Protocols and message boundaries

TCP delivers a byte stream: one send does not necessarily correspond to one read. A codec identifies messages before onMessage runs.

SVG ↗

ProtocolInterface

public static function input(string $buffer, ConnectionInterface $connection): int;
public static function decode(string $buffer, ConnectionInterface $connection): mixed;
public static function encode(mixed $data, ConnectionInterface $connection): string;

input() returns 0 until it can determine a packet boundary, or the expected packet length. Transport accumulates bytes and decodes complete packets. Bound lengths before allocating large buffers; reject invalid framing instead of waiting forever.

Codec	Message boundary
Text	Newline; trailing CR/LF is removed
Frame	Network-order uint32 payload length followed by payload
Http	HTTP headers, Content-Length/chunked and HTTP semantics
Websocket	Handshake and WebSocket frames

Frame rejects declared payloads above 64 MiB; the connection’s maxPackageSize also applies. UDP preserves datagram boundaries without TCP ordering/delivery guarantees.

Custom codecs

Implement the interface and assign the class to $server->protocol. Encode an unambiguous packet and treat incomplete headers as incomplete input. Test fragmented messages and multiple messages in one buffer. Raw send bypasses encode; reserve it for already encoded wire data.