[MUD-Dev] MUD Design Fundamentals (Was: Looking for

Jeff Kesselman jeffk at tenetwork.com
Fri Aug 29 14:45:58 New Zealand Standard Time 1997


At 02:25 PM 8/29/97 PST8PDT, you wrote:
>
>A relational db corresponds to the store layer in a persistance model 
>with one major difference, the store layer in a typical OO 
>persistance model is unaware of the structure and type of stored 
>data.  A relational db can well be used as the store layer for a 
>persistance model but you lose the structure and type ignorance.  
>
>Thus if you change the type of a class data member you must make a 
>corresponding change in the relational db structure.  Although this 

The relational Db suggestionw as just a way of illustarting how one can
cdoe data structure (in the3 case the table links) by using a fixed
usper-struxcture that can contain the info as data. It wasnt meant as a
literla.

HOWEVER in practive there really IS no reason a relational Db cannto be
sued to store OO info.  It just a question of where you cut the model.  A
typical OO system involed param,eters and methods o nan object.  If you
have a parameters table, that links to an obecjt record, and amethod table
that contains mthod code that links to the same object, then yo ucan stoer
any obecjt structure in the fixed tables. Follow?

In fact Cold uses basicly this technique I believe, witha  ahsing lookup
for efficiency, as do many smalltalk implementations.
>On the other hand, if you are implementing your app in an 
>early-binding language (C,C++, etc) you might well consider using an 
>rdbms as your persistance store.  Primarily because you will need to 

I fell thsi is not avlid distinction. All you are sayign i nearly v. late
bindign is what DATA is stored in the rdbms.  In teh cas eof a late binsign
system bindings are ALSO stored  in the RDBMS, not hard coded.  Thats
really the only functional difference.


Jeff Kesselman
Snr. Game Integration Engineer
TEN -- The Total Entertainment Network -- www.ten.net

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