Hi Markus,

OIC. Bringing in an ODBMS complicates the issue. I played with one last year (named after a flower, I think, but I forget the name) and was amazed at what you could do...with that sort of data engine, you don't have that translation layer between the object model and the relational model.


>>OK....here's what I mean: You have a table of addresses for customers. There must be at least one address per customer (1:1+). You enter a new customer and forget to enter an address. You save. Business tier returns error code; it never gets to the data.
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>>You go to delete a customer with 3 addresses. Business tier passes this on to the data tier (or to a stored proc in the database) which deletes the addresses and then the customer within a transaction.
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>>So....
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>>Can I add a customer? Biz rule with RI rule
>>Can I delete? Biz rule.
>>What do I delete? RI rule.
>
>No, that's not what I mean. The address(es) belong(s) to the customer. A customer and it's addresses are one entity. On XML there would be a customer node and address subnodes. In object databases, we wou have an addresses collection. So the fact that we have multiple tables in this scenario is only an implementation detail. Everything that goes along with this implementation details belongs to whereever the implementation takes place. In this case, the data tier.
>
>But if we store deliveries to a certain address, this would be a seperate entity alltogether. Therefore, everything that goes on between those two entities is business logic.
>
>Markus