>Are you sure you're not talking about n-tier applications? Where you can switch and swap any of the components? For example: you have a Database tier, a business process tier or middleware and presentation tier. You would be able to swap any of the three without affecting any of the other layers.

the n tier is not only 3 tiers, a tier can be a workflow, because this is a orchesta director for process, not necessary can be in the business process tier or database o presentation tier.

because fox is data intensive i can make a workflow database with all process running in workflow tier, send request to business process and send warnings to the users , because the workflow can be stay in a tier, this can be send message to presentation tier (HTML o GUI)

i expect explain good (the english is NOT my second language)

Best Regards