[Hawkular-dev] Properties store?

[John Sanda]

> On May 19, 2015, at 7:53 AM, Heiko W.Rupp <hrupp at redhat.com> wrote:
> 
> On 4 May 2015, at 14:03, Lukas Krejci wrote:
> 
>> In my mind almost anything "is changing like a metric", because 
>> everything changes over time.
> 
> Well. Then lets stop your project and make metrics store inventory
> data :;->

I agree with Lukas. At lease in RHQ, we treated most things as time series because we are interested in changes over time. Metrics is one type of time series.

> 
> 
>> Also IMHO  "key-value pairs" are just JSON. I think that the 
>> structured data
>> support for configs and operation params served us well in RHQ.
> 
> I don't say that the structured data in RHQ is by itself bad (the 
> implementation
> has IMO room for improvement). I also don't say that the traits in RHQ
> are a bad thing.
> But: with traits and configuration we have some very similar concepts
> that have in RHQ some very different implementation.
> 
>> So IMHO we need a time-series store for structured data. I am not sure 
>> inventory
>> is that -  it is good for storing relationships among entities but I 
>> am not
>> sure if it is well suited for storing (versioned) structured data.
> 
> I do not think that each single property needs to be a separate object.
> I can imagine that we keep one (JSON) object per version (with some 
> additional
> metadata) and the respective "client" of the store know how to deal with 
> it.
> My understanding was that Inventory can have such a list of things
> hanging on a resource.
> 
> The question remains though if inventory is the right place or metrics.
> Also for Traits, I think we should not (like for Availability) store the 
> whole
> string every 20sec, but only store an update when a change occurred (1),
> which may or may be applicable for configuration too. In fact RHQ had
> logic inside the agents to only send updates when it detected changes.
> Also Traits are most likely r/o, while configuration data may be 
> modified from
> the UI.
> 
> 1) And perhaps the last time the old version was still detected.
> 
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