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The client tier consists of a client program that makes requests to the middle tier (associative version)

Here we see an alternative "focus" Class Diagram for a «wrapper» Component of one sentence, this time usually a purely "associative" approach, with no inline composite structure (and thus also no Connectors for delegation from/to the boundary of Ports of Classes. It certainly makes it easier to handle at least some tracing to the Classes of analysis elements mentioned, however it is not clear (unless the attributes compartments are shown) how to relate the text to Properties like :Request, and it is also harder to show some flows.