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Re: Searching OO Associations with RDBMS Persistence Models

From: Dmitry A. Kazakov <mailbox_at_dmitry-kazakov.de>
Date: Mon, 19 Jun 2006 17:08:10 +0200
Message-ID: <14dwy0wgjorrf$.16p30eqkcg2m$.dlg@40tude.net>


On 18 Jun 2006 21:03:14 -0700, Aloha Kakuikanu wrote:

> Dmitry A. Kazakov wrote:

>> On 16 Jun 2006 13:03:30 -0700, Aloha Kakuikanu wrote:
>>
>>> Then logical connection is a
>>> path in the graph.
>>
>> No. That's routing issues. A connection is either peer-to-peer or
>> multicast. It does not mention any nodes passed. Some protocols use dynamic
>> routing.
> 
> OK. Now please explain what RM meant by
> "A logical connection between two endpoint is a list of circuits"

I cannot tell for him. I would consider connections are relations on peers.

>>> There is nothing challenging in modelling graph in
>>> RDBMS and creating application objects that correspond to paths in a
>>> graph.
>>
>> Incidence matrix? Huh.
>>
>>> Why "object id" is significant in this picture? |
>>
>> Because an object can be mobile. Connection can obviously be described by a
>> trivial relation between nodes. But it is an implementation detail in, say,
>> a middleware, which deals with objects, not connections.

> 
> OK. Now please explain why this elusive "object id" can't be a key of
> some tuple. I even suggest a name for this relation: ConnectionNode.

That's the same. You can call it key if the relation is global. But in real frameworks the scopes of object names / identities aren't global, for safety and reliability reasons. No doubts, relations can be used to describe a state of a network

But what about transitions between them?

Ii cannot serve as a basis for any reasonable implementation. Reasonable means: fits minimal functional and non-functional requirements.

The major problem, as I see it. is that when RM is used as you did, it is to the network as a whole, which clashes with the idea of network as a distributed computing system. So a technically correct description of, isn't very helpful.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
Received on Mon Jun 19 2006 - 10:08:10 CDT

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