Certificates can be requested and distributed through any transport mechanism. Microsoft® Certificate Server accepts certificate requests from an applicant through HTTP, RPC, disk file, or by custom transport. Certificate Server posts certificates to the applicant through HTTP, RPC, disk file, or custom transport.
Transports are supported by intermediary applications and exit module DLLs, usually written in Microsoft C/C++. The intermediary applications and exit modules isolate the Certificate Server functions from communicating with any specific transport.