TCP / MLLP Destination

The TCP destination forwards processed messages over raw TCP or MLLP (Minimal Lower Layer Protocol) connections. This is the standard transport for sending HL7 v2 messages to clinical systems, laboratory information systems, and interface engines.

Configuration

Add a TCP destination to a channel in intu.yaml:

destinations:
  - name: lab-system
    type: tcp
    properties:
      host: "lis.hospital.local"
      port: 6661
      mode: mllp

Properties

Property	Type	Default	Description
host	string	(required)	Hostname or IP address of the remote system.
port	integer	(required)	TCP port number.
mode	string	raw	Transport mode: raw for plain TCP, mllp for MLLP-framed connections.
timeout_ms	integer	30000	Connection and read/write timeout in milliseconds.
keep_alive	boolean	false	Keep the TCP connection open between messages instead of reconnecting each time.

Note

When mode is set to mllp, intu automatically wraps outbound messages with the standard MLLP framing characters (VT 0x0B header, FS 0x1C + CR 0x0D trailer). Do not add MLLP framing in your transformer — it will be doubled.

Tip

Enable keep_alive for high-throughput channels. Persistent connections eliminate the overhead of repeated TCP handshakes and significantly improve latency under load.

TLS

Encrypt the TCP connection with TLS:

tls:
  enabled: true
  ca_cert: "/etc/intu/certs/ca.pem"
  client_cert: "/etc/intu/certs/client.pem"
  client_key: "/etc/intu/certs/client-key.pem"
  insecure_skip_verify: false

Complete Example

An MLLP destination sending HL7 messages to a laboratory system with TLS and persistent connections:

destinations:
  - name: lis-outbound
    type: tcp
    properties:
      host: "lis.hospital.local"
      port: 6661
      mode: mllp
      timeout_ms: 15000
      keep_alive: true
    tls:
      enabled: true
      ca_cert: "/etc/intu/certs/hospital-ca.pem"