Wire Protocol

What are the actual bytes travelling on the wire? They all seem to be json payload followed by a newline character…

S->C State stream

Channel: 0 (“CHANNEL_STATEDIFFS”)
Kind: Unreliable
Payload specification: State

<<JSON-payload>>\n

C->S Intent

Channel: 0 (“CHANNEL_STATEDIFFS”)
Kind: Unreliable
Payload specification: Intent

<<JSON-payload>>\n

S->C Interaction

Channel: 1 (“CHANNEL_COMMANDS”)
Kind: Reliable
Payload specification: Entity to entity interaction

<<JSON-payload>>\n

Version 0 implements this packet as:

{
  "cmd": "interact",
  "interact": {
    "from_entity": "...",
    "to_entity": "...",
    "cmd": "..."
  }
}\n

C->S Interaction

Channel: 1 (“CHANNEL_COMMANDS”)
Kind: Reliable
Payload specification: Entity to entity interaction

<<JSON-payload>>\n

C->S->C Media track packet

Channel: 3 (“CHANNEL_MEDIA”)
Kind: Unreliable
Related interaction: allocate_track

<<track-id as 32bit big endian integer>><<raw media payload>>

Note that in older versions of the protocol, even audio/media packets had that stupid newline at the end.

C->S->C Clock sync packet

Channel: 4 (“CHANNEL_CLOCK”)
Kind: Unreliable
Payload:

{
  "client_clock": 123.0,
  "server_clock": 456.0
}\n

This packet is sent from the client once a second with only the client_clock field set to its local monotonic clock time. It is immediately bounced back from the server, with its server_clock set.

The client can thus calculate its round-trip latency (now() - response["client_clock"]), and delta between its clock and the server clock. Using all this information, it can then extrapolate the world time and update place’s clock component.

Unspecified

C->S asset request/response
S->C asset request/response
S->C asset force delivery