>Markus,
>
>A real life question to help me make sure I understand your points.
>
>I have 3 separate systems that are share portions of the data.
>
>1) There is a SQL system that collects data
>2) A VFP billing system that determines a customers bill based on the collected data from (1).
>3) An off the shelf accounting system that creates the invoices and tracks Accounts Receivable based on the billing data from (2).
>
>Some of the data entry control will be contained outside the 3 above systems. The outside system will collect the basic entity data for creating new customers. Some of this data must be sent to each one of the 3 above systems.
>
>Based on what I understand from the prior discussion, to minimize system maintenance headaches, the system that will be separate from the main 3 systems should have 2 separate parts.
>
>A data services tier handles chores such as verifying the links between the 3 main systems. And a business logic tier that handles verifying specific information such as information entered for a new customer.
>
>Do you have anything else to add that I should watch out for when development starts?
>
>TIA,
>
>PF
Not exactly sure. We are talking about three tiers here ("parts"). We are also potentially (but not necessarrily) talking about a COM (WinDNA) based system. In either way, data has to be sent to the back end through a middle tier layer. I'm not sure whether this is what you describe above.
Markus