it should be set in
> > CacheConfiguration and can contain following settings:
> > - list of fields to use in 'equals' and 'hashCode' calculation
> > - alternatively for equals/hashCode we can provide possibility to
> implement
> > custom comparator/hash code calculator
> > - JsonConfiguration can have setting for affinity key
> >
> > So JsonConfiguration can look like this:
> >
> > *class JsonConfiguration {*
> > *    /***
> > *     * Field names for hash code calculation.*
> > *     */*
> > *    public Collection<String> getKeyHashCodeFields();*
> >
> > *    /***
> > *     * Field names to use .*
> > *     */*
> > *    public Collection<String> getKeyEqualsFields();*
> >
> > *    /***
> > *     * Field name to get key which will be used for node affinity
> > calculation.*
> > *     */*
> > *    public String getAffinityKeyField();*
> > *}*
> >
>
> It looks like we are over architecting here.
>
> Keys should not have many fields, and most likely will have one or two.
> Iterating through fields and generating hash-code or equals the standard
> way seems reasonable (as opposed to creating a whole architecture around
> how to get hash and equals fields).
>
> If it makes sense, we should cache the hash code value inside the key
> object after it has been generated once.
>
>
> >
> >
> > I need your feedback on these questions:
> > - is it ok to implement 'javax.json' API to support json for Ignite
> caches?
> >
>
> Can we get some existing implementation instead?
>
>
> > - if we implement 'javax.json' what is best way to add it in Ignite (see
> my
> > suggestion above: just add dependency for 'javax.json' API in 'core'
> > module, add special module or plugin)
> >
>
> Optional module?
>
>
> > - do we need to adde JsonConfiguration I described above?
> >
>
> Most likely not
>
>
> >
> > Thanks!
> >
>



-- 
Sergey Kozlov
GridGain Systems
www.gridgain.com

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