The middle tier is generally used for all the logic of the application. How to collect data for reports, validation, etc. The advantage is that it separates the business rules from the UI and data. You're looking at Tastrades and seeing that the invoice information is only used in one place .. but it isn't...you have a) the form and b) the printed invoice, so that's two places. The UI should not know anything about how to create an invoice or access the data.


>Hi all,
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>I have a question about multi-tier development.
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>I am using MSDE and SQL Server for Database and I use primary keys, master-details constraints, and cluster-indexes to maintain data integrity.
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>According to multi-tier theory, all logic should be in middle tier so that one can change the front end or port it without any difficulty.
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>If we take famous Tasmanian Traders as example, how we can develop it in a 3-tier structure? I mean what parts would be in the middle tier? Will we use a class file to create our invoice form although this class will not be used in any other form, why not develop it without class, what are the advantages and disadvantages of this approach? Kindly explain.
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>Regards,