techCommunication Reference

Module defined in lua/common/tech/techCommunication.lua. TCP socket communication layer for BeamNG's tech/co-simulation interface. Handles client connections, MessagePack-encoded message exchange, and request routing.

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Exports

Functions

M.openServer(port, ip)

Open a TCP server on the given port and IP.

• Parameters:
  • port - number - TCP port to listen on
  • ip - string|nil - Bind IP address (default: all interfaces)
• Returns: table - Server object with socket handle

M.checkForClients(servers)

Accept pending client connections on server sockets.

• Parameters:
  • servers - table - Array of server objects
• Returns: table - Newly connected client sockets

M.receive(skt)

Receive a complete message from a socket (length-prefixed protocol).

• Parameters:
  • skt - socket - Connected TCP socket
• Returns: string, nil - Received data and error (nil on success)

M.checkMessages(E, clients)

Poll all client sockets for incoming messages, decode via MessagePack, and dispatch to request handlers.

• Parameters:
  • E - table - Extension/environment with request handlers
  • clients - table - Array of connected client sockets
• Returns: boolean - false if no messages processed

M.callRequestHandler(E, request)

Route a decoded request to the appropriate handler function on E.

• Parameters:
  • E - table - Extension table with handler functions
  • request - table - Decoded request with type field
• Returns: boolean - false if handler not found

M.sendMessage(skt, message)

Encode and send a MessagePack message with length prefix.

• Parameters:
  • skt - socket - Target socket
  • message - table - Message to encode and send

M.sendLegacyError(skt, error)

Send a legacy-format error message.

• Parameters:
  • skt - socket - Target socket
  • error - string - Error message

M.sanitizeTable(tab)

Recursively sanitize a table for MessagePack serialization (remove unsupported types).

• Parameters:
  • tab - table - Input table
• Returns: table - Sanitized copy

M.newSet()

Create a simple set data structure (from LuaSocket samples).

• Returns: table - Set with insert/remove via metamethods

M.enableDebug()

Enable debug logging for communication.

M.disableDebug()

Disable debug logging.

Variables

M.protocolVersion

• Type: string
• Description: Current protocol version string ('v1.26')

Internal Notes

• Wire protocol: 4-byte big-endian unsigned length prefix + MessagePack payload
• Uses LuaSocket for TCP networking
• Uses FFI for packUnsignedInt32Network / unpackUnsignedInt32Network
• Request handlers are methods on the extension table E matching request type names
• Supports recording mode integration via checkIfRecording