not quite understanding ntier using MEF, any help

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C#

ASP.NET

MEF

so ive setup an n tier infrastructure for a social network site im building, I have the following 5 projects im going to use.

WEB - UI
BLL - Business Logic
Components - will be discovered from 'Interfaces using MEF
Interfaces - Plugins are discovered by Components using MEF
DAL - Data Access


so if im following this right, when a user requests something through WEB, its then passed on to BLL
BLL then grabs the data it needs from 'DAL' to work with whatever components it needs from 'Components'
Components then discovers the plugins it needs from 'Interfaces' using MEF

is that right..?


if it is right my referencing should be something like

WEB refs BLL
BLL refs Components, DAL
Components refs Interfaces, componentcompositionmodel
Interfaces refs componentcompositionmodel



any help on this one.?