#+title: pCloudCC Request-Response Flow

~pcloudcc~ is built upon a client-server
architecture. When the user runs ~pcloudcc -u <username>~, this starts
the server. The server listens for request messages and sends back
response messages.

When the user runs ~pcloudcc -k~, this starts the client's command
line interface. The client sends request messages to and expects a
corresponding response message from the server.

The client and server send and receive messages over a Unix socket
that gets created when the server is started.

#+begin_src plantuml :file img/request-response-00.png :export results
  participant user
  participant control_tools <<client>>
  participant overlay_client <<client>>
  participant socket <<net>>
  participant poverlay <<server>>

  user -> control_tools: input command
  control_tools -> control_tools : parse command
  control_tools -> overlay_client : SendCall(msgType, reqData, ...)
  overlay_client -> socket : write_request
  socket -> poverlay : request
  poverlay -> poverlay : poverlay_handle_request
  poverlay -> poverlay : poverlay_get_response
  poverlay -> socket : response
  socket -> overlay_client : read_response
  overlay_client -> control_tools : (msg, msgsz, payload, payloadsz)
  control_tools -> user : print results
#+end_src

[[file:img/request-response-00.png]]