This code is fairly complex, so it has been split up into a package of modules, rather than being a single large module. Refer to the individual module docstrings for details.
Server-side request handlers are registered in the bzrlib.smart.request
module.
The domain logic is in bzrlib.remote: RemoteBzrDir, RemoteBranch,
and so on.
There is also an plain file-level transport that calls remote methods to
manipulate files on the server in bzrlib.transport.remote.
The protocol is described in doc/developers/network-protocol.txt.