TCP

Raw TCP server and client with pluggable codecs. Use it for low-level communication, custom binary protocols, or interop with NestJS TCP microservices.

Server Configuration

connector "tcp_server" {
  type     = "tcp"
  driver   = "server"
  host     = "0.0.0.0"
  port     = 9000
  protocol = "json"    # "json", "msgpack", "nestjs"
}

Client Configuration

connector "tcp_client" {
  type            = "tcp"
  driver          = "client"
  host            = "localhost"
  port            = 9000
  protocol        = "json"
  connect_timeout = "10s"
}

Options

Option	Type	Default	Description
driver	string	—	server or client
host	string	"0.0.0.0"	Bind address (server)
port	int	—	Listen port (server)
protocol	string	"json"	Wire format: json, msgpack, nestjs

msgpack is MessagePack as the specification defines it, so the peer can be anything that implements it. Before 2.19.0 it encoded JSON under that name: two Mycel services configured for it did understand each other — both were sending JSON — and nothing else could read a word of it. | timeout | duration | "10s" | Connection timeout (client) |

Operations

Server (source): Message pattern matching — incoming messages are routed by their pattern field.

Client (target): Send messages to the remote TCP server.

Example

flow "handle_tcp_message" {
  from {
    connector = "tcp_server"
    operation = "get_users"
  }
  to {
    connector = "db"
    target    = "users"
  }
}

flow "forward_to_tcp" {
  from {
    connector = "api"
    operation = "POST /send"
  }
  to {
    connector = "tcp_client"
    operation = "process"
  }
}

See the tcp example for a complete working setup.

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Full configuration reference: See TCP in the Configuration Reference.