Server Dispatch

This allows engine drivers to register new servers for devices that might connect to engine vs engine connecting to devices.

• Drivers can indicate a port they want open and the IP addresses they'll accept data from.
• The details of the clients and data is then streamed to the drivers.
• Servers are only opened if there is a driver listening and ports are closed otherwise.

ENV Vars

• PLACE_SERVER_SECRET = shared bearer token for driver auth
• SG_ENV = set to production for production log levels

Usage

There are two websocket endpoints one for TCP and one for UDP

• /api/dispatch/v1/tcp_dispatch
• /api/dispatch/v1/udp_dispatch

The query string should include the

• bearer_token used to authenticate the request
• port the server should run on
• accept a comma delimited list of client IP addresses that are expected to connect to the server

WS /api/dispatch/v1/tcp_dispatch?bearer_token=testing&port=6001&accept=127.0.0.1

The websocket only communicates over BINARY frames and has the following message types:

• OPENED == 0 dispatcher => driver - a TCP client connected to the server
• CLOSED == 1 dispatcher => driver - a TCP client disconnected
• RECEIVED == 2 dispatcher => driver - data was received from a UDP or TCP client
• WRITE == 3 driver => dispatcher - request some data be written to a UDP or TCP client
• CLOSE == 4 driver => dispatcher - request a TCP client be disconnected

The message structure sent down the websocket looks like:

uint8 message_type (OPENED, CLOSED etc)
string ip_address (remote IP, with null character termination)
uint64 id_or_port (client id for TCP, remote port for UDP)
uint32 data_size (number of bytes of data included)
bytes data (any data associated with the message, RECEIVED and WRITE messages only)

Statistics

Statistics are available via a GET request

• GET /api/server?bearer_token=testing

{
  # Engine drivers requesting a UDP server be open
  "udp_listeners": {"162": 8},

  # Engine drivers requesting a TCP server be open
  "tcp_listeners": {"6001": 1},

  # Remote clients connected to the live servers
  "tcp_clients": {"6001": 1}
}

Deployment

When deployed in the cloud, one can configure K8s load balancer to forward data coming in on required ports to Dispatch.

Contributing

See CONTRIBUTING.md.