Re: Mixing OO and DB

From: Dmitry A. Kazakov <mailbox_at_dmitry-kazakov.de>
Date: Wed, 13 Feb 2008 22:30:17 +0100
Message-ID: <xstn12ovsdw3$.1jze6eg9q6qr$.dlg_at_40tude.net>


On Wed, 13 Feb 2008 02:25:15 +0100, mAsterdam wrote:

> Dmitry A. Kazakov schreef:

>> mAsterdam wrote:
>>> Dmitry A. Kazakov wrote:
>>>> mAsterdam wrote:
>>>>
>>>>> In your extension, you appear to map your slaves to data.
>>>>> Slaves behave, objects do. Data doesn't.
>>>> If data did not behave how would it be possible to use data?
>>> Being active is not, as your question presupposes,
>>> a prerequisite to being used.

>> No, I didn't meant that. Behavior is independent on who acts on whom.
>> Consider it as a list of all things you could ever do with data.
> 
> It is not clear what you are asking with
> "If data did not behave how would it be possible to use data?"
> Please rephrase.

use : data -> something

The mapping "use" is behavior of data x something (=> it is also behaviour of data.)

>> But why is recording essential?

>
> To facilitate the sharing of observations.

So, we have now:

  1. observations
  2. entities (busy with sharing observations)
  3. actions (state?) of sharing something (like observations)
  4. identity (of "same" thing being shared/observed)
  5. identity (of "different" entities observing "same" thing)

Isn't it a bit too much in order to define an allegedly fundamental thing called data?

This question is only relevant if you are going to define 1-5 within your formal system, provided that were possible. In case it rather falls under the category of meaning (=hand waving), then that is exactly same trick I used in my definition. I just said that in the formal system there are values with some semantics attached to, which (semantics) lies outside that system. Call it recording, encoding, observation, sharing whatsoever. All this is irrelevant to what we are going to do with data.

>> Or to put it otherwise, can you consider unrecorded,
>> not memorized data?
>
> No.

Bad. It means that you have to formalize "memorize" in some quite tricky way. Honestly I don't know what could be the difference between "memorized Pi", "not-yet-memorized Pi", "once-memorized-but-forgotten-by-now Pi" and so on.

>> May I translate data into a different
>> representation and then erase the original record?
>> Will data still be there?
>
> Iff it conveys the same facts as the original record, sure.

OK, that means that data = facts + record medium of:

D = (F, R)

It also states that

F1 = F2 => D1 = D2

Why should I care about R, then? Pi is Pi and retains all its property independently on where and how you write it (or not). Let's declare F = D and forget about R.

(BTW, some of DB people regularly posting to comp.object vehemently denied that DB is about persistency. Could you clarify it?)

>> A formal system operates on data
>> without any clue of the meaning of.

> 
> I think that is to crude.
> The meaning itself is informal, hence inherently impossible to fully
> access from within the formal system (I think we agree on that).
> However, without meaning to associate it with, a formalism is useless.

It is a tautology. You say that without meaning there is no meaning. Yes, we cannot reason about meaning while staying within the same formal system. Because you seem to bind data with a meaning (as I do), that immediately kicks the notion of data out of the formal system. So data do not exist there. Which is all my point! No data, nothing to worry about.

>>>> (The type of values describes the behavior of data.)]
>>> How? I don't understand what you are saying here -
>>> this may be a language thing, though.
>>> An example might clarify.

>>
>> Consider the value 1. It has no behavior (and no use) so long you don't
>> tell us its type. It you say that 1 is an integer, then its behavior will
>> include "has negative inverse." If the type is Positive, then the behavior
>> will be "no negative inverse", "can be squared in R" etc.
>
> Is this what you mean: All operations for which the set is closed?

All operations at all. Actually all provable predicates involving at leas one value of the given type.

> If so - how is this behaviour of the data itself?

I don't know what you mean here. What is "data itself"? Or possibly "data for others"?

>> (Behavior does not presume anything like tiny cogwheels hidden inside 1.
>> The cogwheels are rather big and all outside (:-))
>>

>>>> If the ultimate goal is same, then managing the thing called data is mere
>>>> one possible thread of the process.
>>> That does not follow.
>>> Furthermore: after the process stops, the data remains.

>>
>> Really? You wrote just above:
>>
>> "it only makes sense to talk about data when the medium on
>> which they are recorded is readable by some mechanism to
>> achieve electronic representation, but that is not inherent
>> to data."
>>
>> Which is all true. So let you have a medium without a process that can read
>> it, what did remain of data? It what sense do data remain? As a possibility
>> to start a process by some other process which still runs? Consider it on
>> the example with 1.
> 
> In that sense all phonographs are part of the same process.
> It's process, Jim, but not as we know it. Define process.

I just took your "readable by some mechanism" and named it "process." I wanted to know how do you want to distinguish "readable" and "unreadable data." I concede it was a leading question. The suggested answer is: if the thing was ever readable, it will ever be. You can always repeat the things you did once in some equivalent way, at least in mathematics you can.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
Received on Wed Feb 13 2008 - 22:30:17 CET

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