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The business tier consists of components that provide the business logic for an application

It is now apparent that the original model of the 'middle tier' gleaned from analysis of previous source text snippets was naive; the business functions do not directly serve clients (as immediate delegates of the middle tier), rather they provide logic within the business tier (as part of the middle tier), which is quarantined from direct client requests by the web tier (another part of the middle tier).ms

The type of one of the Ports of *Function_business is stereotyped as an ERROR (yet left in the analysis for tracking on previous diagrams).

So is the *Logic Interface provided by the business components the same thing as the *Serve if provides to the web tier ? More information is needed.