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UDP server

UDP is connectionless: a single listening socket fields datagrams from every peer. initphp/socket makes the abstraction look more connection-shaped without lying about it.

What "connection" means for UDP here

Each unique peerHost:peerPort seen on the wire gets its own UdpChannel and ServerConnection. The server demultiplexes inbound datagrams into the right channel via the channel's internal buffer (feed()), so your callback can call $conn->read() and get only the datagrams that came from that peer.

broadcast() sends to every tracked peer. There is no peer discovery — a peer exists only after it has spoken to the server.

Quick reference

use InitPHP\Socket\Socket;
use InitPHP\Socket\Enum\Transport;

$server = Socket::server(Transport::UDP, '0.0.0.0', 9000);
$server->listen();

$server->live(function ($srv, $conn) {
    $payload = $conn->read(65535);
    if ($payload !== null) {
        $conn->write("pong: {$payload}");
    }
});

Datagram sizing

The internal read size is UdpChannel::MAX_DATAGRAM = 65535. The practical upper bound for a UDP payload over IPv4 is 65 507 bytes; keep messages comfortably under MTU (≈1472 bytes on Ethernet) if you care about avoiding fragmentation.

No backlog, no listen() call

UDP doesn't have a listen queue, so backlog() does not exist. The listen() method only performs socket_create + socket_bind for this transport.

Caveats

  • No reliability, no ordering. That's UDP. If your protocol needs retransmits, build them on top.
  • Peer eviction is your job. The server never removes a UDP connection on its own — you decide when a silent peer has gone away (heartbeat, TTL, etc.) and call $conn->close().
  • No isAlive() truth. UdpChannel::isAlive() simply tracks whether you have closed it; the protocol cannot tell you the peer is gone.