controller -> server:
Just lines of text, see either program's main.c.

server -> controller:
Data frames compressed using zlib. Data frames look as follows:
- Timestamp: (as from gettimeofday)
  - seconds (8 bytes)
  - microseconds (4 bytes)
- numpids (8 bytes)
- [numpids times:]
  - pid (4 bytes)
  - namelen (8 bytes)
  - process name (namelen bytes)
  - total user time (8 bytes)
  - total system time (8 bytes)
  - resident size (8 bytes)