Framing

TCP is a byte stream, not a message stream. Without explicit framing the boundary between two messages is essentially random: a single logical frame may be split across multiple kernel reads, or several frames may arrive in one read. The TCP Receive (tcp-in) and TCP Request (tcp-request) nodes solve this by applying one of four framing strategies to the raw byte stream.

The same framing options also exist as terminator strategies on tcp-request's response side.

Modes

Mode	Use when
stream	Downstream is byte-oriented (e.g. assembling frames yourself in a Function node).
delimiter	Line protocols — JSON-lines, telnet, GPS NMEA, AT commands.
length-prefix	Most binary protocols — Modbus-TCP, Postgres wire, custom industrial.
fixed-length	Block protocols where every record is exactly N bytes.

stream

Pass-through. Every kernel read produces one message. The split between messages is whatever the kernel decided to deliver — useful only when the downstream flow does its own framing.

delimiter

Split on a configurable byte sequence. The delimiter is stripped from the emitted frames.

The delimiter accepts JS-style escape syntax:

Escape	Bytes	Note
\n	0x0A	LF
\r\n	0x0D 0x0A	CRLF
\0	0x00	NUL
\xFF	0xFF	Arbitrary byte
\t	0x09	Tab
\\	0x5C	Literal backslash

Partial frames straddling read boundaries are buffered. A frame that exceeds maxFrameBytes causes a catchable error and tears down the connection, so a runaway peer can't exhaust memory.

length-prefix

Read a fixed-size header that announces the payload size, then read exactly that many payload bytes. Header is stripped.

Field	Meaning
bytes	Header size: 1, 2, 4, or 8.
endianness	big (default, network) or little.
includesHeader	Does the announced length include the header itself?

Example — 4-byte big-endian header announcing payload size only (includesHeader=false):

00 00 00 05 'h' 'e' 'l' 'l' 'o'
└── header ──┘ └─ payload (5 bytes) ─┘

→ one frame, payload = hello.

fixed-length

Every frame is exactly fixedLength bytes. No framing metadata on the wire; the agreement is purely out-of-band.

Common pitfalls

• Delimiter inside the payload. The framer does not understand escaping. A protocol that allows newlines inside a record needs length-prefix instead of delimiter.
• Length prefix too small. A 1-byte header caps frames at 255 bytes. Match the header size to the largest frame the protocol can legitimately produce.
• Mismatched endianness. Most modern protocols are big-endian ("network byte order"), but legacy industrial protocols are often little-endian.
• maxFrameBytes. Default 1 MiB. Raise it for protocols that legitimately exceed that — but only after confirming the peer is trusted, since the cap is a memory-exhaustion guardrail.