The Intermediary is the architectural component that receives new certificate requests from clients and submits them to the Server Engine. The intermediary is composed of two parts, the intermediary application that performs actions on behalf of clients, and the Certificate Server Client Interface (shown as Certificate Server Web Client in the Setup program) that handles communications between the intermediary application and the server engine.
Intermediaries can be written to handle certificate requests from different types of clients, across multiple transports or according to policy-specific criteria. Microsoft® Internet Information Server is an intermediary that provides support for clients over HTTP. Intermediaries can also check on the status of a previously submitted request and obtain the Certificate Server's configuration information.